Schiff Bases from α-ionone with Adenine, Cytosine, and l-leucine Biomolecules: Synthesis, Structural Features, Electronic Structure, and Medicinal Activities

Tea is a very important source of the terepenoid α-ionone, which is much appreciated as a medicinal beverage. Schiff bases are a very important class of organic compounds usually formed by the condensation of carbonyl compounds with amines. α-ionone is a carbonyl terpenoid obtained from Schiff bases on condensation with nucleobases like adenine and cytosine and the amino acid l-leucine. We synthesized these three Schiff bases and characterized them using UV, FTIR, and H1 and C13-NMR spectra. The molecules were optimized using B3LYP/6-311+G(2d,p) level followed by the simulation of FT-IR spectra, of which the simulated and experimental spectra showed complete agreement. The UV spectra were simulated using TD-DFT, and the electronic excitations were carefully analyzed. Natural bond orbitals provided an analysis of the stability of the compound, which is supplemented by the data from frontier molecular orbital analysis. Detailed wavefunction analysis is reported which predicts the active centers, reactivity profile, and the extent of non-covalent interactions. PASS indicated that compounds show antieczemic properties and antiarthritic properties, which is confirmed with the help of molecular docking results.