Synthesis of new azobenzo[c]cinnolines and investigation of electronic spectra and spectroelectrochemical behaviours

Abstract

A series of disazobenzo[c]cinnoline dyes was prepared by coupling reaction of 3,8-dihydroxybenzo[c]cinnoline with diazotised aromatic amines. The structures of these dyes were confirmed using UV-Vis, FTIR, H-1 NMR, LC-MS/MS and LC-MS/TOF spectroscopic techniques. C-13 NMR, C-13-DEPT, H-1-H-1 COSY, H-1-C-13 HMQC and H-1-C-1(3) HMBC spectra of dye 12 were demonstrated in this study. In addition, the effects of the substituent attached to the phenyl ring, solvent and acid-base on the UV-Vis spectra of the dyes were investigated. Besides, voltammetric and spectroelectrochemical behaviours of four disazobenzo[c]cinnolines (2, 8, 11 and 13) in acetonitrile (ACN) solution were also evaluated. It was observed that the disazobenzo[c]cinnoline derivatives indicated reversible voltammetric behaviour in acetonitrile-tetrabutylammonium perchlorate (ACN-TBAP) solution. A square-wave potential step method coupled with optical spectroscopy was used to probe switching times and optic contrast of the dyes. (C) 2021 Elsevier B.V. All rights reserved.