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Evidence for a strong sulfur-aromatic interaction derived from crystallographic data.
R J Zauhar1, C L Colbert, R S Morgan
1Department of Chemistry and Biochemistry, University of the Sciences in Philadelphia, 600 S. 43rd Street, Philadelphia, PA 19104-4495, USA. r.zauhar@usip.edu
Biopolymers
|February 19, 2000
Summary
This study reveals a significant interaction between divalent sulfur and aromatic rings, confirmed by statistical analysis of crystal structures. The preferred geometry of this sulfur-aromatic interaction differs from previous findings.
Area of Science:
- Chemical Crystallography
- Computational Chemistry
- Structural Chemistry
Background:
- The interaction between sulfur-containing functional groups and aromatic systems is crucial in various chemical and biological contexts.
- Previous studies have suggested the importance of sulfur-aromatic interactions, but a definitive understanding of their preferred geometry has been lacking.
- Analyzing crystal structures provides a powerful method for elucidating intermolecular interactions in the solid state.
Purpose of the Study:
- To statistically analyze and define the preferred geometric arrangement of divalent sulfur atoms interacting with aromatic rings.
- To compare the observed sulfur-aromatic interaction geometry with that of a non-interactive control moiety (X-CH(2)-X).
- To investigate the physical basis of the sulfur-aromatic interaction using molecular mechanics.
Main Methods:
- Statistical analysis of interatomic distances and geometric descriptors from the Cambridge Crystallographic Database.
- Computation of probability distributions for sulfur-aromatic and CH(2)-aromatic interactions.
- Application of the Smirnov-Kolmogorov nonparametric test for statistical significance testing (99% confidence level).
- Molecular mechanics simulations to explore the physical underpinnings of the interaction.
Main Results:
- A statistically significant interaction between divalent sulfur and aromatic rings was identified, with a defined preferred geometry.
- The observed sulfur-aromatic interaction geometry significantly differs from that predicted or observed by other computational or experimental methods.
- Molecular mechanics studies provided insights into the physical forces driving this interaction.
Conclusions:
- This study provides robust statistical evidence for a specific preferred geometry of interaction between divalent sulfur and aromatic rings based on small-molecule crystal data.
- The findings confirm the importance of sulfur-aromatic interactions, previously suggested by protein crystallography and computational studies.
- The distinct geometry identified highlights the need for re-evaluation of sulfur-aromatic interactions in various scientific disciplines.