Strong Inhibition of Singlet Oxygen Sensitization in Pyridylferrocene−Fluorinated Zinc Porphyrin Supramolecular Complexes

Abstract

A supramolecular pyridylferrocene (PyFc)-fluorinated zinc porphyrin (ZnTFPP) dyad system was developed, and its photodynamics was investigated in dichloromethane and acetonitrile. The nitrogen of PyFc coordinates to the metal center of zinc porphyrin to form a supramolecular donor-acceptor complex. Formation of the pyridylferrocene-zinc porphyrin supramolecule was probed by 1 H NMR and UV-vis spectroscopy. The one-electron reduction potential of ZnTFPP in dichloromethane is shifted to a negative direction by 0.08 V due to formation of the supramolecular complex with PyFc. The binding constant of ZnTFPP •-with PyFc in the supramolecular complex determined from the potential shift is much smaller than the binding constant of the neutral form, ZnTFPP. The fluorescence of ZnTFPP is strongly quenched by electron transfer from PyFc to the singlet excited state ( 1 ZnTFPP*) in the supramolecular complex of ZnTFPP with PyFc. The lifetime of 1 ZnTFPP* is also shortened significantly in the supramolecular complex. No transient absorption spectrum due to the charge-separated state (ZnTFPP •--PyFc + ) or the triplet excited state ( 3 ZnTFPP*-PyFc) was detected even at the picosecond time scale due to the ultrafast back electron transfer from ZnTFPP •-to PyFc + to yield the ground state supramolecular complex rather than the triplet excited state. This leads to strong inhibition of singlet oxygen sensitization of the zinc porphyrin by formation of the supramolecular complex.

Construction of SnIV Porphyrin/Trinuclear Ruthenium Cluster Dyads Linked by Pyridine Carboxylates: Photoinduced Electron Transfer in the Marcus Inverted Region

“…Recently, in order to improve accessibility, supramolecular assemblies having light harvesting functionalities were developed by virtue of noncovalent interactions to self-organize electron donors and electron acceptors. [9][10][11][12][13][14][15][16][17][18][19] However, Abstract: Novel conglomerates consisting of saddle-distorted Sn IV A C H T U N G T R E N N U N G (DPP) (H 2 DPP = dodecaphenylporphyrin) complexes and m 3 -O-centered and carboxylato-bridged trinuclear Ru III clusters linked by pyridine carboxylates were synthesized and characterized. Sn IV -DPP complexes with Cl À , OH À , and 3-and 4-pyridine carboxylates ligands were characterized by spectroscopic methods and X-ray crystallography.…”

Triphenylamine Functionalized Unsymmetrical Quinoxalines

“…The introduction of donor moiety in triphenylamine substituted quinoxalines 11 results in substantial decrease in the emission intensity of 12 – 16 due to fast non‐radiative deactivation of the state with intramolecular charge transfer . The introduction of the acceptor moiety in 17 and 18 completely quenches the signal, which confirms the strong electronic communication between the triphenylamine unit and electron withdrawing TCNE/TCNQ unit.…”

Selective accumulation of [62Zn]-labeled glycoconjugated porphyrins as multi-functional positron emission tomography tracers in cancer cells

“…ZnGlc1-4 should be applied as an antioxidant, and not only a PET agent, for inhibiting the side effects of PDT through suppression of inflammation. Zinc is a basic component of antioxidants in the blood 36 , and zinc porphyrin is well known as a scavenger of reactive oxygen species (ROS) 37 . ROS scavengers are expected to suppress cancerous growth, invasion, and metastasis 17,38,39 and inhibit inflammation in the intestine 40 .…”