Porphyrinic based dyes are an important class of molecules for light harvesting applications due to their chemical stability, broad spectral profile, low cost and long lived excited states. Non-covalent encapsulation of organic dyes within the pores of metal organic framework materials provides unique opportunities to develop novel light harvesting applications. Metal organic frameworks (MOFs) are an important class of scalable nanoporous materials composed of metal building blocks and organic linkers which can be derivatized to impart functionality. A number of porphyrins and porphyrin derivatives have now been non-covalently encapsulated within the pores of MOFs and their photophysicas examined. These studies have indicated that porphyrin conformational flexibility is a critical factor particulary with regard to phenyl group orientation on tetraphenyl based porphyrins. Here, we present photophysica studies for two different systems, Zn(II) phthalocyanine tetrasulphonic acid (ZnPhTSA) and Zn(II) tetra(4-sulphonatophenyl)porphyrin (Zn4SP) encapsulated within the pores of HKUST-1(Zn). The data indicated that both systems have very similar photophysics that are distinct from solution. It is of interest that the differences conformational flexibility between ZnPhTSA and Zn4SP do not impact the photophysics of the encapsulated dyes. The perturbations are then largely due to the electronic structure and/or solvent parameters within the cavities of HKUST-1(Zn).

Effects of confinement on the photophysics of Zn(II) phthalocyanine tetrasulphonic acid and Zn(II) tetra(4-sulphonatophenyl)porphyrin encapsulated within the pores of HKUST-1(Zn)

ACS Spring Meeting 2021

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