Peculiarities of the Environmental Influence on the Optical Properties of Push–Pull Nonlinear Optical Molecules: A Theoretical Study

Abstract

Gas-phase geometry optimization of NLO-active molecules is one of the standard approaches in the first principle computational methodology, whereas the important role of the environment is usually not considered during the evaluation of structural parameters. With a wide variety of environmentally influenced models in most cases only the high quality single point calculations are prepared. Among different approaches, the most used polarizable continuum model (PCM) seems to be promising. In this study, we have compared the electronic properties of gas-phase optimized geometries of imidazole-derived push-pull compounds with those optimized using PCM solvation approach including CH(2)Cl(2) and PMMA as media. We have focused particularly on the linear optical properties of investigated molecules, namely on the UV-vis absorption spectra. The analysis of presented results shows the applicability of the different quantum chemical (QC) methods for the UV-vis spectra calculations of linear NLO molecules. Herein we also present the need of molecule geometry optimization affected by the environment. Following the performed calculations, the electronic properties of gas-phase optimized molecules give conformable results with respect to those obtained by more time-consuming continuum optimizations. All computational data are supported by experimental investigations.

First Principle Calculations of the Electronic and Vibrational Properties of the 3-(1,1-Dicyanoethenyl)-1-phenyl-4,5-dihydro-1H-pyrazole Molecule

“…Comparing these data to the charge transfer parameter calculated for the DCNP molecule in vacuum, which is equal to 0.053420 one can say that the solvent environment supports the charge transfer mechanism but the molecule shows already a partial charge transfer and the observed effect is not so strong. The obtained results are summarised in Table 3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 16 accordance with our previous work 66 . The most impressive are changes calculated by the DFT/B3LYP methodology.…”

Systematic study on the optimization of a bis(N,N-diethyl)aniline based NLO chromophore via a stronger electron acceptor, extended π-conjugation and isolation groups

“…The HOMO and LUMO levels of chromophores can be calculated from their corresponding oxidation and reduction potentials. 36 The difference between HOMO and LUMO levels provides energy gaps…”

Auxiliary donor for tetrahydroquinoline-containing nonlinear optical chromophores: enhanced electro-optical activity and thermal stability

“…The relative data of 1×10 -4 mol/L chromophores were recorded, as shown in Table 2 and Fig. 26 The difference between these two values provides the HOMO-LUMO energy difference ∆E (CV). The HOMO and LUMO levels of chromophores L1 and L2 can be calculated from their corresponding oxidation and reduction potentials.…”

“…The HOMO and LUMO levels of chromophores L1 and L2 can be calculated from their corresponding oxidation and reduction potentials. 26 The difference between these two values provides the HOMO-LUMO energy difference a l max was measured in chloroform. b l max was measured in dioxane.…”