Crystal structure from laboratory X-ray powder diffraction data, DFT-D calculations, Hirshfeld surface analysis, and energy frameworks of a new polymorph of 1-benzothiophene-2-carboxylic acid

Several benzothiophene-based compounds, including 1-benzothiophene-2-carboxylic acid, exhibit a wide variety of pharmacological activities. They have been extensively used to treat various types of diseases with high therapeutic effectiveness. In this contribution, the crystal structure of a new polymorph of 1-benzothiophene-2-carboxylic acid (BTCA) was determined from laboratory X-ray powder diffraction data with DASH, refined by the Rietveld method with TOPAS-Academic. and optimized using DFT-D calculations. The new form of 1-benzothiophene-2-carboxylic acid crystallizes in space group C2/c (No. 15) with a = 14.635(4), b = 5.8543(9), c = 19.347(3) angstrom, beta= 103.95(1)degrees, V = 1608.8 (6) angstrom(3), and Z= 8. The structure is a complex 3D arrangement which can be described in terms of hydrogen-bonded dimers of BTCA molecules, joined by the acid-acid homosynthon, which interact through C-H center dot center dot center dot O hydrogen bonds to produce tapes further connected through head-to-tail pi center dot center dot center dot pi and edge-to-face C-H center dot center dot center dot pi interactions. A comparison with a previously reported triclinic polymorph and with the related 1-benzofuran-2-carboxylic acid (BFCA) is also presented. (C) The Author(s), 2021. Published by Cambridge University Press on behalf of International Centre for Diffraction Data.

Automated summary

This study presents the crystal structure of a new polymorph of 1-benzothiophene-2-carboxylic acid (BTCA), determined from laboratory X-ray powder diffraction data and refined using the Rietveld method. The structure features a complex 3D arrangement with hydrogen-bonded dimers of BTCA molecules and various intermolecular interactions, such as pi stacking and hydrogen bonding. A comparison with previously reported polymorphs and related compounds is also provided.