ChemInform Abstract: Powerful Fluoroalkoxy Molybdenum(V) Reagent for Selective Oxidative Arene Coupling Reaction.

A novel dinuclear fluoroalkoxy Mo(V)-complex is efficient as reagent for the oxidative arene coupling of electron-rich arenes with superior reactivity compared to MoCl5 and MoCl5/TiCl4.

Structure and Electronic Properties of an Expanded Terpyridine Complex of Nickel(II) [Ni(ddpd)2](BF4)2

Cover Picture: Photo-Chromium: Sensitizer for Visible-Light-Induced Oxidative C−H Bond Functionalization-Electron or Energy Transfer? (ChemPhotoChem 8/2017)

On the mechanism of imine elimination from Fischer tungsten carbene complexes

(Aminoferrocenyl)(ferrocenyl)carbene(pentacarbonyl)tungsten(0) (CO)5W=C(NHFc)Fc (W(CO)5(E-2)) is synthesized by nucleophilic substitution of the ethoxy group of (CO)5W=C(OEt)Fc (M(CO)5(1Et)) by ferrocenyl amide Fc-NH– (Fc = ferrocenyl). W(CO)5(E-2) thermally and photochemically eliminates bulky E-1,2-diferrocenylimine (E-3) via a formal 1,2-H shift from the N to the carbene C atom. Kinetic and mechanistic studies to the formation of imine E-3 are performed by NMR, IR and UV–vis spectroscopy and liquid injection field desorption ionization (LIFDI) mass spectrometry as well as by trapping experiments for low-coordinate tungsten complexes with triphenylphosphane. W(CO)5(E-2) decays thermally i…

Preparation and Thermochromic Switching between Phosphorescence and Thermally Activated Delayed Fluorescence of Mononuclear Copper(I) Complexes

Instructive, inexpensive, and environmentally friendly laboratory syntheses of two highly luminescent copper(I) complexes CuI(PPh3)2(pyR) (pyR = pyridine, 4-cyanopyridine) are described for second-year/upper-division undergraduate inorganic chemistry students. Both complexes exhibit bright thermally activated delayed fluorescence (TADF) at ambient temperature and phosphorescence at low temperature. The laboratory experiments familiarize the students with mechanochemical syntheses, cluster and complex formation, ligand substituent effects, and the fascinating phenomenon of luminescence thermochromism.

Ferrocene compounds: methyl 1′-aminoferrocene-1-carboxylate

The title compund, [Fe(C(5)H(6)N)(C(7)H(7)O(2))], features one strong intermolecular hydrogen bond of the type N-H...O=C [N...O = 3.028 (2) A] between the amine group and the carbonyl group of a neighbouring molecule, and vice versa, to form a centrosymmetric dimer. Furthermore, the carbonyl group acts as a double H-atom acceptor in the formation of a second, weaker, hydrogen bond of the type C-H...O=C [C...O = 3.283 (2) A] with the methyl group of the ester group of a second neighbouring molecule at (x, -y - 1/2, z - 1/2). The methyl group also acts as a weak hydrogen-bond donor, symmetry-related to the latter described C-H...O=C interaction, to a third molecule at (x, -y - 1/2, z + 1/2) t…

Leistungsstarkes Fluoralkoxy-Molybdän(V)-Reagens für die selektive oxidative Arenkupplung

Wir stellen ein neues Fluoralkoxy-Molybdan(V)-Reagens 1, mit im Vergleich zu MoCl5 oder MoCl5/TiCl4 hoherer Reaktivitat und Selektivitat in der oxidativen Kupplung von Arenen vor. Haufige Nebenreaktionen wie Chlorierung und/oder Oligomerenbildung werden erheblich reduziert, sodass ein leistungsstarkes und nutzliches Reagens fur die oxidative Kupplung erhalten wird. Theoretische Untersuchungen der Wechselwirkung des Reagens mit 1,2-Dimethoxybenzol-artigen Substraten deuten auf einen Innenspharen-Elektronentransfer gefolgt von einem radikalkationischen Reaktionspfad fur den oxidativen Kupplungsprozess hin. ESR-spektroskopische und elektrochemische Untersuchungen, Rontgenkristallstrukturanalys…

The Quest for Mononuclear Gold(II) and Its Potential Role in Photocatalysis and Drug Action.

The chemistry of gold strongly focuses on the ubiquitous oxidation states +I and +III. The intermediate oxidation state +II is generally avoided in mononuclear gold species. In recent years, gold(II) has been increasingly suggested as a key intermediate in artificial photosynthesis systems, with gold(III) moieties acting as electron acceptors, as well as in gold-catalyzed photoredox catalysis and radical chemistry. This Minireview provides a concise summary of confirmed and characterized mononuclear open-shell gold(II) complexes. Recent findings on structural motifs and reactivity patterns will be discussed. Exciting developments in the fields of photosynthesis, photocatalysis, and potentia…

A Ferrocenyl Amino Substituted Stannylene as an Intramolecular Fe→Sn Lewis Adduct

Anticancer Effect of an Electronically Coupled Oligoferrocene

The mode of anticancer activity of simple ferrocenes often relies on their intracellular oxidation with the formation of cytotoxic ferrocenium species. The former compounds should be considered as ...

“Tail–Tail Dimerization” of Ferrocene Amino Acid Derivatives

Acid anhydrides of N-protected 1'-aminoferrocene-1-carboxylic acid (Fca) have been prepared and spectroscopically characterized (protection group Boc, Fmoc, Ac; 4a―4c). The structure of the Boc-derivative 4a has been determined by single-crystal X-ray crystallography. An intramolecular N― H···O hydrogen bond involving the carbamate units results in a ring structure containing the two ferrocene units, the anhydride moiety, and the hydrogen bond. In the crystal, the individual molecules are connected by intermolecular N-H···O hydrogen bonds of the carbamate unit. Experimental and theoretical studies suggest that the ring motif is also a dominant species in solution. Electronic communication a…

A Strongly Luminescent Chromium(III) Complex Acid

The synthesis, structure, reactivity, and photophysical properties of a novel acidic, luminescent chromium(III) complex [Cr(H2 tpda)2 ]3+ (23+ ) bearing the tridentate H2 tpda (2,6-bis(2-pyridylamino)pyridine) ligand are presented. Excitation of 23+ at 442 nm results in strong, long-lived NIR luminescence at 782 nm in water and in acetonitrile. X-ray diffraction analysis and IR spectroscopy reveal hydrogen-bonding interactions of the counter ions to the NH groups of 23+ in the solid state. Deprotonation of the NH groups of 23+ by using a non-nucleophilic Schwesinger base in CH3 CN switches off the luminescence. Re-protonation by using HClO4 restores the emission. In water, the pKa value of …

Distinct photodynamics of κ-N and κ-C pseudoisomeric iron(ii) complexes

Two closely related FeII complexes with 2,6-bis(1-ethyl-1H-1,2,3-triazol-4yl)pyridine and 2,6-bis(1,2,3-triazol-5-ylidene)pyridine ligands are presented to gain new insights into the photophysics of bis(tridentate) iron(II) complexes. The [Fe(N^N^N)2]2+ pseudoisomer sensitizes singlet oxygen through a MC state with nanosecond lifetime after MLCT excitation, while the bis(tridentate) [Fe(C^N^C)2]2+ pseudoisomer possesses a similar 3MLCT lifetime as the tris(bidentate) [Fe(C^C)2(N^N)]2+ complexes with four mesoionic carbenes. Financial support from the Deutsche Forschungsge-meinschaft [DFG, Priority Program SPP 2102] "Light-controlled reactivity of metal complexes" (BA 4467/7-1, LO 714/11-1, …

Proton and Electron Transfer to a Polymer‐Supported Nitrido Molybdenum(VI) Complex

Invited for the cover of this issue is the group of Katja Heinze at Johannes Gutenberg University of Mainz, Germany. The cover image shows the reactive imido molybdenum(V) intermediate that has been obtained by protonation followed by reduction of the nitrido molybdenum(VI) precursor anchored to a polymeric environment.

Redox-responsive organometallic foldamers from ferrocene amino acid: Solid-phase synthesis, secondary structure and mixed-valence properties

Oligoferrocenes Fmoc-Fca(n)-OMe (n=3-5) are assembled in a stepwise precise manner from Fmoc-protected ferrocene amino acid Fmoc-Fca-OH (H-Fca-OH = 1-amino-1'-ferrocene carboxylic acid; Fmoc = 9-fluorenylmethyloxycarbonyl) via amide bonds on solid supports by sequential Fmoc deprotection, acid activation and coupling steps. The resulting well-defined oligomers form ordered zigzag structures in THF solution with characteristic hydrogen bonding patterns. Electrochemical experiments reveal sequential oxidations of the individual ferrocene units in these peptides giving mixed-valent cations. Optical intervalence electron transfer is detected by intervalence transitions in the near-IR.

Proton and Electron Transfer to a Polymer‐Supported Nitrido Molybdenum(VI) Complex (Eur. J. Inorg. Chem. 36/2013)

Redox‐Controlled Stabilization of an Open‐Shell Intermediate in a Bioinspired Enzyme Model

Die Suche nach einkernigem Gold(II) und seine mögliche Rolle in Photokatalyse und Medizinalchemie

Transient FTIR spectroscopy after one- and two-colour excitation on a highly luminescent chromium(III) complex.

The development of photoactive transition metal complexes with Earth-abundant metals is a rapidly growing research field, where a deeper understanding of the underlying photophysical processes is of great importance. A multitude of potential applications in the fields of photosensitizing, optical sensing, photoluminescence and photoredox catalysis motivates demanding spectroscopic studies. We applied a series of high-level spectroscopic methods on the previously reported highly luminescent chromium(iii) complex [Cr(ddpd)2](BF4)3 (ddpd = N,N'-dimethyl-N,N'-dipyridine-2-ylpyridine-2,6-diamine) possessing two near-IR emissive doublet states with microsecond lifetimes. Luminescence measurements…

Impact of O → S Exchange in Ferrocenyl Amides on the Structure and Redox Chemistry

The conformations and redox chemistry of ferrocenyl amides have been investigated in considerable depth in the last few years, while ferrocenyl thioamides have attracted less interest so far, although distinctly different conformations and reactivity patterns are expected. Monoferrocenyl amides Fc-NHC(O)CH3 (1) and 1,1′-CH3O(O)C-Fn-NHC(O)CH3 (2) and diferrocenyl amides Fc-NHC(O)-Fc (5) and Fc-NHC(O)-Fn-NHC(O)CH3 (6) are easily transformed into the corresponding thioamides (3, 4, 7, 8) by treatment with Lawesson’s reagent (2,4-bis(p-methoxyphenyl)-1,3-dithiaphosphetane-2,4-disulfide) (Fc = Fe(C5H4)(C5H5), Fn = Fe(C5H4)2). The thioamide conformations (cis/trans) in 3, 4, 7, and 8 and the hydr…

Photochemistry and Redox Chemistry of an Unsymmetrical Bimetallic Copper(I) Complex

The bimetallic copper(I) complex Cu2L2 (cis-1) is formed with high diasteroselectivity from [Cu(NCCH3)4][BF4] and HL (4-tert-butyl phenyl(pyrrolato-2-yl-methylene)amine) in a kinetically controlled reaction. cis-1 features a rather short Cu···Cu distance of 2.4756(6) A and is weakly emissive at room temperature in solution. Oxidatively triggered disproportionation of cis-1 yields elemental copper and the mononuclear copper(II) complex CuL2 (trans-2). One-electron reduction of trans-2 gives cuprate [2]– with a bent bis(pyrrolato) coordinated copper(I) entity. The imine donor atoms of [2]– can insert an additional copper(I) ion giving exclusively the bimetallic complex cis-1 closing the oxida…

Radical cation and dication of a 4H-dithieno[2,3-b:3′,2′-e][1,4]-thiazine

A p-tert-butylphenyl substituted 4H-dithieno[2,3-b:3′,2′-e][1,4]thiazine was synthesized by twofold Buchwald–Hartwig coupling. The electronic properties (UV/Vis, cyclic voltammetry and spectroelectrochemistry) and the DFT- and TD DFT-calculated electronic structure reveal that the parent system and the radical cation and dication oxidation products are highly polarizable π-systems with strong charge transfer contributions. The radical cation and the dication were prepared by oxidation with antimony(V) pentachloride, giving stable deeply colored salts. EPR spectroscopy of the radical cation furnishes hyperfine coupling constants with the nitrogen nucleus and the α-thienyl protons. The dicati…

Biferrocene Amino Acid, a Ferrocenylogoue of Ferrocene Amino Acid: Synthesis, Cross-Linking, and Redox Chemistry

Access of the novel biferrocene amino acid 7 is provided by two different routes, namely, via desymmetrization of a biferrocene and via palladium-catalyzed cross-coupling of two substituted ferrocenes. The dissymmetric biferrocene 7 is head−head coupled to ureylene-bridged bis(biferrocene) 9 and also head−tail coupled to amide-bridged bis(biferrocene) 14. The monomer 7 and the dimers 9 and 14 are oxidized to mixed-valent cations 7+, 9+, 92+, and 142+. The valencies are trapped in the solid state as shown by Mossbauer and EPR spectroscopy and by X-ray diffraction analysis of [7](I3). Paramagnetic NMR shift studies (7 → 7+) suggest that the hole is localized at the N-substituted ferrocene uni…

Porphyrin amino acids-amide coupling, redox and photophysical properties of bis(porphyrin) amides.

