Characterization and Photophysical Properties of Porphyrins Based Metal-Organic Framework (RWLCAA-1) Obtained by Self-Assembly of Zinc 5,10,15,20-Tetra(4-Pyridyl)-21H,23H-Porphine

Abdulaziz A. Alanazi, Randy W. Larsen, Jake Mayers and Lukasz Wojtas

Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620, United States

A new topology of metal−organic frameworks (MOF) have been synthesized based on Zn(NO₃)₂.6H₂O units linked by zinc 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (ZnT4PyP) and 1,3,5 benzene tricarboxylate (H₃BTC). The structure of RWLAA-1 was confirmed by Single-crystal X-ray diffraction. Here we present a complete photophysical characterization of this new functionalized porphyrin-based MOF including steady-state optical absorption, steady-state emission, and triplet-triplet transient absorption. The absorption spectrum of the RWLAA-1 displays optical bands similar to ZnT4MPyP, consistent with the presence of unperturbed ZnT4MPyP links associated with the framework. The corresponding emission spectra for ZnT4MPyP in methanol solution gives rise to an emission maximum centered at 656 nm with a pronounced shoulder at 606 nm. In contrast, a suspension of the RWLAA-1 material exhibits a red shift to 662 nm with a pronounced shoulder at 608 nm due to the rotational restriction of the pyridinium group due to the framework.