Solvent Effects on Nonlinear Optical Properties of Novel Para-nitroaniline Derivatives: A Density Functional Approach

The ground state geometrical energy, dipole moment, polarizability and first static hyperpolarizability of para-nitroaniline (PNA), 2-methyl-4-nitroaniline (MNA), N-methyl-4-nitroaniline (HMNA), N-methyl-2-methyl-4-nitroaniline (HMMNA), 4-nitrodimethylaniline (NDMA) and N- (4-nitrophenyl) -N-methylaminoacetonitrile (NPAN) has been investigated by density functional theory (DFT) using B3LYP/6-311G* basis set. The calculation results revealed that hyperpolarizability and its related properties were enhanced in various degrees upon successive substitution of alkyl groups at amino group of the PNA molecule. In order to study the effects of solvents, quantum chemical calculations on the studied molecules were carried out in different dielectric constants media, in vacuum, chloroform, ethanol and DMSO. The solvent induced effects on the non-linear optical properties were studied and found to be enhanced NLO properties of the molecules as dielectric constants of the solvents increases. The frontier molecular orbital of the compounds also computed and it was found that for all of the studied molecules the enhanced NLO properties are associated with the decrease in the EHOMO-ELUMO gap.