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

Fluorescence emission from 378 nm excitation yielded fluorescence quantum y ields Q(f), radiative lifetimes tau(0), and fluorescence rate constants k(f ), in the range of 0.0004-0.0069, 17-132 ns and (0.9-18.2) x 10(6) s(-1), r espectively, for seven 4-aroyl(acyl) derivatives of 1-phenyl-1,2,3-triazole s in chloroform solutions. The fluorescence lifetimes, tau(f), are estimate d to be 0.01-0.45 ns. Some substitution effects are detected in the fluores cence emission parameters. The strong pi-electron donor, 5,10-dihydrocarbaz olo[3,4-c]carbazole,is found ito be quenched by triazoles at quenching rate s of 7.7 x 10(10)-2.8 x 10(12) M-1 s(-1). The high rates of fluorescence qu enching, k(q), are attributed to a ground state complexation between 1,2,3- triazoles and the strong pi-electron donor carbazolocarbazole. 1,2,3-Triazo les have shown intense solvatochromic absorbance shifts in n-hexane, chloro form and methanol. Absorbance shifts reaching 44 nm were observed from pola r to protic solvents. (C) 1999 Elsevier Science B.V. All rights reserved.