A DFT Investigation on the Structure, Spectroscopy (FT-IR and NMR), Donor-Acceptor Interactions and Non-Linear Optic Properties of (±)-1,2-Dehydroaspidospermidine

In this study, (+/-)-1,2-Dehydroaspidospermidine was analyzed by elemental analysis, H-1 and C-13 NMR, and FT-IR spectra. Also, because the starting geometry is essential to evaluate the structural, electronic, and spectral properties of this compound, we used the potential energy surface (PES) scan by the B3LYP/6-31G(d,p) hybrid functional to determine the stable structures of the (+/-)-1,2-Dehydroaspidospermidine. Thus, three stable conformations of the compound were used in all of the electronic and spectroscopic simulations performed by the M06-2X, G96LYP, and B3LYP functionals at the 6-311++G(d,p) basis set in a vacuum and chloroform. After the observed and simulated FT-IR and NMR data were compared, the second order perturbative theory in the NBO (Natural Bond Orbital) basis was used to interpret the critical donor-acceptor interactions; the dominant contribution to the lowering of the second order energy for all conformers was the pi -> pi* and sigma -> pi* interactions. Also, we used both NLO (Non Linear Optic) and FMO (Frontier Molecular Orbital) analyses to investigate the non-linear optical property and the biochemical reactivity of the compound. The results of this work demonstrated that the compound has an available non-linear optical property (beta=6.62 x 10(-30) esu) that can be used in optoelectronic technology, and, besides, it has biological activity because of its strong intramolecular interactions.