Supramolecular coordination

This concept may also be extended to polynuclear helicates [38]. When 2-amino-quinoline and 4-chloroaniline were mixed with the phenanthroline dialdehyde shown in Scheme 1.10, a dynamic library of potential ligands was observed to form. The addition of copper(I) causes this library to collapse, generating only dicopper and tricopper helicates. As in the mononuclear case of Scheme 1.9, the driving force behind this selectivity appeared to be the formation of structures in which all ligand and metal valences are satisfied. The use of supramolecular (coordination) chemistry to drive the covalent reconfiguration of intraligand bonds thus... 

An interesting ferrocene-bridged zinc porphyrin macrocycle was synthesized by Shoji et al. [146], This group succeeded in visualizing a single molecule of a supramolecular coordination assembly on Au(lll) in UHV [147], The discrete... 

The large field of supramolecular coordination chemistry could be divided into polymers [1-5] and discrete compounds [6-10]. Coordination polymers or metal organic frameworks (MOF) are not only described in the literature but are also... 

Further studies on the supramolecular coordination chemistry of copper(II) focused on the synthesis of oligonuclear complexes by self-assembly with the pentadentate ligand (L3)2 with 2,6-pyridinyl-spacer [70]. To this end, H2L3 (4) was treated with calcium hydride and copper(II) acetate to give the metallocoronate [(Cac Cu2(L3)2 )(OAc)2] (5 Scheme 2). In the crystal, 5 is present as a dinuclear copper(II) coronate in which a calcium ion is encapsulated in the center two acetates act as counterions. 

For further developments in the field of supramolecular coordination chemistry, it is of great interest to investigate how nature copes with electronically mismatched metal/ligand combinations. In other words, this type of approach transfers the intellectual responsibility for design to the molecules themselves [76, 77]. 

The construction of supramolecular coordination polymers requires the ability to assemble small supramolecular units that can be further aggregated in a controlled... 

Przychodzen P, Korzeniak T, Podgajny R, Sieklucka B. Supramolecular coordination networks based on octacyanometalates From structure to function. Coord Chem Rev 2006 250 2234-60. 

Since Prussian blue chemistry is currently enjoying an active revival, several groups are exploring the closely related octacyanometalate building block [M(CN)8]", where M is a transition metal ion, for the self-assembly of novel supramolecular coordination compounds [20,68]. 

At the outset of this chapter, we noted that the beauty of symmetry and pattern is ultimately the beauty of simplicity. The elegance of the chemistry of these supra-molecular capsules, too, lies in the profound chemical consequences of simple changes wrought by the defined microenvironments within these assemblies. The earliest examples of altered chemical activity within supramolecular coordination compounds come from Fujita and coworkers, in which they employed their palla-dium-vertexed octahedra (Fig. 16) in the Diels-Alder cycloaddition of isoprene with naphthoquinone [26], accelerating this bimolecular addition 113-fold. 

This is not to say, however, that supramolecular assemblies can only affect reactivity kinetically (i.e., by bringing reagents into proximity or providing a spatial barrier between them, as in the P4 example earlier). An important example of the perturbation of a thermodynamic equilibrium by a supramolecular coordination cage is the increased acidity of encapsulated amines within the M4L6 assembly shown in Fig. 17 [29], A wide variety of amines can be encapsulated within the supramolecular framework, bound as the protonated ammonium species. 

Complementary to this strategy, the inner space of these supramolecular assemblies has been employed to enforce the reactive conformations of substrates. Unlike the previous example, instead of promoting an otherwise unstable chemical intermediate, the spatial restrictions of the supramolecular coordination cage promote the formation of reactive intermediates, as in the aza-Cope electrocyclization in Fig. 19. Furthermore, the enantipure form of the assembly could be used to make... 

Supramolecular coordination compounds with chiral pyridine and polypyridine ligands derived from terpenes 03CCR(242)87. 

The above results show how combining the principles of supramolecular coordination chemistry with those of de novo protein design can produce a new family of metal-peptide nanoassemblies in which metal coordination is used to promote the formation of a-helical coiled-coils having discrete molecular... 

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