Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Mechanochemical Synthesis and Structure of the Tetrahydrate and Mesoporous Anhydrous Metforminium(2+)-N,N’-1,4-Phenylenedioxalamic Acid Cocrystal Salt: The Role of Hydrogen Bonding and N→π* Charge Assisted Interactions

Version 1 : Received: 23 September 2020 / Approved: 27 September 2020 / Online: 27 September 2020 (04:12:17 CEST)

How to cite: Chong-Canto, S.; García-Báez, E.V.; Martínez-Martínez, F.J.; Ramos-Organillo, Á.; Padilla-Martínez, I.I. Mechanochemical Synthesis and Structure of the Tetrahydrate and Mesoporous Anhydrous Metforminium(2+)-N,N’-1,4-Phenylenedioxalamic Acid Cocrystal Salt: The Role of Hydrogen Bonding and N→π* Charge Assisted Interactions. Preprints 2020, 2020090660 (doi: 10.20944/preprints202009.0660.v1). Chong-Canto, S.; García-Báez, E.V.; Martínez-Martínez, F.J.; Ramos-Organillo, Á.; Padilla-Martínez, I.I. Mechanochemical Synthesis and Structure of the Tetrahydrate and Mesoporous Anhydrous Metforminium(2+)-N,N’-1,4-Phenylenedioxalamic Acid Cocrystal Salt: The Role of Hydrogen Bonding and N→π* Charge Assisted Interactions. Preprints 2020, 2020090660 (doi: 10.20944/preprints202009.0660.v1).

Abstract

A new cocrystal salt of metformin, an antidiabetic drug, and N,N’-(1,4-phenylene)dioxalamic acid, was synthesized by mechanochemical synthesis, purified by crystallization from solution and characterized by single X-ray crystallography. The structure revealed a salt-type cocrystal 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 supramolecurar structure of the anhydrous microcrystalline mesoporous solid H2Mf(HpOXA)2. The results suggest that their structures, conformation and hydrogen bonding schemes are very similar between them. 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(-)∙∙∙C(), O(-)∙∙∙N+ and bifacial O(-)∙∙∙C()∙∙∙O(-) of n→* charge-assisted interactions are herein described in H2MfA cocrystal salts which could be responsible of the interactions of metformin in biologic systems. The results, support the participation of n→* charge-assisted interactions independently, and not just as a short contact imposed by the geometric constraint due to the hydrogen bonding patterns.

Subject Areas

metformin cocrystal; mechanochemical synthesis; dicationic metformin; water channels; pi-interactions; mesoporous anhydrate

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