Nonlinear optical properties of curcumin: solvatochromism-based approach and computational study

Nonlinear optical (NLO) properties of curcumin were studied using solvatochromic method and density functional theory (DFT). DFT calculations were performed to determine the static first hyperpolarisability (β_ο) and its related properties (μ, α₀, Δα, β, )  for curcumin, using B3LYP functional with 6−31G (d), 6−311+G (d) and 6−311+G (d,p) basis sets at the ground-state and excited-state geometries and with CAM-B3LYP using 6−311+G (d,p) basis sets at the ground-state geometry in different solvent environments. In polar solvent environment, the values are slightly lower as compared to the non-polar solvent environments. The results obtained are correlated with the polarisability parameter α_CT, first hyperpolarisability parameter β_CT and the solvatochromic descriptor of γ_SDobtained by the solvatochromic method. The static first hyperpolarisability (β_ο) and its related properties were compared with urea and dibenzoylmethane (β-diketonate) and it is observed that curcumin shows very large values for first hyperpolarisability and its components.