Manifestations of Chirality in Molecular Transport Phenomena

Prof. Abraham Nitzan of the University of Pennsylvania is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to investigate manifestations of molecular chirality in molecular transport phenomena. Molecular chirality, a property associated with the symmetry of molecular structures, is a long-studied subject with implications ranging from the origin of life to spectroscopy and chemical reactivity.

Energy (in its electromagnetic, mechanical, and heat incarnations) and charge transport is another long-studied subject, currently back in focus as molecules become important components of nano-devices. The interplay between chirality and transport properties has been repeatedly demonstrated but many aspects of its manifestations are not well understood.

Nitzan and coworkers aim to develop a fundamental understanding of such phenomena by developing the underlying theory that connects molecular symmetry to molecular dynamics, as well as numerical methods for the quantitative evaluation of such effects. Successful completion of their work will provide a valuable tool for predicting, applying and controlling chiral induced transport processes in molecular systems and other nanostructures.

Nitzan and coworkers will start from the connection between structural chirality and the symmetry properties of nuclear and electronic motions and will look at consequences for energy and charge transport, diffusion, friction, localization, and interfacial behaviors of charge and energy carriers: (a) The connection between the chirality of the molecular equilibrium structure and its electronic and nuclear dynamics will be established and characterized. (b) Mathematical measures of chiral dynamics (e.g. the scalar product of linear and angular momenta that measure their “locking”) will be developed and applied. (c) Chirality-induced asymmetries (e.g. rectification) in charge and energy transport will be characterized and quantified. (d) Classical and quantum aspects of Brownian motion, diffusion, friction, mobility, (thermal and electrical) conduction, and localization (e.g. polaron formation) in chiral environments will be studied and characterized (e) interfacial phenomena at the interface between chiral and non-chiral environments will be studied. Finally, the suitability of different methods of characterizing and quantifying molecular chirality for the analysis of the interplay between chirality and dynamics will be studied.

At the same time, numerical codes to impose a ‘controlled amount’ of chiral character in a molecular structure will be developed to provide a numerical laboratory for these studies. Importantly, the processes that will be studied are ubiquitous in chiral chemical systems, hence it is expected that the results of this research will be relevant to the behavior of all chiral chemical systems, reaching far beyond the scope of the present studies.

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.