Intermolecular interactions and electrostatic properties of the β-hydroquinone apohost: implications for supramolecular chemistry

J Phys Chem A. 2011 Nov 17;115(45):12962-72. doi: 10.1021/jp2041789. Epub 2011 Aug 3.

Abstract

The crystal structure of the β-polymorph of hydroquinone (β-HQ), the apohost of a large family of clathrates, is reported with a specific focus on intermolecular interactions and the electrostatic nature of its cavity. Hirshfeld surface analysis reveals subtle close contacts between two interconnecting HQ networks, and the local packing and related close contacts were examined by breakdown of the fingerprint plot. An experimental multipole model containing anisotropic thermal parameters for hydrogen atoms has been successfully refined against 15(2) K single microcrystal synchrotron X-ray diffraction data. The experimental electron density model has been compared with a theoretical electron density calculated with the molecule embedded in its own crystal field. Hirshfeld charges, interaction energies and the electrostatic potential calculated for both models are qualitatively in good agreement, but small differences in the electrostatic potential persist due to charge transfer from all hydrogen atoms to the oxygen atoms in the theoretical model. The electrostatic potential in the center of the cavity is positive, very shallow and highly symmetric, suggesting that the inclusion of polar molecules in the void will involve a balance between opposing effects. The electric field is by symmetry zero in the center of the cavity, increasing to a value of 0.0185 e/Å(2) (0.27 V/Å) 1 Å along the 3-fold axis and 0.0105 e/Å(2) (0.15 V/Å) 1 Å along the perpendicular direction. While these values are substantial in a macroscopic context, they are quite small for a molecular cavity and are not expected to strongly polarize a guest molecule.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Hydroquinones / chemical synthesis
  • Hydroquinones / chemistry*
  • Macromolecular Substances / chemical synthesis
  • Macromolecular Substances / chemistry
  • Models, Molecular
  • Powder Diffraction
  • Quantum Theory
  • Static Electricity

Substances

  • Hydroquinones
  • Macromolecular Substances
  • hydroquinone