RUI: Promoting Through-Space Charge Transfer via Arylene Ethynylene Templates

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Nathan Bowling of the University of Wisconsin-Stevens Point will design and synthesize new molecules that display behavior potentially useful for modern catalysts, organic light-emitting diodes (OLEDs), and molecular sensing devices. Specifically, Professor Bowling and his students will generate molecular templates that hold different molecular components in proximity and study how the relative orientation of the components affects their interactions and electronic properties. The fundamental knowledge to be gained will help advance the development of next generation, charge transfer-based devices and catalysts. Synthesis, purification, and characterization of these compounds will be performed exclusively by undergraduate students and Professor Bowling at the University of Wisconsin-Stevens Point. Hands-on experience with cutting edge research projects will position these students well to excel in the chemical industry or in graduate studies. This project aims to develop a variety of templates to promote efficient charge-transfer between electron-rich and electron-poor aromatic subunits in solution and the solid state. The primary method for promoting through-space interaction of these subunits is a twisted arylene ethynylene framework upon which the subunits interact in an intramolecular fashion. Rotation around a central tolane forces complementary electron-rich/electron-poor arms of the rotor to collide. Electronic (UV-vis) and crystallographic (x-ray) studies will provide insight into how the orientation of subunits in these through-space collisions impacts charge transfer behavior. Additionally, halogen bonding and metal complexation will be used as driving forces to mimic the geometry of the twisted arylene ethynylene systems. The onset of visible color expected with charge transfer may provide opportunities for colorimetric quantification of host-guest interaction in these dynamic systems. After initial characterization, template design will focus on controlling the relative orientations of electron-rich/electron-poor pairs for optoelectronic, sensing, and catalyst applications. The designed systems are expected to provide a method for studying charge transfer behavior that is otherwise difficult to study. In the longer term, the work has the potential to establish a foundation for advances in next-generation electronic devices and light-driven catalysis. 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.