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A Near-Infrared-II Emissive Chromium(III) Complex
Narayan Sinha1, Juan-Ramón Jiménez2, Björn Pfund1
1Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland.
Abstract:
The combination of π-donating amido with π-accepting pyridine coordination units in a tridentate chelate ligand causes a strong nephelauxetic effect in a homoleptic CrIII complex, which shifts its luminescence to the NIR-II spectral range. Previously explored CrIII polypyridine complexes typically emit between 727 and 778 nm (in the red to NIR-I spectral region), and ligand design strategies have so far concentrated on optimizing the ligand field strength. The present work takes a fundamentally different approach and focusses on increasing metal-ligand bond covalence to shift the ruby-like 2 E emission of CrIII to 1067 nm at 77 K.
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