Cofacial phthalocyanine dimer

Fig. 11 Supramolecular structure of a cofacial phthalocyanine dimer - C60 conjugate (reproduced from [97] with permission from the American Chemical Society)...

Figure 8.6.1. Cofacial phthalocyanine dimer with a 4-atom bridge, adsorbed on an electrode, is a catalyst for electroreductions. The central metal atom is cobalt. (Reproduced by permission from C. C. Leznoff and the National Research Council of Canada).

This self-assembly strategy has recently been extended to construct an interesting biomimetic model for the bacterial photosynthetic reaction center complex [97], In this system, a cofacial zinc(II) phthalocyanine dimer is formed via the interactions between K+ ions and the four 15-crown-5 units fused to the phthalocyanine ring. 

Unsymmetrical zinc phthalocyanine analogs with three 15-crown-5 ether ligands appended at the 3,4-positions were synthesized and characterized. Introduction of alkali metal ions results in cofacial dimer formation with evidence for this dimerization from NMR.841... 

Cation-induced supramolecular formation of crown ether substituted phthalocya-nines can also be regarded as due to host-guest interactions. Fig. 10 shows the proposed structure for the K+- and Ca2+-induced dimer of metallophthalocya-nines fused with four 15-crown-5 units, which serves as a typical example. The formation of these cofacial dimers has been found to go through a two-step three-stage process. The earlier works have been briefly reviewed [93, 94], Recently, Jiang et al. have prepared a series of copper(II) phthalocyanines fused with one to four 15-crown-5 unit(s) [CuPc(15-C-5) ] (n = 1 1) by heating a solution of the double-decker complexes Eu(Pc)[Pc(15-C-5) ] (n = 1-4) with Cu(OAc)2 in... 

Figure 2. Cofacial macrocycles associated via electrostatic interactions to give (a) dimers, (b) trim-ers and (c) higher aggregates. Typical cationic groups are pyridinium or trimethylanilinium typical anionic groups are sulfonate or carboxylate. Boxes represent porphyrin, phthalocyanine or por-phyrazine M = 2H, Zn, Cu, MnCl, etc.

Bolze, R, C.P. Gros, P.D. Harvey, and R. Guilard (2001). Luminescence properties of a cofacial dipalladium porphyrin dimer under argon and in the presence of dioxygen. J. Porphyrins Phthalocyanines 5(7), 569-574. 

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