PROTON TRANSFER DYNAMİCS AND HYDROGEN-BOND NETWORK TOPOLOGY İN (E)-1-(2,3-DİMETHOXYBENZYLİDENE)-2-PHENYLHYDRAZİNE: AN İNTEGRATED EXPERİMENTAL–THEORETİCAL STUDY

Hydrazone derivatives are known for their rich tautomeric behavior and the ability to form intra- and intermolecular hydrogen-bond networks that directly influence molecular stability, proton mobility, and electronic structure. This study investigates the proton transfer potential and hydrogen-bond topological features of the synthesized compound (E)-1-(2,3-dimethoxybenzylidene)-2-phenylhydrazine through a combined experimental and theoretical approach. The research integrates FTIR, UV-Vis spectroscopy, and single-crystal X-ray diffraction with advanced quantum chemical methods, including DFT, QTAİM, NCİ index, RDG analysis, and potential energy surface scanning of proton migration pathways. The results show that the molecule exhibits stable intramolecular N–H•••N and N–H•••O hydrogen-bond motifs, forming a partially conjugated H-bond network that lowers the proton-transfer energy barrier. QTAİM analysis confirms the presence of strong bond critical points, while NCI surfaces reveal additional weak interactions stabilizing the molecular conformation. The correlation between electronic distribution, tautomers, and H-bond energetics provides new insights into hydrazone proton dynamics, which are relevant for molecular switches, proton conductors, and functional organic materials.