Anion-pi and halogen-bonded complexes in thermal and photochemical reactions

Ball State University, Muncie IN

Investigators

Abstract

Professor Sergiy Rosokha of Ball State University is supported by the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry to study weak interaction forces between molecules and their role in chemical reactions that need heat or light energy to form products. The specific non-bonding interactions under study (anion-pi and halogen bonding) enable the aggregation of molecules in elaborate supramolecular structures. The project helps define the requirements to efficiently incorporate the non-bonding interactions into molecular design, producing a new tool for more efficient and environmentally benign synthetic procedures for unique chemicals from charged and halogenated molecules, which are ubiquitous in biological systems and the environment. The project is expected to impact many fields, such as drug development, environmental remediation and materials development. The interdisciplinary nature of the project provides a diverse group of undergraduate students in a primarily undergraduate institution with training in a variety of modern experimental chemistry research techniques, as well as computational chemistry. The project builds on the recent findings by Professor Rosokha that, in addition to controlling the structures of supramolecular complexes, anion- and halogen bonding facilitate electron movement between interacting species, which can initiate a variety of chemical transformations. The specific objectives of the project are to identify and characterize halogen bonding and anion-pi complexes in the systems undergoing thermal or light-induced reactions (e.g., halogen and/or electron transfer, nucleophilic substitution, etc.) and to determine the mechanistic role of these complexes in such reactions. To achieve these objectives, the systems in which formation of anion-pi or halogen-bonded complexes is followed by the chemical or photochemical reactions between bonded species, are studied. Transient complexes in such systems are isolated and characterized using low-temperature and stopped-flow UV-Vis measurements and X-ray structural analysis. Together with the measurements of the kinetics of thermal and light-induced reactions, as well as computational analysis, this allows to establish the nature of the intermediate complexes and their role in the reaction mechanisms. 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.