Synthesis, crystal structure, spectroscopic properties, antibacterial activity and theoretical studies of a novel difunctional acylhydrazone

► A novel acylhydrazone from 5-methylisoxazole-4-carboyl hydrazine and benzaldehyde. ► In this work, both crystalline and molecular structure is determined. ► Fluorescence emission peak at 485.96 nm was assigned to ILCT by TD DFT/HF CIS. ► UV–Vis absorption peaks at 194, 217.5 and 290.5 nm were attributed to ILCT by DFT. ► The title compound has both antibacterial activity and photoluminescent property. A novel difunctional acylhydrazone has been synthesized by the reaction of 5-methylisoxazole-4-carboyl hydrazine with benzaldehyde and characterized by X-ray crystallography and spectroscopy. The obtained results demonstrate the crystal belongs to triclinic, space group P 1 ¯ . Moreover, the spectroscopic properties were evaluated through density functional theory (DFT) and time-dependent density functional theory (TD DFT) calculations. The results reveal that UV–Vis absorption peaks at 194, 217.5 and 290.5 nm are mainly attributed to (p, π) → π ∗, partly (p, π) → π ∗ and partly π → π ∗, and predominantly π → π ∗, respectively, with intraligand charge-transfer transition (ILCT) character. The fluorescence emission peak at 485.96 nm should be assigned to ILCT. In addition, the results of antibacterial activities indicate the title compound has certain modest antibacterial activity as well as the broad-spectrum bacteriostasis, which can be supported by the molecular electrostatic potential (MEP). Therefore, the title compound exhibits both antibacterial activity and photoluminescent property, which has potential applications in many fields such as material science and photodynamic therapy.