Synthesis and Properties of Helical Conjugated Molecules

With the support of the Organic and Macromolecular Chemistry Program, Professor Thomas J. Katz, of the Department of Chemistry at Columbia University continues work to synthesize rigid chemical structures in which electrons can move easily on helical paths of a single handedness. Heretofore such molecules had hardly been studied because they were preparable in only very tiny amounts and with substituents that were neither useful nor easily elaborated to be so. The procedures developed in the PI's laboratory are producing such compounds in large amounts, easily, and with useful functional groups. The work has two goals. One is to design and synthesize helical conjugated molecules that should aggregate spontaneously into giant corkscrew-shaped structures and in consequence exhibit exceptional optical properties. The second goal is to design and synthesize helical conjugated molecules with large chiral clefts that should endow the molecules with two benefits. First, some of the examples synthesized should act as superb asymmetric catalysts, providing a way to make chiral medicines and other physiologically active compounds selectively and in the desired mirror image forms. Others should act as much more sensitive probes to analyze the amounts of mirror image forms in these and other samples, even when the constituent molecules have centers of asymmetry that are very remote from any functional groups to which reagents can attach.

This very important research of Professor Thomas Katz is being supported by the Organic and Macromolecular Chemistry Program to allow his unique methods of synthesis and analysis to deliver new materials and to make them available to the wider scientific community. Among the reasons this research is important is that approximately 40% of chiral medicines (themselves about half of all drugs) are stereochemically inhomogeneous, even though contamination by undesired stereoisomeric impurities could be deleterious. Although an international effort is being devoted to synthesizing molecules in a single handed form (for example, similar to making a number of keys to fit a specific lock), these efforts have not been matched by methods to analyze the degree of handedness the syntheses achieve (determining how many keys are perfect and without defects). The helical molecules to be studied in this project promise to be far more sensitive than any now available.