Integrated Calendar

Most molecular self-assembly strategies involve equilibrium systems. Yet, strong noncovalent interactions may result in nonequilibrium self-assembly, where structural diversity is achieved by forming several kinetic products based on a single covalent building block. I demonstrate that well-defined amphiphilic molecular systems based on perylene diimide/peptide conjugates exhibit kinetically controlled self-assembly in aqueous medium, enabling pathway-dependent assembly sequences, in which different organic nanostructures are evolved in a stepwise manner. In order to better understand the processes leading to the ordered self-assembly of aromatic amphiphiles in water, a kinetic mechanistic study was performed. In this study, aqueous self-assembly of chiral perylene diimide (PDI) amphiphile into highly ordered crystalline arrays was investigated using UV-vis and circular dichroism (CD) spectroscopy coupled with cryogenic transmission electron microscopy (cryo-TEM). The latter provides direct structural imaging of self-assembly progress. Molecular dynamics calculations were performed as well. We observed a three-step mechanism: 1) nucleation; 2) growth; 3) coarsening. The nucleation-growth process fits a modified Kolmogorov /Johnson/Mehl/Avrami (KJMA) model. We observed that the initial state of the system is an amorphous aggregate that gradually transforms into a highly ordered system. Activation parameters suggest that de-solvation plays a significant role in the process.
Photophysical measurements of a set of materials similar to the ones studied in the kinetic part revealed excellent exciton mobility in ordered PDI arrays. The relation between structure and function was demonstrated using a set of kinetically formed structures that allow tuning of the exciton mobility via morphology of the self-assembled structures.

The exact solution of the BCS pairing Hamiltonian was found by Richardson in 1963. While little attention was paid to his solution for the remainder of the century, there began in the early 2000s a flurry of activity that focused on its applications in different areas of quantum physics. In this talk, following a brief historical overview of pairing in quantum systems, I will review Richardson's solution and its generalization to the wider class of Richardson-Gaudin integrable models and then discuss applications of these various models to problems of contemporary importance in nuclear physics.

Pincer-ligated iridium complexes have been well demonstrated to act as catalysts for alkane dehydrogenation. Studies of the mechanism and scope of dehydrogenations will be discussed, as well as coupling with secondary reactions (tandem catalysis). In addition, the ability of such complexes to effect the critical step of C-H bond addition is explored and exploited for reactions other than dehydrogenation, such as C-O or C-F bond cleavage, as well as the microscopic reverse, e.g. C-O bond formation.