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Intermolecular interactions, charge‐density distribution and the electrostatic properties of pyrazinamide anti‐TB drug molecule: an experimental and theoretical charge‐density study
Author(s) -
Rajalakshmi Gnanasekaran,
Hathwar Venkatesha R.,
Kumaradhas Poomani
Publication year - 2014
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s205252061303388x
Subject(s) - chemistry , intermolecular force , charge density , density functional theory , molecule , hydrogen bond , electron density , crystallography , lattice energy , crystal structure , computational chemistry , electron , physics , organic chemistry , quantum mechanics
An experimental charge‐density analysis of pyrazinamide (a first line antitubercular drug) was performed using high‐resolution X‐ray diffraction data [(sin θ/λ) max = 1.1 Å −1 ] measured at 100 (2) K. The structure was solved by direct methods using SHELXS 97 and refined by SHELXL 97. The total electron density of the pyrazinamide molecule was modeled using the Hansen–Coppens multipole formalism implemented in the XD software. The topological properties of electron density determined from the experiment were compared with the theoretical results obtained from CRYSTAL09 at the B3LYP/6‐31G** level of theory. The crystal structure was stabilized by N—H...N and N—H...O hydrogen bonds, in which the N3—H3 B ...N1 and N3—H3 A ...O1 interactions form two types of dimers in the crystal. Hirshfeld surface analysis was carried out to analyze the intermolecular interactions. The fingerprint plot reveals that the N...H and O...H hydrogen‐bonding interactions contribute 26.1 and 18.4%, respectively, of the total Hirshfeld surface. The lattice energy of the molecule was calculated using density functional theory (B3LYP) methods with the 6‐31G** basis set. The molecular electrostatic potential of the pyrazinamide molecule exhibits extended electronegative regions around O1, N1 and N2. The existence of a negative electrostatic potential (ESP) region just above the upper and lower surfaces of the pyrazine ring confirm the π‐electron cloud.