Specific Ligand Design

Specific Ligand Design.—The specificity of crown and related ligands for certain metal and ammonium cations is well known, and is rationalized, at least partially, by a best fit relationship between ionic radius and macrocycle cavity size. A 

Seyden-Penne, and B.Tchoubar, Tetrahedron Letters, 1976, 1677 (for exceptions). R. A. Moss, M. A. Joyce, and F. G. Pilkiewicz, Tetrahedron Letters, 1975, 2425 R. A. Moss, M. A. Joyce, and J. K. Huselton, Tetrahedron Letters, 1975, 4621. 

The 27-crown-9 system was predicted from models to be a potential host for guanidinium ions, and it has been found that a benzo derivative assists efficiently in extraction of guanidinium salts from aqueous solution into CDCI3, presumably as complex (50). A bis-crown (51) has been designed to accommodate bifunctional 

Obviously more examples and applications of ligand design will appear in future, but at the present time the major area of advance is in the construction of chiral macrocycles which can distinguish between different stereoisomers of chiral guest 

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Because of the comparatively large space requirements of a lone pair, low coordination numbers favor the expression of a stereochemically active lone pair [25]. Specific ligand design can trigger the stereochemical activity of a lone pair in complex compounds. 

Devendra LP, Gaikar VG (2011) Purification of forskolin by adsorptive separation using functionalized polymer bearing specific ligands designed by molecular simulation. Ind Eng Chem Res 50(20) 11667-11676. doi 10.1021/ie2004175... 

One way to reduce the number of independent variables in the FRET-adjusted spectral equation is to use samples with a fixed donor-to-acceptor ratio. Under these conditions, the values of d and a are no longer independent, but rather the concentration of d is now a function of a and vice-versa. This approach is typical for the situation of FRET-based biosensor constructs. These sensors normally are designed to have a donor fluorophore attached to an acceptor by a domain whose structure is altered either as a result of a biological activity (such as proteolysis or phosphorylation), or by its interaction with a specific ligand with which it has high affinity. In general, FRET based biosensors have a stoichiometry of one... 

Molecular mechanics have become more and more important in the study of the correlation between cavity size and ionic radius of coordinated metal ions (84CCR1, 93CCR177). The different aspects of metal ion reactivity and ligand design for specific and selective binding can be modeled and understood in detail. 

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