Physicochemical properties of (Z)-3-(4-((Hydroxymethyl)(methyl)amino)phenyl)-2-(4-halophenyl) acrylonitriles: A comprehensive experimental and theoretical study

Abstract

In this study, halogen-substituted (-F, -Cl, and -Br) and unsubstituted (Z)-3-(4-((hydroxymethyl)(methyl)amino)phenyl)-2-(4-halophenyl)acrylonitriles (1–4) were synthesised to investigate the effect of halogen atoms and N-2-hydroxyethyl group on their physicochemical properties. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were employed to investigate their frontier molecular orbitals, global reactivity descriptors, optical properties, and internal reorganization energies in comparison to their precursors (A–D). The N-2-hydroxyethyl group significantly altered the optical and electronic properties, leading to fluorescence quenching in compounds 1–4. Crystal structure analysis of compounds 1 and 4, using CLP-PIXEL, Hirshfeld surface (HS) analysis, and Bader's quantum theory of atoms in molecules (QTAIM), revealed lattice energies 5–6 kcal mol^-1 higher than those of their precursors (A and D), attributed to O–H···O/N interactions facilitated by the N-2-hydroxyethyl group. A slight red shift in λ_max values followed the trend 1 <2 <3 <4, indicating halogen substitution effects. In contrast a significant shift between compounds 1–4 and their precursors (A–D) demonstrated the influence of the N-2-hydroxyethyl group. Experimental band gap values from electrochemical and UV–Vis measurements aligned well with TD-DFT calculations, further supporting the theoretical findings.