Solvent effects on the electronic structure, excited states, and nonlinear optical properties of two anthracene-based chalcone derivatives: a DFT and TD-DFT study.

CONTEXT: Anthracene-based chalcones are π-conjugated donor-acceptor chromophores with potential second-order nonlinear optical applications, but solvent-field polarization and solvent-induced geometry relaxation can affect their response in different ways. This work compares ANT-IND and ANT-DMNAF, which differ in donor environment, to identify how the medium controls absorption and static first hyperpolarizability. Solvation red-shifts the principal UV band by about 14 nm and substantially increases the computed nonlinear optical response. Methanol-optimized ANT-DMNAF reaches β ‖ = 10269 a . u . ( 88.7 × 10 - 30 e s u ) , exceeding ANT-IND under the same conditions and indicating a solvent-dependent crossover in the computed NLO ranking.

METHODS: Gas-phase and solvated geometries were optimized with density functional theory at the CAM-B3LYP/6-31 + G(d,p) level using the SMD continuum model in Gaussian 16. Harmonic frequency calculations confirmed true minima. The six media considered comprise the gas phase plus five solvents: n-hexane, toluene, dichloromethane, methanol, and DMSO. Time-dependent DFT calculations with 30 excited states provided UV-Vis spectra, and static dipole moments, isotropic polarizabilities, and first hyperpolarizabilities were obtained analytically. NLO properties were evaluated with both fixed gas-phase geometries (GasGeom) and solvent-relaxed geometries (SolvGeom); this comparison is used as a computational sensitivity analysis and not as an experimentally separable partition of the response.