November 7, 2023 11:00 am
November 7, 2023 12:15 pm
Design Strategies for Luminescent Titanocenes
Paul Wagenknecht
Professor of Chemistry
Furman University
Complexes of d0 transition metals with photoactive ligand-to-metal charge-transfer (LMCT) excited states have recently shown significant promise as photocatalysts involving earth-abundant metals. Arylethynyltitanocenes of the type Cp2Ti(C2R)2 (where R = ferrocene or an aryl substituent) have recently been investigated for their C2R-to-TiIV LMCT states. The first example of a TiIV complex with an emissive (FP ~ 10–4) ligand-to-TiIV LMCT state in RT fluid solution is Cp2Ti(C2Ph)2. However, this complex undergoes photodecomposition with a high quantum yield (Frxn = 0.99). Coordination of CuX between the alkyne ligands to give Cp2Ti(C2Ph)2CuX (X = Cl or Br) has been shown to significantly increase the photostability, but such complexes are not emissive in RT solution. The mechanism for photodecomposition and nonradiative decay have been investigated and have led to design strategies for luminescent titanocenes. Based on these strategies, we have developed titanocenes with increased photostability that are also luminescent to the naked eye in room-temperature fluid solution.