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Synthesis, Mesogenic and Spectroscopic Properties of 2,5‐Disubstituted Thiophene Derivatives
Author(s) -
Han Jie,
Wang YanMei,
Wang XiaoGuang
Publication year - 2006
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.200690298
Subject(s) - mesogen , thiophene , chemistry , mesophase , liquid crystal , crystallography , proton nmr , conjugated system , elemental analysis , carbon 13 nmr , polymer , organic chemistry , liquid crystalline , phase (matter) , physics , optics
Two series of 2,5‐disubstituted thiophene derivatives (series 1 : 2,5‐bis( p ‐alkoxyphenylethynyl)thiophene and series 2 : 2,5‐bis[ p ‐( p ‐alkoxyphenylethynyl)(phenylethynyl)]thiophene) were synthesized and characterized by 1 H NMR, 13 C NMR, HRMS and elemental analysis. The relationship between the structure and the mesogenic and spectroscopic properties has been discussed. The results show that compounds 1a – 1f all exhibited an enantiotropic nematic mesophase, which was confirmed by the polarized optical microscopy (POM), differential scanningcalorimeter (DSC) and variable temperature powder X‐ray diffraction (PXRD). In contrast, the extended conjugated analogues 2a – 2b had no liquid crystal properties. As for the spectroscopic properties, incorporating more phenylethynyl units results in red‐shifted absorption and emission spectra, greatly enhanced quantum efficiency.