Copper-containing enzymes are important participants in O2 activation and subsequent substrate oxidation in biological systems. Lots of efforts have been devoted to mimicking the active sites of these enzymes via chemical synthesis, where studies have shown that ligation plays a significant role in controlling the reaction rates and directions. In order to gain a fundamental understanding of the correlation among structure, dynamics, and reactivity, we used nonlinear ultrafast infrared spectroscopies to investigate the model molecules, tren-tris(phosphiniminato) copper(I) complexes, which can react with O2 to form end-on cupric superoxides that can participate further in hydrogen atom transfer reactions. We studied the role of structural variation around the metal center by systematically changing the composition of the phosphiniminato ligands (PMe3, PMe2Ph, PMePh2). An azide group (-N3) was bound to the copper center to serve as an IR reporter for the ultrafast dynamical information without inducing major structural and electronic changes in the system. Polarization-dependent infrared pump probe measurements were conducted to obtain the population and orientational relaxation dynamics, and two-dimensional infrared (2DIR) spectroscopy was employed to investigate the solvent dynamics. We find that the increasing steric bulkiness of the phosphiniminato ligands creates more spatial restrictions on the reorientation of -N3, and the electrostatic interactions between phenyl groups and -N3 slows down its orientational motion. The slow down of solvent rearrangements around the molecule is also attributed to the electrostatic interactions among phenyl groups and solvent molecules.

Probing ligand effects on ultrafast dynamics of copper complexes via nonlinear infrared spectroscopies

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.