Rhenium complexes 2,2 -bipyridyl

The stability of the polypyridyl rhenium(I) compounds mentioned above stimulated applications of this coordination chemistry. Thus, new heterotopic bis(calix[4]arene)rhenium(I) bipyridyl receptor molecules have been prepared and shown to bind a variety of anions at the upper rim and alkali metal cations at the lower rim. A cyclodextrin dimer, which was obtained by connecting two permethylated /3-cyclodextrins with a bipy ligand, was used for the preparation of a luminescent rhenium(I) complex. The system is discussed as a model conipound to study the energy transfer between active metal centers and a bound ditopic substrate. The fluorescence behavior of rhenium(I) complexes containing functionalized bipy ligands has been applied for the recognition of glucose. ... 

Raman spectroscopy metal in water complexes, 309 Rare earth complexes acetylacetone synthesis, 377 guanidinium, 282 hydroxamic acids, 506 Redox properties bipyridyl metal complexes, 90 Reductive coupling nitrile metal complexes, 265 Resorcinol, 2,4-dinitro-metal complexes, 273 Rhenium complexes acetylacetone, 376 synthesis, 375, 378... 

Several calixarenes 17-20 bridged on the lower rim with ruthenium(II) and rhenium(I) bipyridyl complexes have been prepared and studied for anion recognition [19]. When compared to acyclic receptor 21 having a similar active structure (ruthenium complex), all receptors show significantly better complexation of AcO" and chloride in DMSO-d6. Thus, calixarene 17 exhibits an almost 30 times higher association constant for AcO (Kl7=9,990 M 1 vs K21=... 

The luminescence spectra of all receptors in CH3CN were found to be dramatically affected by the addition of acetate or chloride. While compound 19 exhibits an emission decrease, the other receptors 17,18 and 20 show a remarkable intensity increase (up to 500%) with a slight concomitant blue shift of the emission maximum (660 nm for 17). The anion-induced enhancement of luminescence intensity in the case of 17 is clearly due to the decrease of the electron transfer between the ruthenium(II) bipyridyl centre and the quinone moieties. Alternatively, receptors bearing ruthenium or rhenium complexes on the upper rim were also described [20]. 

Heteroditopic ruthenium(n) and rhenium(l) bipyridyl bis(benzo-15-crown-5) ion-pair receptors 19 and 20 display, upon K+ complexation, a remarkable switch in anion selectivity <1998CC825>. In the absence of K+, receptors 19 and 20 exhibit a selectivity preference for II2PO4 over CP. However, addition of KPF6 caused in both cases, the formation of a sandwich K+ complex, which shows a reversed CP over H2POP binding selectivity because of a more favorable electrostatic attraction between K+- and CP-bound ions (positive binding cooperativity). 

Figure 1 lV,lV-Diethylaniline bound in JJ-cyclodextrin functionalized with a rhenium complex (bipy=2,2 -bipyridyl) [6]... 

Low-valent rhenium complexes with Tp and bpy (bpy = bipyridine) ligands that do not include CO in the coordination sphere have been synthesized. Complexes of the type TpRe(bpy)Y (Y = Cl or cyclopentene bpy = 2,2 -bipyridyl) are derived from [TpRe bpy)Cl][OTf with the accompanying one or two electron reduction by Zn/Hg or Na/Hg amalgam, respectively (Scheme 60). " TpRe(bpy)(f/ -cyclopentene) is a potent 7i-base as evidenced by the II/I oxidation potential of —0.66 V versus NHE, 0.89 V more cathodic than TpRe(CO)(PMe3)( -cyclohexene). 

Metal-to-hgand charge transfer (MLCT) systems are mostly based upon complexes of ruthenium and rhenium. The simplest and best known example of a MLCT lumophore is tris(2,2 -bipyridyl)ruthenium(ii) where photon absorption leads to an excited state composed of a centre and a radical anion on one of the bipyridyl units. 

Complexes of rhenium(I) tricarbonyl chloride with pyridyl ligands are often luminophores and hence in anion sensing have principally been used as reporter groups. In many cases this Re(I) fragment is compatible with the same bipyridyl receptor ligands that have been used in [Ru(bpy)3]2+ examples. 

Hsu et al. [75,76] reported a new method for incorporating metal complexes into polyfluorenes to prepare phosphorescent polymers (polymer 47 and 48). A pyridine end-capped polyfluorene has been synthesized. The pyridine was used to form a polymer metal complex with 2,2-bipyridyl(tri-carbonyl)rhenium(I) chloride. Using the end-capping approach not only can control the molecular weight of polymer, but also avoid the interference of the metal complex and conjugated polymer in energy transfer. They can... 

Rhenium(V) complexes, 177 2-aminobenzenethiol, 188, 192 2,2 -bipyridyl, 187 4-chloro-2-aminobenzenethiol, 192 cyanides, 187... 

Crayston, J., A. Iraqi, J.J. Morrison, and J.C. Walton. 1997. Synthesis of thiophene substituted ruthenium and rhenium bipyridyl complexes. Synth Met 84 441-442. 

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