Phthalocyanines hydrogen-bonded

The pseudorotaxane self-assembles through hydrogen bonding, and the binding constant, calculated using steady-state fluorescence, is 1.4 x 10. The zinc phthalocyanine derivative exhibited an excited-state lifetime of approximately 3.1 ns. The fast decay of the excited state of 1 ZnPc upon complexation with the fullerene... 

Discrete supramolecular Pc-porphyrin-Pc assemblies have also been prepared using saddle distorted components, namely a protonated dodecaphenylporphyrin and octaphenyl Zn(II) phthalocyaninate complex, using 4-pyridinecarboxylate as a supramolecular linking unit. Both metal-ligand and hydrogen bonding interactions allow the assembly of the components [27],... 

Hydrogen-Bonded Phthalocyanine-Fullerene Hetero-Arrays. 190... 

In addition to axial coordination, hydrogen bonding is another important approach to construct various supramolecular systems. This strategy, however, has not been widely used to assemble phthalocyanines and other functional units. To our knowledge, examples are so far confined to several phthalocyanine-fullerene arrays and self-assembled phthalocyanine aggregates, which are described in this section. 

Nucleobases and nucleosides are common motifs for hydrogen-bonded supramolecular arrays. Ng et al. first reported a series of phthalocyanine-nucleobase conjugates [64], The tetra-adenine phthalocyanine 64 was prepared by standard <9-alkylation of zinc(II) tetrahydroxyphthalocyanine with 9-(2-bromoethyl)adenine in the presence of K2CO3. The fluorescence of 64 is quenched substantially upon addition of thymine-substituted 9,10-anthraquinone 65, and the rate is much faster compared with that for the situation when the unsubstituted 9,10-anthraquinone is used as the quencher. These results suggest that 64 forms a supramolecular complex with 65 through the Watson-Crick base-pairing interactions. 

While supramolecular chemistry of porphyrins has been extensively studied over the last few decades, related study of phthalocyanines is still in its infancy. Despite the great potential of phthalocyanine-based supramolecular arrays in various applications as mentioned earlier, only a handful systems have been reported so far. Self-assembled systems held by hydrogen bonding, donor-acceptor interactions, and host-guest interactions are still very rare. There is certainly much room for further investigation in the chemistry of this important class of compounds, particularly on their structural and functional aspects. We hope this article can provide the grounding for further studies. 

Ni(ii) forming 4 coplanar bonds. Planar diamagnetic complexes include the Ni(CN)4 ion, which has been studied in the and other salts (Ni-C, 1-85 A), and molecules such as (a) and (b). The numerous complexes with bidentate ligands include the thio-oxalate ion, (c), molecules of the types (d) ) and (e), and the glyoximes, (0> notable for the short intramolecular hydrogen bonds. Many divalent metals form phthalocyanins, M(ii) replacing 2 H in C32H18N8 (Fig. 27.9). 

The solid state tautomerism of solid phthalocyanine was discovered [66a] and studied by Limbach et al. [66b[. As illustrated in Fig. 6.22(b), there are two forms which differ in the arrangement of the central nitrogen atoms. They are arranged in a square in the a- form but in a rectangular way in the yS-form [66b]. Thus, the latter contains two weak inner NHN-hydrogen bonds. 

Figure 6.14D) form hydrogen bonds with the cyanide ligands of the adjacent Cobalt-phthalocyanine rings. 

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