Search results for "Single"

Spin crossover (SCO) iron(II) coordination polymer chain: Synthesis, structural and magnetic characterizations of [Fe(abpt)2(μ-M(CN)4)] (M=PtII and N…

2013

Abstract New iron(II) coordination polymeric neutral chain of formula [Fe(abpt) 2 (μ-M(CN) 4 )], with M = Pt II ( 1 ), Ni II ( 2 ) and abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole, have been synthesized and characterized by infrared spectroscopy, X-ray diffraction and magnetic measurements. The two compounds are isostructural as deduced from a Rietveld analysis of X-ray powder diffraction data of 2 simulated from the single crystal structure of 1 . The crystal packing of 1 is formed by regular chains running along the crystallographic [−1 0 1] direction where the planar [Pt(CN) 4 ] 2− anion acts as a μ 2 -bridging ligand via two nitrogen atoms of two different trans cyano groups, whi…

Photochemically Produced Singlet Oxygen: Applications and Perspectives

2018

This Review aims to provide early stage researchers with an updated guide to applications of photochemically produced singlet oxygen and, at the same time, widen the experienced researcher's perspectives in a holistic approach to singlet oxygen chemistry. Without being exhaustive, literature between 2010 and early 2018 has been surveyed by focusing on a critical evaluation of new knowledge and applications. After an introductory section concerning singlet oxygen production, detection, and interactions with biological systems, subsequent sections describe current applications of singlet-oxygen-enabled technology. Besides strictly chemical synthesis applications, attention has been given to t…

Mechanism of activated chemiluminescence of cyclic peroxides: 1,2-dioxetanes and 1,2-dioxetanones

2017

Almost all chemiluminescent and bioluminescent reactions involve cyclic peroxides. The structure of the peroxide and reaction conditions determine the quantum efficiency of light emission. Oxidizable fluorophores, the so-called activators, react with 1,2-dioxetanones promoting the former to their first singlet excited state. This transformation is inefficient and does not occur with 1,2-dioxetanes; however, they have been used as models for the efficient firefly bioluminescence. In this work, we use the SA-CASSCF/CASPT2 method to investigate the activated chemiexcitation of the parent 1,2-dioxetane and 1,2-dioxetanone. Our findings suggest that ground state decomposition of the peroxide com…

Harnessing Fluorescence versus Phosphorescence Ratio via Ancillary Ligand Fine-Tuned MLCT Contribution

2016

A series of gold(I) alkynyl-diphosphine complexes (XC6H4C2Au)PPh2—spacer—PPh2(AuC2C6H4X); spacer = —C2(C6H4)nC2— (A1, n = 2, X = CF3; A2, n = 2, X = OMe; A3, n = 3, X = CF3; A4, n = 3, X = OMe), —(C6H4)n— (B5, n = 3, X = OMe; B6, n = 4, X = OMe) were prepared, and their photophysical properties were investigated. The luminescence behavior of the titled compounds is dominated by the diphosphine spacer, which serves as an emitting ππ* chromophore. The complexes exhibit dual emission, comprising low and high energy bands of triplet (phosphorescence) and singlet (fluorescence) origins, respectively. The electron-donating characteristics of ancillary groups X significantly affect the LLCT/MLCT c…

2020

New soluble and intensely near-IR-absorbing transition metal (Ti, Zr, V, Ni) complexes were synthesized using a redox non-innocent N,N’-bis(3,5-di-tertbutyl-2-hydroxy-phenyl) -1,2-phenylenediamine (H4L) as a ligand precursor. In all the complexes, ([Ti(Lox)2, [Zr(Lox)2], [V(Lsq1)(HLox)] and [Ni(HLox)2], two organic molecules coordinate to the metal center as tri- or tetradentate ligands. The solid-state structures of the complexes were determined using single crystal XRD, and the compounds were further characterized with Electrospray Ionisation Mass Spectrometry (ESI-MS). Thermoanalytical measurements indicated the thermal stabilities of the complexes. All compounds absorb strongly in the n…

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

2017

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.

A Molecular Electron Density Theory Study of the Role of the Copper Metalation of Azomethine Ylides in [3 + 2] Cycloaddition Reactions.

2018

The copper metalation of azomethine ylides (AYs) in [3 + 2] cycloaddition (32CA) reactions with electron-deficient ethylenes has been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G(d,p) level, in order to shed light on the electronic effect of the metalation in the course of the reaction. Analysis of the Conceptual Density Functional Theory reactivity indices indicates that the metalation of AYs markedly enhances the nucleophilicity of these species given the anionic character of the AY framework. These 32CA reactions take place through stepwise mechanisms characterized by the formation of a molecular complex. Both nonmetalated and metalated 32CA reactions …

Organotin(IV) derivatives containing heteroditopic pyridyl-quinolin-8-olate ligands: Synthesis and structures

2021

Abstract Six novel neutral organotin(IV) complexes, viz. [n-Bu2Sn(L4-PyAQ)2] 1, [Bz2Sn(L4-PyAQ)2] 2, [Ph2Sn(L4-PyAQ)2] 3, [Ph2Sn(L3-PyAQ)2] 4, [Bz3Sn(L4-PyAQ)] 5 and [Ph3Sn(L4-PyAQ)] 6 have been synthesized via reactions of 3/4-pyridyl-quinolin-8-ol pro-ligands, with appropriate diorganotin oxide and triorganotin hydroxide precursors, respectively. The compounds 1-6 were characterized in solution by means of NMR spectroscopy while the solid-state structures of 1, 6, and of the solvates 2·1.5C6H6, 3·0.25C6H6, 2·4·C6H6, and 5·0.5H2O were authenticated by single crystal X-ray diffraction analysis. In the solid-state, the tin centers in 1-2·4·C6H6 are hexacoordinated and reveal a distorted cis-…

Exploring the Slow Relaxation of the Magnetization in CoIII -Decorated {DyIII 2 } Units

2016

We have prepared and structurally characterized a new member of the butterfly-like {CoIII 2DyIII 2} single-molecule magnets (SMMs) through further CoIIIdecoration, with the formula [CoIII 4DyIII 2(OH)2(teaH)2(tea)2(Piv)6] (teaH3=triethanolamine; Piv=trimethylacetate or pivalate). Direct current (DC) susceptibility and magnetization measurements were performed allowing the extraction of possible crystal-field parameters. A simple electrostatic modeling shows reasonable agreement with experimental data. Alternating current (AC) susceptibility measurements under a zero DC field and under small applied fields were performed at different frequencies (i.e., 10–1500 Hz) and at low temperatures (i.…

A rare polymeric azido-bridged copper(II) chain with a pentameric repeating unit: Synthesis, structure and magnetic properties

2013

International audience; The novel polymeric chain copper(II) complex [Cu4(μ-Mesalpn)2(μ1,1,1-N3)2(μ1,1-N3)2Cu]n (1) was prepared by the reaction of Cu(NO3)2·3H2O with Mesalpn in the presence of an excess of NaN3. A single-crystal X-ray diffraction study showed an unusual 1D polymeric chain based on pentanuclear Cu5 units with both μ1,1,1-N3 and μ1,1-N3 bridges, and with three independent Cu(II) ions presenting three different coordination numbers (4, 5 and 6). The magnetic susceptibility data show the presence of dominant anti-ferromagnetic interactions.