Porphyrin tetrapyridinium

This new type of supramolecular assembly opens the route to the design of more elaborated systems and for instance the propensity of the phosphorylated cavitand 12b to bind to poly-methylammonium guests, was further illustrated by the formation of the supramolecular complex depicted in Fig. 12. The fourfold symmetrical tetrapyridinium porphyrin [porphyry ll insoluble in chloroform was used as guest and was readily dissolved in chloroform solution in the presence of four equivalents of 12b [93]. 

Figure 7.27 Even inorganic salts, such as cadmium nitrate, can be entrapped in crystals of meso-tetrasubstitutedporphyrins. Here one cadmium ion binds two pyridine rings from meso-tetrapyridinium porphyrin, two nitrate counterions and two water molecules (all symbolized by a blue spot)...

Fig. 2.22 Dispersive interactions measured with tetrapyridinium porphyrin TPyP in water binding energies AG [kj/mol, italics], with in-...

The construction of self-assembled capsules based on ionic interactions to be tested as supramolecular hosts in polar solvents such as alcohols or water is a timely goal that, compared to hydrogen-bonded capsules, is still in its infancy even though important steps have been taken. Few examples have been reported regarding ionic capsules between cationic fiat tetrapyridinium-Zn(II)-porphyrinate and anionic tetrasulfonate-calix[4]arenes that form a hemispherical entropy-driven capsule that displayed high stability in the presence of water or competing salts. Apart from solvent molecules, such capsules showed encapsulation of small guests like 1-methylimidazole or 4-methylpyridine via coordination to the Zn(II) metal... 

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