Extensive Study of Rhodanine-Arylamine-Based Chromophores: Consolidated Optical, DFT/TD-DFT and Non-Linear Optical Properties

摘要： Three push-pull rhodanine-arylamine based D-π-A dyes (2a-2c) are prepared to study the effect of donor on electronic, linear and nonlinear optical properties. The dyes, 2a,2b and 2c have a vinyl spacer conjugated with triphenylamine, julolidine, and carbazole donors respectively, with a methoxy group and rhodanine-3-acetic acid. The dyes exhibited solvent dependent absorption-emission up to the red region with large Stokes shifts (2a = 77-130 nm). This dyes possess charge transfer characteristics as established by transition dipole moment (μeg), dipole moment ratio (μe/μg), Generalised Mulliken-Hush analysis, and electron distribution (DFT). The non-linear optical study revealed that quadratic hyperpolarizability (μβCT) are 1098.9 (2a), 515.0 (2b) and 339.6 x 10-48 e.s.u. (2c) depending on donor strength. The intrinsic hyperpolarizabilities fall below βint0 = 10-3/2 limit i.e. less than unity. Solvatochromic two-level model is used to study the trends in two photon cross-section (σ2PA). The dye 2a exhibited high σ2PA, 216 GM (λmax 485 nm and 564 nm). The dyes 2a and 2c with analogue dye 3a show reverse saturable absorption (RSA) therefore, show positive third order nonlinear absorption coefficient, β and reasonable values of third order nonlinear susceptibility and high laser damage threshold. The Re χ(3) factors are responsible for the high values of χ(3) in the range of 0.77 to 8.09 x 10-12 e.s.u. Therefore, this material would serve as good candidate in the photonic application.