Bruce C. Gibb Research Professor – Organic & Biochemistry B.S., Robert Gordon's University 1987 Ph.D., Robert Gordon's University 1992 email: bgibb@uno.edu phone: (504) 280-3152 office: CBS 343 Group Page

Research Interests The focus of our studies is supramolecular chemistry. In other words, we are interested in orchestrating non-covalent forces between molecules, such that nanotechnology can be approached from, “the bottom up”. Key to this goal is the careful design of our molecular targets. Hence synthesis plays a pivotal role in our research. One family of molecules that is prominent in our endeavors possesses the general structure 1. In these ‘cavitands’, the R and R^1 groups can be used to control the solubility of these large hosts, while the R^2 groups can be used to control the type of guest that bind to the cavity. One long-term goal involving these molecules is the formation of novel catalysts that can differentiate between substrates that differ by as little as one methylene unit. 1 Another interest within the group is drug delivery. Cavitands that are water-soluble, e.g., 1, where R and R^1 are water-solubilizing groups, can form either open 1:1 complexes (Scheme 1, left), or capsular complexes in which two cavitands dimerize to entrap a guest (Scheme 1, right). We use a variety of NMR techniques (1D, 2D, and Pulse Gradient Spin-Echo (PGSE) experiments) and Isothermal Titration Calorimetry (ITC) to study these complexes. Concomitantly, we also examine how these capsules stabilize (guest) compounds that could be useful drug candidates if their stability in aqueous solution were enhanced. Scheme 1: Cartoon of 1:1 and 2:1 complexes formed by cavitand 1 (R and R^1 = water solubilizing groups) In a collaboration with V. Ramamurthy (U. of Miami), these capsules are also being investigated as nano-scale reaction chambers. These capsules not only allow reactions of water-insoluble molecules to be carried out in aqueous solution, they can also control the outcome of the reaction. In essence, the capsule acts as an external template, redirecting the outcome of reaction relative to the analogous reaction carried out in an organic solvent. The reaction between alkenes and singlet oxygen (Scheme 2) is one example. In solution, it is not possible to control the regioselectivity of this reaction. However, in the presence of the capsule an encapsulated sensitizer can excite oxygen, which in turn enters a capsule containing the substrate and reacts with the most accessible allylic position of the guest. Scheme 2: An encapsulated sensitizer (red capsule) excites oxygen, which in turn selectively reacts with the mostaccessible allylic position of an encapsulated guest A second collaboration, with the Advanced Materials Research Institute (AMRI), examines how cavitands (and their corresponding guests) that bind to gold surfaces can be used to direct the assembly of nano- and micro-scale objects. As with all of the above projects, synthesis is central to this endeavor, but many other techniques, such as atomic force microscopy, are also required.

Selected Publications "Directed Ortho Lithiation of Deep-Cavity Cavitands: Functionalizing Molecular Concavity," Laughrey, Z. R.; Gibb, B. C., J. Org. Chem., 2006, 71, 1289-1294 (Cover article issue #4). "A Hydrophobic Nano-Capsule Controls the Photophysics of Aromatic Molecules By Suppressing their Favored Solution Pathways," Kaanumalle, L. S., Gibb, C. L. D., Gibb, B. C., Ramamurthy, V., J. Am. Chem. Soc., 2005, 127, 3674-3675. "Controlling Photochemistry With Distinct Hydrophobic Nano-Environments," Kaanumalle, L. S., Gibb, C. L. D., Gibb, B. C., Ramamurthy, V., J. Am. Chem. Soc., 2004, 126, 14366-14367. "Well Defined, Organic Nano-Environments in Water: The Hydrophobic Effect Drives a Capsular Assembly," Gibb, C. L. D., Gibb, B. C., J. Am. Chem. Soc., 2004, 126, 11408-11409. "Resorcinarenes as Templates: The Synthesis of Large Crown Ethers," Li, X., Upton, T.; Gibb, C. L. D.; Gibb, B. C., J. Am. Chem. Soc. 2003, 125, 650-651.