Bipyridine Complex Amino Acid

For the palladium compounds, the 4,4 -disubstituted derivatives show an MLCT band at ca. 310-320 nm in water as found for usual palladium-bipyridine complexes. On the other hand, the 5,5 -disubstituted derivatives exhibit characteristic absorption at 344 (for 48-lb), 361 (for 48-2b) and 367 nm (for 48-3b) due 

The UV-visible spectra of the ruthenium complexes show a trend similar to that of the corresponding palladium compounds. Tlie lowest energy n-n transition was observed at 357 nm for 47-3b. MLCT bands were observed in the normal region (ca. 450-470 nm) for typical tris(bipyridine)ruthenium complexes. The proposed structure of 47-3b is shown in Fig. 3.38. 

The amide-substituted bipyridine ligand is reduced more easily than the normal bipyridine. Ered separates into two peaks in the dimeric derivatives, 47-2a and 47-2b, and into three in the trimeric 47-3b, whereas the Ru(III/II) redox couple is found as only one peak. This indicates that the LUMO (lowest unoccupied molecular orbital) of the current Ru-complexes is localized on the bipyridine ligands interacting with each other through the amide bridges, without detectable delocalization onto the metal atoms. 

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Crystal stmctures of complexes of copper(II) with aromatic amine ligands and -amino acids " " and dipeptides" have been published. The stmctures of mixed ligand-copper complexes of L-tryptophan in combination with 1,10-phenanthroline and 2,2 -bipyridine and L-tyrosine in combination with 2,2 -bipyridine are shown in Figure 3.2. Note the subtle difference between the orientation of the indole ring in the two 1,10-phenanthroline complexes. The distance between the two... 

Studies of the thermodynamics of formation of complexes of zinc with 2,2 -bipyridine in the presence of halide and thiocyanate ions in DMF has been carried out.205 The zinc complexes of 2,2 -bipyridine with A-(benzenesulfonyl)glycine and A-(toluene- -sulfonyl)glycine were synthesized and infrared data implied a structural analogy with the cadmium complexes. This suggests that the zinc promotes sulfonamide nitrogen deprotonation in the amino acid ligands in the solid state.206... 

Tris(2,2 -bipyridine)ruthenium(UI) complex ions (44) produce a chemiluminescence in the presence of amino acids in a FTA system. Amino acids containing secondary amino groups have the strongest response LOD 20 pmol for proline to 50 nmol for... 

There has been considerable interest in the chemistry of ternary complexes of copper(II) containing a bidentate aromatic nitrogen base such as 1,10-phen-anthroline (phen) or 2,2,-bipyridine (bpy) and a bidentate oxygen donor ligand or an amino acid,1 6 as some of these could possibly serve as models for enzyme-metal ion-substrate complexes. Two procedures are described below for the convenient, high-yield preparation of two such complexes. 

The coordination geometry around the copper atom in 4 is similar to simple Cu complexes of 6,6 -bis-(acylamino)-2,2 -bipyridine amino acids in that the Cu(II) is coordinated by the two bpy nitrogen atoms and the amide oxygens. Amide oxygen coordination to Cu(n) is observed also in Fairlie s complex. In their work, Fairlie and coworkers have... 

Figure I. Conformational changes mediated by Cu(II) eoordination to the bipyridine group of the transoid 6,6 -bis-(acylanuno)-2,2 -bipyridine-peptide 3 to complex 4 having a cisoid conformation R = a-amino acid side chain (adapted from [8]).

Using same strategy, a catalytic, enantioselective addition of amines to meso-epoxides was established employing a scandium-bipyridine complex in emulsion (Scheme 8.12). In this work, Kobayashi and coworkers demonstrated that high yields and excellent enantioselectivities could be achieved using an amphiphilic Lewis acid combined with chiral Hgand as the catalyst in water. This work offered a green method for the synthesis of a-amino alcohols, which are important... 

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