Crystal engineering of a new pharmaceutical polymorph of Gallic acid monohydrate: A structural comparative study and chemical computational quantum investigations
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Date
2023-11
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Publisher
Royal Society of Chemistry
Abstract
This study reports the synthesis, crystal structure, and theoretical characterization of a novel, seventh pharmaceutical polymorph of Gallic acid monohydrate (GAM-VII). Single-crystal X-ray diffraction at 100 K reveals that GAM-VII crystallizes in the triclinic $P\bar{1}$ space group, featuring a unique disordered water molecule ($\text{O2W}$) that forms extensive hydrogen-bonding networks and bridges adjacent layers. Within the crystal lattice, Gallic acid molecules adopt a syn $\text{COOH}$ orientation to form centrosymmetric $(\text{COOH})_2$ dimers with an $R_2^2(8)$ motif, while Hirshfeld surface analysis confirms that $O-H\cdots O$ hydrogen bonds and $\pi\cdots\pi$ stacking interactions primarily drive the 3D structural stabilization. Furthermore, quantum chemical computations show that GAM-VII possesses the highest dipole moment among all known GAM polymorphs, highlighting strong polar interactions that enhance its overall stability and demonstrating the crucial role of water molecules as design elements in crystal engineering for active pharmaceutical ingredients (APIs).
Description
Author Affiliation: Dr. Redouane Tekouacht - Abbes Laghrour University, Khenchela, Algeria.
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Citation
CrystEngComm, 2023, 25(45), 6279-6290.