New trans-AB2C meso-substituted porphyrin amino acid esters with meso-substituents of tunable electron withdrawing power (B = mesityl, 4-C6H4F, 4-C6H4CF3, C6F5) were prepared as free amines 3a-3d, as N-acetylated derivatives Ac-3a-Ac-3d and corresponding zinc(II) complexes Zn-Ac-3a-Zn-Ac-3d. Several amide-linked bis(porphyrins) with a tunable electron density at each porphyrin site were obtained from the amino porphyrin precursors by condensation reactions (4a-4d) and mono- and bis(zinc(II)) complexes Zn(2)-4d and Zn(1)Zn(2)-4d were prepared. The electronic interaction between individual porphyrin units in bis(porphyrins) 4 is probed by electrochemical experiments (CV, EPR), electronic abso…

Deuterated Molecular Ruby with Record Luminescence Quantum Yield

The recently reported luminescent chromium(III) complex 13+ ([Cr(ddpd)2]3+; ddpd=N,N’-dimethyl-N,N’-dipyridine-2-yl-pyridine-2,6-diamine) shows exceptionally strong near-IR emission at 775 nm in water under ambient conditions (F=11%) with a microsecond lifetime as the ligand design in 13+ effectively eliminates non-radiative decay pathways, such as photosubstitution, back-intersystem crossing, and trigonal twists. In the absence of energy acceptors, such as dioxygen, the remaining decay pathways are energy transfer to high energy solvent and ligand oscillators, namely OH and CH stretching vibrations. Selective deuteration of the solvents and the ddpd ligands probes the efficiency of these o…

Gold(II) Porphyrins in Photoinduced Electron Transfer Reactions

Chemistry - a European journal 25(23), 5940 - 5949 (2019). doi:10.1002/chem.201900050

Überoxidation als Schlüsselschritt im Mechanismus der MoCl5 - vermittelten dehydrierenden Arenkupplung

Dual emission and excited-state mixed-valence in a quasi-symmetric dinuclear Ru-Ru complex.

The synthesis and characterization of the new dinuclear dipeptide [(EtOOC-tpy)Ru(tpy-NHCO-tpy)Ru(tpy-NHCOCH3)](4+) 3(4+) of the bis(terpyridine)ruthenium amino acid [(HOOC-tpy)Ru(tpy-NH2)](2+) 1(2+) are described, and the properties of the dipeptide are compared to those of the mononuclear complex [(EtOOC-tpy)Ru(tpy-NHCOCH3)](2+) 4(2+) carrying the same functional groups. 3(4+) is designed to serve a high electronic similarity of the two ruthenium sites despite the intrinsic asymmetry arising from the amide bridge. This is confirmed via UV-vis absorption and NMR spectroscopy as well as cyclic voltammetry. 4(2+) and 3(4+) are emissive at room temperature, as expected. Moreover, 3(4+) exhibit…

Conductive Directly Fused Poly(Porphyrin) Coatings by Oxidative Chemical Vapour Deposition - From Single- to Triple-Fused

Competitive NH···Ru/Fe Hydrogen Bonding in Ferrocenyl Ruthenocenyl Tosyl Hydrazone

A strong nonclassical NH···Fe intramolecular hydrogen bond (IHB) is present in the literature-known diferrocenyl tosyl hydrazone (1). Here, we confirm by NMR and IR spectroscopy as well as by XRD methods that an analogous NH···Ru IHB is present in the heavier homologue diruthenocenyl tosyl hydrazone (2). The NH···Ru IHB in 2 is stronger than the NH···Fe IHB in 1 by 6 kJ mol–1, as determined by IR spectroscopy. Further, we probed the E/Z isomer directing abilities of NH···M IHBs in the synthesis of the mixed metallocenyl compound ferrocenyl ruthenocenyl tosyl hydrazone (3). 3 is obtained as a mixture of the Z and E isomers (3a,b) with NH···Ru and NH···Fe IHBs, respectively. At 111 °C, 3a is …

Crystalline Non‐Equilibrium Phase of a Cobalt(II) Complex with Tridentate Ligands

In six-coordinate complexes, flexible tridentate ligands enable mer, cis-fac, and trans-fac stereoisomers. With labile metal ions of the first transition metal series, typically only the final thermodynamic product is available because of the rapid isomerization processes. Here we report on the structural characterization of a so far elusive kinetic intermediate of [Co(ddpd)2](BF4)2 (1; ddpd = N,N′-dimethyl-N,N′-dipyridine-2-yl-pyridine-2,6-diamine). Microcrystals of the cis-fac isomer of 1 were obtained by rapid precipitation. The solid-state structure of cis-fac-1 was determined from electron diffraction data.

Over-Oxidation as the Key Step in the Mechanism of the MoCl5-Mediated Dehydrogenative Coupling of Arenes.

Molybdenum pentachloride is an unusually powerful reagent for the dehydrogenative coupling of arenes. Owing to the high reaction rate using MoCl5, several labile moieties are tolerated in this transformation. The mechanistic course of the reaction was controversially discussed although indications for a single electron transfer as the initial step were found recently. Herein, based on a combined study including synthetic investigations, electrochemical measurements, EPR spectroscopy, DFT calculations, and mass spectrometry, we deduct a highly consistent mechanistic scenario: MoCl5 acts as a one-electron oxidant in the absence of TiCl4 and as two-electron oxidant in the presence of TiCl4, bu…

Conformational Switching of Multi-Responsive Ferrocenyl-Phenol Conjugates

Multifunctional conformational switches based on the ferrocenyl-salicylic acid amide motif with increasing additional complexity at the Fc moiety (R = COOMe, CONHEt, CONHFc; H-2–H-4; Fc = ferrocenyl) have been prepared and their preferred secondary structures in solution have been elucidated by NMR and IR spectroscopy in combination with conformational searches based on DFT calculations. Their distinct conformational responses to deprotonation ([2]––[4]–) and oxidation ([H-2]+·–[H-4]+·) have been revealed by IR, EPR, and UV/Vis spectroscopy as well as by DFT calculations. Deprotonation inverts all amide units (double amide twist) whereas oxidation selectively flips the terminal amide unit (…

A Heteroleptic Push-Pull Substituted Iron(II) Bis(tridentate) Complex with Low-Energy Charge-Transfer States

A heteroleptic iron(II) complex [Fe(dcpp)(ddpd)](2+) with a strongly electron-withdrawing ligand (dcpp, 2,6-bis(2-carboxypyridyl)pyridine) and a strongly electron-donating tridentate tripyridine ligand (ddpd, N,N'-dimethyl-N,N'-dipyridine-2-yl-pyridine-2,6-diamine) is reported. Both ligands form six-membered chelate rings with the iron center, inducing a strong ligand field. This results in a high-energy, high-spin state ((5) T2 , (t2g )(4) (eg *)(2) ) and a low-spin ground state ((1) A1 , (t2g )(6) (eg *)(0) ). The intermediate triplet spin state ((3) T1 , (t2g )(5) (eg *)(1) ) is suggested to be between these states on the basis of the rapid dynamics after photoexcitation. The low-energy …

Solution Conformation and Self‐Assembly of Ferrocenyl(thio)ureas

Conformations and (dis)assembly processes of ureas and thioureas are of fundamental importance in supramolecular chemistry, anion binding, or crystal engineering, both in solution and in the solid state. For sensing and switching processes a redox-active unit, such as the ferrocene/ferrocenium couple, is especially suitable. Here, self-assembly processes of redox-active ferrocenyl(thio)ureas FcNHC(X)NHR [X = O, R = Fc (1), Ph (2), 1-naphthyl (3), Me (4), Et (5); X = S, R = Fc (6), 1-anthracenyl (7)] through hydrogen bonds – both in the solid state and in THF and CH2Cl2 solution – are reported. Special emphasis is placed on the impact of nonclassical intramolecular NH···Fe hydrogen bonds in …

Excited state decay of cyclometalated polypyridine ruthenium complexes: insight from theory and experiment.

Deactivation pathways of the triplet metal-to-ligand charge transfer ((3)MLCT) excited state of cyclometalated polypyridine ruthenium complexes with [RuN5C](+) coordination are discussed on the basis of the available experimental data and a series of density functional theory calculations. Three different complex classes are considered, namely with [Ru(N^N)2(N^C)](+), [Ru(N^N^N)(N^C^N)](+) and [Ru(N^N^N)(N^N^C)](+) coordination modes. Excited state deactivation in these complex types proceeds via five distinct decay channels. Vibronic coupling of the (3)MLCT state to high-energy oscillators of the singlet ground state ((1)GS) allows tunneling to the ground state followed by vibrational rela…

Light-induced charge separation in a donor–chromophore–acceptor nanocomposite poly[TPA-Ru(tpy)2]@ZnO

The synthesis and characterisation of a new donor–chromophore–acceptor system based on poly(vinyltriphenylamine) as the electron donor and a glycine-functionalised bis(2,2′;6′,2′′-terpyridine)ruthenium(II) complex acting both as a chromophore and as an anchor group attached to ZnO nanorods as the electron acceptor are described. The TPA-containing block copolymer was synthesised by Reversible Addition Fragmentation Chain Transfer (RAFT) polymerisation and the ruthenium complex glycine conjugates prepared by Solid Phase Peptide Synthesis (SPPS) were attached via post-polymerisation esterification. GPC, NMR, IR and UV-Visible spectroscopy were used to characterise the multifunctional chromoph…

Cover Feature: A Strongly Luminescent Chromium(III) Complex Acid (Chem. Eur. J. 48/2018)

Bis- and Trisamides Derived From 1′-Aminoferrocene-1-carboxylic Acid and α-Amino Acids: Synthesis and Conformational Analysis

Ferrocene derivatives with one or two achiral and chiral arms based on α-amino acids (Gly, l-Ala, l-Val) attached to the cyclopentadienyl rings were prepared by solution-phase peptide synthesis from N-acetyl- and N-Boc-protected 1′-aminoferrocene-1-carboxylic acids (Boc = tert-butoxycarbonyl). The conformational preference in the solid state of selected examples was elucidated by X-ray crystallography. The chiroptical properties of chiral bis- and trisamides were investigated by circular dichroism (CD) spectroscopy in solution. The conformational preference was studied by NMR and IR spectroscopy, as well as by molecular modeling (DFT). For the bisamides, a conformational library is observed…

Higher MLCT lifetime of carbene iron(ii) complexes by chelate ring expansion

Combining strong σ-donating N-heterocyclic carbene ligands and π-accepting pyridine ligands with a high octahedricity in rigid iron(ii) complexes increases the 3MLCT lifetime from 0.15 ps in the prototypical [Fe(tpy)2]2+ complex to 9.2 ps in [Fe(dpmi)2]2+12+. The tripodal CNN ligand dpmi (di(pyridine-2-yl)(3-methylimidazol-2-yl)methane) forms six-membered chelate rings with the iron(ii) centre leading to close to 90° bite angles and enhanced iron-ligand orbital overlap.

[Cr(ddpd)2]3+: ein molekulares, wasserlösliches, hoch NIR-lumineszentes Rubin-Analogon

Titelbild: Luminescence and Light‐Driven Energy and Electron Transfer from an Exceptionally Long‐Lived Excited State of a Non‐Innocent Chromium(III) Complex (Angew. Chem. 50/2019)

Atmospheric pressure plasma polymerisation of metalloporphyrins containing mesoporous membranes for gas sensing applications

Abstract Metalloporphyrins are embedded in an organosilicon matrix by an easily up-scalable atmospheric pressure dielectric barrier discharge method. The integrity of the metalloporphyrins, followed by UV–visible spectroscopy, is successfully preserved and their aggregation prevented. The single molecule properties, rather than the bulk ones, are thus enhanced. Exposure to triethylamine, which reaches the metalloporphyrins through the pores of the organosilicon membrane, led to a shift in the absorption spectrum and confirms the gas sensing potential of such coatings.

