Investigations of the non-covalent CH--pi interactions using molecular torsional balances.

摘要

Several bicycle N-arylimide based molecular balances were designed to study aliphatic CH-π interactions and aromatic CH-π interactions (edge-to-face arene-arene interactions). In each case, the geometries of the interactions were characterized in the solid-state via X-ray analysis, and the strengths of interactions were characterized in solution by their folded/unfolded ratios, as measured by integration of their 1H NMR spectra.;The balances are very sensitive to variations in the strengths of weak non-covalent interactions. Several different aspects of the CH-π interactions were studied, such as sterics, conformational entropy, cooperativity, deuterium isotope effect, substitution effects, and solvent effects. It showed that due to the weak nature of CH-π interactions, many forces can contribute on determining their interacting energies with similar magnitudes. Approaches using "double-mutant cycles" to isolate the interactions of interest from secondary effects were presented. The balances can also be used to the study of other non-covalent interaction, and the investigations were included in the last chapter.