A Near-Infrared-II Emissive Chromium(III) Complex

摘要

The combination of pi-donating amido with pi-accepting pyridine coordination units in a tridentate chelate ligand causes a strong nephelauxetic effect in a homoleptic Cr-III complex, which shifts its luminescence to the NIR-II spectral range. Previously explored Cr-III 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 E-2 emission of Cr-III to 1067 nm at 77 K.