Search results for "ferrocene"
showing 10 items of 306 documents
Ferrocene-quinoxaline Y-shaped chromophores as fascinating second-order NLO building blocks for long lasting highly active SHG polymeric films
2016
The first example of a Y-shaped ferrocene quinoxaline derivative with a surprisingly high and stable second harmonic generation (SHG) response in composite polymeric films is reported. The interesting quadratic hyperpolarizability values of different substituted Y-shaped chromophores are also investigated in solution by the EFISH technique.
Pulsed-current versus constant-voltage light-emitting electrochemical cells with trifluoromethyl-substituted cationic iridium(iii) complexes
2013
We report on five cationic iridium(III) complexes with cyclometalating 2-(3′-trifluoromethylphenyl)pyridine and a diimine, [(C⁁N)2Ir(N⁁N)](PF6), N⁁N = 4,4′-R2-2,2′-dipyridyl or 4,7-R2-1,10-phenanthroline (R = H, Me, tert-Bu, Ph), and characterize three of them by crystal structure analysis. The complexes undergo oxidation of the Ir–aryl fragment at 1.13–1.16 V (against ferrocene couple) and reduction of the N⁁N ligand at −1.66 V to −1.86 V, and have a redox gap of 2.84–2.99 V. The complexes exhibit bluish-green to green-yellow phosphorescence in an argon-saturated dichloromethane solution at room temperature with a maximum at 486–520 nm, quantum yield of 61–67%, and an excited-state lifetim…
Structural and Magnetic Insights into the Trinuclear Ferrocenophane and Unexpected Hydrido Inverse Crown Products of Alkali‐Metal‐Mediated Manganatio…
2008
With the aim of introducing the diisopropylamide [NiPr(2)](-) ligand to alkali-metal-mediated manganation (AMMMn) chemistry, the temperature-dependent reactions of a 1:1:3 mixture of butylsodium, bis(trimethylsilylmethyl)manganese(II), and diisopropylamine with ferrocene in hexane/toluene have been investigated. Performed at reflux temperature, the reaction affords the surprising, ferrocene-free, hydrido product [Na(2)Mn(2) (mu-H)(2){N(iPr)(2)}(4)]2 toluene (1), the first Mn hydrido inverse crown complex. Repeating the reaction rationally, excluding ferrocene, produces 1 in an isolated crystalline yield of 62 %. At lower temperatures, the same bimetallic amide mixture leads to the manganati…
Ferrocene compounds: methyl 1′-aminoferrocene-1-carboxylate
2010
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…
Oligonuclear Ferrocene Amides: Mixed‐Valent Peptides and Potential Redox‐Switchable Foldamers
2010
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…
Redox-responsive organometallic foldamers from ferrocene amino acid: Solid-phase synthesis, secondary structure and mixed-valence properties
2011
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.
Stepwise sequential redox potential modulation possible on a single platform.
2011
Step by step: The cluster [3,3'-Co(1,2-C(2)B(9)H(11))(2)](-) is an excellent platform for making a stepwise tunable redox potential system by dehydroiodination. With the addition of up to eight iodine substituents (purple; see picture), there is a fall in the E(1/2)(Co(III)/Co(II)) value from -1.80 V to -0.68 V (vs. Fc(+)/Fc; Fc = ferrocene). A practical application of this tunability has been observed in the growth of polypyrrole.
Ferrocenyl (P,N)-diphosphines incorporating pyrrolyl, imidazolyl or benzazaphospholyl moieties: Synthesis, coordination to group 10 metals and perfor…
2013
Abstract Three novel symmetrical ferrocenyl diphosphines with tertiary phosphorus atoms holding respectively nitrogen-containing heterocyclic derivatives of pyrrole, imidazole and benzazaphosphole were synthesized and characterized. Up to now, integration of heteroaromatic fragments, or more generally hetero-cycles, as substituents on the tertiary phosphines of symmetrical ferrocenyl diphosphines has been limited to the furyl motif. Their coordination to palladium and platinum group 10 transition metals was exemplified, and analyzed using single crystal X-ray diffraction. The performances obtained in palladium-catalyzed copper-free Sonogashira and Suzuki cross-coupling reactions using bromo…
Comparative enantioseparation of planar chiral ferrocenes on polysaccharide‐based chiral stationary phases
2022
Planar chiral ferrocenes are well-known compounds that have attracted interest for application in synthesis, catalysis, material science, and medicinal chemistry for several decades. In spite of the fact that asymmetric synthesis procedures for obtaining enantiomerically enriched ferrocenes are available, sometimes, the accessible enantiomeric excess of the chiral products is unsatisfactory. In such cases and for resolution of racemic planar chiral ferrocenes, enantioselective high-performance liquid chromatography (HPLC) on polysaccharide-based chiral stationary phases (CSPs) has been used in quite a few literature articles. However, although moderate/high enantioselectivities have been ob…
Vinyl ferrocenyl glycidyl ether: an unprotected orthogonal ferrocene monomer for anionic and radical polymerization
2015
The first orthogonal ferrocene monomer, vinyl ferrocenyl glycidyl ether (VfcGE), for both anionic and radical polymerization – without the need of a protection group – is presented. Anionic ring-opening copolymerization of VfcGE and ethylene oxide (EO) generates stimuli-responsive, multifunctional poly[(vinyl ferrocenyl glycidyl ether)-co-(ethylene oxide)] (P[VfcGE-co-EO]) copolymers (molecular weights of ca. 7500 g mol−1 and low molecular weight dispersities (Đ ≤ 1.14)). The amount of the equimolar ferrocenyl and vinyl groups are controlled by the comonomer ratio up to 15.4 mol% VfcGE. The pendant vinyl groups of P[VfcGE-co-EO] were post-modified with 3-mercaptopropionic acid via thiol–ene…