Substituent effects on edge-to-face aromatic interactions.
Chemical double mutant cycles have been used to measure the magnitude of edge-to-face aromatic interactions in hydrogen-bonded zipper complexes as a function of substituents on both aromatic rings. The interaction energies vary depending on the combination of substituents from +1.0 kJ mol-1 (repulsive), to -4.9 kJ mol-1 (attractive). The results correlate with the Hammett substituent constants which indicates that electrostatic interactions are responsible for the observed differences in interaction energy. The experiments can be rationalised based on local electrostatic interactions between the protons on the edge ring and the pi-electron density on the face ring as well as global electrostatic interactions between the overall dipoles on the two aromatic groups.
Carver
Fiona J
FJ
Centre for Chemical Biology, Krebs Institute for Biomolecular Science, Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
Hunter
Christopher A
CA
Livingstone
David J
DJ
McCabe
James F
JF
Seward
Eileen M
EM
D000577:Amides / Q000737:chemistry*; D001665:Binding Sites; D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D011506:Proteins / Q000737:chemistry
D000577:Amides; D006841:Hydrocarbons, Aromatic; D011506:Proteins