An Intra‐Ionic Pyridinium‐Thiophene Dithiocarbazate: Synthesis, Crystal Structure, DFT and Hirshfeld Analyses, and Anticancer Evaluation

Abstract

Cancer remains a critical global health challenge, necessitating the development of novel therapeutics to overcome treatment resistance, systemic toxicity, and limited efficacy of current interventions. A new compound, 1‐(((pyridinium‐2‐ylmethyl)thio)carbonothioyl)‐2‐(thiophene‐2‐carbonyl)hydrazide ( HPyTch ), was synthesized and characterized using elemental analysis, UV–vis, IR, NMR, and SC‐XRD. The compound is stabilized through proton transfer from the hydrazine moiety to the pyridine nitrogen, generating a pyridinium species. DFT calculations showed excellent agreement with experimental data. Fluorescence spectroscopy confirmed the fluorescent nature of HPyTch , with emission at 425 nm upon excitation at 340 nm, indicative of electronic stability and efficient charge transfer. The calculated HOMO–LUMO energy gap of 3.63 eV suggests high reactivity and soft character. Hirshfeld surface analysis and fingerprint plots identified key weak intermolecular interactions, including N···H─C and S···C contacts, visualized as prominent red regions on the Hirshfeld surface. Cytotoxicity against Dalton's lymphoma and HEK cell lines was evaluated using the MTT assay, demonstrating significant anticancer activity with an IC 50 of 35 ± 3.0 µg/mL. Mechanistic investigations revealed that HPyTch induces cytotoxicity by disrupting mitochondrial membrane potential and elevating reactive oxygen species (ROS) levels.