Dynamic coordination chemistry

CDC also encompasses dynamic coordination chemistry [35, 38, 40], whereby the coordination of metal ions induces the preferential formation of specific ligand molecules and/or induces reversible changes in them. Such processes may be traced back to early work on coordination reactions of imine-based macrocyclic ligands, when now revisited in the light of constitutional dynamics [52],... 

A more recent example of dynamic coordination chemistry controlled by anion recognition was demonstrated with the series of ligands 2, which formed linear binuclear triple helicates with Co2+ anions (Fig. 4) [16,17]. The asymmetric ligand 2a, functionalized at one end with an amide hydrogen-bond donor group, may form two types of helicate structures head-to-head-to-head (HHH) and head-to-head-to-tail (HHT) isomers. With the weak hydrogen-bond acceptor C104 as counteranion, a 3 1 mixture of HHH HHT isomers was observed. However, with the... 

Karan, C. Miller, B. L. RNA-selective coordination complexes identified via dynamic combinatorial chemistry. J. Am. Chem. Soc. 2001, 123, 7455-7456. 

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... 

This radical change in outlook builds on the richness of constitutional diversity and the benefits of variability. It stresses the virtues of instructed mixtures [3, 31], such as was revealed in the self-selection processes occurring in the side-by-side self-assembly of double helical metal complexes (helicates), whereby only the correctly paired double helicates were produced from a mixture of ligands and metal ions in dynamic coordination equilibrium [31, 37c]. It is this work that first led us in the early 1990s to envisage a dynamic chemistry bringing into play the constitution of chemical species. 

This review deals with the applications of photolurainescence techniques to the study of solid surfaces in relation to their properties in adsorption, catalysis, and photocatalysis, After a short introduction, the review presents the basic principles of photolumines-cence spectrosajpy in relation to the definitions of fluorescence and phosphorescence. Next, we discuss the practical aspects of static and dynamic photoluminescence with emphasis on the spectral parameters used to identify the photoluminescent sites. In Section IV, which is the core of the review, we discuss the identification of the surface sites and the following coordination chemistry of ions at the surface of alkaline-earth and zirconium oxides, energy and electron transfer processes, photoluminesccncc and local structure of grafted vanadium oxide, and photoluniinescence of various oxide-... 

This review covers adsorption, catalysis, and photocatalysis that can be investigated and understood by photoluminescence spectroscopy. Most of the results discussed in this review have been obtained by photoluminescence techniques, but other, complementary techniques, are also discussed to emphasize the originality and potential value of photoluminescence spectroscopy, particularly with regard to anion coordination chemistry, excited states, and reaction dynamics. The latter field is of utmost importance in chemistry (35). Additional applications of photoluminescence spectroscopy to the study of solid surfaces are reviewed in the books Photochemistry on Solid Surfaces"(. 6) and Surface Photochemistry (37). 

More recently, D. Gatteschi et al. have reported on a dysprosium-nitronyl nitroxide ID compound with interesting dynamic properties [76]. Their work illustrates nicely how presently coordination chemistry can modulate a known system [Dy(hfac)3NITEt] [77-80] (with hfac hexa-fluoroacetylacetonate and NITEt 4 -ethyl-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide) to achieve fine control of the physical properties. [Dy(hfac)3 NITEt] is composed of alternating chains of Dy(hfac)3 units and NITEt radicals. This compound displays a transition to a three-dimensional mag-... 

Abstract The most significant developments in quantum chemistry and wave packet dynamics providing the theoretical tools to study the electronic spectroscopy and photoreactivity of transition metal complexes are presented. The difficulties inherent to this class of molecules as well as the degree of maturity of the computational methods are discussed. Recent applications in transition metal coordination chemistry are selected to outline and to illustrate the necessity for a strong interplay between theory and experiments. 

The health and dynamism of contemporary coordination chemistry is well exemplified in the many and varied lectures and posters presented at the 34th ICCC. This would have pleased Joseph Chatt. He would also have been gratified to see his own contributions recognised in the session in his honour. 

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