RUI: CAS: Quinone-Based Macrocyclic Systems for Supramolecular Applications

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Dr. Jay W. Wackerly of Central College plans to design and synthesize a new class of "host" molecules with "catch-and-release" capabilities.

The "host" molecule has a cavity into which a smaller "guest" molecule can fit. Two unique features of this new class of hosts are: 1) the modular framework that enables control of the size, shape and electronic properties of the host for selective binding of a specific guest target, and 2) the switchable electronic property that permits the binding of target to be turned on and off.

The binding properties and the reversible capture and release of electron-rich guest molecules and negatively charged ions, such as halide and phosphate ions, will be investigated. The research aims to gain a deeper fundamental understanding of intermolecular interactions and provide insights to the design of molecular receptor for water purification and waste treatment.

The project will provide research training opportunities to undergraduate students, including students of underrepresented groups. The results of research will be integrated into undergraduate laboratory course and scientific demonstrations in the middle and high school science classrooms to arouse students’ interest in science.

One notable aspect of these supramolecular host macrocycles to be developed is that they can change their electronic state when subjected to a redox stimulus due to the presence of two parallel facing quinone rings. This class of structures was given the name "cambiarene" from the Latin word "cambiare" meaning "to change". This research will explore how the embedded quinone rings can be modulated to give rise to different structural, electronic, and binding properties.

The upper-rim of the macrocycle, which contains the quinone rings, will be lengthened and shortened from the original form to investigate how different sized guests can be accommodated within the cavity and how strongly guests bind with special attention being paid to the contributions from anion-pi interactions. The lower-rim of the macrocycle will be modified to control the cavity size and the distance between the parallel quinone rings.

Additionally, the pendant groups of the macrocycle will be modified to increase the solubility properties of the cambiarenes. This project should allow for the development of new small molecule and macrocyclic synthetic methodology, a greater understanding of the anion-pi interaction, and the establishment of the cambiarene as a useful supramolecular host molecule.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.