Covalently linking two square planar platinum(II) centers using two pyrazolate bridging ligands allows the filled dz2 orbitals on each Pt center to overlap, producing a Pt�Pt s interaction and a new low energy ds*?p* metal�metal-to-ligand charge transfer (MMLCT) transition, terminating onto a 2-phenylpyridine (ppy) cyclometalating ligand.  Increasing the steric bulk of these bridging ligands systematically decreases the Pt�Pt distance, a phenomenon resulting in chromophores with visible absorption and emission energies predictably tuned with small structural modifications. In an effort to extend the lifetime of the associated MMLCT excited state, we introduced piperidinyl naphthalimide (PNI) chromophores into the 2-phenylpyridine charge transfer ligands. This structural modification introduces low-lying PNI-based triplet states serving as long-lived triplet population reservoirs, thermally capable of repopulating the charge transfer state at RT, thereby extending its excited state lifetime. This presentation will discuss the success of this approach, detailing the first example of excited state equilibrium applied to a Pt2-based MMLCT chromophore and its associated static and dynamic spectroscopic characterization.

Excited state equilibrium in a dinuclear platinum(II) complex

248th National Meeting (2014)

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