21-30 September 2021
Online Conference
Europe/Berlin timezone

Metal-Ligand Covalency as a New Design Principle for Fe(II) Photosensitizers: Insights from Resonant Inelastic X-Ray Scattering

30 Sep 2021, 11:05
20m
Online Conference

Online Conference

CYSS2021 will be hosted online using Zoom. The poster session will follow a dual-format approach using a chat-platform and videoconference rooms.
Plenary Talk Spectroscopy Spectroscopy II

Speaker

Dr Christopher Larsen (University of Geneva)

Description

There have been significant efforts in recent years to destabilize ligand-field with respect to charge-transfer excited states in Fe(II) complexes, towards the goal of accessing long-lived luminescent charge-transfer excited states and developing viable, sustainable and affordable alternatives to Ru(II) and other precious metal photosensitizers,[1] which have found wide application in solar fuel, photovoltaic, photocatalytic and biological applications. The most effective strategy to date has been to increase 10Dq using strong-field ligands,[2] but this appears to have hit a ceiling at sub-optimal charge-transfer excited state lifetimes – necessitating conceptually new molecular design strategies.

The Herbert group recently reported a new strategy, employing weak-field amido ligands that enhance metal-ligand covalency.[3] We have therefore investigated the electronic structure and excited-state ordering of this new class of Fe(II) photosensitizer using resonant inelastic x-ray scattering (RIXS). RIXS probes Raman-allowed valence excited states with atomic specificity, and is therefore a powerful tool for investigating the electronic structure of transition-metal complexes from both metal and ligand perspectives.

This presentation will focus on determining the electronic structure of Fe(II) complexes bearing amido ligands using N 1s2p (K-edge) and Fe 2p3d (L-edge) RIXS, and on a previously unreported competition between ligand-field strength and metal-ligand covalency with respect to destabilizing ligand-field relative to charge-transfer excited states, derived from Tanabe-Sugano analysis of the Fe 2p3d (L-edge) RIXS data.

[1] Oliver S. Wenger, Chem. Eur. J., 2019, 25, 6043-6052, https://doi.org/10.1002/chem.201806148
[2] Pavel Chabera et al., J. Phys. Chem. Lett., 2018, 9, 459-463, https://doi.org/10.1021/acs.jpclett.7b02962
[3] Jason D. Braun et al., Nat. Chem., 2019, 11, 1144-1150, https://doi.org/10.1038/s41557-019-0357-z

Primary authors

Dr Christopher Larsen (University of Geneva) Dr Jason Braun (University of Manitoba) Mr Issiah Lozada (University of Manitoba) Dr Kristjan Kunnus (SLAC National Accelerator Laboratory) Dr Elisa Biasin (SLAC National Accelerator Laboratory) Dr Amy Cordones (SLAC National Accelerator Laboratory) Prof. Kelly Gaffney (SLAC National Accelerator Laboratory) Prof. David Herbert (University of Manitoba)

Presentation Materials