Encapsulation, supramolecular complexes

The complexation of anionic species by tetra-bridged phosphorylated cavitands concerns mainly the work of Puddephatt et al. who described the selective complexation of halides by the tetra-copper and tetra-silver complexes of 2 (see Scheme 17). The complexes are size selective hosts for halide anions and it was demonstrated that in the copper complex, iodide is preferred over chloride. Iodide is large enough to bridge the four copper atoms but chloride is too small and can coordinate only to three of them to form the [2-Cu4(yU-Cl)4(yU3-Cl)] complex so that in a mixed iodide-chloride complex, iodide is preferentially encapsulated inside the cavity. In the [2-Ag4(//-Cl)4(yU4-Cl)] silver complex, the larger size of the Ag(I) atom allowed the inner chloride atom to bind with the four silver atoms. The X-ray crystal structure of the complexes revealed that one Y halide ion is encapsulated in the center of the cavity and bound to 3 copper atoms in [2-Cu4(//-Cl)4(//3-Cl)] (Y=C1) [45] or to 4 copper atoms in [2-Cu4(/U-Cl)4(/U4-I)] (Y=I) and to 4 silver atoms in [2-Ag4(/i-Cl)4(/i4-Cl)] [47]. NMR studies in solution of the inclusion process showed that multiple coordination types take place in the supramolecular complexes. 

Jones, P. L., Byrom, K. J., Jeffery, J. C., McCleverty, J. A., Ward, M. D., A cyclic supramolecular complex containing eight metal ions, twelve bridging ligands, and an anion encapsulated in the central cavity. Chem. Commun. 1997, 1361-1362. 

In inclusion complexation, a core is encapsulated by complexation (e.g., cyclodextrin). A supramolecular assembly is formed because of the noncovalent inclusion of an apolar core (e.g., oil) of suitable size within the hydrophobic cavity of the cyclodextrin. An example of inclusion complexation is the interaction between cyclodextrin and lycopene (Mele et al. 2002). The inclusion complex increases the water... 

The more versatile and stable modular interface was successfully used to investigate supramolecular complexations based on the metal-ligand interaction between Zn-porphyrin 1 and the nitrogen-containing guest molecules 2, 3, 4, 5 and 6 or the encapsulation of guests 8 and 9 in the cavity of p-CD (7). 

Some formally square four-coordinate structures are also fiuxional.Rearrangement of metal clusters and carbonyls which are bound to them have also been studied extensively.DNMR is not limited to solutions and can also be studied in solid materials. DNMR has also been observed with supramolecular complexes.Calixarene complexes based on Ir(l) and Rh(l) complexes also show dynamic motions associated with encapsulation of other molecules. " Although not an organometaiiic, a study of ring inversion in Fe(lll) porphyrins provides a particularly well-documented discussion of the methodologies that can be applied to DNMR. ... 

Reviews of gas encapsulation by supramolecular complexes (a) Hoiike, S., Shimomura,... 

Enzymes have also been incorporated into the PAMAM dendrimer to produce silica nanoparticles. At physiological pH, the interaction between an enzyme and the cationic surface of the PAMAM dendrimer plays an important role in forming supramolecular complexes. As a result, the cationic dendrimer (pXa 9.5) interacts with low-pf enzymes, for example, glucose oxidase (GO, pf -4.2) was encapsulated in water with a quantitahve yield. As phosphate ions compete with the enzyme, GO was poorly encapsulated as phosphate buffer concentrations increased because the phosphate ions significantly reduced the electrostatic interactions between the enzyme and dendrimer (Figure 1.25). 

ZhaoX-L, Mak TCW (2004) Silver cages with encapsulated acetylenediide as building blocks for hydrothermtil synthesis of supramolecular complexes with n-cyanopyridine and pyridine-n-carboxamide (n = 3,4). Dalton Trans 3212-3217... 

Ebitani, K. and Kaneda, K. (2004) Supramolecular catalysts by encapsulating palladium complexes within dendrimers. Journal of the American Chemical Society, 126,1504. 

J. Santamaria, T. Martin, G. Hilmersson, S. L Craig, J. Rebek, Jr, Guest exchange in an encapsulation complex A supramolecular substitution reaction , Proc Natl. Acad. Sci. USA 1999, 96, 8344-8347. 

This chapter describes the synthesis, properties, and biomedical applications of cyanine and squaraine dyes encapsulated in CDs, CBs, Leigh-type tetralactam macrocycles, aptamers, and micro- or nano-particles. The optical and photochemical properties of supramolecular guest-host nanostructures that are based on intra-and intermolecular complexes of crown-containing styryl dyes with metal cations, and aggregates of carbocyanine dyes are discussed in a separate review [18]. 

This range is for tripodal ligands - a log value of about 59 has been estimated for the Fe + complex of an encapsulating tris-catecholate ligand (Vogtle, F. Supramolecular Chemistry -, Wiley Chichester, 1991, Section 2.3.7.)-... 

Sabbatini, N. Guardigli, M. Lehn, J.-M. Luminescent lanthanide complexes as photochemical supramolecular devices. Coord. Chem. Rev. 1993,123, 201-228. Sabbatini, N. Guardigli, M. Manet, I. Lanthanide complexes of encapsulating ligands as luminescent devices. Adv. Photochem. 1997, 23, 213—278. 

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