Chiroptical Spectroscopic Studies on Supramolecular Aggregates

Vanderbilt University, Nashville TN

Investigators

Abstract

With this award, the Chemical Structure, Dynamics, and Mechanisms (CSDM-A) Program of the Division of Chemistry is funding Professor Prasad Polavarapu at Vanderbilt University to study "chiral" molecules - that is, molecules with handedness associated with them. Differences in pharmacological activity between a left-handed chiral molecule and its right-handed mirror image make it necessary to isolate these molecules from one another to investigate their properties. Dr. Polavarapu's group specifically studies chiral surfactant molecules which form special aggregate structures with encapsulation properties (used, for example, for drug delivery). They seek improved understanding of the properties of these molecules to enable better control and use. Involvement of students from both Vanderbilt and Tennessee State University through collaboration with Dr. Nsoki Phambu, is expected to provide valuable research training opportunities for undergraduates interested in the STEM disciplines. The work focuses on chiral aggregates based on tartaric acid chemical templates. Recently developed vibrational circular dichroism (VCD) is used to probe the aggregates, along with established electronic circular dichroism (ECD) and optical rotatory dispersion (ORD). Three-dimensional molecular structures of chiral aggregates are determined with these tools and additional data from methods such as electron microscopy and atomic force microscopy. Molecular dynamics simulations provide further understanding of possible structures. Quantum chemical predictions of chiroptical spectroscopic properties and comparison to corresponding experimental observations are used to further unravel the relation between chiral aggregates and their spectroscopic properties. These studies are expected to help establish the relationship between the structures of chiral aggregates and their chiroptical properties. This work is is also expected to better define the analytical capabilities of chiroptical spectroscopic methods for characterizing chiral aggregates.