Mechanochemical Synthesis and Structure of the Tetrahydrate and Mesoporous Anhydrous Metforminium(2+)-<i>N</i>,<i>N</i>'-1,4-Phenylenedioxalamic Acid (1:2) Salt: The Role of Hydrogen Bonding and n→π * Charge Assisted Interactions
A new organic salt of metformin, an antidiabetic drug, and <i>N</i>,<i>N</i>'-(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-typ...
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| Main Authors: | , , , , |
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| Format: | Book |
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MDPI AG,
2020-10-01T00:00:00Z.
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| Summary: | A new organic salt of metformin, an antidiabetic drug, and <i>N</i>,<i>N</i>'-(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 H<sub>2</sub>Mf(HpOXA)<sub>2</sub>∙4H<sub>2</sub>O. X-ray powder, IR, <sup>13</sup>C-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 H<sub>2</sub>Mf(HpOXA)<sub>2</sub>. 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<sup>−</sup>, as well as its structure in the solid, is herein reported for the first time. Regular O(δ−)∙∙∙C(δ), O(δ−)∙∙∙N<sup>+</sup> and bifacial O(δ−)∙∙∙C(δ)∙∙∙O(δ−) of n→π * charge-assisted interactions are herein described in H<sub>2</sub>MfA 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. |
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| Item Description: | 10.3390/pharmaceutics12100998 1999-4923 |