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Carnegie Mellon Department of Chemistry

Speakers & Abstracts

photo of Santosh KumarSantosh Kumar, Carnegie Mellon University

Synthesis and Optical Properties of Water-soluble Gold Nanoclusters

Metal nanoclusters lie at the boundary between small molecules and nanoparticles, and can provide insights into the origins of the optical,electronic and chemical properties of nanomaterials. The synthesis of metal nanoclusters ligated with various thiols has been explored in recent years, but the synthesis process is generally mediated by organic solvents; and as a result, the choice of thiol has been focused on those that can be dissolved in organic solvents only. This apparently limits the application of metal nanoclusters in biology and other fields where water-solubility is critical. This work focuses on the synthesis of water-soluble Au cluster with high thermal stability and unique optical properties. For this purpose the thiol (2S)-1-[(2S)-2-methyl-3-sulfanylpropanoyl] pyrrolidine-2-carboxylic acid (known as Captopril) and Glutathione are used as capping agents. The thermal stability, chirality, and the luminescence properties of these nanoclusters have been compared with the previously reported Au clusters capped with other thiols.

photo of Violeta MarinVioleta Marin, Abbott Laboratories — Global Pharmaceutical Research and Development

From Bench to Market — Drug Discovery at Abbott

This presentation will briefly describe the drug discovery process at Abbott with focus on the contributions from the Molecular Probes Groups within Advanced Technology. The ability to affect several targets within a disease-impacting biological pathway, or avoid toxicity associated targets in other pathways depends on rapidly obtaining data with many compounds against many targets/off-targets. Using kinases as an example, I will present the development of a time-resolved fluorescence resonance energy transfer (TR-FRET) based binding assays for efficient compound profiling. TR-FRET acceptor ligands for every kinase attempted were successfully prepared using an efficient modular chemistry approach to attach spacer groups to active compounds and subsequently attach fluorescent reporter molecules as TR-FRET acceptors for high-throughput profiling assays. The modular synthetic approach allows immediate switching of reporter groups to create probes for alternative applications such as chemoproteomic identification of unknown targets. All of these methods are in routine use for drug discovery at Abbott.

photo of Codrina PopescuCodrina Popescu, Ursinus College

Mössbauer Spectroscopy and the Exploration of Novel Iron-Containing Catalytic Systems

Iron is the most abundant transition metal in biological systems. Iron proteins and enzymes are involved in life processes, from electron transport in respiration, to substrate oxidation for energy generation, detoxification, and DNA synthesis. This chemical versatility of one element was achieved through millions of years of evolution. 57Fe-Mossbauer spectroscopy can bring insight into the electronic structure of iron compounds, often allowing us to elucidate the nature of the active sites of enzymes directly, or by probing small-molecule models, which can be used as catalysts. Frontier problems in fundamental research have implications for environmental problems, such as the need for cleaner energy sources and increasing pollution. Examples include studies of monovalent iron complexes, in search for a good hydrogen-producing catalyst and exploring dehaloperoxidase enzymes. Since it has been recognized that the active site of the enzymes hydrogenases contains a low-spin Fe(I), monovalent iron has become a focus of bio-organometallic chemistry. In spite of its intriguing capacity to catalyze hydrogen production and oxidation, the electronic structure of low-spin Fe(I) has not been elucidated. A different class of enzymes, containing heme centers, have been evolved by the worm A. ornata to oxidize toxic trihalophenols. From details of 57Fe-Mossbauer spectra we are attempting to learn how iron is used to perform vastly different feats of chemistry, in environmentally benign ways.