Low Oxidation Potential Tetrathiafulvalene Analogues Based on 3,4-Dialkoxythiophene π-Conjugating Spacers
摘要:
Tetrathiafulvalene analogues involving dihexyloxythiophene (1), ethylenedioxythiophene (2), and bis(3,4-dihexyloxy-2-thienyl)ethylene (3) as conjugating spacer and diversely substituted at the 1,3-dithiole ring (R) have been synthesized. Electronic absorption spectra show the expected decrease of HOMO-LUMO gap when increasing the electron-releasing power of R or the length of the conjugating spacer. Cyclic voltammetry (CV) shows that whereas compounds 1 and 2 are reversibly oxidized into their cation radical and dication through two one-electron steps, for compounds 3 the dication is formed directly via a two-electron transfer. Comparison of the data for compounds 2 and 3 with those of their respective analogues based on thiophene and dithienylethylene shows that introduction of the electron-donating alkoxy groups at the 3 and 4 positions of the thiophene ring produces a 150-200 mV negative shift of the first redox potential (E degrees(1)). On the other hand, CV data for compounds 1 and 2 reveal several unusual features such as E degrees(1) approximate to 0.10 V/SCE ranking among-the lowest known to date and a Coulombic repulsion between positive charges in the dication larger than for the analogue ct-donors based on unsubstituted thiophene. These results are interpreted by a major reorganization of the electronic distribution in the donor molecule due to alkoxy groups: the highest electron density moving from the 1,3-dithiole moiety toward the central thiophene ring.
Two series of push-pullchromophores built around thiophene-based pi-conjugating spacersrigidified either by covalent bonds or by noncovalent intramolecular interactions have been synthesized and characterized by UV-vis spectroscopy, electric field induced second harmonic generation (EFISH) and differential scanning calorimetry. Comparison of the linear and second-ordernonlinear optical properties
New tricyanopyrroline (TCP) chromophores with rigid–flexible dendron were prepared for second‐order nonlinearoptical (NLO) application. The chromophores were fully characterized using ultraviolet‐visible spectroscopy, nuclear magnetic resonance spectroscopy and mass spectrometry. Thermal gravimetric analysis (TGA) revealed that the chromophores had excellent thermal stability. Large λmax and high
Nucleophilic <i>ipso</i>-Substitution of Aryl Methyl Ethers through Aryl C–OMe Bond Cleavage; Access to Functionalized Bisthiophenes
作者:Abhishek Kumar Mishra、Ajay Verma、Srijit Biswas
DOI:10.1021/acs.joc.6b02701
日期:2017.4.7
A metal and solvent free strategy to functionalize aryl methyl ethers through direct nucleophilicsubstitution of aryl C–OMe bond has been described. A wide range of O, S, N, and C-centered uncharged nucleophiles has been successfully employed. Using this protocol, functional derivatives of bisthiophene have been synthesized in a straightforward way. The reactions are highly atom-efficient and generate
Synthesis and Photovoltaic Properties of Polythiophene Incorporating with 3,4-Difluorothiophene Units
作者:Linquan Huang、Dong Yang、Qiang Gao、Yan Liu、Shengmei Lu、Jian Zhang、Can Li
DOI:10.1002/cjoc.201300505
日期:2013.11
Two polythiophene derivatives using fluorine atoms and hexyl or hexyloxy group as electron‐withdrawing and donating substituents have been synthesized. The introduction of fluorine atoms to the polythiophene backbones simultaneously lowers the HOMO and narrows the bandgap, and the stronger electron‐donating ability of hexyloxy side chain further reduces the bandgap. As a result, poly[3‐hexylthiophene‐2