Enhancing porphyrin photostability when locked in metal- organic frameworks

Porphyrins have been widely used in many optical devices given their unique photochemical properties. Their poor photostability has, however, limited their wide applications in bioimaging and biosensing schemes. Herein, we report the remarkable photostability enhancement of the porphyrin, carboxyphenyl porphyrin (TCPP-H-2) when locked in a zirconium based metal-organic framework (MOF-525). Steady-state ensemble fluorescence spectroscopy experiments showed minimal changes (2%) in the recorded signal when MOF-525 was continuously illuminated as compared to a 16% decrease for free porphyrins. Single particle fluorescence imaging revealed bright microparticles with exceptional photostability and no-blinking within the experiment window. This study highlights the use of metal-organic frameworks for preparing photostable microstructures by leveraging on their unique self-assembly properties.