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Synthesis and Halochromic Properties of 1,2,6‐Tri‐ and 1,2,3,6‐Tetra‐aryl Azulenes
Author(s) -
Zhu Qiang,
Png Zhuang Mao,
Lin Tingting,
Loh Xian Jun,
Tang Tao,
Xu Jianwei
Publication year - 2021
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.202100261
Subject(s) - azulene , chemistry , protonation , thiophene , photochemistry , molecule , trifluoroacetic acid , aryl , fluorene , absorption spectroscopy , absorption (acoustics) , organic chemistry , polymer , ion , alkyl , physics , quantum mechanics , acoustics
A series of novel 2,6‐functionalized azulene molecules Azu1‐3 with varied fluorene substituents at the 1‐ and 3‐positions of azulene as well as at the 5’‐position of 2‐thiophene group were synthesized. Their electronic absorption and emission spectra at neutral and protonated states were examined. It was found that after functionalization with fluorenyl groups, Azu1‐3 exhibited absorption maxima at 445, 451 to 468 nm, respectively. In contrast, their corresponding protonated species showed much redshifted absorption maxima at 560, 582 to 643 nm, respectively, mainly due to the extension of conjugation length and the large dipole moment along the C 2v axis of 2,6‐substituted azulene molecules. Azu1‐3 are non‐fluorescent in their neutral forms, but became emissive in their protonated states. Analysis of absorption and emission spectra shows that substitution of the 1‐ or 3‐position of azulene led to decrease in response to trifluoroacetic acid.