Multinuclear self-assembled

Saalfrank and co-workers have described many multinuclear self-assembled rings and cages,... 

In addition to geometrical factors, lability is a critical parameter for self-assembly. While many reported structures contain labile ions, several ions that are normally not considered labile, such as Ti, Cr , Co , and Pt have been successfully incorporated into elaborate multinuclear structures by forcing reaction conditions to reach thermodynamic equilibrium. 

The unlimited possibilities of designing multidentate and multitopic ligands that take advantage of the coordination geometry of specific metal ions to assemble a variety of supramolecular multinuclear architectures are far beyond the scope of this chapter, and the reader will find inspiring and fascinating examples in several reviews, as well as in other chapters of this work (see Self-Assembled Links Catenanes, Templated Synthesis of... 

In addition to the mononuclear nodes conunonly known from coordination chemistry, multinuclear nodes are often encountered in coordination polymers (Figure 4). In general, these are self-assembled under the reaction conditions rather than introduced intact although this is not necessarily the case with polyoxometallate nodes. The dimetallic node is of some interest as it can enter into ihe network through coordination of additional donors at the two axial sites, or through the substituents on the carboxylate ligands. In other words, this unit can act as either a two node or a four node. 

An additional level of complexity can be added to multinuclear systems by moving from homonuclear to heteronuclear systems. Two such approaches that can be used to generate these mixed metal systems are the self-assembly of two preformed complexes through ternary complex formation via a free site on one or both of the complexes and careful ligand design to allow two distinct binding sites where each metal center is selectively bound to a particular set of coordinating atoms. Both approaches will be briefly discussed with appropriate examples for the formation of both heterometallic 4f and heterometallic mixed 3d-4f systems. 

Although the mononuclear Cu half-sandwich scorpionate complexes (see above) are commonly less active than the Fe ones, copper complexes can be more effective in multinuclear assemblies (including coordination polymers) and our approach for these species concerns their self-assembly synthesis by using a suitable combination of a metal source, a main chelating ligand, a spacer or linker, apart from a pH regulator. A wide discussion on the types of self-assembied multicopper complexes and their use for alkane functionlization is presented in Chapter 3, and only a very brief overall view is outlined here. 

MOLECULAR RECOGNITION BY MULTINUCLEAR ZINC(II) COMPLEXES IN AQUEOUS SOLUTION AND SUPRAMOLECULAR COMPLEXES FORMED BY SELF-ASSEMBLY OF TRIMERIC ZINC COMPLEX WITH CYANURIC ACID... 

Dubey, M. Koner, R.R. Ray, M. Sodium and Potassium Ion Directed Self-assembled Multinuclear Assembly of Divalent Nickel or Copper and L-Leucine Derived Ligand. Inorg. Chem. 2009, 48, 9294-9302. 

Figure 2.44. Design of self-assembled multinuclear complexes capable of longdistance vectorial energy transfer. The donor and acceptor units are Ru" and Os" bis(2,2 6, 2"-terpyridine) complexes.

The self-assembly of interconverting multinuclear arrays has been demonstrated recently with the supramolecular products being studied using both NOESY methods and X-ray diffraction. Treatment of a pentatopic decadentate... 

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