2.2. Computational details

Geometry optimization of Fig. 1 was carried out utilizing a semiempirical approach (MP6), Hartree–Fock (HF) with the B3LYP method and a 6-311++G (d, p) basis set, and DFT(B3LYP) with various basis sets such as 3TO-3G*, 3-21G+*, 6-31G++G (d, p), 6-311++G(d, p), LanL2DZ, SDD, and DGDZVP. The calculations were performed with Gaussian 09 software³² in both gas and solvents (such as chloroform, benzene, dichloromethane, ethanol, acetone, methanol, dimethyl sulfoxide, and acetonitrile). Solvation effects were investigated using an integral equation formalism polarizable continuum model (IEFPCM).³⁴ The validation process of the optimized geometries included vibrational analysis to confirm that there were no negative vibrational frequencies and to assess convergence criteria such as the RMS force, maximum force, maximum displacement, energy changes, and RMS displacement. The optimized structures were then used for various analyses, including vibrational assignment, analysis of infrared spectra, determination of thermodynamic parameters, and investigation of photophysical properties such as the HOMO, LUMO, dipole moment, and chemical reactivity of SA. The absorption spectra were obtained by TDDFT calculations on the optimized ground state geometry.³⁵ The emission spectra were also determined using TDDFT calculations on the optimized excited state geometry.²⁴