Supramolecular coordination complexes

Then, it appears, that photochemical cross-linking of an organotin copolymer is the result of complex supramolecular conversions and intermoleeular reactions of anhydride and organotin units involving the formation of transverse coordination-bound organotin carboxylate fragments 109). 

Coordination Complexes Gerfin, T., Gratzel, M., and Walder, L., Molecular and Supramolecular Surface Modification of Nanocrystalline Ti02 Films Charge-Separating and 1 381... 

By employing coordination complexes as branch points, dendrimers can be synthesized that contain metal ions throughout their structure. The repetitive unit of such dendrimers contains M-C, M-N, M-P, or M-S bonds [53,62]. The metal ions act as supramolecular glue [63], in which the complexation chemistry directs the assembly and structure of the dendrimer [53]. One of the synthetic procedures used to prepare organometallic dendrimers with coordination centers in every layer is based on a protection/deprotection procedure in which two complexes are used as dendritic building blocks wherein one acts as a metal and the other as a ligand [64,76]. 

It should be noted that the word complex , often used in supramolecular chemistry, is not very specific. It is applied to charge-transfer complexes like the one formed by 21 with 22 [30] as well as to coordination complexes consisting of one or more atoms or ions with n ligands like K2[Pt(N02)4]. The same name complex also covers the Whitesides hydrogen bonded systems [10] shown in Figure 1.1 and inclusion complexes of 4 embedded in 5. Thus the term complex without any adjective has no specificity and can be applied to any type of molecular associates. 

One of the most studied mononuclear systems that usually leads to supramolecular networks and that also exhibits very rich photophysics and photochemistry is the [Au (CN)2] anion. This complex is among the most stable two-coordinate complexes of the transition ions, with a stability constant of 1037 [9], being reasonably stable to air, moisture, temperature and light, which could make it appropriate for practical applications. 

Coordination Chemistry of 2,5-(2-Pyridyl)phosphole Derivatives Complexes Bearing Bridging Phosphane Ligands and Coordination-driven Supramolecular Organization of -Conjugated Chromophores... 

An interesting dimension of metal-coordinated self-assembly that is often ignored, or at least not exploited to its fullest extent, occurs when the resulting coordination complex is a charged species and, as such, in need of a counterion. This counterion itself presents yet another subtle instance of ionic self-assembly, which often is overshadowed by its partner, the coordination complex. The second multi-functional side-chain supramolecular polymer system is based on this simple but important concept [14, 106-111]. In 2003, Ikkala and coworkers reported a study in which they exploited (1) a side-chain functionalized polymer, poly(vinyl-pyridine), (2) metal-coordination self-assembly via a tridentate Zn2+ complex and (3) ionic self-assembly through functionalized counterions, i.e. dodecylbenzene-sulfonate ions, to form multiple self-assembled complexes which adopted a cylindrical morphology (Fig. 7.23) [112]. 

Catenanes and Molecular Capsule - Complex Molecular Associations Interlocking several rings results in a catenane structure. Catenanes can be obtained efficiently using supramolecular concepts. The spontaneous formation of a palladiiun coordination complex is an elegant process that is used in the synthesis of catenanes and molecular capsules. 

As noted in Section 3.1.2, the introduction of the crown ethers in the late 1960s gave legitimacy to the concept of stable coordination complexes of the alkali metals. Their presence, and that of many other macrocyclic counterparts (e.g., porphyrins) and three-dimensional chelators (e.g., cryptands, calixar-enes) is now pervasive in both alkali and alkaline-earth coordination chemistry, and the literature on these complexes is vast. Early work in this area was summarized in CCC (1987), and examined in a more focused manner in Comprehensive Supramolecular Chemistry. It is not the intent of this section to repeat such material, but rather to highlight new developments since the mid-1990s. In some cases, specialist reviews are available on these subjects they will be noted where relevant. 

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