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The Relevance of Experimental Charge Density Analysis in Unraveling Noncovalent Interactions in Molecular Crystals

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  • Sajesh P. Thomas, Indian Institute of Technology, Delhi
  • ,
  • Amol G. Dikundwar, National Institute of Pharmaceutical Education and Research India
  • ,
  • Sounak Sarkar
  • Mysore S. Pavan, Syngene International Ltd.
  • ,
  • Rumpa Pal, University of Tsukuba
  • ,
  • Venkatesha R. Hathwar, Goa University
  • ,
  • Tayur N.Guru Row, Indian Institute of Science Bangalore

The work carried out by our research group over the last couple of decades in the context of quantitative crystal engineering involves the analysis of intermolecular interactions such as carbon (tetrel) bonding, pnicogen bonding, chalcogen bonding, and halogen bonding using experimental charge density methodology is reviewed. The focus is to extract electron density distribution in the intermolecular space and to obtain guidelines to evaluate the strength and directionality of such interactions towards the design of molecular crystals with desired properties. Following the early studies on halogen bonding interactions, several “sigma-hole” interaction types with similar electrostatic origins have been explored in recent times for their strength, origin, and structural con-sequences. These include interactions such as carbon (tetrel) bonding, pnicogen bonding, chalcogen bonding, and halogen bonding. Experimental X-ray charge density analysis has proved to be a pow-erful tool in unraveling the strength and electronic origin of such interactions, providing insights beyond the theoretical estimates from gas-phase molecular dimer calculations. In this mini-review, we outline some selected contributions from the X-ray charge density studies to the field of non-covalent interactions (NCIs) involving elements of the groups 14–17 of the periodic table. Quantitative insights into the nature of these interactions obtained from the experimental electron density distribution and subsequent topological analysis by the quantum theory of atoms in molecules (QTAIM) have been discussed. A few notable examples of weak interactions have been presented in terms of their experimental charge density features. These examples reveal not only the strength and beauty of X-ray charge density multipole modeling as an advanced structural chemistry tool but also its utility in providing experimental benchmarks for the theoretical studies of weak interactions in crystals.

Original languageEnglish
Article number3690
JournalMolecules
Volume27
Issue12
Number of pages31
ISSN1420-3049
DOIs
Publication statusPublished - Jun 2022

Bibliographical note

Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.

    Research areas

  • crystal, electron density, multipole modelling, non-covalent interactions, qtaim

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