TY - JOUR

T1 - A new guaninate hydrate K+_C5H4N5O H2O: Crystal structure from 100 to 300 K in a comparison with 2Na+_C5H3N5O2__7H2O

AU - Gaydamaka, Anna A.

AU - Arkhipov, Sergey G.

AU - Boldyreva, Elena V.

N1 - Funding Information: The research was supported by the Ministry of Science and Higher Education and carried out jointly by Boreskov Institute of Catalysis (project AAAA-A21-121011390011-4) and Novosibirsk State University. Publisher Copyright: © 2021 International Union of Crystallography. All rights reserved.

PY - 2021/10/1

Y1 - 2021/10/1

N2 - A new guanine salt hydrate, K+C5H4N5O-H2O, was obtained and characterized by single-crystal X-ray diffraction in the temperature range 100 K-300 K and compared with that of the previously documented sodium salt hydrate (2Na+C5H3N5O2-7H2O) [Gur & Shimon (2015). Acta Cryst. E71, 281-283; Gaydamaka et al. (2019). CrystEngComm, 21, 4484-4492]. Both sodium and potassium salt hydrates have channels. However, the structure of the channels, the cation coordination, the protonation (and, respectively, the charge) of the guanine anions, as well as the role of water molecules in the crystal structure are different for the two salt hydrates. In the crystal structures of the potassium salt, the guanine anions are linked via hydrogen bonds into quartets that form open cylindrical channels in a honeycomb framework. Water molecules 'line the walls' of the channels, whereas the potassium cations fill the intra-channel space. This contrasts with the structure of the sodium salt hydrate in which guanine anions form channels with water molecules filling in the channel space together with sodium cations coordinating them. The 1D anionic assembly generated through numerous hydrogen bonds and cation interactions with guanine anions and water molecules is energetically the most distinctive part of the structure of the potassium salt hydrate. In the case of the guanine sodium salt, the structure contains purely inorganic polymeric fragments - sodium cations coordinated to a water molecule forming a 1D polymeric structure and guanine anions interconnecting these polymers via hydrogen bonds with water molecules. The structural differences account for the difference in the anisotropy of strain on temperature variation for the two salt hydrates: whereas in both structures the values of the bulk thermal expansion coefficients are similar in the two structures and the major expansion is observed along the channel axes, the degree of anisotropy for the K salt is more than four times higher than that for the Na salt.

AB - A new guanine salt hydrate, K+C5H4N5O-H2O, was obtained and characterized by single-crystal X-ray diffraction in the temperature range 100 K-300 K and compared with that of the previously documented sodium salt hydrate (2Na+C5H3N5O2-7H2O) [Gur & Shimon (2015). Acta Cryst. E71, 281-283; Gaydamaka et al. (2019). CrystEngComm, 21, 4484-4492]. Both sodium and potassium salt hydrates have channels. However, the structure of the channels, the cation coordination, the protonation (and, respectively, the charge) of the guanine anions, as well as the role of water molecules in the crystal structure are different for the two salt hydrates. In the crystal structures of the potassium salt, the guanine anions are linked via hydrogen bonds into quartets that form open cylindrical channels in a honeycomb framework. Water molecules 'line the walls' of the channels, whereas the potassium cations fill the intra-channel space. This contrasts with the structure of the sodium salt hydrate in which guanine anions form channels with water molecules filling in the channel space together with sodium cations coordinating them. The 1D anionic assembly generated through numerous hydrogen bonds and cation interactions with guanine anions and water molecules is energetically the most distinctive part of the structure of the potassium salt hydrate. In the case of the guanine sodium salt, the structure contains purely inorganic polymeric fragments - sodium cations coordinated to a water molecule forming a 1D polymeric structure and guanine anions interconnecting these polymers via hydrogen bonds with water molecules. The structural differences account for the difference in the anisotropy of strain on temperature variation for the two salt hydrates: whereas in both structures the values of the bulk thermal expansion coefficients are similar in the two structures and the major expansion is observed along the channel axes, the degree of anisotropy for the K salt is more than four times higher than that for the Na salt.

KW - anisotropy of thermal expansion

KW - channel structures

KW - crystal salt hydrates

KW - guanine

KW - intermolecular interactions

KW - nucleobase

KW - role of water in forming a crystal structure

KW - single-crystal X-ray diffraction

KW - structure-properties relations

KW - tautomers

UR - http://www.scopus.com/inward/record.url?scp=85116853746&partnerID=8YFLogxK

U2 - 10.1107/S205252062100754X

DO - 10.1107/S205252062100754X

M3 - Article

AN - SCOPUS:85116853746

VL - 77

SP - 808

EP - 818

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

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

SN - 2052-5192

ER -