Structural and electronic effects of calix[n]pyrrole based anion sensors

Calix[4]pyrroles, a novel yet venerable class of anion binding molecules have been studied. Specifically, we have concentrated on altering both, the structural, and electronic properties of these molecules to approach concerns with selectivity, binding strength and application based uses. Early endeavors focused on appending the calix[4]pyrrole core in such ways to exhibit varying behaviors such as cooperative effects and anion extraction through the synthesis of an anion sponge. Increasing the complexity by adding additional hydrogen binding sights was achieved through the attachment of steroids to the periphery of these molecules. These novel steroidal calix[4]pyrroles gave quite interesting selectivity changes towards chiral molecules. This study also added insight into separation of configurational isomers typically formed when unsymmetrical ketones are employed. The final treatise looked at increasing the core size of calix[n]pyrroles through the use of 3,4-difluoropyrrole, giving novel higher order calixpyrroles with great variance in their selectivity and binding affinity. The syntheses of b-decafluorocalix[5]pyrrole, b-dodecafluoro-calix[6]pyrrole and b-hexadecacalix[8]pyrrole were all achieved. These studies also provided some remarkable insight into the kinetics and thermodynamics of calixpyrrole forming reactions. Fruits of this labor are now being attuned to both biological and wastewater treatment applications.