Spectral-luminescent study of the porphyrin-diketones and their complexes

Syntheses of octaethylporphine-diketone (OEPDK) and its platinum(II) and pa lladium(II) complexes (PtOEPDK, PdOEPDK) were optimized, and the dyes were isolated in a pure form in preparative quantities. They were characterized by the NMR, UV-VIS absorption and emission spectroscopy. Electronic spectra of these dyes (absorption and luminescence) were investigated in detail, a nd compared to corresponding porphyrins and porphyrin-monoketones. OEPDK sh owed a strong fluorescence at about 700 nm, while PtOEPDK and PdOEPDK showe d very weak room-temperature phosphorescence in the region of 850-1100 nm a nd practically no fluorescence. Protonation mechanisms were studied for the se dyes. Protonation at sites other than pyrrole nitrogen atoms was shown t o occur, corresponding protomeric spectral forms are presented. The possibi lities of the use of porphyrin-diketones as longwave fluorescent and phosph orescent probes are discussed. (C) 2001 Elsevier Science B.V. All rights re served.