Coordination dicopper complexes

The large cavity of cryptand 17 allows another approach to anion coordination, the "cascade anion binding. " In a first step, the ligand binds by its tren subunits two Cu(II) cations. In a secorui step, the axial vacant hollow between the two alrecufy bound Cu(IT) cations will allow the binding of cn anion. An early example was based on computer analysis of potentiometric titrations data, and the efficientbinding of the chloride anion by the dicopper complex of 1 was postulated. Many other bis-tren-type figands were studied, and the cascade binding of anions such as Br, OH, N3, WCO. etc. was demonstrated. Many x-ray structures confirm the location of the anions between the various meted cations. ... 

A competitive method for carbonate sensing is based on dicopper complex 17 and coumarin 343 as anion receptor and external fluorophore, respectively. The fluorophore 18 coordinates to the copper atoms through its carboxylic group, and energy transfer between coumarin ring and copper atoms quenches the fluorescence emission. Carbonate showed strong binding to the metal complex and coupled the displacement of the bound fluorophore with concomitant recovery of the coumarin emission. This ensemble showed selective response to carbonate over phosphate or carboxylate. 

With a dicopper complex bearing bis-imidazole ligands (Figure 25d), a strong cooperativity was observed for the 1,3 distal complex. The suggested mechanism involved double activation of the bridging phosphoryl function, followed by nucleophilic attack assisted by the coordinated hydroxide. ... 

Using 1,4,8,11-tetraazacyclotetradecane, the structure of complex (800) (distorted trigonal planar Cu-Cu 6.739 A) was determined. Reactivity with 02 was investigated to demonstrate the formation of trans-l,2-peroxo species.585 As part of their work with copper(I) complexes with 02, the structure of a dicopper(I) complex ((801) distorted tetrahedral 7.04 A), supported by macrocyclic ligand environment, was reported by Comba and co-workers. Tolman and co-workers structurally characterized a three-coordinate copper(I)-phenoxide complex (802) (planar T-shaped) that models the reduced form of GO.587 The copper(I) analogue [Cu(L)][CF3-SO3]-0.43MeOI I (803) of a copper(II) complex (534) was also reported to demonstrate the role of ligand framework conformability in CV /Cu1 redox potentials.434 Wilson and co-workers... 

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