Effect of auxiliary electron-donating group on the microscopic nonlinear optical properties of vinyl and azobenzene based chromophores

Abstract

A series of organic nonlinear optical chromophores containing different auxiliary electron-donating groups (alkoxy, benzyloxy and alkyl) and p-conjugated bridges (vinyl and azobenzene) have been synthesized and systematically characterized using UV-Vis spectroscopy, density functional theory calculation and thermogravimetric analysis. The microscopic molecular hyperpolarizability was obtained via the simple solvatochromism method, where the synthesized chromophores were dissolved in several solvents with different refractive index for absorption spectra measurement. It was found that the introduction of auxiliary groups obviously improved the microscopic molecular hyperpolarizability of all the synthesized chromophores, especially for the benzyloxy modified azobenzene based chromophore, up to sevenfold enhancement of molecular hyperpolarizability as well as good visible light transmittance and thermal stability up to 247°C were obtained, which should be mainly attributed to the enhanced charge transfer enabled by the benzyloxy modification that is confirmed by the electron density distribution in the highest occupied molecular orbital and lowest unoccupied molecular orbital.

Solvent dependent linear and nonlinear optical properties of triphenylamine unit incorporated difluoroboron β-diketonate complexes

“…The strong π-electron delocalization [52] which is beneficial for the charge transfer and the extension of the conjugation length [53] can both increase the nonlinear optical properties. Similar to the situation for the TPA, azobenzene [54,55], thiophene [56,57] and styryl units [53,58] etc. have been adopted to examine the influence of D/A and the conjugation bridge on the nonlinear optical properties in different molecular systems.…”

“…As a heterocyclic ring, the thiophene unit has reduced aromaticity and higher electron density, which is suitable for the application in NLO chromophores as the conjugation bridge [57,61]. In this study, through the introduction of triphenylamine moiety and thiophene ring unit into the BF 2 bdks conjugated system and tuning the conjugation extension with the vinyl moiety, we synthesized four ICT compounds, namely, TBT, TVBVT, TSBST and TSVBVST, and studied their optical properties under various conditions.…”

Tunable Non-linear Refraction Properties and Ultrafast Excited State Dynamics of Dicyanomethylene Dihydrofuran Derivative

“…The second-order non-linear coefficient d 33 was 15.2 pm/V at wavelength of 1,064 nm. Tang et al ( 2016a , b ) synthesized a series of DCDHF derivatives with different substituent groups. They find that the different substituent groups and conjugate length can significantly influence the second order polarizability of DCDHF derivatives.…”