Titanocene as a New Acceptor (A) for Arylamine Donors (D) in D−π–A Chromophores

Charge transfer (CT) transitions are relevant in the fields of solar energy conversion and nonlinear optical materials. Herein, a series of complexes with an alkynyl linkage between an aryl amine donor and a TiIV (titanocene) acceptor is reported. Each complex displays a strong (15000 –1cm–1), low-energy (520 IV ligand-to-metal CT. This characterization is supported by UV–vis spectroscopy, cyclic voltammetry, and TD-DFT calculations. These complexes are not photostable; therefore, an alternate architecture, wherein the amine donor is appended to the titanocene cyclopentadienyl ligand, has been designed. The molar absorptivity of the amine to TiIV CT in this latter architecture is lower (2100 M–1 cm–1), indicating weaker donor–acceptor coupling. This architecture is indeed much more photostable.