Structure and thermodynamical properties of metformin salicylate

Abstract

The behavior under thermal conditions of the cocrystal formed by metformin and salicylic acid was studied by DSC, crystallography (single-crystal), and powder diffraction (WAXS). Metformin salicylate crystallizes in space group P21/c, with the salicylate anion showing a planar structure, stabilized by strong intramolecular hydrogen bonds. The more flexible metformin cations link through the oxygen atoms of salicylate, forming a dense hydrogen-bonding network. The compound exists initially as a salt, metformin salicylate, but after melting and cooling, it is transformed into a glass form that crystallizes and melts again, showing different behaviors depending on the heating rate. © 2013 American Chemical Society.This work was supported by SAF2009-12422-C02-02 and RTA (RED Trastornos Adictivos RD06/001/0014) as well as by FEDER funding and the Spanish Ministerio de Economía y Competitividad MAT2006-01997, MAT2010-15094, and the Factoría de Crystalización (Consolider Ingenio 2010).Peer Reviewe