4 - Acetylpyridine - succinic acid cocrystal: Synthesis, X-ray structure, DFT and Hirshfeld surfaces analysis

Abstract

A new cocrystal (ACP−SA) of 4−acetylpyridine (ACP) with succinic acid (SA) has been synthesized by slow evaporation method and characterized. The single crystal X-ray diffraction technique confirmed the coexistence of ACP and SA molecules in a 1:0.5 ratio in an asymmetric unit. The ACP−SA crystallizes in a monoclinic space group P2₁/n, with a = 9.0185(14) Å, b = 8.8955(14) Å, c = 10.9044(18) Å, β = 93.017(3)°, V = 873.6(2) ų, Z = 4. Classical O−H⋯N and non classical C−H⋯O hydrogen bonds aid in stabilizing the supramolecular architecture of ACP−SA by creating D(2) and $R_4^4(22)$ motifs. In addition, density functional theory (DFT) computations were performed to get insights into the structure and intermolecular interactions of ACP−SA cocrystal. The TGA/DSC thermogram revealed that the cocrystal began to degrade at temperatures over 78 °C and retained its crystallinity up to 106 °C. The nature of the interactions and their contribution to the crystal packing is quantitatively measured using Quantum topological atoms in molecule (QTAIM), 3D Hirshfeld surfaces analysis and 2D fingerprint plots. The maximum percentage contribution of H⋯H (40%), O⋯H (32%) and C⋯H (11.6%) interactions were identified from Hirshfeld surfaces analysis. With the aid of both experimental and computational methods, the crystal packing and hydrogen bonding were examined.

Graphical Abstract

Keywords:

• Cocrystal
• Hirshfeld surfaces
• hydrogen bonding
• QTAIM
• single crystal XRD

Acknowledgments

QIW and CKQ thank the Ministry of Higher Education Malaysia for Fundamental Research Grant Scheme with Project Code: FRGS/1/2020/STG07/USM/02/4. SPJ thanks DST-PURSE Lab, Mangalore University for the thermogravimetric analysis. SPJ also thanks MHRD RUSA Lab, Mangalore University for the NMR analysis. BN thanks UGC for financial assistance through BSR one-time grant (SR/S/Z/-23/2010/32) for the purchase of chemicals. TK acknowledges SASTRA Deemed University for the computational facilities).

Disclosure statement

The authors of this manuscript have no direct financial relationship with the commercial identities mentioned in the manuscript which might lead to a conflict of interest.

Additional information

Funding

BN thanks University Grant Commission for financial assistance through BSR one-time grant [SR/S/Z/-23/2010/32] for the purchase of chemicals. TK acknowledges financial support by the Department of Science and Technology, New Delhi, India under DST-FIST project [Project No: SR/FST/PS-1/2020/135].