A Bis(tridentate)cobalt Polypyridine Complex as Mediator in Dye‐Sensitized Solar Cells

Dye-sensitized solar cells equipped with cationic and neutral RuII-based sensitizers [Ru(ddpd){tpy(COOH)3}]2+ [12+; ddpd = N,N′-dimethyl-N,N′-di(pyridin-2-yl)pyridin-2,6-diamine, tpy(COOH)3 = 2,2″6′,2″-terpyridine-4,4′,4″-tricarboxylic acid] and [Ru(ddpd){tpy(COOH)(COO)2}] (2) with and without the coadsorbent chenodeoxycholic acid were constructed with I3–/I– or the CoIII/II-based redox mediators [Co(bpy)3]3+/2+ (33+/2+; bpy = 2,2′-bipyridine) and [Co(ddpd)2]3+/2+ (43+/2+) in the presence of LiClO4 and 4-tert-butylpyridine. The best photovoltaic performance was achieved by using the 43+/2+ shuttle and the neutral sensitizer 2 without coadsorbent. The higher short-circuit photocurrent densit…

Molecular Ruby under Pressure

The intensely luminescent chromium(III) complexes [Cr(ddpd)2 ]3+ and [Cr(H2 tpda)2 ]3+ show surprising pressure-induced red shifts of up to -15 cm-1  kbar-1 for their sharp spin-flip emission bands (ddpd=N,N'-dimethyl-N,N'-dipyridine-2-yl-pyridine-2,6-diamine; H2 tpda=2,6-bis(2-pyridylamino)pyridine). These shifts surpass that of the established standard, ruby Al2 O3 :Cr3+ , by a factor of 20. Beyond the common application in the crystalline state, the very high quantum yield of [Cr(ddpd)2 ]3+ enables optical pressure sensing in aqueous and methanolic solution. These unique features of the molecular rubies [Cr(ddpd)2 ]3+ and [Cr(H2 tpda)2 ]3+ pave the way for highly sensitive optical pressu…

Gold(ii) in redox-switchable gold(i) catalysis

Chemical communications 55(32), 4615 - 4618 (2019). doi:10.1039/C9CC00283A

Deuterierter molekularer Rubin mit Rekord-Lumineszenzquantenausbeute

Der kurzlich publizierte Chrom(III)-Komplex 13+([Cr(ddpd)2]3+) zeigt in wassriger Losung unter Umgebungsbedingungen eine bemerkenswert starke Emission im nahen Infrarot-Bereich mit einer Emissionswellenlange von 775 nm. Geschicktes Ligandendesign verhindert strahlungslose Desaktivierungsprozesse wie Photosubstitution, Ruck-Intersystem-Crossing und trigonale Verzerrungen und fuhrt damit zu einer Phosphoreszenzlebensdauer im Bereich von Mikrosekunden. In Abwesenheit von Energieakzeptoren wie molekularem Sauerstoff verbleibt nur Energietransfer zu hochenergetischen Oszillatoren der Liganden und Losungsmittelmolekule wie beispielsweise OH- und CH-Streckschwingungen als Desaktivierungspfad. Sele…

Cobaltocenium substituents as electron acceptors in photosynthetic model dyads

Abstract Cobaltocenium carboxylic acid hexafluorophosphate has been attached to a zinc(II) meso-tetraphenyl porphyrin chromophore via an amide linkage. Optical and electrochemical studies reveal that the metallocene and the porphyrin interact only negligibly in the ground state of the dyad. Photoinduced charge-shift from the zinc porphyrin to the cobaltocenium substituent to give the zinc porphyrin radical cation and the cobaltocene occurs upon exciting the porphyrin with light. Steady state emission, time-resolved fluorescence and transient absorption pump–probe spectroscopy in addition to density functional theory calculations suggest that the charge shift to the cobaltocenium substituent…

Effect of chelate ring expansion on Jahn-Teller distortion and Jahn-Teller dynamics in copper(II) complexes.

The expanded ligand N,N'-dimethyl-N,N'-dipyridin-2-yl-pyridin-2,6-diamine (ddpd) coordinates to copper(II) ions in a meridional fashion giving the dicationic complex mer-[Cu(ddpd)(2)](BF(4))(2) (1). In the solid state at temperatures below 100 K the cations of 1 localize in Jahn-Teller elongated CuN(6) polyhedra with the longest Cu-N bond pointing in the molecular x or y directions while the z axis is constrained by the tridentate ddpd ligand. The elongated polyhedra are ordered in an antiferrodistortive way giving an idealized zincblende structure. At higher temperature dynamically averaged (fluxional) polyhedra in the molecular x/y directions are observed by multifrequency variable temper…

Generation and Oligomerization of N-Ferrocenyl Ketenimines via Open-Shell Intermediates

In the presence of oxidant (Ag[SbF6]) and base, N-ferrocenyl thioamide Fc-NHC(S)CH3 (H-1; Fc = Fe(η5-C5H5)(η5-C5H4)) converts in an unexpected multistep reaction sequence to a novel N,S-heterocyclic ring, which initiates an oligomerization reaction. Key intermediates toward the resulting complicated material are Ag6(1)6 silver clusters of the anionic N,S-chelating ligand 1− and EPR-active piano stool complexes resulting from ring-slipped cyclopentadienyl ligands, as well as electrophilic N-ferrocenyl ketenimine Fc-N═C═CH2 (2) and its ferrocenium cation 2•+ formed by hydrosulfide elimination. Mechanistic insight is achieved using X-ray diffraction and mass spectrometry, as well as EPR and NM…

Consequences of the One-Electron Reduction and Photoexcitation of Unsymmetric Bis-imidazolium Salts

Coupling of uronium salts with in situ generated N-heterocyclic carbenes provides straightforward access to symmetrical [4](2+) and unsymmetrical bis-imidazolium salts [6](2+) and [9](2+) . As indicated by cyclic and square-wave voltammetry, [6](2+) and [9](2+) can be (irreversibly) reduced by one electron. The initially formed radicals [6](.+) and [9](.+) undergo further reactions, which were probed by EPR spectroscopy and density functional calculations. The final products of the two-electron reduction are the two carbenes. Upon irradiation with UV light both [6](2+) and [9](2+) emit at room temperature in solution but with dramatically different characteristics. The different fluorescenc…

Molekularer Rubin unter Druck

Green-Light Activation of Push-Pull Ruthenium(II) Complexes.

Abstract Synthesis, characterization, electrochemistry, and photophysics of homo‐ and heteroleptic ruthenium(II) complexes [Ru(cpmp)2]2+ (22+) and [Ru(cpmp)(ddpd)]2+ (32+) bearing the tridentate ligands 6,2’’‐carboxypyridyl‐2,2’‐methylamine‐pyridyl‐pyridine (cpmp) and N,N’‐dimethyl‐N,N’‐dipyridin‐2‐ylpyridine‐2,6‐diamine (ddpd) are reported. The complexes possess one (32+) or two (22+) electron‐deficient dipyridyl ketone fragments as electron‐accepting sites enabling intraligand charge transfer (ILCT), ligand‐to‐ligand charge transfer (LL'CT) and low‐energy metal‐to‐ligand charge transfer (MLCT) absorptions. The latter peak around 544 nm (green light). Complex 22+ shows 3MLCT phosphorescenc…

Constitution and conductivity of metalloporphyrin tapes

Gold(iii) tetraarylporphyrin amino acid derivatives: ligand or metal centred redox chemistry?

EPR spectroscopy and DFT calculations show that the site of reduction of porphyrinato gold(iii) complexes depends on the counterions X, the meso substituents R and the solvent.

Ground- and Excited-State Properties of Iron(II) Complexes Linked to Organic Chromophores

Two new bichromophoric complexes, [Fe(bim-ant)2]2+ and [Fe(bim-pyr)2]2+ ([H2-bim]2+ = 1,1′-(pyridine-2,6-diyl)bis(3-methyl-1H-imidazol-3-ium); ant = 9-anthracenyl; pyr = 1-pyrenyl), are investigate...

Aminoferrocene and Ferrocene Amino Acid as Electron Donors in Modular Porphyrin–Ferrocene and Porphyrin–Ferrocene–Porphyrin Conjugates

New amide-linked porphyrin–ferrocene conjugates [M(PAr)–Fc] were prepared from aminoferrocene and a carboxy-substituted meso-tetraaryl-porphyrin [M = 2H, Zn; Ar = mesityl (Mes), C6F5: 3a, 3e, Zn-3a, Zn-3e]. A further porphyrin building block was attached to the second cyclopentadienyl ring of the ferrocene moiety to give the metallopeptides M(PMes)–Fc–M(PAr) (M = 2H, Zn; Ar = C6H5, 4-C6H4F: 6b, 6c, Zn-6b, Zn-6c). The effects of the Ar substituents, the porphyrin central atom M and the presence of the second porphyrin at the ferrocene hinge on the excited-state dynamics was studied by optical absorption spectroscopy, electrochemistry, steady-state emission, time-resolved fluorescence measure…

Boosting Vis/NIR Charge-Transfer Absorptions of Iron(II) Complexes by N-Alkylation and N-Deprotonation in the Ligand Backbone.

Reversing the 3MLCT / 3MC excited state order in iron(II) complexes is a challenging objective, yet would finally result in longsought luminescent transition metal complexes with an earthabundant central ion. One approach to achieve this goal is based on low-energy charge transfer absorptions in combination with a strong ligand field. Coordinating electron rich and electron poor tridentate oligopyridine ligands with large bite angles at iron(II) enables both low-energy MLCT absorption bands around 590 nm and a strong ligand field. Variations of the electron rich ligand by introducing longer alkyl substituents destabilizes the iron(II) complex towards ligand substitution reactions while hard…

Synthesis and Characterization of Extended Bis(terpyridine)ruthenium Amino Acids

(Oligopyridine)ruthenium(II) complexes have been widely used in dye sensitized solar cells and other sophisticated optical devices due to their outstanding photophysical properties and their chemical stability. Herein, we describe the longitudinal extension of our previously reported bis(terpyridine)ruthenium(II) amino acid [Ru(tpy–NH2)(tpy–COOH)]2+ (tpy = 4′-substituted 2,2′:6′,2″-terpyridine) by insertion of para-phenylene spacers –C6H4– between the terpyridine and the functional groups. The influence of the para-phenylene spacer on the absorption and emission properties is investigated using UV/Vis absorption and emission spectroscopy and is discussed within a qualitative molecular orbit…

Formation and mixed-valent behaviour of a substituted tetraferrocenylstannane.

A tetrasubstituted tetraferrocenylstannane is formed from 1-bromoferrocene-1′-carboxylic acid methyl ester and copper bronze. The molecular structure is almost perfectly tetrahedral with Fe⋯Fe distances of around 6 A. In solution two sequential one-electron processes and one two-electron process are indicative of mixed-valent intermediates. Intermetallic interactions have been probed by preparative oxidation, paramagnetic NMR spectroscopy, Mosbauer spectroscopy, UV/Vis/NIR spectroscopy and DFT calculations.

Strongly Coupled Cyclometalated Ruthenium Triarylamine Chromophores as Sensitizers for DSSCs

A series of anchor-functionalized cyclometalated bis(tridentate) ruthenium(II) triarylamine hybrids [Ru(dbp-X)(tctpy)](2-) [2 a](2-) -[2 c](2-) (H3 tctpy=2,2';6',2''-terpyridine-4,4',4''-tricarboxylic acid; dpbH=1,3-dipyridylbenzene; X=N(4-C6 H4 OMe)2 ([2 a](2-) ), NPh2 ([2 b](2-) ), N-carbazolyl [2 c](2-) ) was synthesized and characterized. All complexes show broad absorption bands in the range 300-700 nm with a maximum at about 545 nm. Methyl esters [Ru(Me3 tctpy)(dpb-X)](+) [1 a](+) -[1 c](+) are oxidized to the strongly coupled mixed-valent species [1 a](2+) -[1 c](2+) and the Ru(III) (aminium) complexes [1 a](3+) -[1 c](3+) at comparably low oxidation potentials. Theoretical calculati…

ChemInform Abstract: Bioinspired Functional Analogs of the Active Site of Molybdenum Enzymes: Intermediates and Mechanisms

Abstract Molybdenum(VI) complexes of the general type MoVI(L)2(E)O (L = 2-(aryl N CH)-pyrrolylato, E = O, NtBu) and their relevance as bioinspired functional analogs for molybdenum-containing oxotransferases are reviewed. All complexes are capable of transfering oxygen atoms to PR3 (forward oxygen atom transfer) giving OPR3 and phosphane molybdenum(IV) complexes MoIV(L)2(E)(PR3) (with a second equivalent PR3) via the transient phosphoryl complex MoIV(L)2(E)(OPR3) and the five-coordinate intermediate MoIV(L)2(E). Reactivity of MoIV(L)2(E) and the favored stereochemistry of products from excess PR3 MoIV(L)2(E)(PR3) depend on the steric demand of the chelate ligands (L)−, the π donor ligand E …

ChemInform Abstract: Ferrocene-Beauty and Function

Photo-Chromium: Sensitizer for Visible-Light-Induced Oxidative C−H Bond Functionalization-Electron or Energy Transfer?

