Glycine, complex anions with

For the tris(amino acidato)metal(III) complexes four geometrical and chiral isomers are possible, as shown in Scheme 2, where NO is the chelated amino acid anion, mer and fac refer to the meridional and facial geometrical isomers and A and A refer to the configuration at the metal centre. For the glycine complexes A and A are an enantiomeric pair, while for the optically pure forms of the other amino acids they form a diastereomeric pair and hence are easier to separate. For most of the simple bidentate amino acids of the kinetically inert metal ions Cr" , Co " and Rh ", the four isomers have been obtained. The isomers are distinguishable by their UV/visible, CD and NMR spectra. Not all the isomers can be found in certain cases, for example, with L-proline the k-fac isomer could not be prepared, a fact which was predicted on steric grounds." ... 

Fluoral has been condensed with an equivalent of chiral glycinate anion. The chirality stems from a chiral nickel complex with a chiral Schiff base derived from proline as hgand (Figure 5.17). (25, 35)-Difluorothreonine has thus been obtained with an excellent selectivity (de > 95%). This method also allows preparation of numerous fluoroalkyl and fluoroaryl analogues of threonine. Enantiopure difluorothreonine could also be prepared from ascorbic acid. ... 

Bis-aquo complexes were also reported with amino acids such as a- and jS-alanine (MeCH(NH2)C02H, CH2(NH2)CH2C02H) and o -aminobutyric acid, EtCHfNH OjH-2558 The anhydrous complexes [NiLj (L = glycinate, alaninate, carboxylate groups both bidentate and bridging.2558,2559... 

X-Ray crystallographic analysis used alongside solution phase techniques such as NMR, is invaluable in the design of selective anion receptors as it can be used to define the solid-state structure of the anion-bound complex. Several X-ray structures of anion-bound complexes of [Ln.la]3+ have been defined recently (acetate, lactate, citrate, alanine, glycine, methionine, serine and threonine) [8,21,22], The complexes adopt a monocapped square antiprismatic structure with one base comprising of four N atoms of the macrocycle and the other base containing three O atoms of the pendent arms. The latter base is completed by a carboxylate O donor of the anion, which binds in a bidentate manner and simultaneously caps this base by O (acetate), OH (a-hydroxy acids) or NH2 (a-amino acids). The nature of the donor atom in the capping (or axial) position correlates well with the observed NMR shift in the solution phase. 

Tonegawa et al. (2004) created a cationic polylysine with a tetrapeptide end sequence (glycine-tyrosine-glycine-lysine), which is a motif common to the consensus sequences of mussel adhesive proteins. They then cross-linked this with the anionic polysaccharide, gellan, enzymatically. The polyionic complexation between the cationic peptide and the anionic polysaccharide formed a hybrid fiber at the aqueous solution interface that, when cross-linked, mimicked the byssus gel that marine mussels use to adhere to surfaces, despite the presence of water and salt. 

Dqbkowska I, Rak J, Gutowski M, Radisic D, Stokes ST, Nilles JM, Bowen Jr KH (2004). Barrier-free proton transfer in anionic complex of thymine with glycine. Phys Chem Chem Phys 6 4351-4357. 

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