Cryptands phthalocyanines

Purex process, 6,940 Barium, pentakis(diacetamide)-stereochemistry, 1, 99 Barium alkoxides synthesis, 2,336 Barium complexes cryptands, 3,53 phthalocyanines, 2, 863 porphyrins, 2,820 pyridine oxide, 3,9 urea, 3,9... 

Schiff base macrocycles and phthalocyanines are readily prepared and pre-date crown ethers and cryptands but are more suitable for binding transition metals or softer main group ions. 

In addition to the ligands above, considerable attention is given to more complex ligand systems [4,5] aromatic and heteroaromatic compounds (heteroarenes) (i.e., five- or six-member cyclic structures with delocalized 7i-bonds in the ring containing, besides carbon atoms, either N, P, As, O, S, Se, or Te compounds [6-8]), various chelate-forming compounds, such as macrocyclic crown-ethers, cryptands, porphyrins, and phthalocyanines. 

One final example of a cryptand-like expanded porphyrin is the niobium(IV) bicyclophthalocyaninato system 9.132 reported by Gingl and Strahle in 1990. Interestingly, 9.132 was isolated as a by-product of a standard phthalocyanine-form-ing reaction (i.e., metal-templated cyclocondensation of phthalonitrile 9.102) in which NbOCls was used as the catalyst (Scheme 9.2.10). As such, it represents the fourth type of system to be prepared using this type of procedure (the other three being the parent phthalocyanines, the subphthalocyanines discussed in Chapter 2, and the superphthaolcyanines discussed in Section 9.2.1 of this chapter). 

The template synthesis represents an elegant method that uses metal ions to direct reactions of ligands and provides a useful route to macrocyclic structures. Several books159-161 describe the template processes that involve reactions on matrices used to synthesize polyazamacrocyles, crown ethers, cryptands, rotaxanes, knots,159 clathrochelates,160 phthalocyanines,161 etc. which are applied, e.g., as molecular switches, in ion exchange, electron transfer or catalysis. An example of clathrochelate synthesis is given in Chapter 1.33... 

A crown ether substituted phthalocyanin was adsorbed on HOPG. presenting several orientations. The molecules can be manipulated with the STM tip to adopt different orientations on the substrate." The STM images of an aromatic cryptand adsorbed on HOPG show the formation of chains of molecular nanoclusters and areas with a 2D arrangement of the molecules. 

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