Comparative theoretical studies on natural atomic orbitals, natural bond orbitals and simulated UV-visible spectra of N-(methyl)phthalimide and N-(2 bromoethyl)phthalimide

摘要

The charge delocalization patterns of phthalimide derivatives such as N-(methyl)phthalimide and N-(2-bromoethyl)-phthalimide have been performed with the help of natural bond orbital (NBO) analyses and simulated UV-visible spectra. The second order perturbation energies of the most interacting NBOs and the population of electrons in core, valance and Rydberg sub-shells have been predicted by density functional theory (DFT) computations in GAUSSIAN 03W software package. In the present study, the natural atomic orbital occupancies showed the presence of charge delocalization within the molecule. The natural hybrid atomic orbital studies enhance us to know about the type of orbitals and its percentage of s-type and p-type character. In addition, the excited electronic transitions along with their absorption wavelengths, oscillator strengths and excitation energies for the gaseous phase of the title molecules have been computed at TD-DFT/B3LYP/6-311++G(d,p) method. The energetic behaviour of the compound in different solvent medium (water, ethanol, and methanol) has been examined by applying polarizable continuum model (PCM). The complete molecular orbital simulations and theoretical UV-visible spectra have been carried out in this study which yield better understanding of charge delocalization pattern and stability of the title molecules to a greater extent.