Decoration of porphyrin with tetraphenylethene: converting a fluorophore with aggregation-caused quenching to aggregation-induced emission enhancement.

Porphyrins have long been used as fluorescence imaging contrast agents. However, they often suffer from aggregation-caused quenching (ACQ) which limits their maximal imaging ability. It is desirable to design new porphyrin derivatives exhibiting aggregation induced emission enhancement (AIEE) with a high photoluminescence (PL) intensity in an aggregated state. Herein, we transform porphyrin from an ACQ molecule to an AIEE one by simply decorating a porphyrin core with four tetraphenylethene arms. We further encapsulate the new AIE porphyrin into nanoparticles and examine their fluorescence imaging in vitro with HeLa cells. This research demonstrates a general approach to produce AIEE porphyrin derivatives that could potentially enhance their performance in various areas.