Syntheses and evaluation of novel porpholactones for photonic applications

Abstract

Previous research by our group has led to the development of a platinum porpholactone-based oxygen permeable luminescent coating that was applied as a Pressure Sensitive Paint (PSP). Oxygen partial pressures can be measured through the oxygen-dependent modulation of luminescence intensity or luminescence decay rate (lifetime). Rapid and sensitive oxygen measurements are much sought after in the physical sciences. Particularly for applications in biological systems, near-IR absorbing and emitting chromophores are desired.We describe here the step-by-step syntheses of a range of novel porpholactones, their dihydroxylation products (dihydroxylactones), and dilactones in which two porphyrinic beta,beta'-bonds have been replaced with lactone moieties. An OsO4-mediated dihydroxylation of porphyrins, porpholactone or dihydroxychlorins was followed by an MnO4- -induced cleavage of the diol moiety under phase transfer catalysis. Both the meso- and metallated versions of the tetraphenyl- and -tetrafluorophenyl-series were prepared, each providing their unique synthetic challenges.Several members of the novel chromophores were characterized by UV-vis and IR spectroscopy, NIR emission and excitation, 1H and 13C NMR, mass spectroscopy, and X-ray crystallography. Further, we report on the unique chemical characteristics of the novel chromophores.