Fluorescence emission studies on 1-phenyl-4-aroyl(and acyl)-1 H-1,2,3-triazoles

Abstract

Fluorescence emission from 378 nm excitation yielded fluorescence quantum yields Q f, radiative lifetimes τ 0, and fluorescence rate constants k f, in the range of 0.0004–0.0069, 17–132 ns and (0.9–18.2)×10 6 s −1, respectively, for seven 4-aroyl(acyl) derivatives of 1-phenyl-1,2,3-triazoles in chloroform solutions. The fluorescence lifetimes, τ f, are estimated to be 0.01–0.45 ns. Some substitution effects are detected in the fluorescence emission parameters. The strong π-electron donor, 5,10-dihydrocarbazolo[3,4-c]carbazole, is found to be quenched by triazoles at quenching rates of 7.7×10 10–2.8×10 12 M −1 s −1. The high rates of fluorescence quenching, k q, are attributed to a ground state complexation between 1,2,3-triazoles and the strong π-electron donor carbazolocarbazole. 1,2,3-Triazoles have shown intense solvatochromic absorbance shifts in n-hexane, chloroform and methanol. Absorbance shifts reaching 44 nm were observed from polar to protic solvents.