Energy upconversion sensitized by a platinum(ii) terpyridyl acetylide complex

The platinum(II) terpyridine acetylide complex, [Pt(ttpy)(CCPh)]ClO4 (1, where ttpy = 4′-p-tolylterpyridine), sensitizes the 3π–π* excited state of 9,10-diphenylanthracene (DPA) that in turn produces upconverted fluorescence via triplet–triplet annihilation (TTA). The photoluminescence of 1 is readily quenched by DPA with a rate constant close to the diffusion limit via energy transfer. Selective excitation of 1 leads to the upconverted fluorescence with a near quadratic dependence of the DPA fluorescence intensity on incident light power. This is the first time that the 3MLCT charge transfer excited state of a platinum polypyridine complex has been used to promote photon upconversion.