2530-10-1Relevant articles and documents
Synthesis of tetrathiafluvalene derivatives with photochromic diarylethene moieties
Uchida, Kingo,Masuda, Go,Aoi, Yoshifumi,Nakayama, Koji,Irie, Masahiro
, p. 1071 - 1072 (1999)
Tetrathiafulvalene (TTF) derivatives with diarylethene moieties have been synthesized. A derivative having 2,4,5-trimethylthiophene rings as the aryl groups showed photochromism, while a derivative with 2,5-dimethylthiophene rings did not show any color change by UV irradiation. The different reactivity was ascribed to the difference in the conformation of thiophene rings in the two derivatives.
Electronic Asymmetry of an Annelated Pyridyl-Mesoionic Carbene Scaffold: Application in Pd(II)-Catalyzed Wacker-Type Oxidation of Olefins
Bera, Jitendra K.,Dutta, Indranil,Kunnikuruvan, Sooraj,Reshi, Noor U Din,Saha, Sayantani,Yadav, Suman
, p. 11385 - 11393 (2020/11/23)
The two donor modules of an annelated pyridyl-mesoionic carbene ligand (aPmic) have different σ- and π-bonding characteristics leading to its electronic asymmetry. A Pd(II) complex 1 featuring aPmic catalyzes the oxidation of a wide range of terminal olefins to the corresponding methyl ketones in good to excellent yields in acetonitrile. The catalytic reaction is proposed to proceed via syn-peroxypalladation and a subsequent rate-limiting 1,2-hydride shift, which is supported by kinetic studies. The electronic asymmetry of aPmic renders a well-defined coordination sphere at Pd. The favored arrangement of reactants on the metal center features an olefin trans to the pyridyl module and a tbutylperoxide trans to the carbene. This arrangement gains added stability by the π-delocalization paved by the compatible orbitals on Pd, the pyridyl module, and the olefin that is perpendicular to the Pd(aPmic) plane. The π-interactions are absent in an alternate arrangement wherein the olefin is trans to the carbene. Density functional theory studies reveal the matching orbital overlaps responsible for the preferred arrangement over the other. This work provides an orbital description for the electronic asymmetry of aPmic.
Electrochromic properties of novel chalcones containing triphenylamine moiety
Jin, Huiyi,Li, Xianggao,Tan, Tingfeng,Wang, Shirong,Xiao, Yin,Tian, Jianhua
, p. 154 - 160 (2014/04/17)
A series of novel electrochromic chalcones containing triphenylamine units were synthesized by Aldol reaction and characterized by NMR, IR and MS. Their optical, electrochemical properties were investigated using UV-vis, photoluminescence spectra and cyclic voltammetry. The molecular orbital energy levels and excitation energies were calculated by quantum chemical calculation. It was found that the fluorescence intensity is decreasing with formation of charge-transfer state. The existence of electron donating group on triphenylamine unites caused a significant bathochromic shift of the UV absorption maximum and increased EHOMO and ELUMO. The electrochromic property of the synthesized compounds was studied by spectroelectrochemical experiments. The results showed that the chalcones containing triphenylamine moiety presented good electrochromic stability, with a color change from yellow to blue as applied potentials ranging from 0.0 to 2.8 V. The coloring and bleaching time was in the range of 2.9-4.2 s and 1.7-3.3 s, respectively.
Single-crystalline photochromism of diarylethene dimers bridged by a spiro structure
Kobatake, Seiya,Kuma, Shunpei,Irie, Masahiro
, p. 960 - 967 (2008/04/13)
New types of diarylethene dimers bridged by a spiro structure were synthesized. One of their dimers formed three kinds of polymorphic forms by recrystallization from different solvents: hexane (1a-α), acetone (1a-β), and acetonitrile (la-γ). In crystals of 1a-α and 1a-β the molecules are packed in solvent-free crystal structures, whereas crystal 1a-γ includes acetonitrile molecules in the crystal. The difference of significant photochromic reactivities in their polymorphic crystals was observed for photocoloration reactions. Crystals 1a-β and 1a-γ showed photochromism in the single-crystal phase, but 1a-α did not do so. Their photochromic reactivity was found to depend on the distance between the reactive carbon atoms by X-ray crystallographic analysis. When the distance is less than 4.2 A in the antiparallel conformation, the molecule can undergo photochromism in the crystal. On the other hand, crystals of bromo-substituted diarylethene dimer (2a) cannot be suitable for X-ray crystallographic analysis when it was recrystallized from hexane, acetone, and acetonitrile. However, it formed single crystal by recrystallization from p-xylene, which showed photochromism in the crystalline phase. The edge-to-face aromatic interaction between p-xylene molecules assisted the crystal growth of the diarylethene dimer. Upon irradiation with ultraviolet light, two kinds of the enantiomers, (M,SS)- and (P,RR)-2b, are produced. Partial photobleaching reactions of either of the two enantiomers by irradiation with linearly polarized visible light were confirmed by polarized absorption spectroscopy. Copyright
