Profile

Research in the Doxsee group revolves around various aspects of molecular recognition phenomena. Through the design, synthesis, and exploitation of molecules that interact with each other or with metal ions, we address a number of fundamental topics, including the phase- and shape-selective assembly of solid-state materials from molecular precursors and the development of ion-selective binding agents. Through these ongoing research efforts as well as separate projects dedicated to the development of new pedagogical materials, we seek to train students in the concepts and practice of green chemistry.

Green Chemistry
Working with Professor Hutchison, Professor Doxsee has transformed the undergraduate organic laboratory curriculum so that all students now learn the fundamentals of organic chemistry within the context of green chemistry. Development of new laboratory experiments that both teach important chemical concepts and illustrate the principles of green chemistry is an ongoing activity in the Doxsee laboratory. Our other research activities, outlined below, also implicitly and explicitly address green chemical issues by focusing on the development of selective reactions that employ safer reagents, and are effected with significantly reduced energy costs.

Phase- and Shape-Selective Assembly of Solid-State Materials
Simple organic and inorganic salts are often completely insoluble in non-polar solvents. However, solutions of complexes of salts with crown ethers in such solvents may be readily prepared. These solubilized salts undergo “metathesis” reactions with other solubilized reactants, resulting in the crystallization of solid-state materials. The unique solvation and complexation interactions presented under these crystallization conditions leads to dramatic alteration of crystal form. For example, crystallization of silver bromide from water generally affords cubic or octahedral crystals, while crystallization from nonaqueous solvents affords a solvent-dependent variety of more complex crystal forms. Further control is frequently exhibited over solid-state phase as well as crystal form. Through use of small-molecule (or ion) precursors under ambient conditions, we routinely access metastable phases. For example, whereas crystallization of calcium carbonate from water affords the thermodynamic phase (calcite); crystallization from methanol solution affords a metastable phase (vaterite). Adaptation of these procedures for the preparation of binary and ternary metal oxides (e.g., WO3, MnWO4) frequently affords new metastable phases. We are applying these crystallization approaches to problems of current technological importance, particularly in the areas of optical and electronic materials.

Ion-Selective Binding Agents
Many pharmacologically active drugs, including anti-inflammatories and antitumor agents, bear the alpha-hydroxyketone functionality. Our studies, which we hope will lead to development of ion-selective sensors and a better understanding of the chemistry of these drugs in vivo, suggest this functionality is quite effective at complexation of the biochemically ubiquitous calcium ion. We have structurally characterized phenacyl alcohol, cortisone, and hydrocortisone complexes of calcium and have quantified the details of their interaction in solution with calcium and other group 2 metal ions. Related studies with hydroxamic acids, tetracycline, and the antitumor agent adriamycin are planned. These investigations, which are primarily analytical and structural in nature, are complemented by our program of design and synthesis of efficient and selective complexation agents for calcium. The latter studies include the synthesis of colorimetric binding agents for calcium, designed to allow simple and quantitative determination of calcium levels in biological fluids.