Banita White Brown
Assistant Professor

Area of research: Organic Chemistry
Undergraduate Institution: Furman University
Graduate Institution: University of Miami
Postdoctoral Experience: Georgia Institute of Technology
Phone: 547-4843
E-mail: bwbrown@unccvm.uncc.edu

Lariat Ether Derivatives

Lariat ethers are derivatives of crown ether macrocycles which contain a sidearm appended to the macroring. The sidearm possesses a group containing a donor atom, D, which provides an additional dimension of coordination to a ring-bound cation, M+. The lariat ether concept is illustrated in the scheme below. These molecules have potential usage as ion carriers. Our studies concentrate on nitrogen-pivot lariat ethers. The sidearm(s) is attached to a nitrogen atom of an aza or diaza crown ether molecule.

It has been found that cation selectivity depends on the nature of the donor group in the sidearm. Sidearms containing the ether functional group preferentially complex to alkali metal ions like Na+ and K+. Sidearms containing ester and amide functional groups prefer to complex to alkaline earth metal ions. Our circular dichroism studies have proven to be a useful tool for evaluating cation binding properties of some peptide derived lariat ethers which are selective for the Ca2+ ion.

Currently, we are studying cation binding properties of a series of nitrogen pivot lariat ethers containing the phenanthroline ligand as part of the sidearm(s) (see next page). In this case, the cation binding properties of the crown ether may be coupled with the binding properties of phenanthroline. These derivatives might be useful ligands for producing complexes containing both alkali metal ions and transition metal ions.

Undisplayed Graphic

Undisplayed Graphic Undisplayed Graphic

We will be using 1H NMR, 13C NMR, as well as UV-Vis to identify complexation properties of lariat ethers containing this type of sidearm.

Transition Metals in Organic Synthesis

Cyclopropylimine Rearrangements

Palladium reagents have been widely used in organic synthesis. Our interest is in the use of palladium to mediate/catalyze rearrangement reactions of various substituted cyclopropylimine compounds. So far our results indicate that this is a novel method for preparing 3-substituted pyrroles (see reaction below).

Undisplayed Graphic

We are currently studying the rearrangement in more detail. Additional cyclopropyl imine derivatives are being prepared. A detailed study of the proposed reaction pathway is also in progress.

3-Substituted pyrroles have a variety of applications. One, in particular, is in the area of Materials Science. These pyrroles may be electropolymerized to conducting polymer thin films. The goal of this project is to be able to synthesize 3-substituted pyrroles containing functional groups in position 3 which may be attached to various types of surfaces. Polymerization of the derivatives would result is a thin film coating onto the surface.