High first‐hyperpolarizabilities of thiobarbituric acid derivative‐based donor‐π‐acceptor nonlinear optical‐phores: Multiple theoretical investigations of substituents and conjugated bridges effect

Abstract

A number of compounds including thiobarbituric acid derivative‐based acceptor unit and diverse donor moieties along with two types of π‐conjugated bridges have been constructed to aid in the design of the superior nonlinear optical (NLO) materials. The effect of varying the donor and bridge parts of this donor‐bridge‐acceptor system was analyzed in terms of structural and opto‐electronic parameters such as bond length alternation and ultraviolet‐visible absorption spectra. Various functionals with aug‐cc‐pVDZ basis set including B3LYP, PBE0, PBE38, BMK, CAM‐B3LYP, and ωB97XD were employed to calculate the static and dynamic first‐hyperpolarizabilities, and also the linear polarizabilities. Furthermore, the variation of the static first‐hyperpolarizabilities has been explained satisfactorily in the light of the sum‐over‐states method and two‐level model. The comprehensive study indicates that the coplanar compound D‐5 with the low electronic absorption energy, strongest oscillator strength paired with the largest ground, and excited state dipole moment difference generates a dramatical increase in its static and dynamic first‐hyperpolarizabilities, which would be the most worthwhile target for development as the NLO‐phores.

Theoretical insights into molecular design of hot-exciton based thermally activated delayed fluorescence molecules

“…However, Δ E ST = 0.18 eV and SOC = 0.13 cm −1 in the S 2 –T 5 channel contribute to a high rate of hRISC from T 5 to S 2 , in the order of 1.1 × 10 7 s −1 , which is significantly quicker than the previously reported k RISC range of 10 2 –10 6 s −1 . 92 The calculated radiative ( k r ) and non-radiative ( k nr ) rates are in the range of previously reported values (Table 1). 92…”

“…1.1 Â 10 7 s À1 , which is significantly quicker than the previously reported k RISC range of 10 2 -10 6 s À1 . 92 The calculated radiative (k r ) and non-radiative (k nr ) rates are in the range of previously reported values (Table 1). 92…”

Synthesis, photophysical and nonlinear optical properties of push–pull tetrazoles

“…The CAM-B3LYP functional is widely utilized to calculate the absorption spectra of organic molecules as well as to predict the hyperpolarizability values of push-pull p-conjugated systems with reliability. [47][48][49] All the geometry optimizations were followed by vibrational analyses to ensure the positive sign of all eigenvalues of the Hessian matrix and to conrm that the stationary point found was a true minimum on the potential energy surface. Vertical excitation energies were computed in acetonitirile using time dependent density functional theory (TDDFT) 58 using the integral equation formalism of the polarized continuum model (IEFPCM) on the optimized ground state geometries in gas phase.…”

“…This suggested that CAM-B3LYP/6-311++G** is a reliable method to calculate hyperpolarizability values of organic molecules, also validated by others. [47][48][49] The calculated b tot values were found to be in the order 1d[ 1b > 1a-1c (Table 3). Compound 1d is predicted to exhibit highest b tot value due to small HOMO-LUMO band gap that results into more efficient charge transfer.…”

DFT and TD-DFT study on quadratic NLO response and optoelectronic activity in novel Y-shaped imidazole-based push-pull chromophores

“…The Coulomb-attenuating method CAM-B3LYP [32] and the Minnesota functional M06-2X [35] in conjunction with 6-311++G(d,p) basis set were used for investigating the gas phase second-order NLO behaviors of the studied chromophores. These two functionals are currently more preferred than the traditional functionals to predict the NLO properties of large π-conjugated systems with a significant CT effect [36][37][38]. In this work, we used the sum-over-states (SOS) method [39] and the two-state model (TSM) [40], based on electronic absorption characteristics, in order to relate the NLO responses of the studied compounds to their linear optical properties.…”