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Abstract In this paper, alkyl groups with different lengths are introduced to the two-dimensional spindle-type chromophores as the steric isolators to improve the poling efficiency and long term stability of the poled polymers for second-order nonlinear optical materials. The structure and thermal properties of alkyl functionalized chromophores are characterized by the 1H NMR, FT-IR, UV–Vis, DSC, TGA et al. The chromophores with different alkyl groups present extremely similar maximum absorbance wavelength (480 nm), which means they have very similar first-order hyperpolarizability. Guest-host polymer doped with chromophores has been prepared. Those materials display different glass transition temperatures and good thermal stability. According to the electro-optic coefficients studies and poling efficiency results, chromophores with longer alkyl side chain groups exhibit better poling efficiency and larger electro-optic coefficients. Especially for the chromophores with octyl group, the poling efficiency increases up to 3 times compared to the reference chromophore 2-(3-{2,5-Phenylmethanol-4-[4-(dimethylamino)styryl]-styryl-5,5-dimethylcyclohex-2-enylidene)malononitrile (STC), while the corresponding electro-optic coefficient of the poled polymers increases up to 4 times, indicating a significant effect of the isolate groups on improving the poling efficiency. Highlights • We synthesized a series of two-dimensional spindle-like chromophores with different length of alkyl groups. • Two-dimensional spindle-like chromophores had good thermal stabilities and met the requirements of the poling process. • Chromophores with longer alkyl groups and linear alkyl group had better long-term stability, poling efficiency and larger electro-optic coefficient. • Poling efficiency of chromophores with octyl group increased up to 3 times and electro-optic coefficient of poled polymers increased up to 4 times compared to STC. [ABSTRACT FROM AUTHOR]

Abstract: A series of two-dimensional spindle-type chromophores has been synthesized. The detailed synthetic procedure was reported. The factors that influence the nonlinear optical properties such as the donors and acceptor character have been investigated. The chemical structures of the target products have been confirmed by IR, UV–Vis and NMR spectroscopy, elemental and thermal analysis. The spindle-type chromophores have been used to prepare host-guest doped films which exhibited very good thermal and temporal stability. The nonlinear electro-optical coefficients of the host-guest doped films were measured by the Teng-Man technique and gave values in the range from 21 to 29 pm/V. [Copyright &y& Elsevier]