Supramolecular host-guest interactions water

Supramolecular spherical assemblies of NPs with photoresponsive adhesion/dispersal behaviour were also obtained in a ternary system hierarchically combining the host-guest interaction of different types of CDs toward porphyrin and azobenzene. The inclusion complexation of an azobenzene modified water soluble porphyrin (1) with phthalo-cyanine-grafted permethyl (3-CDs (2) could be reversibly cross-linked to relatively larger nanospheres with naphthyl bridged bis(a-CD)s (3). The large spheres (12 -3) turned reversibly to small-sized particles (1 2) upon photoisomerization of the azoaromatic group in 1 (Fig. 13). 

A host-guest molecular recognition process of L-tryptophan, with the above various triangular, bowl-shaped Cp Rh-nucleobase/nucleoside/nucleotide cyclic trimer molecular receptors, was also detected in a gas phase by electrospray ionization mass spectrometry.In this case, the supramolecular complex formation was found to occur predominately via non-covalent tt-tt interactions non-covalent hydrophobic forces apparently being weak or nonexistent. Trp-Met-Asp-Phe tetrapeptide with the trimeric-rhodium host [Cp Rh(2 -deoxyadenosine)]3[OTf]3 also formed a host-guest complex in water that is detected in the gas phase. 

Naturally, CD derivatives represent only one approach to creating supramolecular polymers in water. Other host-guest motifs, based on, for instance, caUxarenes [65] and curcubiturils [66-68], can also give rise to a wide variety of supramolecular structures in water. Aromatic jt—tt interactions provide another approach to... 

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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