SAMOP 2021 – scientific programme

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MO: Fachverband Molekülphysik

MO 2: Cluster & Complexes

MO 2.5: Talk

Monday, September 20, 2021, 15:00–15:15, H2

Multi-spectroscopic investigations of NIR emissive Cr(0), Mo(0) and W(0) complexes — •Pit Boden¹, Patrick Di Martino-Fumo¹, Sophie Steiger¹, Tobias Bens², Biprajit Sarkar², Gereon Niedner-Schatteburg¹, and Markus Gerhards¹ — ¹TU Kaiserslautern, Fachbereich Chemie and Research Center Optimas, Kaiserslautern — ²University of Stuttgart, Institute of Inorganic Coordination Chemistry, Stuttgart

In this contribution^[1] a multi-spectroscopic approach is applied for the photophysical and structural characterization of NIR emissive Cr(0), Mo(0) and W(0) carbonyl complexes containing a pyridyl-mesoionic carbene ligand. The idea is to replace luminophores based on rare-earth metals like e.g. iridium and lanthanides by more abundant elements.

Luminescence spectroscopy at variable temperature on solid samples revealed a dual emission (λVIS = 666 - 700 nm, λNIR = 918 - 950 nm, depending on the metal center) at room temperature and an increase of the quantum yields upon cooling to 5 K. The luminescence bands are assigned to phosphorescence according to the lifetimes obtained by time-resolved luminescence and step-scan FTIR spectroscopy. Furthermore, the step-scan FTIR analysis revealed small but significant variations of CO bond lengths in the excited state, in combination with density functional theory calculations. An excited triplet state of metal-to-ligand charge transfer character was attributed to the visible emission.

[1] P. Boden et al., Chem. Eur. J. 2021, accepted.