Chiral Electronic Materials

With support from the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program of the Division of Chemistry, Professors Colin Nuckolls and Xavier Roy of Columbia University will explore the development of a new class of macromolecular materials that exhibit a unique combination of electronic and chiral properties and explore how the combination can manifest itself in functional materials and new technological applications. The project is interdisciplinary in nature, spanning concepts in chemistry, physics, and materials science. It integrates state-of-the-art design and synthesis of chiral macromolecular pi-systems with test structures to study their ability to act as filters and valves for spin transport. The chirality of the macromolecular building blocks will be tuned and the resulting structures will be assembled on surfaces and in junctions. The macromolecules and their properties will be evaluated for quantum mechanical applications such as spintronics, spin-polarized light-emission, and spin-controlled catalysis. In the course of conducting this research project, graduate students will be trained and prepared for future multidisciplinary science careers. This will be complemented with a coordinated effort that spans curriculum development, mentoring of undergraduate students and outreach towards K-8 schools. In addition, the principal investigators will continue to develop science demonstrations and programs to increase public awareness of chemistry through their digital outreach efforts. The project will explore how chirality in a class of designer organic macromolecules can be tuned, dynamically and statically, to create effective spin filters and spin valves. The molecules are an unusual class of synthetically tunable electron-accepting molecules created by the principal investigators. The program is built around two helical π-systems, namely twistacenes and helicenes. These molecules have conduits for electron transport that are helical in nature and some of these molecules exhibit the largest molecular chiroptical activity known. These two important classes of helical π-systems and their chirality form the basis for the project to understand how their chirality can be used to control the spin-selective transport. The team will couple these designed helical π-systems with a set of complementary, well-controlled electrical and electrochemical experimental platforms to quantify the molecules’ spin filtering capabilities. To realize this structure-properties study, the molecules will be integrated into model electrical test structures as a means to probe their spin-selective transport properties. 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.