Tuesday, 24 May 2005
729

This presentation is part of: Organic Posters

The development of a reliable, highly sensitive technique to determine the metal ion concentration of cells using exciton-coupled circular dichroism

Samuel A. Simpson, New York University, New York, NY

This research is to develop a reliable, sensitive technique to determine the metal ion concentrations of cells by making various chromophores that have metal-binding pockets to produce exciton-coupled circular dichroism (ECCD) spectra. When two chromophores are close to each other, ECCD can be used to assign absolute configurations. The synthesis includes attaching two light absorbing compounds such as quinolines, to the nitrogens of biologically active compounds like chiral amines. The addition of metal ion salts like Cu(ClO4)2, fixes the geometries of the chromophores providing ECCD spectra. The ECCD method is non-empirical which eliminates the use of chiral reference compounds. Graphing the wavelength of absorbed light (λ) vs. the change in molar absorptivity of the polarized light (Δε) reveals positive couplets for the R-isomers and negative ones for the S-isomers. This method can use micromolar concentrations and enantiopurity can be assessed. X-ray crystals provide a second verification of chirality and structural conformation. Utilizing ECCD, chiral metal complexes show bisignate curves when the absorbance of left and right circularly polarized light is graphed vs. the wavelength of light. The development of several light-absorbing molecules such as quinolines, phthalocyanines, pyrenes, naphthalenes, and other fluorescent compounds expands the scope of the spectroscopy in the electromagnetic spectrum. This research is designed to lead to finding the concentrations of metal ions such as copper and zinc that build up in the cells of people with diseases such as Alzheimer's, ALS, and Parkinson's without requiring surgery.

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