Premium
Ethynylene‐Bridged Conjugate Carbazole Trimers: Synthesis and their Structural, Photophysical, and Electrochemical Properties
Author(s) -
Shimasaki Toshiaki,
Iwasawa Ryosuke,
Watanabe Motonori,
Teramoto Naozumi,
Shibata Mitsuhiro
Publication year - 2017
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.201700088
Subject(s) - carbazole , chemistry , homo/lumo , sonogashira coupling , time dependent density functional theory , photochemistry , density functional theory , conjugate , fluorescence , monomer , absorption (acoustics) , electrochemistry , crystallography , computational chemistry , molecule , organic chemistry , palladium , polymer , catalysis , materials science , mathematical analysis , mathematics , electrode , physics , quantum mechanics , composite material
A series of six new ethynylene‐bridged conjugate carbazole trimers ( 1 – 6 ) were synthesized through sequential Pd‐catalyzed Sonogashira cross‐coupling reactions. The structural properties of these trimers were examined by using DFT calculations. Compound 6 , in which the two terminal carbazole moieties were substituted at the 1‐position, exhibited the longest‐wavelength UV/Vis absorption maximum in CH 2 Cl 2 , whereas compound 1 , in which the two terminal carbazole moieties were substituted at the 3‐position, exhibited the shortest‐wavelength absorption maximum. These trends were rationalized by using TDDFT calculations. Electrochemical measurements and DFT calculations revealed that trimers 1 – 6 had smaller HOMO–LUMO gaps compared with that for the corresponding monomer ( 14 ), which was caused by a lowering of the LUMO levels, rather than by a raising of the HOMO levels. Trimers 2 – 6 exhibited excellent emission properties with high fluorescence quantum yields, which were derived from their rigid structures.