The chromium(III) sensitizer [Cr(ddpd)2]3+ - based on an earth-abundant metal center - possesses a unique excited state potential energy landscape (ddpd = N,N'-dimethyl-N,N'-dipyridine-2-ylpyridine-2,6-diamine). The very large energy gap between the redox active and substitutionally labile 4T2 state and the long-lived low-energy 2E spin-flip state enables a selective, efficient sensitization of triplet dioxygen to give singlet dioxygen. Ultrafast intersystem crossing after the Franck Condon point from the 4T2 to the 2E excited state within 3.5 ps precludes intermolecular electron transfer pathways from the ultrashort-lived excited 4T2 state. This specific excited state reactivity enables a …

Metal–organic covalent network chemical vapor deposition for gas separation

The chemical vapor deposition (CVD) polymerization of metalloporphyrin building units is demonstrated to provide an easily up-scalable one-step method toward the deposition of a new class of dense and defect-free metal–organic covalent network (MOCN) layers. The resulting hyper-thin and flexible MOCN layers exhibit outstanding gas-separation performances for multiple gas pairs.

Preparation, Properties, and Reactivity of (Aminoferrocenyl)(ferrocenyl)carbene(pentacarbonyl)chromium(0) as Bulky Isolobal Trimetallo-amide

Nucleophilic substitution of the ethoxy substituent in the Fischer carbene complex (ethoxy)(ferrocenyl)carbene(pentacarbonyl)chromium(0) (1) by ferrocenyl amide [Fc-NH]– [2-H]– gives the hetero trimetallic complex (aminoferrocenyl)(ferrocenyl)carbene (pentacarbonyl)chromium(0) (3). As the Cr(CO)5 fragment is isolobal to oxygen or sulfur 3 can be viewed as an isolobal metallo analogue to diferrocenylamide (Fc)(FcNH)C=O (4) and diferrocenylthioamide (Fc)(FcNH)C=S (5). The impact of the formal replacement of O/S by Cr(CO)5 in 3 is studied with respect to steric and electronic consequences as well as reactivity by spectroscopic, diffraction, electrochemical and theoretical methods.

Bioconjugates of 1’-Aminoferrocene-1-carboxylic Acid with (S)-3-Amino-2-methylpropanoic Acid and L-Alanine

Formal CH 2 insertion in bioconjugates composed of 1'-aminoferrocene-1-carboxylic acid (Fca) and alanine Boc-Ala-Fca-Ala-OCH 3 gives Fca bioconjugates with the β-amino acid (S)-3-amino-2-methylpropanoic acid (Aib). The novel homologous conjugates of ferrocene were fully characterized by spectroscopic and analytical methods. NMR, CD and IR spectroscopy in concert with DFT calculations suggest that the formal "L-Ala-to-(S)-β-Aib mutations" can exert ferrocene helix inversion due to the different stereogenic carbon atoms of L -Ala and (S)-β-Aib. Furthermore, the mutation (de-)stabilizes the conserved secondary structure with two intramolecular hydrogen bonds, depending on the "mutation site". …

Cover Feature: Excited‐State Kinetics of an Air‐Stable Cyclometalated Iron(II) Complex (Chem. Eur. J. 51/2019)

Stereochemical Consequences of Oxygen Atom Transfer and Electron Transfer in Imido/Oxido Molybdenum(IV, V, VI) Complexes with Two Unsymmetric Bidentate Ligands

Two equivalents of the unsymmetrical Schiff base ligand (L(tBu))(-) (4-tert-butyl phenyl(pyrrolato-2-ylmethylene)amine) and MoCl(2)(NtBu)O(dme) (dme = 1,2-dimethoxyethane) gave a single stereoisomer of a mixed imido/oxido Mo(VI) complex 2(tBu). The stereochemistry of 2(tBu) was elucidated using X-ray diffraction, NMR spectroscopy, and DFT calculations. The complex is active in an oxygen atom transfer (OAT) reaction to trimethyl phosphane. The putative intermediate five-coordinate Mo(IV) imido complex coordinates a PMe(3) ligand, giving the six-coordinate imido phosphane Mo(IV) complex 5(tBu). The stereochemistry of 5(tBu) is different from that of 2(tBu) as shown by NMR spectroscopy, DFT ca…

Spin Trapping of Carbon-Centered Ferrocenyl Radicals with Nitrosobenzene

In contrast to metal centered 17 valence electron radicals, such as [Mn(CO)5]•, ferrocenium ions [Fe(C5H5)2]+ (1+), [Fe(C5Me5)2]+ (2+), [Fe(C5H5)(C5H4Et)]+ (3+), [Fe(C5H5)(C5H4NHC(O)Me)]+ (4+), and [Fe(C5H5)(C5H4NHC(S)Me)]+ (5+) do not add to nitrosobenzene PhNO to give metal-coordinated stable nitroxyl radicals. In the presence of the strong and oxidatively stable phosphazene base tert-butylimino-tris(dimethylamino)phosphorane, the quite acidic ferrocenium ions 1+–5+ are deprotonated to give a pool of transient and persistent radicals with different deprotonation sites [1–Hx]•–[5–Hx]•. One rather persistent iron-centered radical [4–HN]•, deprotonated at the nitrogen atom, has been detected…

A Vanadium(III) Complex with Blue and NIR-II Spin-Flip Luminescence in Solution.

Luminescence from Earth-abundant metal ions in solution at room temperature is a very challenging objective due to the intrinsically weak ligand field splitting of first-row transition metal ions, which leads to efficient nonradiative deactivation via metal-centered states. Only a handful of 3d

Radical cations and dications of bis[1]benzothieno[1,4]thiazine isomers

Bis[1]benzothieno[1,4]thiazines (BBTT) are particularly electron-rich S,N-heteropentacenes and their radical cations and dications can be relevant intermediates in charge transport materials. All three regioisomers of N-p-fluorophenyl-BBTT (syn–syn, syn–anti, and anti–anti) were studied. A reliable preparation of radical cations and dications using antimony pentachloride as an oxidant gives deeply colored salts. The electronic structure of the radical cations was assessed by EPR spectroscopy, whereas dicationic structures were characterized by NMR spectroscopy. In addition, a deeper insight into the electronic structure was experimentally and computationally obtained by UV/Vis spectroscopy …

The Crystal Structure of the THF Adduct of Monolithioferrocene

Single crystals of [Fe(η5-C5H4)(η5-C5H5)]2Li2(thf)4 (1) were obtained from a tetrahydrofuran solution containing monolithioferrocene. The title compound crystallizes in the monoclinic space group P21 with a = 9.6589(5) A, b = 17.4285(9) A, c = 30.3116(15) A, β = 91.911(2)° and V = 5099.8(5) A3 with three independent molecules of 1. All individual molecules feature a non- symmetric almost planar Li2C2 four-membered ring with two shorter (2.118–2.215 A) and two longer Li–C distances (2.257–2.309 A). The lithium cations are each coordinated by two carbanionic atoms of two ferrocenyl substituents and two tetrahydrofuran molecules in a distorted tetrahedral fashion. All ferrocenyl moieties displ…

Ligand dynamics of tert-butyl isocyanide oxido complexes of molybdenum(IV).

The six-coordinate molybdenum(IV) oxido isocyanide complex 1 [Δ,Λ-OC-6-2-3-[MoO(N(p)∩N(i))2(CN(t)Bu)]; N(p)∩N(i) = 4-tert-butylphenyl(pyrrolato-2-ylmethylene)amine] is obtained in diastereomerically pure form in the solid state, as revealed by single-crystal X-ray diffraction. In solution, this stereoisomer equilibrates with the Δ,Λ-OC-6-2-4 diastereomer 2 at ambient temperature. The stereochemistry of both isomers has been elucidated by NMR, IR, and UV/vis spectroscopy in combination with density functional theory (DFT)/polarizable continuum model and time-dependent DFT calculations. The isomerization 1 → 2 is suggested to proceed via a dissociative trigonal twist with dissociation of the …

A new class of ZnIIand CrIIIporphyrins incorporated into porous polymer matrices via an atmospheric pressure plasma enhanced CVD to form gas sensing layers

Designed ZnII and CrIII porphyrins (ZnIIP, CrIIIP(Cl)(H2O)) and conventional ZnIITPP and CrIIITPP(Cl)(H2O) are immobilized into porous polysiloxane films via chemical vapor deposition enhanced by an atmospheric pressure dielectric barrier discharge. UV/vis spectroscopy and mass spectrometry prove the integrity of the chromophores after the plasma treatment. The optical amine sensing capabilities of the films are investigated spectroscopically on exposure to triethylamine vapors. A series of coatings with different porphyrin loadings indicate influences of the deposition conditions on the growth of the sensing films and hence the device performance. Additionally, the synthesis and characteri…

Molecular flattening effect to enhance the conductivity of fused porphyrin tape thin films.

The straightforward synthesis of directly fused porphyrins (porphyrin tapes) from 5,15-diphenyl porphyrinato nickel(II) complexes with different substituents on the phenyl rings is achieved while processing from the gas phase. The porphyrin tapes, exhibiting NIR absorption, are readily obtained in thin film form. The gas phase approach cuts the need for solubilizing groups allowing for the first time the study of their conductivity according to the substituent. 2-Point probe and conductivity AFM measurements evidence that reducing the size of the meso substituents, phenyl < mesityl < di(3,5-tert-butyl)phenyl < di(2,6-dodecyloxy)phenyl, improves the thin film conductivity by several orders o…

Intrinsic superoxide dismutase activity of MnO nanoparticles enhances the magnetic resonance imaging contrast

Superoxide radicals are associated with the development of many severe diseases, such as cancer. Under nonpathogenic conditions, the natural enzyme superoxide dismutase (SOD) regulates the intracellular superoxide concentrations, but nearly all tumor tissues show reduced SOD levels. Selective imaging in early progression stages remains a key requirement for efficient cancer diagnosis and treatment. Magnetic resonance imaging (MRI) as a noninvasive tool with high spatial resolution may offer advantages here, but MRI contrast agents exhibiting a redox-triggered change in the image contrast towards superoxide radicals have not been reported so far. Here we show that manganese oxide (MnO) nanop…

Structure and reactivity of a mononuclear gold(II) complex.

Mononuclear gold(II) complexes are very rare labile species. Transient gold(II) species have been suggested in homogeneous catalysis and in medical applications, but their geometric and electronic structures have remained essentially unexplored: even fundamental data, such as the ionic radius of gold(II), are unknown. Now, an unprecedentedly stable neutral gold(II) complex of a porphyrin derivative has been isolated, and its structural and spectroscopic features determined. The gold atom adopts a 2+2 coordination mode in between those of gold(III) (four-coordinate square planar) and gold(I) (two-coordinate linear), owing to a second-order Jahn–Teller distortion enabled by the relativistical…

The photochemistry of mono- and dinuclear cyclometalated bis(tridentate)ruthenium(ii) complexes: dual excited state deactivation and dual emission

The synthesis and characterization of a series of weakly emissive mononuclear cyclometalated [Ru(dpb-R)(tpy)](+) complexes with functional groups R of varying electron-donating characters at the dpb ligand are described (dpbH = 1,3-di(2-pyridyl)benzene, tpy = 2,2';6',2''-terpyridine, 1(+): R = NHCOMe, 2(+): R = NH2, 3(+): R = COOEt, 4(+): R = COOH). Steady-state emission spectroscopy in the temperature range between 298 K and 77 K revealed a previously unrecognized excited state deactivation pathway via low-lying triplet ligand-to-ligand ((3)LL'CT) charge transfer states in addition to the well-known pathway via(3)MC states. Thermal activation barriers for depopulation of the emissive metal…

Molecular Multi‐Wavelength Optical Anion Sensors

Polychromatic fingerprinting of simple anions (halides, oxo anions) is achieved by employing neutral and charged multicolor fluorescent probes based on ferrocene-spaced dansyl and naphthyl groups (1/1 + ; 2/2 + ). The conformation of the neutral double dye sensor 2 has been elucidated by NMR spectroscopic techniques (in solution), by X-ray crystallography (solid state) and by DFT calculations (gas phase). The double-dye receptors 2/2 + exhibit specific emission responses in the presence of anions X- when excited at the absorption maxima of the dyes (fingerprint).

Cover Feature: Alkali Blues: Blue‐Emissive Alkali Metal Pyrrolates (Chem. Eur. J. 26/2019)

Redox and Photochemistry of Bis(terpyridine)ruthenium(II) Amino Acids and Their Amide Conjugates – from Understanding to Applications

Invited for the cover of this issue is the group of Katja Heinze at the Johannes Gutenberg University of Mainz, Germany. The cover image shows the bis(terpyridine)ruthenium(II) amino acid [Ru(4′-tpy-COOH)(4′-tpy-NH2)]2+ (tpy = 2,2′;6′,2″-terpyridine), illustrating some of its multifaceted optical and redox chemical properties as well as highlighting its potential applications in light-to-energy conversion and energy-to-light conversion schemes.

