Peripheral structural modification for devising push–pull strategy into 1,3,5-triaryl-2-pyrazoline-based compounds for nonlinear optical insights via density functional theory approach

The nonlinear optical (NLO) insights of triarylpyrazoline-based (Z)-2-(2-((7-(4-(5-[2,4-dimethylphenyl]-1-phenyl-4,5-dihydro-1H-pyrazol-3-yl)phenyl)-4,4,9,9-tetramethyl-4,4a,9,10a-tetrahydro-s-indaceno[1,2-b:5,6-b′]dithiophen-2-yl)methylene)-3-oxo-2,3-dihydro-1H-inden-1-yl)malononitrile (PR) and its derivatives P1–P7 were explored in this study. The compounds: PR and P1–P7 having donor–π–acceptor configurations and M06/6-311G(d,p) functional was selected to inquire the dipole moment (μ), linear polarizability (α), first hyperpolarizability (β), and second hyperpolarizability (γ). The findings of perturbed Kohn–Sham relations were deciphered to derive charge density of the molecules. The optical analysis was performed in gaseous phase and their findings were observed in 544.2–697.1 nm range. Moreover, the natural bond orbitals, frontier molecular orbitals, density of state, and transition density matrices for the aforesaid compounds were also calculated at aforesaid level. Global reactivity parameters of PR and P1–P7 were analyzed by using highest occupied molecular orbital–lowest unoccupied molecular orbital energies. Overall, all above-mentioned findings revealed significant optical nonlinear response in these pyrazoline-based scaffold (PR and P1–P7). However, among all the compounds, P3 has shown the highest nonlinearity with maximum μ_tot, <α>, β_tot, and γ_tot values at 19.4 D, 1.78 × 10⁻²², 2.57 × 10⁻²⁷, and 3.13 × 10⁻³² a.u., respectively. Hence, the current computational study might prove to be fruitful for the exploration of proficient NLO materials for optoelectronic devices.