Computational study of nonlinear optical properties of dihydropyridine analogue (1,4-DHP-CHO) using DFT method

Abstract

In the present study, we designed a compound by one-pot reaction of four compounds to synthesise a heterocyclic scaffold called 1,4-dihydropyridine (DHPo), which was then used to synthesise a novel compound from the reaction of DHPo with Vilsmeier reagent (POCl3/DMF) to form 1,4-DHP-CHO. Computationally, Density Functional Theory is employed to investigate the thermodynamic and geometric properties of molecules. The B3LYP hybrid functional and the 6-311G(2d,p) basis set are employed to determine the HOMO, LUMO energy, and Hirshfeld atomic charges. The electronic spectrum was studied using CAM-B3LYP and 6-311G(2d,p) bases sets of the 1,4-DHP-CHO compound. A continuous wave 473nm laser beam with Gaussian intensity profile in the x–y plane propagates along the z-axis traverses dihydropyridine, producing diffraction patterns. We have studied the diffraction patterns temporal evolution, the effect of laser beam wave front and the variation of the power input. The diffraction patterns appeared symmetric with respect to the z-axis then they lose symmetry and appeared asymmetric when the thermal convection current overcome the conduction thermal current. The number of rings in each pattern and the closed aperture Z-scan are used to estimate the nonlinear refractive index, n₂, of the sample. As high as 3.9978 × 10^–7 cm²/W according to the first technique and 0.15 × 10^–7 cm²/W according to the second technique of n₂ are obtained. Two Gaussian laser beams viz., 473 nm and 532 nm as the controlling and controlled beams are used respectively in the all-optical switching. The first beam forced the second one to generate diffraction patterns are employed to investigate the all-optical switching characteristics in the dihydropyridine analogue.