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Published February 17, 1999 | public
Journal Article

A Selective Receptor for Arginine Derivatives in Aqueous Media. Energetic Consequences of Salt Bridges That Are Highly Exposed to Water

Abstract

Quantitative measures of salt-bridge-type interactions in a highly exposed aqueous environment have been obtained by modifying the well-studied cyclophane platform 1 to include carboxylates in close proximity to bound, cationic guests, producing hosts 2 and 3. Many guests show significantly enhanced binding to 2 and 3, but cations of the RNMe_3+ type show little or no enhancement. We propose that the latter observations result from the fact that RNMe_3+ compounds have very diffuse positive charges. Guests that show enhanced binding have focused regions of large, positive electrostatic potential. The highly charged 3 is able to bind very polar, very well-solvated guests, including a series of arginine-based dipeptides. Neutral, water-soluble host 4 was prepared and found to show a decreased affinity for cationic guests. We propose a novel induced dipole mechanism to rationalize these results.

Additional Information

© 1999 American Chemical Society. Received July 15, 1998. Revised Manuscript Received November 21, 1998. Publication Date (Web): January 22, 1999. We thank the Zeneca Pharmaceuticals Strategic Research Fund for support of this work.

Additional details

Created:
August 19, 2023
Modified:
October 18, 2023