Triazole-functionalized copper(II) porphyrin: Synthesis, structure, photophysics, Hirshfeld analysis and antibacterial activity

A triazole-functionalized copper(II) porphyrin complex, Cu-TTPP, derived from tetrakis[4-(1,2,4-triazol-1-yl)phenyl]porphyrin was synthesized and comprehensively characterized. Successful metalation of the porphyrin macrocycle was confirmed by UV-vis spectroscopy, as shown by a blue shift of the absorption bands and a decrease in the number of Q bands. Single-crystal X-ray diffraction revealed that Cu-TTPP crystallizes in the monoclinic system and that the Cu(II) center adopts a square-planar coordination geometry with four pyrrolic nitrogen atoms of the porphyrin core. Solid-state UV-vis spectroscopy gave an optical band gap of 1.89 eV. Electrochemical measurements indicated the presence of multiple electroactive sites, which facilitate charge transfer and reduce charge-transfer resistance. Frontier molecular orbital calculations and Hirshfeld surface analysis further supported the experimental results. Two-dimensional fingerprint plots and dnorm mapping showed that the crystal packing is mainly stabilized by H⋯H, C⋯H and N⋯H intermolecular interactions, contributing 39.3%, 24.5% and 23.0%, respectively. In vitro antibacterial assays demonstrated that Cu-TTPP exhibits notable activity against Escherichia coli and Staphylococcus aureus, with a stronger inhibitory effect toward the Gram-positive bacterium S. aureus. These results clarify the structural, photophysical, electrochemical and biological properties of this triazole-substituted copper porphyrin complex and indicate its potential for antimicrobial applications.