Iron(II) Coordination Complexes with Panchromatic Absorption and Nanosecond Charge-Transfer Excited State Lifetimes

Thumbnail Image
Braun, Jason
Lozada, Issiah
Kolodziej, Charles
Burda, Clemens
Newman, Kelly M E
van Lierop, Johan
Davis, Rebecca L
Herbert, David E
Journal Title
Journal ISSN
Volume Title
Nature Publishing Group
Replacing current benchmark rare-element photosensitizers with ones based on abundant and low-cost metals such as iron would help facilitate the large-scale implementation of solar energy conversion. To do so, the ability to extend the lifetimes of photogenerated excited states of iron complexes is critical. Here, we present a sensitizer design in which iron(ii) centres are supported by frameworks containing benzannulated phenanthridine and quinoline heterocycles paired with amido donors. These complexes exhibit panchromatic absorption and nanosecond charge-transfer excited state lifetimes, enabled by the combination of vacant, energetically accessible heterocycle-based acceptor orbitals and occupied molecular orbitals destabilized by strong mixing between amido nitrogen atoms and iron. This finding shows how ligand design can extend metal-to-ligand charge-transfer-type excited state lifetimes of iron(ii) complexes into the nanosecond regime and expand the range of potential applications for iron-based photosensitizers.
Coordination Chemistry, photophysics
Nature Chemistry 2019, 11, 1144–1150