The design and development of organic phosphors that exhibit efficient emission at room temperature but do not contain precious metals such as iridium and platinum have attracted increasing attention. We report herein highly efficient green phosphorescence-emitting 1,4-dibenzoyl-2,5-bis(siloxy)benzene crystals in air at room temperature. Remarkable luminescence quantum yields of 0.46 to 0.64 and long lifetimes ranging from 76.0 to 98.3 ms were observed. Xray diffraction analysis of the single crystals revealed that there were several intermolecular interactions causing suppression of intramolecular motion, thereby minimizing nonradiative decay of the triplet excited state. Comparison with the corresponding 2,5-bis(dimethylphenylsilylmethyl) and 2,5-bis(trimethylsilyl) derivatives revealed that the siloxy groups are essential for efficient room temperature phosphorescence. Density functional calculations suggested that σ−n conjugation was operative in the siloxy moieties. Electron spin resonance measurement indicated that the radiative process included generation of the triplet diradical species, whose electron distribution was very similar to that of naphthalene. The present study largely expands the possibilities for the molecular design of precious metal-and halogen-free organic phosphors exhibiting efficient room temperature phosphorescence.

Much interest has been paid to cyclic diaryliodonium salts as bis(electrophile)s in transition-metal-catalyzed annulation reactions to produce polycyclic (hetero)aromatic hydrocarbons. Herein, we report that dibenziodolium triflates smoothly react with potassium thioacetate in the presence of

Crystals of and PMMA films doped with 2,5-bis(silylmethoxy)-1,4-diaroylbenzenes exhibit efficient green phosphorescence at room temperature.

Non-fluorescent 2,5-bis(diphenylamino)-1,4-benzenedicarbothioic acid bis(pentafluorophenyl)ester reacts with cysteine and produces a green-fluorescent amide through native chemical ligation, whereas no fluorescence is observed when the ester is mixed with homocysteine or glutathione. This is the first application of native chemical ligation to selective detection of cysteine (vis-a-vis homocysteine and glutathione).