Low-Power Upconversion in Poly(Mannitol-Sebacate) Networks with Tethered Diphenylanthracene and Palladium Porphyrin

Abstract

Efforts to fabricate low-power upconverting solid-state systems have rapidly increased in the past decade because of their possible application in several fields such as bio-imaging, drug delivery, solar harvesting or displays. The synthesis of upconverting cross-linked polyester rubbers with covalently tethered chromophores is presented here. Cross-linked films were prepared by reacting a poly(mannitol-sebacate) pre-polymer with 9,10-bis(4-hydroxymethylphenyl) anthracene (DPA-(CH2OH)2) and palladium mesoporphyrin IX. These chromophores served as emitters and sensitizers, respectively, and through a cascade of photophysical events, resulted in an anti-Stokes shifted emission. Indeed, blue emission (~440 nm) of these solid materials was detected upon excitation at 543 nm with a green laser and the power dependence of integrated upconverted intensity versus excitation was examined. The new materials display upconversion at power densities as low as 32 mW/cm2, and do not display phase de-mixing, which has been identified as an obstacle in rubbery blends comprising untethered chromophores. ToC Low-power upconverting cross-linked polyester with tethered chromophores was synthesized by polycondensation of poly(mannitol-sebacate) pre-polymers with 9,10-bis(4-hydroxymethylphenyl) anthracene and palladium mesoporphyrin IX. Upconverted blue fluorescence (440 nm) of these solid materials is detected upon excitation at 543 nm with a green laser and the power dependence of integrated upconverted intensity versus excitation is examined in this study.