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Laser flash photolysis measurements are utilized to examine the dynamics of photoinduced electron transfer from the singlet excited state of porphyrin tripod (TP[Zn.sub.3]) to pyridine moiety (Py[C.sub.60]). The efficient intracomplex photoinduced electron transfer in TP[Zn.sub.3]-Py[C.sub.60] in nonpolar solvents is attributed to the [pi]-[pi] interactions between the porphyrin and fullerene moieties, together with intramolecular [pi]-bond formation between the porphyrin radical cation and the neutral porphyrin in TP[Zn.sub.3.sup.*+].

Novel zinc porphyrin tweezers in which two zinc porphyrinswereconnected with π-conjugated boron dipyrromethenes (BDP meso-Por2and BDP β-Por2) throughtriazole rings were synthesized to investigate the photoinduced energytransfer and electron transfer. The UV–vis spectrum of BDPβ-Por2which has less bulky substituents than BDP meso-Por2exhibits splitting of the Soret bandas a result of the interaction between porphyrins of BDP β-Por2in the excited state. Such interaction between porphyrinsof both BDP β-Por2and BDP meso-Por2is dominant at room temperature, while the coordination ofthe nitrogen atoms of the triazole rings to the zinc ions of the porphyrinsoccurs at low temperature. The conformational change of the BDP–porphyrincomposites was confirmed by the changes in UV–vis and fluorescencespectra depending on temperature. Photodynamics of BDP meso-Por2and BDP β-Por2has also been investigatedby laser flash photolysis. Efficient singlet–singlet energytransfer from the ZnP to the π-conjugated BDP moiety of bothBDP meso-Por2and BDP β-Por2occurred in opposite direction as compared to energy transferfrom conventional BDP to ZnP due to the π-conjugation in nonpolartoluene. In polar benzonitrile, however, additional electron transferoccurred along with energy transfer. [ABSTRACT FROM AUTHOR]

B,B-Diporphyrinbenzyloxy-BODIPY derivatives have been prepared in high yields, and the photophysical properties are reported. Singlet energy transfers from BODIPY to the porphyrin units have been analyzed [ABSTRACT FROM AUTHOR]

A novel porphyrin tripod (TPZn3) was synthesized via "click chemistry". Three porphyrin moieties of TPZn3 are geometrically close and linked by a flexible linker. The electron-transfer oxidation of TPZn3 results in intramolecular π-dimer formation between porphyrin moieties as indicated by electrochemical, vis-NIR, and ESR measurements. The cyclic voltammogram of TPZn3 exhibited stepwise one-electron oxidation processes of three porphyrin moieties in the range from 0.58 to 0.73 V (vs SCE in CH2CI2). When TPZn3 was oxidized by tris(2,2'-bipyridyl)-ruthenium(lll) ([Ru(bpy)3]3+), the oxidized species (TPZn3)n+(0 < n ⩽ 3) exhibited a charge resonance band in the NIR region due to the r-dimer formation between porphyrin moieties. A supramolecular electron donor-acceptor system was also constructed using TPZn3. The flexible conformation of TPZn3 makes it possible to capture a fullerene derivative containing a pyridine moiety (PyC60) inside the cavity by π-.π interactions as well as the coordination bond between Zn2+ and the pyridine moiety. The formation of a 1:1 supramolecular complex of TPZn3 with PyC60 (TPZn3-PyC60) was indicated in the UV-vis and 1H NMR spectra in nonpolar solvents. The association constant of TPZn3 with PyC60 (1.1 x 105 M-1 in toluene) is much larger as compared with those of the corresponding monomer (MPZn) and dimer porphyrin (DPZn2). The dynamics of photoinduced electron transfer from the singlet excited state of TPZn3 to PyC60 was examined by laser flash photolysis measurements. The efficient intracomplex photoinduced electron transfer in TPZn3-PyC60 occurred in nonpolar solvents, resulting from the π-π interactions between the porphyrin and fullerene moieties, together with intramolecular v-bond formation between the porphyrin radical cation and the neutral porphyrin in TPZn3∙+. [ABSTRACT FROM AUTHOR]