Phthalocyanine 71-71 interaction

It has long been known (93) that cobalt(II) complexes of phthalocyanines interact with molecular oxygen. The water-soluble tetrasulfonato derivative of the parent phthalocyanine selectively and catalytically oxidizes 2,6-di-tert-butylphenol to the benzoquinone and the dipheno-quinone in both homogeneous solution (94) and when polymer-supported (95). The active intermediate in the catalytic cycle is proposed to be the (as expected) mononuclear dioxygen complex of the cobalt-tetrasulfonatophthalocyanine system (92). It has been proposed that the formation of a peroxo-bridged dinuclear complex is responsible for the deactivation of the cobalt(II)-tetrasulfonatophthalocyanine system, since such a dinuclear system would be unable to further bind and activate dioxygen (96). Such deactivation results, ultimately, in loss of the catalyst and low turnover ratios. 

Iron(ii) porphyrins, like iron(n) phthalocyanin, interact reversibly with Oj in aqueous solution but subsequently dimerize and are oxidized to iron(ra). Sterically hindered o/ /A >-analylamide derivatives of iron(ii) porphyrins, the picket fence porphyrins, prevent dimerization and hence oxidation and serve as models for the high-afl nity J -state of Hb(ii). Using as the proximal base 2-methylimidazoIe, which has a steric interaction with the porphyrin ring and holds the iron in its unliganded position below the ring, a low-affinity T-form of the complex can be produced. In the crystalline state, picket fence porphyrins show co-operativity very similar to that shown by haemoglobin in mechanistic and quantitative detail. ... 

Palacin S, Lesieur P, Stefanelli I and Barraud A 1988 Structural studies of intermolecular interactions in pure and diluted films of a redox-active phthalocyanine Thin Soiid Fiims 159 83-90... 

The X-ray structure of zinc naphthalocyanate has been determined with Zn—N bond lengths of 1.983(4) A.829 Pentanuclear complexes with a zinc phthalocyanine core and four ruthenium subunits linked via a terpyridyl ligand demonstrate interaction between the photoactive and the redox active components of the molecule. The absorbance and fluorescence spectra showed considerable variation with the ruthenium subunits in place.830 Tetra-t-butylphthalocyaninato zinc coordinated by nitroxide radicals form excited-state phthalocyanine complexes and have been studied by time-resolved electron paramagnetic resonance.831... 

A number of these dyes were applied, mixed with a polymer for the control of the aggregation state, to CD-R and DVD-R recording systems. The aggregation state in the recording layer was controlled by choosing the set of axial substituents (Scheme 8 R1, R2, and R3). The interaction between the phthalocyanine dyes and the polymers was dependent on the length of the axial substituents or, more carbon atoms in the alkyl group were found to be necessary for the axial substituents to mix with the polymers.218... 

Abstract In this chapter, recent progress in the synthesis, crystal structures and physical properties of monomeric phthalocyanines (Pcs) is summarized and analysed. The strategies for synthesis and modification of Pcs include axial coordination of central metal ions, peripheral substitution of Pc rings and the ionization of Pcs. The crystal structures of various typical Pcs, especially the effects of different synthetic and modification strategies on the supramolecular assemblies of Pcs via %—% interactions between Pc rings, are discussed in detail. Finally, the UV-vis spectroscopic, conducting, magnetic and catalytic properties of some Pcs with crystal structures are presented briefly, and the correlations between various properties and the molecular structure discussed. 

PXX groups in complexes 87-90 can also slipped-stack to form columns located between the Pc columns and sheets. Since the crystal structures and supramolecular assembles of this type of phthalocyanine were well summarized in 2001 [12] and 2005 [79], we will present briefly only one typical Pc %-% supramolecular structure that has not been included in the previous section. As shown in Fig. 23, the Pc units in 89 form a 2D sheet along the ac plane. The overlap mode is type G Pc %-% interactions along both the a- and c-axes. This sheet further interacts with another sheet by type C overlap, forming a double sheet. 

Metal phthalocyanines functionalized with four helicenes (62) have also been reported to form chiral columnar aggregates.76 In chloroform solutions of these metal phthalocyanines aggregation into columns occurred upon addition of ethanol, as was observed by UV-Vis spectroscopy. CD spectroscopy revealed that the chromophores within the columnar aggregates are in a chiral environment, implying that the chirality of the peripheral helicenes has been transferred to the supramolecular aggregates. These phthalocyanines stack with a typical intermolecular distance of 3.4 A, and calculations have indicated that to allow this distance the two phthalocyanine moieties have to be rotated because of the bulkiness of the helicenes. It can easily be imagined that a phthalocyanine provided with both R and S helicenes cannot stack in such a defined manner because of the steric interactions between the nonconform helicenes. 

Other sensors are mostly grouped towards the triethylamine. In the case of porphyrins 6-8, 13 the coordinated metal is no longer able to drive the selectivity pattern and the presence of the peripheral alkyl chains completely shadows the coordination interactions. This result can explain the failure to observe the coordination interaction in the sensing mechanism of the metal complexes of the closely related alkyl chains functionalized phthalocyanines reported in the past by Gopel and coworkers [22]. 

Recently, by crystal structure studies the number of different polymorphs of Copper Phthalocyanine Blue has been extended to nine, various of which are differing mainly in herringbone-type interaction [17]. 

De la Escosura A, Martinez-Diaz MV, Guldi DM et al (2006) Stabilization of charge-separated states in phthalocyanine-fullerene ensembles through supramolecular donor-acceptor interactions. J Am Chem Soc 128 4112-4118... 

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