Abstract
The linear and nonlinear optical (NLO) properties of methoxybenzylidene (1) and thiophen-2-ylmethylidene (2) tetrahydronaphthalone derivatives are studied using long-range corrected density functional theory (LC-DFT). The calculated hyperpolarisabilities indicate that both compounds have measurable NLO properties (approximately one to two times the hyperpolarisability of p-nitroaniline). Charge-transfer indices and time-dependent DFT calculations suggest that the NLO properties are a result of a charge-transfer excitation, which is typical in conjugated donor-acceptor structures. The ultraviolet-visible spectra of 1 and 2 are also predicted using gap-fitting schemes, and these data are used to assess how accurately the hyperpolarisabilities of 1 and 2 could be estimated by the solvatochromic method.