Broadband Visible Light Harvesting N^N Pt(II) Bisacetylide Complex with Bodipy and Naphthalene Diimide Ligands: Förster Resonance Energy Transfer and Intersystem Crossing

A N^N Pt(II) complex, Pt-1, with two heteroleptic ligands was prepared, which is a rarely reported molecular structure. The two different acetylide ligands, i.e., boron-dipyyromethane (BDP) and naphthalenediimide (NDI) chromophores, show strong absorption in the visible region. The photophysical properties of the complex were investigated by using steady-state and femtosecond/nanosecond time-resolved optical spectroscopies, as well as electrochemical characterization. Upon selective photoexcitation of the coordinated BDP acetylide ligand at 503 nm, the Forster-resonance energy transfer (FRET, kFRET = 1.2 × 1011 s–1) process from the BDP to NDI ligand was observed, which leads to the population of the singlet excited state of the latter. After that, intersystem crossing (ISC) process occurs (kISC = 3.3 × 109 s–1), which generates the triplet excited state of the NDI ligand (τ = 28.1 μs). The overall excited-state dynamics are fairly similar in both nonpolar toluene and polar benzonitrile, indicating that p...