Experimental and computational studies on the absorption properties of novel formazan derivatives

Eight novel 3-(4-(benzyloxy)phenyl)-5-(4-bromophenyl)-1-(4-substituted-phenyl)formazan (4a-4h) were synthesized by coupling of substituted phenylhydrazones with diazonium salts of 4-bromoaniline. The substituted phenylhydrazones, which are intermediate products, were obtained from the condensation of substituted phenylhydrazines with 4-(benzyloxy)benzaldehyde. All target compounds were characterized by using FTIR, $^{1}$H NMR, $^{13}$C NMR, LC$-$MS spectrometry, and elemental analysis. Absorption spectra of these compounds in solvents with different polarities were investigated thoroughly. Time-dependent density functional theory (TD-DFT) studies were conducted to shed light on their electronic structures, Kohn--Sham orbitals, and electronic transitions.