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

Molecules. 2020 Feb 10;25(3):751. doi: 10.3390/molecules25030751.

Abstract

p-Coumaric acid (pCA) and trans-ferulic acid (TFA) were co-crystallised with 2-amino-4-picoline (2A4MP) and 2-amino-6-picoline (2A6MP) producing organic salts of (pCA-)(2A4MP+) (1), (pCA̶ )(2A6MP+) (2) and (TFA̶ )(2A4MP+)·( 3 2 H2O) (3). For salt 3, water was included in the crystal structure fulfilling a bridging role. pCA formed a 1:1 salt with 2A4MP (Z' = 1) and a 4:4 salt with 2A6MP (Z' = 4). The thermal stability of the salts was determined using differential scanning calorimetry (DSC). Salt 2 had the highest thermal stability followed by salt 1 and salt 3. 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.

Keywords: hydroxycinnamic acids; multicomponent crystals; organic sals; p-coumaric acid; trans-ferulic acid.

MeSH terms

  • Calorimetry, Differential Scanning
  • Coumaric Acids / chemistry*
  • Crystallization
  • Crystallography, X-Ray
  • Hydrogen Bonding
  • Picolines / chemistry*
  • Propionates / chemistry*
  • Salts / chemistry
  • Solvents
  • Spectrophotometry, Infrared
  • Spectroscopy, Fourier Transform Infrared

Substances

  • Coumaric Acids
  • Picolines
  • Propionates
  • Salts
  • Solvents
  • 2-amino-4-picoline
  • ferulic acid
  • p-coumaric acid