A new organic salt of metformin, an antidiabetic drug, and N,N′-(1,4-phenylene)dioxalamic acid, was mechanochemically synthesized, purified by crystallization from solution and characterized by single X-ray crystallography. The structure revealed a salt-type crystal hydrate composed of one dicationic metformin unit, two monoanionic units of the acid and four water molecules, namely H₂Mf(HpOXA)₂∙4H₂O. X-ray powder, IR, ¹³C-CPMAS, thermal and BET adsorption–desorption analyses were performed to elucidate the structure of the molecular and supramolecular structure of the anhydrous microcrystalline mesoporous solid H₂Mf(HpOXA)₂. The results suggest that their structures, conformation and hydrogen bonding schemes are very similar. To the best of our knowledge, the selective formation of the monoanion HpOXA⁻, as well as its structure in the solid, is herein reported for the first time. Regular O(δ−)∙∙∙C(δ), O(δ−)∙∙∙N⁺ and bifacial O(δ−)∙∙∙C(δ)∙∙∙O(δ−) of n→π * charge-assisted interactions are herein described in H₂MfA organic salts which could be responsible of the interactions of metformin in biologic systems. The results support the participation of n→π * charge-assisted interactions independently, and not just as a short contact imposed by the geometric constraint due to the hydrogen bonding patterns.

中文翻译：

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四水合物和介孔无水二甲双胍(2+)-N,N′-1,4-苯二草酰胺酸(1:2)盐的机械化学合成和结构：氢键和n→π * 电荷辅助相互作用的作用


采用机械化学方法合成了抗糖尿病药物二甲双胍和N , N '-(1,4-亚苯基)二草氨酸的新型有机盐，通过从溶液中结晶纯化，并通过单 X 射线晶体学表征。结构显示为盐型晶体水合物，由一个二甲双胍单元、两个酸的单阴离子单元和四个水分子组成，即H ₂ Mf(HpOXA) ₂ ∙4H ₂ O。X射线粉末，IR， ¹³ C-通过 CPMAS、热和 BET 吸附-脱附分析来阐明无水微晶介孔固体 H ₂ Mf(HpOXA) ₂的分子结构和超分子结构。结果表明它们的结构、构象和氢键键合方式非常相似。据我们所知，本文首次报道了单阴离子 HpOXA ^-的选择性形成及其在固体中的结构。 n→π 的常规 O(δ−)∙∙∙C(δ)、O(δ−)∙∙∙N ⁺和双面 O(δ−)∙∙∙C(δ)∙∙∙O(δ−) * 本文描述了 H ₂ MfA 有机盐中的电荷辅助相互作用，其可能是二甲双胍在生物系统中相互作用的原因。结果支持 n→π * 电荷辅助相互作用的独立参与，而不仅仅是由于氢键模式造成的几何约束所施加的短接触。