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Accurate H-atom parameters for the two polymorphs of L-histidine at 5, 105 and 295 K

Lookup NU author(s): Dr Mike Probert

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Abstract

© 2021 International Union of Crystallography. All rights reserved.The crystal structure of the monoclinic polymorph of the primary amino acid l-histi­dine has been determined for the first time by single-crystal neutron diffraction, while that of the orthorhombic polymorph has been reinvestigated with an untwinned crystal, improving the experimental precision and accuracy. For each polymorph, neutron diffraction data were collected at 5, 105 and 295 K. Single-crystal X-ray diffraction experiments were also performed at the same temperatures. The two polymorphs, whose crystal packing is interpreted by intermolecular interaction energies calculated using the Pixel method, show differences in the energy and geometry of the hydrogen bond formed along the c direction. Taking advantage of the X-ray diffraction data collected at 5 K, the precision and accuracy of the new Hirshfeld atom refinement method im­ple­mented in NoSpherA2 were probed choosing various settings of the functionals and basis sets, together with the use of explicit clusters of molecules and enhanced rigid-body restraints for H atoms. Equivalent atomic coordinates and aniso­tropic displacement parameters were com­pared and found to agree well with those obtained from the corresponding neutron structural models.


Publication metadata

Author(s): Novelli G, McMonagle CJ, Kleemiss F, Probert M, Puschmann H, Grabowsky S, Maynard-Casely HE, McIntyre GJ, Parsons S

Publication type: Article

Publication status: Published

Journal: Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials

Year: 2021

Volume: 77

Pages: 785-800

Print publication date: 01/10/2021

Online publication date: 16/09/2021

Acceptance date: 18/07/2021

ISSN (print): 2052-5192

ISSN (electronic): 2052-5206

Publisher: International Union of Crystallography

URL: https://doi.org/10.1107/S205252062100740X

DOI: 10.1107/S205252062100740X


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