Investigations in molecular recognition: statistical tools and experimental studies

Author: Barrans, Richard E., Jr.

Year: 1993

Degree: Dissertation (Ph.D.)

Advisor: Dougherty, Dennis A.

Committee Members: Myers, Andrew G.; Dougherty, Dennis A.; Imperiali, Barbara; Baldeschwieler, John D.

Option: Chemistry

DOI: 10.7907/42WC-0V58

Abstract

The free energies of formation of intermolecular complexes in solution are often estimated by fitting a nonlinear model to an NMR titration experiment. A regression procedure that assigns weights to each observation on the basis of expected measurement errors has been developed, and yields better parameter estimates than other methods in common use. Procedures for critically evaluating the fit of the model to the experimental data and for assigning confidence limits to the fitted parameters have also been developed. These employ Monte Carlo simulations of the NMR titration experiment to obtain probability distributions that are not available by theoretical means.

Aspects of the complexation behavior of a family of water-soluble macrocyclic cyclophanes are also described. Significant heat capacity effects, which are interpreted in terms of hydrophobic hydration, are seen in variable-temperature studies. The alkylation reactions of pyridine-based compounds are accelerated by complexation with these cyclophanes; an interpretation based on the dynamic properties of the alkylation reaction, the solvent, and the cyclophane is offered. In addition, accounts of efforts to make axially-substituted cyclophanes, to synthesize cyclophanes incorporating a diphosphine ligand, to append additional water-solubilizing groups to the cyclophanes, and to employ small cyclophanes as complexants for alkali metal cations are given.

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