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D-π-A chromophores based on novel macroacceptors − fused azinylmethylenemalononitriles (fused azine = pyrido [2,3-b]pyrazine, quinoline, quinoxaline and quinoxalin-2-one) − have been synthesized and their linear and nonlinear optical properties in gas, solution and in poled PMMA-based films have been investigated by DFT, UV–vis and second harmonic generation technique. The transition from chromophores with an azine acceptor to ones with azinylmethylenemalononitrile acceptors leads to a 10-fold increase in calculated μβ values. Poled polymer films doped with studied chromophores at 25 wt% load exhibit quadratic nonlinear optical activity with d 33 values up to 42 pm/V. [Display omitted] • Novel acceptors for NLO chromophores - fused azinylmethylenemalononitriles - are proposed. • Various push-pull azinylmethylenemalononitrile-based chromophores have been synthesized. • Macroacceptors provide tenfold increase of calculated μβ compared to azine ones. • Poled polymer films with 25 wt% chromophore load demonstrate d 33 values up to 42 p.m./V. [ABSTRACT FROM AUTHOR]

Impact of π-deficient heterocyclic core (A′) in conjugated bridge of D-π-A′-π-A chromophores (D = N,N- dihexylaniline, A = tricyanofuran derivative) on optical and thermal properties has been investigated. Three new chromophores with vinyl-hetaryl-vinyl bridges containing π-deficient benzoazine moiety (quinoxaline, quinoxalinone and quinoline) have been synthesized along with new chromophores with vinyl-thiophene-vinyl bridge containing π-excessive heterocycle and short vinylene bridge, and their properties are compared to reveal the role of π-deficient hetaryl moiety. Their linear optical properties were systematically investigated by UV–Vis spectroscopy and molecular nonlinear optical (NLO) characteristics were predicted by DFT calculations. As the aromaticity of the heterocycle in the bridge increases, a hypochromicity and hypsochromic shift of the absorption maximum manifest themselves in the UV–Vis spectra, the origin of electron transitions was studied by TD-DFT with CAM-B3LYP and PBE0 density functionals. The calculated first hyperpolarizability, β tot , for A′ = quinoxaline, quinoline and thiophene, was shown to be almost independent on the type of the π-bridge core, being in a narrow interval 800–831⋅10−30 esu, while for A′ = quinoxalinone β tot is essentially higher (996⋅10−30 esu). All chromophores exhibit good thermal stability (T d > 192 °C). Thin films of composite polymer materials with PMMA matrix and studied chromophores as guests as well as of some molecular glasses were spin-cast and corona-poled, and their quadratic NLO activity was measured by two different techniques. For materials with guest chromophores containing quinoxalinone, quinoxaline and thiophene moieties in the bridges NLO coefficients d 33 were found to be rather close and reached 76 pm/V, what is almost 3 times higher than that for polymer film with quinoline-based chromophore. Rather high values of NLO coefficients for molecular glasses based on chromophores with quinoline, thiophene and quinoxalinone cores were obtained: 52, 124 and 132 pm/V, respectively, which notably exceed the values for composite materials with these chromophores as guests. [Display omitted] • First representative of a new class of NLO chromophores with divinylquinoline bridge was synthesized. • UV–vis spectra of quino(xa)line chromophores have high-intensity line in higher energy region. • Polymer composites with quinoxalin(on)e and thiophene chromophores have close d 33 values. • Quinoxalinone chromophore molecular glass exhibits high NLO coefficient value of 132 p.m./V. [ABSTRACT FROM AUTHOR]