A DFT-based systematic study on nonlinear optical properties of cyclocurcumin

The growing demand for efficient and cost-effective nonlinear optical (NLO) materials has led to the exploration of nature-derived compounds and their potential applications in photonic devices. Naturally occurring curcuminoids are of particular interest due to their conjugated structures and biocompatibility. Among them, cyclocurcumin possesses a distinctive conjugated structure and electronic characteristics, making it an attractive candidate for NLO studies. In this work, ab initio- based density functional theory (DFT) calculations were used to determine the electronic and optical properties of cyclocurcumin. These properties were systematically compared with other curcuminoids using the CAM-B3LYP/6-311+G(d,p) computational approach. The NLO properties, including first ( \(\:β\:\) ) and second ( \(\:γ\:\) ) hyperpolarizabilities were examined under static and dynamic conditions (at wavelength ~ 632.8 nm). Computational results demonstrate that cyclocurcumin exhibits promising NLO responses in different solvent phases. In the static gas-phase \(\:β\:\) and \(\:γ\:\) of cyclocurcumin were calculated to be ~ \(\:\:33.709\) \(\:×\:\:{10}⁻³⁰\) e.s.u. and \(\:~\:91.436×\:\) \(\:{10}⁻³⁶\) e.s.u., respectively. The static gas phase \(\:β\:\) value is comparatively higher than those calculated for curcumin, demethoxycurcumin and bisdemethoxycurcumin. The frequency-dependent hyperpolarizability of cyclocurcumin are comparable to all the other curcuminoids. This study also shows that cyclocurcumin exhibits higher hyperpolarizability than the standard NLO material, urea ( \(\:β\:\:~\:0.367×\:\:{10}⁻³⁰\:\) e.s.u. and \(\:γ\:\) ~ 2.632 \(\:×\:\) 10 − 36 e.s.u.), in the static gas phase. In addition, theoretical absorption and Raman spectroscopic studies corroborate well with the NLO properties of curcuminoids. All these computational results confirm that cyclocurcumin is a promising computational NLO material candidate, with further experimental studies might pave the way for the photonics applications.