Properties and applications of the hydrophobic and Hofmeister effect with host–guest systems
The hydrophobic and the Hofmeister effects play essential roles in the biochemistry of life, but their true nature has bemused researchers for over a century. The use of synthetic hosts have proven to be a useful tool for investigating noncovalent interactions, and have illuminating many aspects of these phenomena on the molecular level. Synthetic hosts with well-defined structures provide a simplified approach to circumvent the ambiguities caused by complex natural systems, and owing their vast utility have found a role in several applications including chemical separations, controlled reactions, and molecular recognition. Herein is an examination of the complexation behavior of deep-cavity cavitands with a variety of organic and inorganic ion guests, to impart a better understanding of the structural and electronic properties that promote complexation. Calorimetry experiments reveal the thermodynamic contributions of host–guest binding, and in working with computational chemists, the data contributes to the improvement of predictive modeling tools. Anomalous complexation behavior observed during comparative studies between structurally similar hosts have revealed new aspects of the hydrophobic effect. The results have revealed a novel approach for manipulating guest affinity to nonpolar surfaces of hosts in aqueous media.