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Suresh S, Kandasamy S, Balasubramanian H, Ramakrishnan J, Poomani K. Insights on structure and interactions of 2-amino-4-methoxy-6-methylpyrimidinium salts with 4-aminosalicylate and 5-chlorosalicylate: a combined experimental and theoretical charge–density analysis. ACTA CRYSTALLOGRAPHICA SECTION C STRUCTURAL CHEMISTRY 2022; 78:181-191. [DOI: 10.1107/s2053229622001280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 02/02/2022] [Indexed: 11/10/2022]
Abstract
The proton-transfer complexes 2-amino-4-methoxy-6-methylpyrimidinium (2A4M6MP) 4-aminosalicylate (4AMSA), C6H10N3O+·C7H6NO3
−, I, and 5-chlorosalicylate (5ClSA), C6H10N3O+·C7H4ClO3
−, II, were synthesized by slow evaporation and crystallized. The crystal structures of both I and II were determined by single-crystal X-ray structure analysis. The crystal structures of both salts exhibit O—H...O, N—H...O, N—H...N and C—H...O interactions in their crystals. The 4AMSA and 5ClSA anions in combination with the 2A4M6MP cations form distinct synthons, which are represented by the graph-set notations R
2
2(8), R
4
2(8) and R
2
2(8). Furthermore, the ΔpK
a
values were calculated and clearly demonstrate that 2A4M6MP is a good salt former when combined with carboxylic acids. Hirshfeld surface analysis was used to quantify the weak and strong interactions in the solid state, and energy framework calculations showed the stability of the hydrogen-bonding interactions. QTAIM (quantum theory of atoms in molecules) analysis revealed the nature of the chemical bonding in I and II, and the charge–density distribution in the intermolecular interactions in the crystal structures.
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Anil Kumar GN, Hathwar VR. Quantitative Investigation of Halogen and Hydrogen Bonding in 2‐Chloro, 4‐X‐Benzoic Acids. ChemistrySelect 2022. [DOI: 10.1002/slct.202104338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- G. N. Anil Kumar
- Department of Physics M. S. Ramaiah Institute of Technology Bangalore Goa 500054 India
| | - Venkatesha R. Hathwar
- School of Physical and Applied Sciences Goa University Taleigao Plateau 403206 India
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Sedghiniya S, Soleimannejad J, Janczak J. The salt–cocrystal spectrum in salicylic acid–adenine: the influence of crystal structure on proton-transfer balance. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2019; 75:412-421. [DOI: 10.1107/s2053229619003127] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Accepted: 03/02/2019] [Indexed: 11/10/2022]
Abstract
At one extreme of the proton-transfer spectrum in cocrystals, proton transfer is absent, whilst at the opposite extreme, in salts, the proton-transfer process is complete. However, for acid–base pairs with a small ΔpK
a (pK
a of base − pK
a of acid), prediction of the extent of proton transfer is not possible as there is a continuum between the salt and cocrystal ends. In this context, we attempt to illustrate that in these systems, in addition to ΔpK
a, the crystalline environment could change the extent of proton transfer. To this end, two compounds of salicylic acid (SaH) and adenine (Ad) have been prepared. Despite the same small ΔpK
a value (≈1.2), different ionization states are found. Both crystals, namely adeninium salicylate monohydrate, C5H6N5
+·C7H5O3
−·H2O, I, and adeninium salicylate–adenine–salicylic acid–water (1/2/1/2), C5H6N5
+·C7H5O3
−·2C5H5N5·C7H6O3·2H2O, II, have been characterized by single-crystal X-ray diffraction, IR spectroscopy and elemental analysis (C, H and N) techniques. In addition, the intermolecular hydrogen-bonding interactions of compounds I and II have been investigated and quantified in detail on the basis of Hirshfeld surface analysis and fingerprint plots. Throughout the study, we use crystal engineering, which is based on modifications of the intermolecular interactions, thus offering a more comprehensive screening of the salt–cocrystal continuum in comparison with pure pK
a analysis.
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