Nguyen, Than Ha, Howard, Sian T., Hanrahan, Jane R., Groundwater, Paul William, Platts, James Alexis ORCID: https://orcid.org/0000-0002-1008-6595 and Hibbs, David E 2012. Experimental and Theoretical Charge Density Distribution in a Host-Guest System: Synthetic Terephthaloyl Receptor Complexed to Adipic Acid. The Journal of Physical Chemistry A 116 (23) , pp. 5618-5628. 10.1021/jp210803m |
Abstract
The experimental charge density distributions in a host-guest complex have been determined. The host, 1,4-bis[[(6-methylpyrid-2-yl)amino]carbonyl]benzene (1) and guest, adipic acid (2). The molecular geometries of 1 and 2 are controlled by the presence in the complex of intermolecular hydrogen bonding interactions and the presence in the host 1 of intramolecular hydrogen bonding motifs. This system therefore serves as an excellent model for studying non-covalent interactions and their effects on structure and electron density, and the transferability of electron distribution properties between closely related molecules. For the complex, high resolution X-ray diffraction data created the basis for a charge density refinement using a pseudo-atomic multipolar expansion (Hansen−Coppens formalism) against extensive low-temperature (T = 100 K) single-crystal X-ray diffraction data and compared with a selection of theoretical DFT calculations on the same complex. The molecules crystallize in the non-centrosymmetric space group P212121 with two independent molecules in the asymmetric unit. A topological analysis of the resulting density distribution using the atoms in molecules methodology is presented along with multipole populations, showing that the host and guest structures are relatively unaltered by the geometry changes on complexation. Three separate refinement protocols were adopted in order to determine the effects of the inclusion of calculated hydrogen atom anisotropic displacement parameters on hydrogen bond strengths. For the isotropic model, the total hydrogen bond energy differs from the DFT calculated value by ca. 70 kJ mol-1, while the inclusion of higher multipole expansion levels on anisotropic hydrogen atoms this difference is reduced to ca. 20 kJ mol-l, highlighting the usefulness of this protocol when describing H-bond energetics.
Item Type: | Article |
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Date Type: | Publication |
Status: | Published |
Schools: | Chemistry |
Subjects: | Q Science > QD Chemistry |
Publisher: | American Chemical Society |
ISSN: | 1089-5639 |
Last Modified: | 20 Oct 2022 08:16 |
URI: | https://orca.cardiff.ac.uk/id/eprint/27793 |
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