Synthesis, crystal structure and photoluminescence of 3-(1-benzotriazole)-4-methyl-coumarin

A novel coumarin derivative containing an electron-transporting moiety (benzotriazole), 3-(1-benzotriazole)-4-methyl-coumarin (BMC), was synthesized from starting substances, i.e. benzotriazole and 2-hydroxyacetophenone. The compound structure was verified by FT-IR, 1H NMR, element analysis and single crystal X-ray crystallography. Crystallographic data reveal a dihedral angle of 108° between the coumarin and benzotriazole rings, which is attributed to the spatial hindrance of a 4-positioned methyl group. The fluorescence and UV–vis absorption of BMC were discussed. The compound exhibits a strong UV emission peak at 385 nm under 360 nm excitation. The molecular structure of BMC was optimized using density functional theory (DFT) at B3LYP/6-31G(d) level, showing that the optimized geometric parameters are in good agreement with experimental data. In addition, the HOMO and LUMO levels of BMC were deduced.