Synthesis, crystal structure, Hirshfeld surface analysis and theoretical studies of bis(substituted benzylidene)ethan-1,2-diamines

•Two novel Schiff bases were prepared and characterized.•Single crystal XRD of the compounds I (monoclinic, P21/n), and II (triclinic, Pī) were confirmed.•DFT calculations and Hirshfeld surface analysis of compounds I and II were performed. In the present work, two novel diamine-based benzylidine were synthesized via conventional reaction. The structures of the resulting N,N'-(ethane-1,2-diyl)bis[1-(3,5-dimethoxyphenyl)methanimine] (I) and N,N'-(ethane-1,2-diyl)bis{1-[4-(diethoxymethyl) phenyl]methanimine} (II) were established with the help of spectral-analytical techniques like; FTIR, ¹H, and ¹³C NMR spectrometry. The compounds were further characterized by TG/DSC. The structures were further confirmed by single-crystal XRD. Compounds I and II were analysed using Density Functional Theory (DFT) through the B3LYP method with 6–31G(d,p), as basis sets to determine bond lengths, bond angles, dihedral angles, Mulliken atomic charges and molecular electrostatic potential (MEP) of compounds. The MEP analysis revealed that electronegative elements in the structure possess the maximum electronic cloud. The distributions of the various atoms were probed by Mulliken population analysis. Hirshfeld surface analysis gives an idea about the close contacts associated with molecular interactions. Fingerprint plots of the Hirshfeld surfaces were used to locate and analyse the percentage of hydrogen bonding interactions.