Fluorous Phase-Based Fluorescent Chiral Discrimination

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In this project funded by the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, Professor Lin Pu of the Department of Chemistry at University of Virginia is developing new enantioselective fluorescent sensors for the recognition of chiral amines in perfluorocarbon solvents (fluorous phase). These sensors are used to facilitate the high throughput screening of chiral catalysts for the asymmetric synthesis of chiral amines that are useful in the synthesis of organic compounds of pharmaceutical and biological importance. This project provides extensive education and training for graduate and undergraduate students in areas such as organic synthesis, spectroscopic study, and catalyst development. This group also participates in an outreach program to carry out chemistry-based demonstrations for elementary school students and teachers. This outreach program is dedicated to providing inquiry-based chemistry instruction at the elementary school level.Enantioselective fluorescent sensors containing perfluoroalkyl chains are expected to be more soluble in fluorous solvents than in common organic solvents. They are used to conduct the enantioselective fluorescent recognition of functional chiral amines such as diamines, amino alcohols and amino acids in fluorous solvents. Pseudoenantiomeric pairs of such sensors are prepared. In each pair there are two sensors having the opposite enantioselective fluorescent response with two distinctively different emission wavelengths upon interaction with the two enantiomers of a chiral amine substrate. These sensors are applied to chiral catalyst screening. A fluorous solution of a pseudoenantiomeric sensor pair are used to extract the products, generated from the chiral catalyst screening experiments conducted in common organic solvents or aqueous solution, into the fluorous phase. Because only the sensors and their adducts with the chiral products could be dissolved in the fluorous phase, the interference of other species such as reagents, catalysts and starting materials is minimized. Through fluorescent measurement, both the yield and enantiomeric composition of the chiral products is simultaneously determined. The structure of the sensors is modified in order to conduct the enantioselective fluorescent recognition of un-functionalized amines. The fluorous phase-based fluorescent detection of this project has potential to be automated to conduct high throughput catalyst screening. Under the direction of PI, graduate students and undergraduate students of diverse backgrounds are recruited to conduct research in organic synthesis, spectroscopic studies, and catalyst development. Students will learn many laboratory skills that are useful for their future employment and allow them to make contributions to the society.