Three‐in‐One Crystal: The Coordination Diversity of Zinc Polypyridine Complexes

The synthesis, structural and photophysical properties of two novel zinc(II) complexes bearing the tridentate ddpd (N,N' dimethyl N,N' dipyridin 2 ylpyridine 2,6 diamine) ligand are presented. Structural investigations have been carried out by single crystal X-ray diffractometry, NMR spectroscopy and Density Functional Theory calculations, revealing a diverse coordination behavior depending on the counter ion. Spectroscopic (UV-VIS and emission spectroscopy) and theoretical techniques (density functional theory and time dependent DFT calculations) have been employed to explore the photophysical properties of the complexes.

Proton-Coupled Electron Transfer in Ferrocenium–Phenolate Radicals

Electron and proton transfer (ET, PT) can be intimately coupled, provided suitable redox and acid/base sites are available. The amide-linked ferrocene–phenol H-1 is deprotonated to the phenolate [1]– by phosphazene bases and oxidized to the ferrocenium ion [H-1]+ by silver hexafluoroantimonate. Concomitant oxidation and deprotonation yields the radical [1]•, featuring a characteristic near-IR absorption band. The ground state of [1]• is best described as the ferrocenium–phenolate zwitterion [1b]• with a dynamic dissymmetric N···H···O hydrogen bond (PT). The ferrocenium–iminolate N···H–O tautomer [1b]•-NHO′ can undergo a thermal structural rearrangement to the high-energy OH···O tautomer [1b…

Push‐Pull Design of Bis(tridentate) Ruthenium(II) Polypyridine Chromophores as Deep Red Light Emitters in Light‐Emitting Electrochemical Cells

Light-emitting electrochemical cells (LECs) with a simple device structure were prepared by using heteroleptic bis(tridentate) ruthenium(II) complexes [1](PF6)(2)-[3](PF6)(2) as emitters. The push-pull substitution shifts the emission energy to low energy, into the NIR region. The devices emit deep red light up to a maximum emission wavelength of 755 nm [CIE (International Commission on Illumination) coordinates: x = 0.731, y = 0.269 for [3](PF6)(2)], which, to the best of our knowledge, is the lowest emission energy for LECs containing bis(tridentate) ruthenium(II) complexes. A device structure of ITO/PEDOT:PSS/ruthenium(II) complex/Ag was used, and the thickness of the emitting layer was …

Spin Crossover and Long-Lived Excited States in a Reduced Molecular Ruby.

Abstract The chromium(III) complex [CrIII(ddpd)2]3+ (molecular ruby; ddpd=N,N′‐dimethyl‐N,N′‐dipyridine‐2‐yl‐pyridine‐2,6‐diamine) is reduced to the genuine chromium(II) complex [CrII(ddpd)2]2+ with d4 electron configuration. This reduced molecular ruby represents one of the very few chromium(II) complexes showing spin crossover (SCO). The reversible SCO is gradual with T 1/2 around room temperature. The low‐spin and high‐spin chromium(II) isomers exhibit distinct spectroscopic and structural properties (UV/Vis/NIR, IR, EPR spectroscopies, single‐crystal XRD). Excitation of [CrII(ddpd)2]2+ with UV light at 20 and 290 K generates electronically excited states with microsecond lifetimes. This…

Solid Phases as Protective Environments for Biomimetic Catalysts

Strongly Red-Emissive Molecular Ruby [Cr(bpmp)2]3+ Surpasses [Ru(bpy)3]2+

Gaining chemical control over the thermodynamics and kinetics of photoexcited states is paramount to an efficient and sustainable utilization of photoactive transition metal complexes in a plethora of technologies. In contrast to energies of charge transfer states described by spatially separated orbitals, the energies of spin-flip states cannot straightforwardly be predicted as Pauli repulsion and the nephelauxetic effect play key roles. Guided by multireference quantum chemical calculations, we report a novel highly luminescent spin-flip emitter with a quantum chemically predicted blue-shifted luminescence. The spin-flip emission band of the chromium complex [Cr(bpmp)2]3+ (bpmp = 2,6-bis(…

Reactivity of Nickel(II) Porphyrins in oCVD Processes—Polymerisation, Intramolecular Cyclisation and Chlorination

Abstract Oxidative chemical vapour deposition of (5,15‐diphenylporphyrinato)nickel(II) (NiDPP) with iron(III) chloride as oxidant yielded a conjugated poly(metalloporphyrin) as a highly coloured thin film, which is potentially useful for optoelectronic applications. This study clarified the reactive sites of the porphyrin monomer NiDPP by HRMS, UV/Vis/NIR spectroscopy, cyclic voltammetry and EPR spectroscopy in combination with quantum chemical calculations. Unsubstituted meso positions are essential for successful polymerisation, as demonstrated by varying the porphyrin meso substituent pattern from di‐ to tri‐ and tetraphenyl substitution. DFT calculations support the proposed radical oxi…

Biological Evaluation of the NIR-Emissive Ruby Analogue [Cr(ddpd) 2 ][BF 4 ] 3 as a Photodynamic Therapy Photosensitizer

International audience; Photodynamic therapy relies on the bioavailability of photosensitizers with suitable photophysical, chemical and biochemical properties. Although the photophysical properties, stability and high water solubility of the chromium(III) complex [Cr(ddpd)2][BF4]3 (ddpd = N,N'-dimethyl-N,N'-dipyridin-2-ylpyridine-2,6-diamine) are very favorable, its photocytotoxicity against cancerous and non-cancerous cell lines has not yet been elucidated. We now report the cytotoxicity and photocytotoxicity of the complex [Cr(ddpd)2][BF4]3 against human cervical cancer cells, human primary glioblastoma cells, human glioblastoma astrocytoma cells and non-cancerous retinal pigment epithel…

Luminescent TOP Nanosensors for Simultaneously Measuring Temperature, Oxygen, and pH at a Single Excitation Wavelength

Two nanosensors for simultaneous optical measurements of the bioanalytically and biologically relevant analytes temperature (“T”), oxygen (“O”), and pH (“P”) have been designed. These “TOP” nanosensors are based on 100 nm-sized silica-coated polystyrene nanoparticles (PS-NPs) doped with a near-infrared emissive oxygen- and temperature-sensitive chromium(III) complex ([Cr(ddpd)2][BPh4]3, CrBPh4) and an inert reference dye (Nile Red, NR or 5,10,15,20-tetrakis(pentafluorophenyl) porphyrin, TFPP) and are covalently labeled with pH-sensitive fluorescein isothiocyanate (FITC). These emitters can be excited at the same wavelength and reveal spectrally distinguishable emission bands, allowing for r…

Alkali Blues: Blue‐Emissive Alkali Metal Pyrrolates

2-Iminopyrroles [HtBu L, 4-tert-butyl phenyl(pyrrol-2-ylmethylene)amine] are non-fluorescent π systems. However, they display blue fluorescence after deprotonation with alkali metal bases in the solid state and in solution at room temperature. In the solid state, the alkali metal 2-imino pyrrolates, M(tBu L), aggregate to dimers, [M(tBu L)(NCR)]2 (M=Li, R=CH3 , CH(CH3 )CNH2 ), or polymers, [M(tBu L)]n (M=Na, K). In solution (solv=CH3 CN, DMSO, THF, and toluene), solvated, uncharged monomeric species M(tBu L)(solv)m with N,N'-chelated alkali metal ions are present. Due to the electron-rich pyrrolate and the electron-poor arylimino moiety, the M(tBu L) chromophore possesses a low-energy intra…

Unexpected C–C bond formation with a ferrocenyl Fischer carbene complex

Oligonuclear Ferrocene Amides: Mixed‐Valent Peptides and Potential Redox‐Switchable Foldamers

Trinuclear ferrocene tris-amides were synthesized from an Fmoc- or Boc-protected ferrocene amino acid, and hydrogen-bonded zigzag conformations were determined by NMR spectroscopy, molecular modelling, and X-ray diffraction. In these ordered secondary structures orientation of the individual amide dipole moments approximately in the same direction results in a macrodipole moment similar to that of α-helices composed of α-amino acids. Unlike ordinary α-amino acids, the building blocks in these ferrocene amides with defined secondary structure can be sequentially oxidized to mono-, di-, and trications. Singly and doubly charged mixed-valent cations were probed experimentally by Vis/NIR, param…

Resonance Raman Studies of Bis(terpyridine)ruthenium(II) Amino Acid Esters and Diesters

Resonance Raman (rR) spectroscopy in combination with DFT calculations was used to elucidate the nature of the 1metal-to-ligand charge-transfer states (1MLCT) of ester derivatives of homo- and heteroleptic bis(terpyridine)ruthenium(II) complexes [RuII(tpy–COOC2H5)(tpy–R)](PF6)2 with R = NH2 (1a), R = COOC2H5 (1b) and R = NHCOCH3 (1c). The rR spectra provide evidence that the 1MLCT states of 1b and 1c are well described by the expected 1[(“t2g”)5{π*(tpy–COOC2H5)}1] electron configuration, while the 1MLCT state of the donor/acceptor-substituted complex 1a also involves the amine-substituted terpyridine ligand. The excited state of 1a can be described by a 1[{dyz/π(tpy–NH2)}1{π*(tpy–COOC2H5)}1…

Intramolecular electron transfer between molybdenum and iron mimicking bacterial sulphite dehydrogenase

Diferrocenyl/diferrocenium substituted dioxido molybdenum(VI) complexes [Fe2MoO2] 2(Fc)/[2(FC)]²⁺ mimic the catalytic active site including the redox subunits as well as the catalytic function of bacterial sulphite oxidases.

A heteroleptic bis(tridentate)ruthenium(II) polypyridine complex with improved photophysical properties and integrated functionalizability.

The synthesis and photophysical properties of a ruthenium(II) complex bearing an electron-accepting 2,2';6',2''-terpyridine ligand and an electron-donating N,N'-dimethyl-N,N'-dipyridin-2-ylpyridine-2,6-diamine (ddpd) ligand are presented. The heteroleptic complex is easily prepared isomerically pure and features intense low-energy metal-to-ligand charge-transfer (MLCT) absorption bands and intense room temperature (3)MLCT emission with a long (3)MLCT lifetime. The favorable photophysical properties are due to the strong ligand field imposed by the ddpd ligand.

Chromium(iii)-based potential molecular quantum bits with long coherence times

Molecular quantum bits based on copper(ii) or vanadium(iv) have been shown to possess long coherence times on multiple occasions. In contrast, studies in which non-spin-½ ions are employed are relatively scarce. High-spin ions provide additional states that can be used to encode further quantum bits. Furthermore, an optical rather than a microwave readout of molecular quantum bits is highly desirable, because in principle it could allow addressing at the single quantum bit level. The chromium(iii) complex [Cr(ddpd)2]3+ (ddpd = N,N'-dimethyl-N,N'-dipyridine-2-yl-pyridine-2,6-diamine) combines both the large spin (S = 3/2) and optical activity (strong, long lived luminescence). Here we demons…

Synthesis of copper(II) and gold(III) bis(NHC)-pincer complexes

Abstract CuII and AuIII chlorido complexes bearing the bis(NHC) carbazolide pincer ligand (bimca) were synthesized by transmetallation from the respective lithium complex [Li(bimca)] (NHC=N-heterocyclic carbene). In the case of copper, two different molecular structures were obtained depending on the copper source. With Cu(II) chloride the paramagnetic mononuclear [Cu(bimca)Cl] complex is formed and has been characterized by EPR spectroscopy and X-ray structure analysis, while copper(I) chloride leads under oxidation to a dinuclear structure in which two cationic [CuII(bimca)] moieties are bridged by one chlorido ligand. The positive charge is compensated by the [CuCl2]− counter ion, as pro…

Luminescence and Light‐Driven Energy and Electron Transfer from an Exceptionally Long‐Lived Excited State of a Non‐Innocent Chromium(III) Complex

Abstract Photoactive metal complexes employing Earth‐abundant metal ions are a key to sustainable photophysical and photochemical applications. We exploit the effects of an inversion center and ligand non‐innocence to tune the luminescence and photochemistry of the excited state of the [CrN6] chromophore [Cr(tpe)2]3+ with close to octahedral symmetry (tpe=1,1,1‐tris(pyrid‐2‐yl)ethane). [Cr(tpe)2]3+ exhibits the longest luminescence lifetime (τ=4500 μs) reported up to date for a molecular polypyridyl chromium(III) complex together with a very high luminescence quantum yield of Φ=8.2 % at room temperature in fluid solution. Furthermore, the tpe ligands in [Cr(tpe)2]3+ are redox non‐innocent, …

How Hydrogen Bonds Affect Reactivity and Intervalence Charge Transfer in Ferrocenium‐Phenolate Radicals

The ferrocenyl-phenol 2,4-di-tert-butyl-6-(ferrocenylcarbamoyl)phenol (H-1) forms intramolecular hydrogen bonds which are absent in its constitutional isomer 2,6-di-tert-butyl-4-(ferrocenylcarbamoyl)phenol (H-2). Their corresponding bases 1– and 2– show intra- and intermolecular NH···O hydrogen bonds, respectively. The phenolate 1– is reversibly oxidized to 1·, whereas 2– only undergoes a quasi-reversible oxidation to 2·, which suggests a higher reactivity. The radical pools of 1· and 2· formed by the oxidation/deprotonation of H-1 and H-2 have been probed by (rapid-freeze) electron paramagnetic resonance (EPR) spectroscopy and by spin-trapping techniques to elucidate the types of radicals …

Effects of sequence, connectivity, and counter ions in new amide-linked Ru(tpy)2-Re(bpy) chromophores on redox chemistry and photophysics.

