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Formation and optical properties of self-organized pentameric porphyrin arrays

✍ Scribed by Andrei V. Chernook; Ulrich Rempel; Christian von Borczyskowski; Alexander M. Shulga; Edward I. Zenkevich


Publisher
Elsevier Science
Year
1996
Tongue
English
Weight
946 KB
Volume
254
Category
Article
ISSN
0009-2614

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✦ Synopsis


Principles of formation, electronic absorption and fluorescence spectra are reported for self-organized pentameric arrays of tetrapyrrolic macrocycles. In these arrays two molecules of Zn-porphyrin dimers, Zn(II)l,4-bis [5-(10,15,20+tri-p-hexylphenylporphyrinyl)]-benzene ((ZnHTPP) 2) are bound via one molecule of a tetrapyridyl-substituted free base of porphyrin or tetrahydroporphyrin. The process of self-assembly is based on the twofold coordination of the central Zn ions !n the dimer with the nitrogen atoms of the pyridyl rings in the free base which is strong enough to make the complexes stable at room temperature. The formation of the complexes can be followed by changes in the absorption bands of (ZnHTPP) 2 characteristic of an axial extra-ligation of Zn-porphyrins with pyridine or pyridyl-substituted compounds. The spectral behavior of the free bases in the pentads is determined by a non-planar distortion of their macrocycle caused by the two-point binding with the dimers. The fluorescence intensity of the Zn-porphyrin dimer decreases essentially upon complexation with the tetrapyridyl-substituted free bases. This quenching effect is assigned to a singlet-silaglet energy transfer from the complexed Zn-porphyrin dimers to the free base subunit in the pentad.


πŸ“œ SIMILAR VOLUMES


Optical and photophysical properties of
✍ I. Salabert; T.-H. Tran-Thi; H. Ali; J. van-Lier; D. Houde; E. Keszei πŸ“‚ Article πŸ“… 1994 πŸ› Elsevier Science 🌐 English βš– 392 KB

The formation of electrostatically linked mixed pentamers of porphyrins and porphyrazines is reported. The photophysical properties of two mixed complexes of well-defined stoichiometry are investigated, using femtosecond laser spectroscopy coupled with pump-and-probe technique and steady-state irrad