New Anions to Understand Recognition Chemistry and Drive Hierarchical Assembly with Cyanostars

With support of the Macromolecular, Supramolecular, and Nanochemistry Program in the Division of Chemistry, Professor Amar Flood of Indiana University will undertake a project to understand how to design molecular compounds to capture negatively charged ions (anions) and use them to synthesize more complex chemical compounds. The significance of studying anions stems from their many global impact areas spanning from the use of nitrate and phosphate as fertilizer, which impact food production and water quality, through to organic phosphates that are the workhorse anions in lithium ion batteries.

The significance of anion-directed synthesis is inspired by Nature's use of bottom-up self-assembly and has the potential to impact the future of nano-manufacturing. The planned activity will benefit society by training graduate, undergraduate and postdoctoral coworkers in research, communication and collaboration both nationally and internationally.

Inclusive practices will be developed that foster a culture that embraces diversity and equity in STEM (Science, Technology, Engineering and Mathematics). This project also has the potential to broaden understanding of anion-based chemistry for the public and undergraduate communities with videos and laboratory experiments. Outputs from this research are expected to offer benefits to researchers in other areas of chemistry, and to industries that need to manipulate anions.

In this project on anion recognition and anion-driven hierarchical assembly, Professor Amar Flood and his team will synthesize a series of anions to control their modes of self-assembly, study their anion recognition by cyanostar macrocycles, and examine their mechanisms and cooperativities of self-assembly. The project has three Aims. Aim 1 seeks to determine how the sterics, electronics and charge of substituents on anions composed of trifluoroborates control formation of cyanostar complexes by using synthesis, titration data and crystal structures.

Aim 2 aims to establish the correlation between the structures of substituted phosphates and their mechanisms of threading inside cyanostar macrocycles and to make threaded polymers with beads-on-a-string structures. Aim 3 seeks to expand the role of anions in hierarchical self-assembly synthesis by understanding how anions and cyanostar structures need to be programmed to produce specific architectures that include network gels, cyclic polymers, and spherical cages.

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.