T. Murai, Hidenori Furukawa, K. Yamaguchi
2018
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Journal
Heterocycles
Abstract
5-Amino-2-(4-methylsulfanylphenyl)thiazoles were prepared by reacting 4-methylsulfanylbenzthioamides and N,N-diarylthioformamides. Demethylaiton of the resulting thiazoles gave 4-sulfhydrylphenylthiazoles. Starting from these thiazoles, a range of thiazoles with sulfur-containing functional groups were prepared. Oxidation of the thiazoles also gave thiazoles with sulfenyl and sulfonyl groups. The photophysical properties of a series of thiazoles were determined. The effects of sulfur-containing functional groups on the electronic structures of the thiazoles were elucidated by DFT calculations. Oxidation of the divalent sulfur atoms introduced to thiazoles helped to lower the energy levels of the LUMOs of the resulting thiazoles. INTRODUCTION The development of a wide range of fluorescent molecules is of paramount importance since they have been shown to be useful in a variety of applications in the material sciences, in the sensing of hazardous compounds and metals, and in the biomolecular sciences. Most low-molecular-weight fluorescent compounds possess ring-fused polycyclic aromatic moieties. In contrast, we have focused on monocyclic aromatic compounds that have thiazole cores. In particular, we recently established synthetic methods for compounds with N-arylamino groups at the 5-position of thiazoles in a series on main group chemistry. We also determined their fundamental photophysical properties and used them in white-light emission, the generation of radical cations showing near-infrared absorption, and the detection of halogenated solvents via vapochromic behaviors. In some cases, pyridyl groups were used as anchor moieties to interact with Lewis acidic compounds. Sulfur-containing functional groups may be useful as alternative anchor moieties, since thiols and sulfonic acids are acidic and nucleophilic, and the sulfur atom can be HETEROCYCLES, Vol. 97, No. 1, 2018 409