Crystal and Quantum Chemical Exploration of the Potent Monocarbonyl Curcuminoids to Unveil Their Structural and Intriguing Electronic Properties

The two isomeric trifluoromethane and nitro containing monocarbonylcurcuminoids: (1E,4E)-2-methyl-1-(4-nitrophenyl)-5-(4 (trifluoromethyl)phenyl)penta-1,4-dien-3-one (DI-MNTDO ) and (1E,4E)-2-methyl-5-(4-nitrophenyl)-1-(4-(trifluoromethyl)phenyl)penta-1,4-dien-3-one (MO-MNTDO)have been prepared by two consecutive aldol condensation reactions. The chemical structures of the DI-MNTDO and MO-MNTDO have been determined using X-ray crystallographic and spectrometric methods. The single crystal X-Ray diffraction (SC-XRD) data reveals that DI-MNTDO contains two geometrically different molecules in the asymmetric unit, while, MO-MNTDO contains one molecule in the asymmetric unit. Additionally, molecular geometric parameters, vibrational spectral analysis, as well as electronic properties of the above-mentioned molecules have been studied utilizing DFT/B3LYP/6-31G (d, p) approach. The UV-Vis spectral analysis was performed utilizing the time-dependent density functional theory (TD-DFT) with the same level. The natural bond orbitals (NBOs) investigation has been carried out at the B3LYP/6-311+G(d,p) approach to explain the intramolecular hyper conjugative interactions. A plausible concurrence is acquired between experimental and theoretical findings. The frontier molecular orbitals (FMOs) have been achieved by above-mentioned level of theory. Subsequently, the global reactivity parameters are calculated using the energies of FMOs. The chemical potential (mu) order: [MO-MNTDO (mu=-5.0785 eV)] < [DI-MNTDO (mu=-4.9465 eV)]. The obtained findings in context of stability as well as reactivity indicate that DI-MNTDO is more stable and less reactive as compared to MO-MNTDO.