Spectroscopic and DFT approach for structure property relationship of red emitting rhodamine analogues: A study of linear and nonlinear optical properties

Abstract

Abstract Linear and nonlinear optical (NLO) properties of triphenyl fused rhodamine analogues were estimated by spectroscopic based mathematical calculations and compared with computed values using density functional theory (DFT) calculations. Various Global hybrids (GHs) and range separated hybrids (RSHs) were utilized for reliable estimations of NLO properties. Spectroscopic based mathematical calculations of polarizability (αCT), first order hyperpolarizability (βCT) and second order hyperpolarizability (γ) were performed in varying polarity solvents. Spectroscopic based mathematical calculted αCT, βCT and γ values are found to have much closer agreement with the DFT computed values obtained by using RSHs. Comparative analysis of αCT, βCT and γ values suggested that these values increases with the increase of triphenylamine substitutions. Moreover, αCT, βCT and γ values increase with decreasing HOMO-LUMO band gap for all the dyes. N-[9-(isobenzofuran-1(3H)-one)-6-(dipnenylamino)-xanthene]-N-diphenyl amine having bis-triphenylamine substituent showed the largest NLO response among all analogues dyes.