New cationic metallo ligands L1-L3 based on bis(terpyridine) ruthenium(II) complexes decorated with differently substituted 2,2'-bipyridines attached via amide groups (5-NHCO-bpy, 4-CONH-bpy, 5-CONH-bpy) were prepared. Coordination of Re(I)Cl(CO)(3) fragments to the bpy unit gives the corresponding bimetallic Ru~Re complexes 1-3. Hydrogen bonds of the bridging amide groups to [PF(6)](-) counterions or to water molecules are observed both in the solid state and in solution. The impact of the amide orientation, the connecting site, and the coordination of counterions on redox and photophysical properties is explored. Both the metallo ligands L1-L3 and the bimetallic complexes 1-3 are emissive…

Plasma Polymer Membranes for Immobilising Metalloporphyrins

Atmospheric pressure dielectric barrier discharge formation of organosilicon thin films loaded with zinc 5,10,15,20-tetraphenylporphyrin (Zn(TPP)) was investigated for different deposition conditions. UV–visible spectroscopy and scanning electron microscopy revealed the effects of the metalloporpyhrins injection parameters and the plasma polymerisation conditions can affect the dispersion of the metalloporphyrins and the morphology of the coatings. The stability of the embedded Zn(TPP) molecules was investigated by orbitrap mass spectrometry.

Thermo-Chromium: A Contactless Optical Molecular Thermometer.

The unparalleled excited-state potential-energy landscape of the chromium(III)-based dye [1]3+ ([Cr(ddpd)2 ]3+ ; ddpd=N,N'-dimethyl-N,N'-dipyridin-2-yl-pyridin-2,6-diamine) enables a strong dual emission in the near infrared region. The temperature dependence of this dual emission allows the use of [1]3+ as an unprecedented molecular ratiometric thermometer in the 210-373 K temperature range in organic and in aqueous media. Incorporation of [1]3+ in biocompatible nanocarriers, such as 100 nm-sized polystyrene nanoparticles and solutol micelles, provides nanodimensional thermometers operating under physiological conditions.

Tuning Reductive and Oxidative Photoinduced Electron Transfer in Amide‐Linked Anthraquinone–Porphyrin–Ferrocene Architectures

Porphyrin amino acids 3a–3h with meso substituents Ar of tunable electron-donating power (Ar = 4-C6H4OnBu, 4-C6H4OMe, 4-C6H4Me, Mes, C6H5, 4-C6H4F, 4-C6H4CF3, C6F5) have been linked at the N terminus to anthraquinone Q as electron acceptor through amide bonds to give Q-PAr dyads 4a–4h. These were conjugated to ferrocene Fc at the C terminus as electron donor to give the acceptor-chromophore-donor Q-PAr-Fc triads 6a–6h. To further modify the energies of the electronically excited and charge-separated states, the triads 6a–6h were metallated with zinc(II) to give the corresponding Q-(Zn)PAr-Fc triads Zn-6a–Zn-6h. The Q-PAr1 dyad (Ar1 = C6H5) was further extended with a second porphyrin PAr2 (…

Front Cover: Redox‐Controlled Stabilization of an Open‐Shell Intermediate in a Bioinspired Enzyme Model (Eur. J. Inorg. Chem. 31/2018)

Ultrafast and long-time excited state kinetics of an NIR-emissive vanadium(iii) complex I: synthesis, spectroscopy and static quantum chemistry.

In spite of intense, recent research efforts, luminescent transition metal complexes with Earth-abundant metals are still very rare owing to the small ligand field splitting of 3d transition metal complexes and the resulting non-emissive low-energy metal-centered states. Low-energy excited states decay efficiently non-radiatively, so that near-infrared emissive transition metal complexes with 3d transition metals are even more challenging. We report that the heteroleptic pseudo-octahedral d2-vanadium(iii) complex VCl3(ddpd) (ddpd = N,N′-dimethyl-N,N′-dipyridine-2-yl-pyridine-2,6-diamine) shows near-infrared singlet → triplet spin–flip phosphorescence maxima at 1102, 1219 and 1256 nm with a …

Excited-State Kinetics of an Air-Stable Cyclometalated Iron(II) Complex.

The complex class [Fe(N^N^C)(N^N^N)]+ with an Earth-abundant metal ion has been repeatedly suggested as a chromophore and potential photosensitizer on the basis of quantum chemical calculations. Synthesis and photophysical properties of the parent complex [Fe(pbpy)(tpy)]+ (Hpbpy=6-phenyl-2,2'-bipyridine and tpy=2,2':6',2''-terpyridine) of this new chromophore class are now reported. Ground-state characterization by X-ray diffraction, electrochemistry, spectroelectrochemistry, UV/Vis, and X-ray spectroscopy in combination with DFT calculations proves the high impact of the cyclometalating ligand on the electronic structure. The photophysical properties are significantly improved compared to …

Cover Feature: Triplet–Triplet Annihilation Upconversion in a MOF with Acceptor‐Filled Channels (Chem. Eur. J. 5/2020)

Diferrocenyl tosyl hydrazone with an ultrastrong NHFe hydrogen bond as double click switch.

The intramolecular NH⋯Fe hydrogen bond in diferrocenyl hydrazone 2 raises the barrier for intramolecular electron transfer in its mixed-valent cation 2+ and is only disrupted by double oxidation to 22+.

N-Cobaltocenium Amide as Reactive Nucleophilic Reagent for Donor–Acceptor Bimetallocenes

Deprotonation of the aminocobaltocenium ion [Cc-NH2]+ ([H-1]+) generates the nucleophilic imine CcNH (1). Reaction of 1 with acid chlorides R–COCl (R = Ph, Fc, and Cc+) yields the reference amide [Ph-CO-NH-Cc]+ (2+) and the amide-linked hetero- and homobimetallocenes [Fc-CO-NH-Cc]+ (3+) and [Cc-CO-NH-Cc]2+ (42+), respectively. Cation–anion interactions of charged amides 2+–42+ in the solid state and in solution are probed by single crystal X-ray diffraction and NMR and IR spectroscopy. Intramolecular metal–metal interactions in donor–acceptor heterobimetallocene 3+ and in mixed-valent homobimetallocene 4+ (prepared electrochemically) are discussed within the Marcus–Hush framework aided by s…

Protic Ferrocenyl Acyclic Diamino Carbene Gold(I) Complexes

Understanding the Excited State Behavior of Cyclometalated Bis(tridentate)ruthenium(II) Complexes: A Combined Experimental and Theoretical Study

The synthesis and characterization of the donor-acceptor substituted cyclometalated ruthenium(II) polypyridine complex isomers [Ru(dpb-NHCOMe)(tpy-COOEt)](PF6) 1(PF6) and [Ru(dpb-COOEt)(tpy-NHCOMe)](PF6) 2(PF6) (dpbH = 1,3-dipyridin-2-ylbenzene, tpy = 2,2';6,2"-terpyridine) with inverted functional group pattern are described. A combination of resonance Raman spectroscopic and computational techniques shows that all intense visible range absorption bands arise from mixed Ru → tpy/Ru → dpb metal-to-ligand charge transfer (MLCT) excitations. 2(PF6) is weakly phosphorescent at room temperature in fluid solution and strongly emissive at 77 K in solid butyronitrile matrix, which is typical for r…

Bioinspired functional analogs of the active site of molybdenum enzymes: Intermediates and mechanisms

Abstract Molybdenum(VI) complexes of the general type MoVI(L)2(E)O (L = 2-(aryl N CH)-pyrrolylato, E = O, NtBu) and their relevance as bioinspired functional analogs for molybdenum-containing oxotransferases are reviewed. All complexes are capable of transfering oxygen atoms to PR3 (forward oxygen atom transfer) giving OPR3 and phosphane molybdenum(IV) complexes MoIV(L)2(E)(PR3) (with a second equivalent PR3) via the transient phosphoryl complex MoIV(L)2(E)(OPR3) and the five-coordinate intermediate MoIV(L)2(E). Reactivity of MoIV(L)2(E) and the favored stereochemistry of products from excess PR3 MoIV(L)2(E)(PR3) depend on the steric demand of the chelate ligands (L)−, the π donor ligand E …

Understanding and exploiting long-lived near-infrared emission of a molecular ruby

Coordination chemistry reviews 359, 102 - 111 (2018). doi:10.1016/j.ccr.2018.01.004

Polysubstituted ferrocenes as tunable redox mediators

A series of four ferrocenyl ester compounds, 1-methoxycarbonyl- (1), 1,1’-bis(methoxycarbonyl)- (2), 1,1’,3-tris(methoxycarbonyl)- (3) and 1,1’,3,3’-tetrakis(methoxycarbonyl)ferrocene (4), has been studied with respect to their potential use as redox mediators. The impact of the number and position of ester groups present in 1–4 on the electrochemical potential E1/2 is correlated with the sum of Hammett constants. The 1/1+–4/4+ redox couples are chemically stable under the conditions of electrolysis as demonstrated by IR and UV–vis spectroelectrochemical methods. The energies of the C=O stretching vibrations of the ester moieties and the energies of the UV–vis absorptions of 1–4 and 1+–4+ c…

Light-Controlled Reactivity of Metal Complexes.

Redox and Photochemistry of Bis(terpyridine)ruthenium(II) Amino Acids and Their Amide Conjugates – from Understanding to Applications (Eur. J. Inorg. Chem. 32/2014)

ChemInform Abstract: Excited State Decay of Cyclometalated Polypyridine Ruthenium Complexes: Insight from Theory and Experiment

Deactivation pathways of the triplet metal-to-ligand charge transfer (3MLCT) excited state of cyclometalated polypyridine ruthenium complexes with [RuN5C]+ coordination are discussed on the basis of the available experimental data and a series of density functional theory calculations. Three different complex classes are considered, namely with [Ru(N^N)2(N^C)]+, [Ru(N^N^N)(N^C^N)]+ and [Ru(N^N^N)(N^N^C)]+ coordination modes. Excited state deactivation in these complex types proceeds via five distinct decay channels. Vibronic coupling of the 3MLCT state to high-energy oscillators of the singlet ground state (1GS) allows tunneling to the ground state followed by vibrational relaxation (path A…

Strong circularly polarized luminescence of an octahedral chromium(iii) complex

The chiral spin-flip luminophore [Cr(ddpd)2]3+ can be resolved into enantiopure material by chiral HPLC. The corresponding enantiomers show very high luminescence dissymmetry factors of up to ∣glum ∣≈ 0.093 in circularly polarized luminescence (CPL) measurements for the "ruby-like" phosphorescence transition 2E/2T1 → 4A2 in the near-IR region around λ ≈ 775 nm.

Conformational stability of oligoferrocene oligoamide foldamers

Abstract Organometallic oligoamides built from three to four ferrocene amino acid units ( H-Fca-OH , 1-amino-1′-ferrocene carboxylic acid) fold into hydrogen bonded secondary structures featuring eight-membered rings by cooperative hydrogen bonds. NMR studies and DFT calculations (CAM-B3LYP, LANL2DZ, IEFPCM (THF)) reveal that the organometallic zigzag foldamer structures are highly resistant toward denaturation by hydrogen bond acceptors such as dimethyl sulfoxide and 2,4-lutidine. Replacing one ferrocene amino acid unit by the organic α -amino acid glycine at the C -terminal end (Fca → Gly) significantly destabilizes the secondary zigzag structure facilitating denaturation by DMSO. Highly …

Rhenium(I) and platinum(II) complexes with diimine ligands bearing acidic phenol substituents: hydrogen-bonding, acid-base chemistry and optical properties.

