Ether, sulfide and sulfone derivatives of cinnamaldehyde: Insights into synthesis, structural elucidation and solvatochromism

Abstract

Symmetric ether, sulfide and sulfone derivatives based on Schiff base functionalized group (3a-c) were synthesized via classical condensation of 4,4′-diaminodiphenyl precursors (1a-c) and cinnamaldehyde (2) in methanol at ambient reaction settings. The compounds were characterized using CHN, UV–Vis, FTIR, and 1H- and 13CNMR. The origin of absorption spectra was chased using Time-Dependent Density-Functional Theory (TD-DFT) in order to figure out the electronic transitions. The compounds exhibited almost a similar electronic potential as displayed by the molecular electrostatic potential. The energy gap of these materials was extracted from the computational approaches, showing ΔE of 3.778, 3.724, and 4.014 eV respectively for 3a, 3b, and 3c. These values were further harnessed to estimate the global reactivity parameters. Moreover, the electrophilic and nucleophilic points were examined through surface analysis of the optimized structures via DFT simulations. Such investigations support the compounds’ molecular structures via common noncovalent interaction, like hydrogen bonding and non-classical C–H…π forces. Experimental and computational findings were in a respectable agreement to display that only compound 3c possesses the ability of altering its maximum absorption under different solvent conditions. A substantial shifting of the maximum absorption was noticed with ethyl alcohol at λmax = 321 nm, referring to a 32 nm of blue shift in respect to acetic acid, which could be responsible for the partial protonation of the sulfone group.