Organic Salts of p -Coumaric Acid and Trans -Ferulic Acid with Aminopicolines

<i>p</i>-Coumaric acid (<i>p</i>CA) and <i>trans</i>-ferulic acid (TFA) were co-crystallised with 2-amino-4-picoline (2A4MP) and 2-amino-6-picoline (2A6MP) producing organic salts of (<i>p</i>CA^&#8722;)(2A4MP⁺) (<b>1</b>), (<i>p</i>CA^̶ )(2A6MP⁺) (<b>2</b>) and (TFA^̶ )(2A4MP⁺)&#183;(<inline-formula> <math display="inline"> <semantics> <mrow> <mfrac> <mn>3</mn> <mn>2</mn> </mfrac> </mrow> </semantics> </math> </inline-formula>H₂O) (<b>3</b>). For salt <b>3</b>, water was included in the crystal structure fulfilling a bridging role. <i>p</i>CA formed a 1:1 salt with 2A4MP (<i>Z</i>&#8217; = 1) and a 4:4 salt with 2A6MP (<i>Z</i>&#8217; = 4). The thermal stability of the salts was determined using differential scanning calorimetry (DSC). Salt <b>2</b> had the highest thermal stability followed by salt <b>1</b> and salt <b>3</b>. The salts were also characterised using Fourier transform infrared (FTIR) spectroscopy. Hirshfeld surface analysis was used to study the different intermolecular interactions in the three salts. Solvent-assisted grinding was also investigated in attempts to reproduce the salts.

Abstract licence: CC BY

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