Tricarbonylchloro-rhenium(i) (1-4) and catecholato-platinum(ii) complexes (6, 7) of diimine ligands bearing phenol and O-protected phenol substituents have been prepared and fully characterised including single crystal structure analyses of 1, 4 and 7. The redox behaviour of the catecholato platinum(ii) complexes 6 and 7 has been probed by cyclic voltammetry, preparative oxidation and EPR spectroscopy (6˙(+), 7˙(+)). Reversible deprotonation of the hydroxy substituted complexes 1, 3 and 6 to 1(-), 3(-) and 6(-) resulted in significant changes in their electronic spectra. The luminescence properties of the diamagnetic complexes have been investigated using emission spectroscopy. DFT and TD-D…

Conformational Analysis of beta-Lactam-Containing Ferrocene Peptides

The homochiral 3-amino-1-(4-methoxyphenyl)-4-phenyl-beta-lactam (≡ Alm) was conjugated with Boc-Ala giving Ala-Alm (9) after Boc-deprotection (Boc = tert-butoxycarbonyl, Ala = alanine). Coupling of FcCOOH (1) and Boc-Fca (10) with “ dipeptide” 9 resulted in the formation of FcCO-Ala-Alm (12) and the trisamide Boc-Fca-Ala-Alm (13), respectively (Fc = ferrocenyl, Fca = 1’ -aminoferrocene-1-carboxylic acid). The reactions were accomplished by the HOBt/EDC procedure and the products were obtained in good yields (HOBt = 1-hydroxybenzotriazole, EDC = N-(3-dimethylaminopropyl)-N’ -ethylcarbodiimide hydrochloride). Symmetrically 1, 1’ -disubstituted “ tetrapeptide” Fn(CO-Ala-Alm)2 (14) was prepared…

αα- and αβ-Zinc-meso-A2B2-tetraarylporphyrins with large optical responses to triethylamine

Synthesis and separation of αα- and αβ-meso-A(2)B(2)-zinc(II) tetraarylporphyrin atropisomers with A = mesityl and B = ortho-phenylethynyl-phenyl are reported. Both isomers exhibit large optical responses upon axial NEt(3) coordination which are visible to the human eye and could therefore be beneficial for the design of smart amine sensing materials. The larger spectral changes as compared to Zn(TPP) are attributed to pronounced distortions of the porphyrin π-system due to steric interactions of the coordinating amine with the porphyrin periphery. This effect as well as the coordination site of NEt(3) at the αα-isomer have been studied by NMR experiments and were rationalized by DFT calcul…

Conductive Fused Porphyrin Tapes on Sensitive Substrates by a Chemical Vapor Deposition Approach.

Abstract Oxidative polymerization of nickel(II) 5,15‐diphenyl porphyrin and nickel(II) 5,15‐bis(di‐3,5‐tert‐butylphenyl) porphyrin by oxidative chemical vapor deposition (oCVD) yields multiply fused porphyrin oligomers in thin film form. The oCVD technique enables one‐step formation, deposition, and p‐doping of conjugated poly(porphyrins) coatings without solvents or post‐treatments. The decisive reactions and side reactions during the oCVD process are shown by high‐resolution mass spectrometry. Owing to the highly conjugated structure of the fused tapes, the thin films exhibit an electrical conductivity of 3.6×10−2 S cm−1 and strong absorption in the visible to near‐infrared spectral regio…

Elucidation of the Conformational Freedom of Ferrocene Amino Acid (Bio)Conjugates: A Complementary Theoretical and Experimental Approach

C2-Symmetric Ferrocene-Bis(ureido)peptides : Synthesis, Conformation and Solid-State Structure

The extension of peptide derivatives of ferrocene-1,1'-dicarboxylic acid by formal insertion of NH units between ferrocene and peptide strands results in ferrocene-bis(ureido)-peptides. Experimentally, alanine and dialanine methyl esters were attached to the 1- and 1'-position of 1,1'-diiso-cyanoferrocene to give the corresponding bis(ureido)peptide derivatives 3 and 4. The conformation of 3 has been determined in the solid state by X-ray crystallography. In solution the preferred conformation of 3 and 4 has been elucidated by NMR, IR and CD spectroscopy in concert with DFT calculations. The secondary structure of ferrocene―bis(ureido)peptides 3 and 4 is determined by double bifurcated intr…

Solid-Phase Synthesis of Peptide Libraries Combining α-Amino Acids with Inorganic and Organic Chromophores

The synthesis of two series of peptidic chains composed of bis(terpyridine)ruthenium(II) acceptor units and organic chromophores (coumarin, naphthalene, anthracene, fluorene) by stepwise solid-phase peptide synthesis (SPPS) techniques is described. The first series of dyads comprises directly amide linked chromophores, while the second one possesses a glycine spacer between the two chromophores. All dyads were studied by UV/Vis and NMR spectroscopy, steady-state luminescence, luminescence decay and electrochemistry, as well as by DFT calculations. The results of these studies indicate weak electronic coupling of the chromophores in the ground state. Absorption spectra of all dyads are domin…

Near-IR to Near-IR Upconversion Luminescence in Molecular Chromium Ytterbium Salts

Abstract Upconversion photoluminescence in hetero‐oligonuclear metal complex architectures featuring organic ligands is an interesting but still rarely observed phenomenon, despite its great potential from a basic research and application perspective. In this context, a new photonic material consisting of molecular chromium(III) and ytterbium(III) complex ions was developed that exhibits excitation‐power density‐dependent cooperative sensitization of the chromium‐centered 2E/2T1 phosphorescence at approximately 775 nm after excitation of the ytterbium band 2F7/2→2F5/2 at approximately 980 nm in the solid state at ambient temperature. The upconversion process is insensitive to atmospheric ox…

Thermal and Photoinduced Electron Transfer in Directional Bis(terpyridine)ruthenium(II)–(Bipyridine)platinum(II) Complexes

Metalloligands L1 and L2 consisting of directional bis(terpyridine)ruthenium(II) units and bipyridine moieties were constructed by amide formation. From these metalloligands two Ru–Pt heterobimetallic complexes 1 and 2 were derived by a building-block method by means of platination with [PtCl2(dmso)2]. Both bimetallic complexes 1 and 2 feature metal-to-ligand charge transfer (MLCT) absorptions, and emission occurs at room temperature in fluid solution from 3MLCT(Ru) states in all cases. Energy transfer from platinum to ruthenium is observed in 2 but not in 1 (light harvesting). The one-electron-reduced species [1]– and [2]– were prepared by reduction of 1 and 2 with decamethylcobaltocene. E…

Dinuclear bis(terpyridine)ruthenium(II) complexes by amide coupling of ruthenium amino acids: Synthesis and properties

Abstract Two redox-asymmetric amide-bridged bis(terpyridine)ruthenium(II) complexes (3a, 3b) have been prepared by amide coupling of a carboxylic acid functionalized complex with an amine substituted complex and they were fully characterized by spectroscopic analyses. They emit at 692 and 750 nm at room temperature in fluid solution with quantum yields larger than 10−3 and 3MLCT lifetimes of 22 ns. Ru···Ru distances were estimated from DFT models as 17.7 and 13.4 A for 3a and 3b, respectively. Cyclic voltammetry gives two oxidation potentials for the differently substituted ruthenium sites with splittings of 0.10 and 0.23 V for 3a and 3b, respectively. Oxidation of 3b with CeIV ions gives t…

Dual application of (aqua)(chlorido)(porphyrinato)chromium(III) as hypersensitive amine-triggered ON switch and for dioxygen activation.

Although synthesis and substitution reactions of chlorido chromium(III) porphyrins Cr(III)(TPP)(Cl)(L) (H2TPP = 5,10,15,20-tetraphenyl porphyrin, L = pyridine, H2O, ROH, etc.), have been well-established in coordination chemistry for decades, an unexpected dichotomous reactivity of Cr(III)(TPP)(Cl)(H2O) (1) toward amines is disclosed here. This reactivity leads to the application of 1 as highly sensitive substoichiometric and irreversible ON switch for amine detection by an autocatalytic pathway. The concomitant activation of O2 by the 1/amine system is furthermore exploited in an electrochemically driven epoxidation of norbonene using O2 as initial oxidant.

Excited State Tuning of Bis(tridentate) Ruthenium(II) Polypyridine Chromophores by Push-Pull Effects and Bite Angle Optimization: A Comprehensive Experimental and Theoretical Study

The synergy of push-pull substitution and enlarged ligand bite angles has been used in functionalized heteroleptic bis(tridentate) polypyridine complexes of ruthenium(II) to shift the (1) MLCT absorption and the (3) MLCT emission to lower energy, enhance the emission quantum yield, and to prolong the (3) MLCT excited-state lifetime. In these complexes, that is, [Ru(ddpd)(EtOOC-tpy)][PF6 ]2 , [Ru(ddpd-NH2 )(EtOOC-tpy)][PF6 ]2 , [Ru(ddpd){(MeOOC)3 -tpy}][PF6 ]2 , and [Ru(ddpd-NH2 ){(EtOOC)3 -tpy}][PF6 ]2 the combination of the electron-accepting 2,2';6',2''-terpyridine (tpy) ligand equipped with one or three COOR substituents with the electron-donating N,N'-dimethyl-N,N'-dipyridin-2-ylpyridin…

Coordination of expanded terpyridine ligands to cobalt

Abstract The tridentate expanded terpyridine-like ligand N,N′-dimethyl-N,N′-dipyridin-2-yl-pyridin-2,6-diamine (ddpd) and [Co(H2O)6](BF4)2 give the high-spin complex mer-[Co(ddpd)2](BF4)2 with a tetragonally compressed CoN6 coordination geometry according to X-ray diffraction and SQUID measurements. UV–Vis–NIR spectra indicate a large ligand field splitting close to the high-spin/low-spin crossover point. Oxidation of the CoII complex to CoIII is achieved with silver triflate. The self exchange between high-spin CoII and low-spin CoIII is slow on the NMR time scale.

Ferrocenyl-Labeled Sugar Amino Acids: Conformation and Properties

Novel organometallic sugar amino acid conjugates 1–5 have been prepared by amide coupling of O-protected N-acetylmuramic acid and iso-muramic acid (2-[3-amino-2, 5-dihydroxy-6-(hydroxymethyl)oxan-4-yl]oxypropanoic acid) with 1-aminoferrocene, 1-aminoferrocene-1′-carboxylic acid (H-Fca-OH), or 1, 1′-diaminoferrocene, respectively. The influence of the ferrocenyl moiety and presence of additional remote potential hydrogen atom acceptors and donors at the ferrocenyl core on the conformation and lipophilicity is investigated by TLC, IR, NMR, and CD spectroscopic methods augmented by density functional calculations. Furthermore, the redox potential of the ferrocene/ferrocenium couple is tuned by…

Powerful Fluoroalkoxy Molybdenum(V) Reagent for Selective Oxidative Arene Coupling Reaction

We introduce the novel fluoroalkoxy molybdenum(V) reagent 1 which has superior reactivity and selectivity in comparison to MoCl5 or the MoCl5 /TiCl4 reagent mixture in the oxidative coupling reactions of aryls. Common side reactions, such as chlorination and/or oligomer formation, are drastically diminished creating a powerful and useful reagent for oxidative coupling. Theoretical treatment of the reagent interaction with 1,2-dimethoxybenzene-type substrates indicates an inner-sphere electron transfer followed by a radical cationic reaction pathway for the oxidative-coupling process. EPR spectroscopic and electrochemical studies, X-ray analyses, computational investigations, and the experim…

Photophysics and photochemistry with Earth-abundant metals - fundamentals and concepts.

Recent exciting developments in the area of mononuclear photoactive complexes with Earth-abundant metal ions (Cu, Zr, Fe, Cr) for potential eco-friendly applications in (phosphorescent) organic light emitting diodes, in imaging and sensing systems, in dye-sensitized solar cells and as photocatalysts are presented. Challenges, in particular the extension of excited state lifetimes, and recent conceptual breakthroughs in substituting precious and rare-Earth metal ions (e.g. Ru, Ir, Pt, Au, Eu) in these applications by abundant ions are outlined with selected examples. Relevant fundamentals of photophysics and photochemistry are discussed first, followed by conceptual and instructive case stud…

Triplet–Triplet Annihilation Upconversion in a MOF with Acceptor‐Filled Channels

Abstract Photon upconversion has enjoyed increased interest in the last years due to its high potential for solar‐energy harvesting and bioimaging. A challenge for triplet–triplet annihilation upconversion (TTA‐UC) processes is to realize these features in solid materials without undesired phase segregation and detrimental dye aggregation. To achieve this, we combine a palladium porphyrin sensitizer and a 9,10‐diphenylanthracene annihilator within a crystalline mesoporous metal–organic framework using an inverted design. In this modular TTA system, the framework walls constitute the fixed sensitizer, while caprylic acid coats the channels providing a solventlike environment for the mobile a…

Gas Selective Ultrathin Organic Covalent Networks Synthesized by iPECVD: Does the Central Metal Ion Matter?

