In this work, we present the theoretical quantum chemical calculation of UV–Vis spectroscopy and electronic effect delocalization of π-conjugated molecular system variation based of benzodifuran (BDF) derivatives with 6-substituted by furan, thiophene or pentafluorophenyl cycles by azomethine bonds. For the geometrical optimization, dipole moments and frontier molecular orbital HOMO and LUMO energies we use the Becke’s functional B3LYP with a polarized and diffused 6-31+G(d,p) basis set. For the first (β) and second (γ) hyperpolarizabilities calculation we use the time-dependent Hartree–Fock (TDHF) method with 6-31+G(d,p) basis set. In particular, we discuss correlation between the chemical structures of benzodifuran based derivatives and their NLO properties.

Simulation of UV–VIS spectra and microscopic third-order nonlinear optical (NLO) coefficients at 532 nm wavelength of molecules based of anthocyanidin structure in gas phase environment using semi-empirical PM3 method was calculated. One-photon absorption characterizations of the investigated molecules have been theoretically obtained by configuration interaction method with doubly occupied molecular orbitals. Estimated theoretical spectra shows a sensibility to the different functional groups such as hydroxyl and methoxyl substitution in radicals. These groups causes red shift in absorption spectra in comparison to the other samples what agree well with the experimental data. Adjunction of such functional donor character group in the investigated molecule slightly decreases the HOMO–LUMO energy splitting gap but increases the ground state dipole moment resulting the substantial increase of NLO coefficient in this system comparing to the other samples. According to presented investigations the tested molecules have large nonlinear optical properties.