Photoredox catalysis has been a growing field in chemistry over the past decade due to its selectivity and ability to drive thermodynamically unfavorable reactions. More recently, iridium based photocatalysts have become the catalyst of choice, often in an ionic form. Many spectroscopic efforts have been made to understand how various parameters such as redox potentials, absorption energy, excited-state lifetime, and state mixing modify these photoredox catalyst’s activity; however, very little consideration has been reported in literature as to how the counter-ion identity effects activity. In this presentation, I will show there is a four-fold difference between oxidative and reductive electron transfer rates depending on if the anion (X-) is a tightly or loosely in [Ir[dF(CF3)ppy]2(dtbpy)]X based on steady-state Stern-Volmer quenching experiments. Demonstrating that tight ion-pairing is beneficial for reductive chemistry but harmful for oxidative. In addition, I will evince through microwave spectroscopy how excited-state ion-pair reorganization accounts for this difference.

Counter-ion association regulates electron transfer in photoredox catalysts

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

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