No abstract

A new type of viologen-linked or -bridged N-alkylporphyrin and metalloporphyrin diads was synthesized and characterized by 1 H NMR spectroscopy. Although the viologen moiety of free base diads linked with a methylene chain is flexible in solution, the insertion of metal ions results in the extended conformation, where the viologen moiety is located nearly perpendicular to the N-alkylporphyrin plane. The diad, having two porphyrin units bridged by a viologen moiety, is more rigid in conformation than the diad containing one porphyrin unit. The fluorescence quantum yields in the viologen-linked and -bridged N-alkylporphyrins become larger by insertion of H + , Mg 2+ , Al 3+ , and Si 4+ into the N-alkylporphyrins. This may arise because the extended and orthogonal conformer due to the electrostatic repulsion between the viologen and the central metal ion decelerates the ET quenching of N-alkylporphyrin by the bound viologen unit.

No abstract

Substances in UniversityThe effect of the solid support on thermally activated delayed fluorescece (TADF) was investigated. Comparison of the molecular structures of supports and consideration of the energy levels of the absorption band and the fluorescence, and of lifetimes of emissions allowed the postulation of certain molecular criteria for the supports of TADF. The interactions of Tin-protoporphyrin IX dimethyl ester (Sn-PPDE) with a polyvinyl alcohol (PVA) were considered in detail. The hydrogen bonds (-OH--it-electron systems of Sn-PPDE) were found to contribute to fix Sn-PPDE rigidly in the PVA matrix, thereby minimizing non-radiative decay of the excited molecule in the triplet state.

ABSTRACT:The formation of a sitting-atop complex of a N-alkylporphyrin, containing a 6-hydroxyhexyl group, with Al 3 was studied in moist acetonitrile by equilibrium and kinetic measurements. A sandwich type of metalloporphyrin, where a metal ion binds two N-alkylporphyrins, appears to be formed under the conditions that porphyrins exist in excess over a metal ion. When a large excess of metal ion was used, a 1:1 type of sitting-atop complex of Al(III) N-alkylporphyrin was produced through formation of the sandwich type of Al(III) Nalkylporphyrin.