Quasi liquid Schiff bases from trans-2-hexenal and cytosine and l-leucine with potential antieczematic and antiarthritic activities: Synthesis, structure and quantum mechanical studies

•Two quasi liquid Schiff bases from trans-2-hexenal with cytosine and l-leucine.•Structure, IR, NMR and UV analysis and electronic properties analysed.•Quantum mechanical studies map reactivity centres and electrostatic surface.•Drug candidates: drug-likeness analysis.•Docks well with eczema and arthritis proteins. Trans-2-hexenal, a naturally compound found to be present abundantly in tea. We synthesized imines/Schiff bases by the condensation of trans-2-hexenal with bioactive molecules like cytosine and l-leucine. We characterized the Schiff bases using various spectroscopic methods like FT-IR, UV–Vis, and FT-NMR, etc., followed by detailed electronic structure studies using different theoretical models. Detailed vibrational and electronic spectral explanations are reported using experimental spectra and theoretically simulated spectra. The electronic spectra were generated using TD-DFT and same basis sets. Schiff base from cytosine was found to show good light-harvesting properties (61.98%). Physical and chemical properties, active sites, biological activities, stabilities, light-harvesting efficiency, light-polarization properties, occupancies of electrons in nature of bonding orbitals, weak, and strong hydrogen bonds, steric force of interactions, delocalization of electrons, and reactive sites for nucleophilic, electrophilic attacks, and drug likeness property were determined and reported. PASS and subsequent docking studies indicate that the first Schiff base show anti-eczematic and second Schiff base shows acrocylindropepsin inhibitor properties.