Charge transfer and nonlinear optical properties of anthraquinone D-π-A dyes in relation with the DFT based molecular descriptors and perturbational potential

Abstract

The static and dynamic NLO properties of Anthraquinone based (D-π-A) dyes are determined by using the Density Functional Theory in ten different functionals. Five global hybrids and five long-range corrected hybrid functionals used based on Hartree-fork exchange contribution. The investigation of vertical excitation is also performed in the equivalent set of functionals. The elaborate study of molecular configuration i.e. intramolecular charge transfer character is analyzed by Frontier Molecular Orbital study, bond length alternation, bond order alternation, molecular electrostatic potential plot, quinoidal character (δr), and electrophilicity index (ω). Benchmarking studies are initiated with the standard deviation method and, the functionals BHHLYP and ωB97 resulted as the suitable functionals for determining the NLO properties of anthraquinone based dyes. The less studied reactivity descriptor hyper-hardness (Γ) and perturbation potential (Vo) is also explored and correlated with the NLO properties. The substitution effect on NLO properties is further confirmed by Hammett constant and excited state Hammett substituent constant.