Transition metal ion recognition

Fan L-J, Zhanga Y, Murphy CB, Angell SE, Parker MFL, Flynn BR, Jones WE Jr (2009) Fluorescent conjugated polymer molecular wire chemosensors for transition metal ion recognition and signaling. Coord Chem Rev 253 401 122... 

Figure 6. Construction of molecular recognition sites in mesoporous silica. The first step is the formation of close packed monolayers. The second step is the incorporation of a transition metal ions, followed by coordination of the metal ions with the ligands to form host sites that match the shape and size of the targets.

Polyaza-, polythia-ligands. Recognition of transition metal ions. Replacing the oxygen sites with nitrogen or sulphur yields macrocycles and cryptands that show marked preference for transition metal ions and may also allow highly selective complexation of toxic heavy metals such as cadmium, lead and mercury [2.41-2.44, A.14]. 

All these ligands present a very rich complexation chemistry with transition metal ions that depends on their specific structure. Thus, they can perform transition metal ion recognition by selecting metal ions [2.65,2.66] according to the coordination features of the ion and the nature, number and disposition of the binding... 

The last of the important concepts that we will consider is self-assembly. Most chemists have, at some time in their careers, wondered why molecules cannot just make themselves. The process by which molecules build themselves is termed self-assembly and is a feature of many supramolecular systems. If the molecular components possess the correct complementary molecular recognition features and their interaction is thermodynamically favourable then simply mixing them could result in the specific and spontaneous self-assembly of the desired aggregate. This assumes that there is no significant kinetic barrier to the assembly process. The recognition features within the components may be any of the intermolecular bonding processes mentioned above, but we will be concerned with interactions between transition metal ions and polydentate ligands. 

Transition metal ions as modifiers of ligand electronic properties and/or recognition units 354... 

Excitation of the Lnm ion by a d-transition metal ion is an alternative to chromophore-substituted ligands, and proof of principle has been demonstrated for several systems. The lack of quantitative data, however does not allow an evaluation of their real potential, except for their main advantage, which is the control of the luminescent properties of the 4f-metal ion by directional energy transfer. In this context, we note the emergence of self-assembly processes to build new edifices, particularly bi-metallic edifices, by the simultaneous recognition of two metal ions. This relatively unexplored area has already resulted in the design of edifices in which the rate of population, and therefore the apparent lifetime, of a 4f-excited state can be fine-tuned by energy transfer from a d-transition metal ion (Torelli et al., 2005). 

The 4,4 -bipyridine ligand has been utilized in the synthesis of linear coordination polymers as well as grids and networks through reaction with transition metal ions. These inorganic-organic polymers and frameworks are potential candidates for use in catalysis, molecular recognition, and nonlinear optics.257-262... 

An understanding of the mechanism of activation of DtxR and recognition of its cognate DNA requires knowledge of the oligomeric state of the active protein, the role of transition metal ions in this activation, and identification of critical residues involved in DNA recognition and binding. 

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