Our research is concerned with the chemistry of both organic and organometallic polyfunctional Lewis acids. While an important component of our work deals with the synthesis of new examples of such polyfunctional Lewis acids, it is our ultimate intent to harness and utilize the cooperative effects occurring in such systems for the discovery of unusual structures, bonding modes, supramolecules and reactivities. Our research efforts present important ramifications in the domain of molecular recognition, supramolecular materials and catalysis.

Synthesis: Organic and organometallic synthesis lies at the focal point of our program. We strive to discover high yield synthetic routes for the preparation of both organic and organometallic polyfunctional Lewis acids. These efforts have allowed us to prepare a variety of bidentate and tridentate Lewis acids in which the electrophilic sites are simple carbocations or main-group elements such as mercury(II) and boron(III).

Bonding: In an effort to broaden our fundamental understanding of bonding interactions, we study atypical bonding situations that might arise in the chemistry of polyfunctional Lewis acids. While we have been interested in the formation of radicals featuring one-electron σ-bonds, some of our current efforts are devoted to the synthesis of fluoronium ions.

Molecular recognition: Some of these polyfunctional Lewis acids act as polytopic receptors for anions. The significance of this research relates to the discovery of new molecular recognition units for sensory application. For example, we have recently demonstrated that boron-based bidentate Lewis acids can be used as selective colorimetric sensors for fluoride ions. Taking into account the importance of fluoride in the treatment of osteoporosis and in dental care, such sensors may find biomedical applications.

Supramolecular materials: In addition to discovering receptors for small organic molecules including diazines, ketones, aldehydes, oxiranes, and phosphonates, we have also found that trimeric perfluoro-ortho-phenylene mercury, a tridentate Lewis acid, is able to complex many arenes including benzene, naphthalene, biphenyl and pyrene. The resulting adducts form unusual supramolecular binary stacks. In addition, these adducts display unique luminescent properties which make them useful materials for organic light emitting diodes (OLED).

Catalysis: For some time, we have been interested in the use of polyfunctional Lewis acids as organic reaction catalysts. As an extension of this chemistry, we recently turned our attention to bimetallic catalytic systems that allow for the oligomerization of ethylene. As part of these efforts, we have discovered a bifunctional system consisting of triethylaluminum and a chromium(III) pentafluorophenyl complex that catalyze the living “Aufbaureaktion” at room temperature and under 1 atm of ethylene.

The structure and properties of the molecular and supramolecular derivatives prepared in the group are studied by a number of analytical methods including multinuclear NMR, IR, UV/Vis and luminescence spectroscopy, electrochemistry, mass spectrometry, single crystal X-ray diffraction and electronic microscopy. We also use DFT calculations to elucidate the electronic structure of the derivatives.