3,3′-Azothiophene

Abstract

Methyl 3-nitrothiophene-2-carboxylate was reduced with bismuth(III) chloride/potassium borohydride to give an unstable hydroxylamine which was oxidised without isolation using iron(III) chloride to give methyl 3-nitrosothiophene-2-carboxylate. Condensation of this with methyl 3-aminothiophene-2-carboxylate furnished the azodiester. This was more conveniently obtained by manganese dioxide oxidation of the aminoester. Hydrolysis of the azodiester to give the diacid followed by decarboxylation gave 3,3′-azothiophene which could be oxidised to 3,3′-azoxythiophene with hydrogen peroxide. The azodiester was oxidised to the corresponding azoxydiester with urea-hydrogen peroxide/trifluoroacetic anhydride and reduced to the related hydrazothiophenediester with diimide.

The structural and electronic properties of 3,3′-azothiophene photo-switching systems

“…Using UV-VIS and FTIR spectroscopy and assisted with DFT calculations, we explore the photo-physical and photo-chemical properties of novel 3,3-AT and 3,3-ATM molecular systems, the synthesis of which we reported previously. 25 Comparing experimental results and theoretical predictions, we confirm that both systems demonstrate anti 15 (or trans) to syn 15 (or cis) and syn to anti photo-induced isomerizations upon exposure to radiation at 365 nm and 530 nm, respectively. In contrast to the results of analogous experiments on azobenzenes, 16,[34][35][36] the photo-products of 3,3-AT and 3,3-ATM, where the -N=Nmoiety is expected to be in syn(cis) geometry, demonstrate persistent stability under darkness at room temperature.…”

“…Synthesis and purification of 3,3-azothiophene (3,3-AT) and 2,2-bismethoxycarbonyl-3,3-azothiophene (3,3-ATM) was conducted as reported previously. 25 We conducted ultravioletvisible (UV-VIS) spectroscopy and temperature dependent kinetic studies using an ATi Unicam UV/VIS spectrometer, Akribis Scientific Ltd., and a F12-GB refrigerated/heating circulator, JULABO GmbH, Seelbach, Germany. We equipped the UV-VIS spectrometer with a shutter to secure darkness between sampling intervals (of 0.1 second) during the kinetic studies.…”

“…24 Success in photo-switching of bioactive functionalities using a range of molecular mechanisms 14,24 is inspiring. In a recent publication 25 we reported the synthesis of 3,3-azothiophene. In this article we report on the structural and photo-physical properties of 3,3-azothiophene and 2,2-bismethoxycarbonyl-3,3-azothiophene: see Fig.…”