A Convenient Synthesis of Pentaporphyrins and Supramolecular Complexes with a Fulleropyrrolidine.

A simple and straightforward synthesis of diporphyrins and pentaporphyrins is reported here. The supramolecular interactions of the new porphyrin derivatives with C60 and PyC60 (a pyridyl [60]fulleropyrrolidine) were evaluated by absorption and fluorescence titrations in toluene. While no measurable modifications of the absorption and fluorescence spectra were observed upon addition of C60 to the porphyrin derivatives, the addition of PyC60 to the corresponding mono-Zn(II) porphyrins resulted in the formation of Zn(porphyrin)-PyC60 coordination complexes and the binding constants were calculated. Results show that the four free-base porphyrin units in pentaporphyrin 6 have a significant contribution in the stabilization of the 6-PyC60 complex. The crystal and molecular features of the pentaporphyrin Zn5 were unveiled using single-crystal X-ray diffraction studies.

Porphyrin Macrocycle Modification: Pyrrole Ring-Contracted or -Expanded Porphyrinoids.

In recent years, several synthetic strategies aiming at the peripheral functionalization of porphyrins were developed. Particularly interesting are those involving the modification of ß-pyrrolic positions leading to pyrrole-modified porphyrins containing four-, five-, six- or seven-membered heterocycles. Azeteoporphyrins, porpholactones and morpholinoporphyrins are representative examples of such porphyrinoids. These porphyrin derivatives have recently gained an increasing interest due to their potential application in PDT, as multimodal imaging contrast agents, NIR-absorbing dyes, optical sensors for oxygen, cyanide, hypochlorite and pH, and in catalysis.

Study of Multiporphyrin Compounds as Colorimetric Sitting-Atop Metal Complexes: Synthesis and Photophysical Studies.

Mono-, di-, tri-, and hexaporphyrin derivatives were synthesized and their sensorial ability toward Na+ , Li+ , Ca2+ , Cu2+ , Ni2+ , Co2+ , Fe3+ , Zn2+ , Cd2+ , Hg2+ , Ag+ , Cr3+ , Pb2+ , and Al3+ was explored by absorption and emission spectroscopy and 1 H NMR spectroscopy. For all of the studied porphyrin derivatives the most significant spectral changes were observed upon addition of Zn2+ , Cd2+ , Cu2+ , Co2+ , Pb2+ , Hg2+ , and Fe3+ , which resulted in a color change from red to green. When the remaining metal ions were tested, no significant changes were observed. The results reveal, as expected, the formation of mononuclear complexes for porphyrin 4, dinuclear complexes for diporphyrin 7, and trinuclear complexes for triporphyrins 9 and 10. In addition, complexes of type M6 L were determined for hexaporphyrin 8. The NMR spectroscopy studies suggest that the interaction with the metals occurs with the formation of sitting-atop complexes. This study also shows that the sensitivity increases with increasing number of coordination sites, with the most pronounced case observed for Hg2+ . The lowest value of detectable concentration of 0.05 µm for Hg2+ was achieved for hexaporphyrin 8.