Quadratic Nonlinear Optical Response of Composite Polymer Materials Based on Push-pull Quinoxaline Chromophores with Various Groups in Aniline Donor Moiety

Composite polymer materials doped with original push-pull choromophores with quinoxaline core in conjugated bridge have been developed. Chromophores with various substituents in aniline donor moiety and tricyanofuran acceptor are characterized...

Composing NLO Chromophore as a Puzzle: Electrochemistry-based Approach to Design and Effectiveness

A series of D-π-A, D-π-D'-π-A, D-π-A'-π-A nonlinear optical chromophores with vinylene π-electron bridges or bridges with π-deficient/π-excessive heterocyclic moieties along with the corresponding precursors D-vinylene, D-π-D', D'-π-A, D-π-A' and A'-π-A are synthesized and studied both experimentally and computationally. The effect of the heterocycle in the π-electron bridge on the oxidation/reduction potentials and the energy gap (ΔE^el ) is investigated in detail. The properties of the D-π-A'(D')-π-A chromophores are shown to correlate with those of building blocks: the oxidation potential is determined by the D-vinylene, and the reduction potential is determined by A'(D')-π-A truncated compounds. The contribution of the acceptor to the oxidation potential of chromophores in comparison with those of the precursors was estimated and analyzed in terms of electronic communication between the end groups. A good correlation between the ΔE^el and the chromophores' first hyperpolarizability is revealed.

Characterization of Conjugation Effects in the Series of Quinoxaline-2-ones by Means of Vibrational Raman Spectroscopy

A broad series of quinoxalinone-based π-conjugated donor-acceptor fluoro- and NLO-phores is characterized by means of Raman spectroscopy and single-crystal X-ray analysis supported by quantum chemical computations. Intense Raman spectroscopic markers that allow the differentiation of even closely related structures are identified. The intensities of these bands are shown to be related to the conjugation of the different molecular moieties, and they can provide an estimation of its extent. The intensity redistribution between these markers serves as a source of auxiliary structural information capable of pointing to a distortion of the conjugation or to the influence of aggregation effects in the condensed state. A simple relation between the intensity of the marker and the position and oscillator strength of the lowest-energy electronic absorption band of quinoxalinones allows a linking of the Raman effect with the optical properties of these compounds, which can be used for the rational design of novel species with improved optical characteristics.