We herein report the first sodium borate-squarate, namely, Na₂(C₄O₄)(H₃BO₃)(H₂O)₄·H₃BO₃ (1). It has been successfully synthesized via introducing the planar π-conjugated (C₄O₄)²⁻ into a borate system. Compound 1 exhibits a strong second-harmonic-generation (SHG) response (2.1 × KDP), wide transparency in the ultraviolet (UV) region and a suitable birefringence of 0.26 at 1064 nm. Theoretical calculations indicate that the synergy effect between inorganic planar π-conjugated species H₃BO₃ and organic moiety (C₄O₄)²⁻ dominates the SHG process.

中文翻译：

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Na2(C4O4)(H3BO3)(H2O)4·H3BO3：第一个通过优异的协同作用获得的具有强 SHG 响应的硼酸盐-正方形

我们在此报道了第一种方硼酸钠，即Na ₂ (C ₄ O ₄ )(H ₃ BO ₃ )(H ₂ O) ₄ ·H ₃ BO ₃ (1)。它已通过将平面 π 共轭 (C ₄ O ₄ ) ²⁻引入硼酸盐系统而成功合成。化合物 1 表现出强烈的二次谐波产生 (SHG) 响应 (2.1 × KDP)、在紫外 (UV) 区域的宽透明度以及在 1064 nm 处适当的双折射率为 0.26。理论计算表明无机平面π共轭物种H _{3之间的协同作用}BO ₃和有机部分 (C ₄ O ₄ ) ²⁻主导 SHG 过程。