Encapsulation of ions

Fullerene-type materials are also found to show remarkable ER effect. Fullerene enriched soot and fullerenes mixture, particularly C6o mixed with C70 with trace amount of Cs4 and C97, display an electrorheological behavior [105], The ER properties of fullerene type materials can be tailored by appropriate encapsulation of ions within the hollow sphere or adsorbed on the surface. 

Luetzen A, Renslo AR, Schalley CA, O Leary BM, Rebek J Jr (1999) Encapsulation of ion-molecule complexes second-sphere supramolecular chemistry. J Am Chem Soc 121(32) 7455-7456... 

Taira T, Ajami D, Rebek J (2012) Encapsulation of ion pairs in extended, self-assembled structures. J Am Chem Soc 134(29) 11971-11973... 

Complexes containing encapsulated metal ions (clathrochelates ) with the formula [M(dioxime)3(BR)2] are known with iron(II) 135, cobalt(ll) 136, cobalt(III) 137, and ruthenium(ll) 138 (Fig. 37) [205-220]. Generally, these macrobicyclic complexes are prepared by template synthesis from a mixture of... 

Fig. 37. [M(dioxime)3(BR)2] complexes 135-138 contain encapsulated metal ions and are clathrochelates. The coordination geometry of the metal ion is described by the distortion angle 4>...

As is well known, many experimental smdies have been made extensively to search for a possibility of encapsulation of atoms by hollow fullerenes since the discovery of Cgo by Kroto et al. [143]. These methods, however, usually require high tempratures and high pressures, or ion implantation. The yields are also as low as 0.4—10 %. In this sense, the efficiency in our case is much higher and the required conditions are much milder with collison energy of 2 eV. However, the boron substimtion is a bottle neck, although Smalley and co-workers successfully synthesized boron-doped fullerenes [144]. 

Appropriate fabrication of sol-gel-derived membranes encapsulating neutral carriers such as valinomycin can afford an excellent type of neutral-carrier-type ion-sensing membranes for ISFETs [27] as already mentioned. The simple encapsulation of neutral carriers in sol-gel-derived membranes, however, has a drawback the encapsulated neutral carriers are still apt to exude from the membranes into aqueous sample solutions, which thereby makes the resulting ion sensors less durable and more toxic. Incorporation of neutral carriers to sol-gel-derived membranes by covalent bonding is desirable. 

Figure 7.7. X-ray structure of anion 10 and the cryptand encapsulated lithium ion (Newman projection of the carbanion is shown in the box). (Adapted from reference 47.)...

Figure 5 Cyclic octacobalt(II) complex of (39) with encapsulated C104 ion. H-atoms omitted (reproduced with permission from the Royal Society of Chemistry from J. Chem. Soc., Chem. Commun., 1997,...

Muller, A., Das, S.K., Kogerler, P., Bogge, H., Schunemann, V., Krickmeyer, E. and Preetz, W. (2000) A new type of supramolecular compound molybdenum-oxide-based composites consisting of nanocapsules with encapsulated keggin-ion electron reservoirs cross-linked to a two-dimensional network. Angewandte Chemie-Intemational Edition, 39, 3413-3417. 

Miura S, Teramura Y, Iwata H (2006) Encapsulation of islets with ultra-thin poly ion complex membrane through polyethylene glycol)-phospholipids anchored to cell membrane. Biomaterials 27 5828-5835... 

Encapsulation of a metal ion by a saturated organic framework is expected to lead to robust metal derivatives which are stable over a wide pH range and thus, for example, inhibit the hydrolysis which is characteristic of certain metal ions in aqueous solution. In this manner, the non-hydrolytic coordination chemistry of these ions in solution becomes accessible. Similarly, the redox chemistry of such encapsulated ions is of special interest, since there exists the prospect that the saturated organic shell might insulate the metal ion to a greater or lesser degree from the surrounding medium and hence markedly influence electron transfer reactions. 

Jizomoto, H Hirano, K. Encapsulating of drugs by lyophilized empty dipalmitoyl-choline (DPPC) liposomes Effects of calcium ion. Chem. Pharm. Bull., 37 (11), p. 3066-3069,1989... 

Dendrimer interior functional groups and cavities can retain guest molecules selectively, depending on the nature of the guest and the dendritic endoreceptors, the cavity size, the structure, and the chemical composition of the peripheric groups. Two main methods are known for the synthesis of metal nanoparticles inside dendrimers. The first method consists of the direct reduction of dendrimer-encapsulated metal ions (Scheme 9.4) the second method corresponds to the displacement of less-noble metal clusters with more noble elements [54]. 

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