Mixed ligand approach

Choudhary, S. Morrow, J. R. Dynamic acylhydrazone metal ion complex libraries A mixed-ligand approach to increased selectivity in extraction. Angew. Chem. Int. Ed. 2002, 41, 4096-4098. 

Goldberg, S. and Traina, S.J. (1987) Chemical modelling of anion competition on oxides using the constant capacitance model-mixed-ligand approach. Soil Sci. Soc. Am.J., 51,... 

Scheme 12 Two different mixed-ligand approaches based on [99mTc(OH2)3(CO)3]+ a the [2+1b] approach, in which the bidentate ligand is coordinated first, followed by the labelling of the targeting biomolecule (BM) with a pendant monodentate ligand (the synthesis of the intermediate can be performed in one step), and b the [2B+1] approach, in which the bidentate ligand is attached to the BM and the monodentate ligand represents the variable portion...

Fig. 2.2.5. Schematic drawing of mixed-ligand approaches using combination of mono- and biden-tate ligand systems coupled to biomolecules...

Bombesin was derivatized at the C terminus with bidentate chelators (Smith et al. 2003 a, b). The labeled peptide fully retained the biological activity and was stable in vitro and in vivo. Since the bidentate coordination is not optimal with respect to stability (pharmacokinetics), the coordination sphere of the metal tricarbonyl core has been saturated with a highly hydrophilic phosphine. This additional coordination is an example of the 2-Hl approach mentioned in the previous section. The mixed-ligand approach resulted in significantly higher hydrophilicity of the radioconjugates and an improved biodistribution labeled with Tc-99m and also with Re-188 (Smith et al. 2003). 

Simms MS, Perkins AC, Price MR et al (2001) Technetiiun-C595 radioimmimoscintigraphy a potential staging tool for bladder cancer. BJU Int 88 686-691 Spies H, Pietzsch HJ, Johannsen B (1999) The n+I mixed-ligand approach in the design of specific technetium radiopharmaceuticals potentials and problems. In Nicolini M, Mazzi U (eds) Tc, Re and other metals in chemistry and nuclear medicine, vol. 5. SG Editoriali, Padova, Italy, pp 101-108... 

The mixed ligand approach was followed by the RAFT approach. RAFT polymerization is a free radical process that is controlled and ensures the... 

Boogers JAF, Felfer U, Kotthaus M, Lefort L, Steinbauer G, de Vries AHM, de Vries JG. A mixed-ligand approach enables the asymmetric hydrogenation of an a-isopropylcin-namic acid en route to the renin inhibitor aliskiren. Org. Process Res. Dev. 2007 11(3) 585-591. 

A simple and straightforward approach to their synthesis is the reaction between simple metal salts and the alkali metal or complex anion pseudohalides. Mixed ligand complexes can easily be made via addition of a neutral ligand to the anionic complex species (cf. preparation of trans-ML2(NCS)2, e.g. 103). However, all these methods have been well reviewed202 209 and representative examples can be found in the references of Section 13.5.5.3. 

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