The potential of porphyrin-derived metal organic covalent networks (OCN) thin films on light gas separations has been recently demonstrated. However, whether or not the central metal ion of the porphyrin plays a key role on separation performance has yet to be elucidated. Here, one metal-free and three metal-containing (zinc(II), manganese(III), and cobalt(II)) porphyrin-derived OCN thin films are successfully deposited on various substrates via an easily scalable initiated plasma-enhanced chemical vapor deposition approach. Among these four porphyrin-derived OCN thin films exhibiting superior light gas separation performances, three of them are synthesized for the first time. The gas perme…

Oxidomolybdenum(IV), ‐(V), ‐(VI) Complexes with Relevance to Molybdenum Enzymes: Oxygen Atom Transfer, Redox Chemistry and EPR Spectroscopy

The cis-dioxidomolybdenum(VI) complex Mo(NN′)2O2 (1) [(NN′) = N-(4-hydroxyphenyl)-2-pyrrolatocarbaldimine] transfers one oxygen atom to phosphanes PMenPh3–n (n = 0–3) to give quantitatively the respective phosphane oxides OPMenPh3–n (OAT, oxygen atom transfer). The kinetics of these OAT reactions has been investigated spectrophotometrically. When offering excess PMenPh3–n (n = 1–3), oxido(phoshane)molybdenum(IV) complexes Mo(NN′)2O(PMenPh3–n) 5a–5c are isolated and characterized by multinuclear NMR spectroscopy (1H, 13C, 31P, 15N), IR spectroscopy, UV/Vis spectroscopy and mass spectrometry. The redox chemistry of the molybdenum(IV) complexes 5a–5c and of molybdenum(VI) complex 1 has been pr…

Cover Feature: Green‐Light Activation of Push–Pull Ruthenium(II) Complexes (Chem. Eur. J. 30/2020)

V2O5 nanowires with an intrinsic peroxidase-like activity

V2O5 nanowires exhibit an intrinsic catalytic activity towards classical peroxidase substrates such as 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 3,3,5,5,-tetramethylbenzdine (TMB) in the presence of H2O2. These V2O5 nanowires show an optimum reactivity at a pH of 4.0 and the catalytic activity is dependent on the concentration. The Michaelis-Menten kinetics of the ABTS oxidation over these nanowires reveals a behavior similar to that of their natural vanadium-dependent haloperoxidase (V-HPO) counterparts. The V2O5 nanowires mediate the oxidation of ABTS in the presence of H2O2 with a turnover frequency (k(cat)) of 2.5 x 10(3) s(-1). The K-M values of the V2O5 nanowire…

Anchor‐Functionalized Push‐Pull‐Substituted Bis(tridentate) Ruthenium(II) Polypyridine Chromophores: Photostability and Evaluation as Photosensitizers

Stable push-pull substituted heteroleptic bis(tridentate) ruthenium(II) polypyridine complexes with COOH or 2,2′-bipyridine anchor groups have been prepared and characterized by 1H, 13C and 15N NMR 1D and 2D spectroscopy, infrared spectroscopy, elemental analysis, high-resolution ESI mass spectrometry, electrochemistry, UV/Vis absorption spectroscopy, luminescence spectroscopy, and density functional calculations. The complexes feature a pronounced electronic directionality and high absorption wavelengths up to λmax = 544 nm extending to 720 nm as a result of favorable push-pull substitutions. A remarkable photostability in the presence of water and coordinating ions (I–) was discovered for…

Gas Separation: Metal-Organic Covalent Network Chemical Vapor Deposition for Gas Separation (Adv. Mater. 34/2016)

Molybdenum Complex with Bulky Chelates as a Functional Model for Molybdenum Oxidases

The novel bulky Schiff base chelate ligand [(4,5-diisopropyl-1H-pyrrole-2-yl)methylene]-4-(tert-butyl)aniline ((iPr2)HL) bearing two isopropyl groups close to the pyrrole nitrogen atom reacts with MoCl2(dme)O2 (dme = 1,2-dimethoxyethane) to give the sterically congested complex Mo(VI)((iPr2)L)2O2 ((iPr2)1; OC-6-4-4 configuration). In spite of the increased steric shielding of the [MoO2] unit (iPr2)1 is active in oxygen-atom transfer to PMe3 and PPh3 to give OPMe3 and OPPh3, respectively. Because of the increased steric bulk of the chelate ligand, formation of dinuclear complexes [Mo(V)((iPr2)L)2O]2(μ-O) ((iPr2)3) by comportionation is effectively prevented in contrast to the highly favored …

[Cr(ddpd) 2 ] 3+ : A Molecular, Water‐Soluble, Highly NIR‐Emissive Ruby Analogue

Bright, long-lived emission from first-row transition-metal complexes is very challenging to achieve. Herein, we present a new strategy relying on the rational tuning of energy levels. With the aid of the large N-Cr-N bite angle of the tridentate ligand ddpd (N,N'-dimethyl-N,N'-dipyridine-2-ylpyridine-2,6-diamine) and its strong σ-donating capabilities, a very large ligand-field splitting could be introduced in the chromium(III) complex [Cr(ddpd)2](3+), that shifts the deactivating and photoreactive (4)T2 state well above the emitting (2)E state. Prevention of back-intersystem crossing from the (2)E to the (4)T2 state enables exceptionally high near-infrared phosphorescence quantum yields a…

NIR‐NIR‐Aufkonvertierung in molekularen Chrom‐Ytterbium‐Salzen

Photonen-Aufkonvertierung in hetero-oligonuklearen, Metallkomplex-Architekturen mit organischen Liganden ist ein interessantes, aber bisher selten beobachtetes Phanomen, trotz des grosen Potentials sowohl aus Sicht der Grundlagenforschung als auch aus der Anwendungsperspektive. Nun wurde ein neues photonisches Material aus molekularen Chrom(III)- und Ytterbium(III)-Komplexionen entwickelt. Dieses zeigt im Festkorper bei Raumtemperatur abhangig von der Anregungsleistungsdichte nach Anregung des 2F7/2! 2F5/2-3berganges des Ytterbiums bei ca. 980 nm eine kooperative Sensibilisierung der Chrom(III)-zentrierten 2E/2T1-Phosphoreszenz bei ca. 775 nm. Der Aufkonvertierungsprozess ist unempfindlich …

Front Cover: Constitution and Conductivity of Metalloporphyrin Tapes (Eur. J. Inorg. Chem. 20/2020)

Optical sensing responses of CrIIICl(TPP)(H2O)-based coatings obtained by an atmospheric pressure plasma method – Application to the detection of volatile amines

Food spoilage processes are a considerable concern for both the food industry and the consumer, due to financial, food quality and food safety aspects. A primary issue is the prevention/monitoring of the formation of biogenic and volatile amines, such as occurring in fish and in other microbiologically unstable food items rich in proteins, produced by e.g. oxidative decarboxylation of amino acids. One strategy for their monitoring is the development of films with colorimetric sensing properties that are able to indicate food spoilage. The aim of this investigation was the development of a novel metalloporphyrin-based coating allowing the sensitive detection of typical volatile amines, such …

Initial Radical Cation Pathway in the Mo2Cl10-Mediated Dehydrogenative Arene Coupling

Experimental (EPR) and theoretical (DFT) evidence is provided for radical cation formation as initial step in the Mo2Cl10-mediated dehydrogenative arene coupling. The initial electron transfer from methoxyarenes to molybdenum proceeds via an inner sphere mechanism.

CCDC 1426094: Experimental Crystal Structure Determination

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CCDC 1962440: Experimental Crystal Structure Determination

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CCDC 930312: Experimental Crystal Structure Determination

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CCDC 1475564: Experimental Crystal Structure Determination

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CCDC 1993737: Experimental Crystal Structure Determination

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CCDC 965850: Experimental Crystal Structure Determination

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CCDC 1042437: Experimental Crystal Structure Determination

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CCDC 965852: Experimental Crystal Structure Determination

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CCDC 1534633: Experimental Crystal Structure Determination

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CCDC 1555799: Experimental Crystal Structure Determination

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CCDC 1876390: Experimental Crystal Structure Determination

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CCDC 2107164: Experimental Crystal Structure Determination

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CCDC 1441949: Experimental Crystal Structure Determination

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CCDC 895382: Experimental Crystal Structure Determination

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CCDC 1855069: Experimental Crystal Structure Determination

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CCDC 1426154: Experimental Crystal Structure Determination

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CCDC 978126: Experimental Crystal Structure Determination

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CCDC 1035257: Experimental Crystal Structure Determination

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CCDC 956709: Experimental Crystal Structure Determination

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CCDC 1426095: Experimental Crystal Structure Determination

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CCDC 1492154: Experimental Crystal Structure Determination

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CCDC 1832900: Experimental Crystal Structure Determination

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CCDC 966311: Experimental Crystal Structure Determination

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CCDC 1581720: Experimental Crystal Structure Determination

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CCDC 1989536: Experimental Crystal Structure Determination

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CCDC 1581721: Experimental Crystal Structure Determination

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CCDC 1958562: Experimental Crystal Structure Determination

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CCDC 2050317: Experimental Crystal Structure Determination

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CCDC 934080: Experimental Crystal Structure Determination

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CCDC 952600: Experimental Crystal Structure Determination

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CCDC 1855071: Experimental Crystal Structure Determination

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CCDC 965851: Experimental Crystal Structure Determination

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CCDC 1016554: Experimental Crystal Structure Determination

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CCDC 959158: Experimental Crystal Structure Determination

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CCDC 1475563: Experimental Crystal Structure Determination

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CCDC 1829268: Experimental Crystal Structure Determination

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CCDC 885078: Experimental Crystal Structure Determination

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CCDC 984218: Experimental Crystal Structure Determination

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CCDC 1526745: Experimental Crystal Structure Determination

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CCDC 1494856: Experimental Crystal Structure Determination

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CCDC 2083757: Experimental Crystal Structure Determination

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CCDC 2107165: Experimental Crystal Structure Determination

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CCDC 1993738: Experimental Crystal Structure Determination

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CCDC 956710: Experimental Crystal Structure Determination

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CCDC 1522073: Experimental Crystal Structure Determination

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CCDC 930313: Experimental Crystal Structure Determination

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CCDC 1958093: Experimental Crystal Structure Determination

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CCDC 1494853: Experimental Crystal Structure Determination

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CCDC 1494855: Experimental Crystal Structure Determination

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CCDC 1989537: Experimental Crystal Structure Determination

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CCDC 1843133: Experimental Crystal Structure Determination

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CCDC 1494851: Experimental Crystal Structure Determination

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CCDC 1855070: Experimental Crystal Structure Determination

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CCDC 1538078: Experimental Crystal Structure Determination

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CCDC 1876389: Experimental Crystal Structure Determination

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CCDC 1962439: Experimental Crystal Structure Determination

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CCDC 1494858: Experimental Crystal Structure Determination

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CCDC 2003421: Experimental Crystal Structure Determination

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CCDC 1016552: Experimental Crystal Structure Determination

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CCDC 895383: Experimental Crystal Structure Determination

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CCDC 930311: Experimental Crystal Structure Determination

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CCDC 2003420: Experimental Crystal Structure Determination

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CCDC 1484852: Experimental Crystal Structure Determination

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CCDC 1855068: Experimental Crystal Structure Determination

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CCDC 1492153: Experimental Crystal Structure Determination

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CCDC 930310: Experimental Crystal Structure Determination

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CCDC 1494852: Experimental Crystal Structure Determination

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CCDC 1031559: Experimental Crystal Structure Determination

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CCDC 1458703: Experimental Crystal Structure Determination

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CCDC 1494857: Experimental Crystal Structure Determination

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CCDC 1526744: Experimental Crystal Structure Determination

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CCDC 1520924: Experimental Crystal Structure Determination

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CCDC 1016553: Experimental Crystal Structure Determination

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CCDC 1904835: Experimental Crystal Structure Determination

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CCDC 1494854: Experimental Crystal Structure Determination

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CCDC 1587133: Experimental Crystal Structure Determination

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CCDC 2049729: Experimental Crystal Structure Determination

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CCDC 1555798: Experimental Crystal Structure Determination

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CCDC 1016551: Experimental Crystal Structure Determination

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CCDC 1044691: Experimental Crystal Structure Determination

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CCDC 930315: Experimental Crystal Structure Determination

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CCDC 1409670: Experimental Crystal Structure Determination

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CCDC 966309: Experimental Crystal Structure Determination

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CCDC 885077: Experimental Crystal Structure Determination

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CCDC 1852838: Experimental Crystal Structure Determination

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CCDC 966310: Experimental Crystal Structure Determination

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CCDC 1538079: Experimental Crystal Structure Determination

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