Synthesis, Characterization, and Investigation of Non-covalent Interactions Between Novel Pyrene-appended Porphyrins and C60

Abstract

Two different sets of novel pyrene-containing porphyrins were synthesized. The first set, which consists of asymmetric A3B1 and A2B2 porphyrins, was synthesized by the condensation of t-butylphenyl dipyrromethane and newly reported 4-(1-pyrenylmethoxy)benzaldehyde. The second set consists of asymmetric A3B1 and A2B2 porphyrins, which were synthesized by condensation of the dipyrromethane of the newly reported 4-(1-pyrenylmethoxy)benzaldehyde and 1-ferrocenecarboxaldehyde. All four porphyrins were fully characterized by UV-Vis-NIR spectroscopy, NMR spectroscopy, MCD spectroscopy and high-resolution mass spectrometry. Fluorescence spectroscopy studies were performed to qualitatively observe the interactions of the porphyrins with C60 fullerene. It was observed that C60 significantly quenches the fluorescence of pyrene, thus blocking fluorescence, suggesting there is a large amount of interaction between pyrene and C60. DFT and TDDFT calculations were performed in order to further investigate the electronic structure and nature of the excited states of the target porphyrins by first optimizing the equilibrium geometries at the DFT level using the CAM-B3LYP exchange-correlation functional and furthermore using TDDFT. Transient absorption spectroscopy data is being analyzed to elucidate the electron transfer properties of the new porphyrins.