Lanthanide complexes biochemical applications

There have been several reviews published on the general use of CPL to study chiral molecular systems. Steinberg wrote the first review on CPL spectroscopy emphasizing applications to biochemical systems (Steinberg, 1975), and Richardson and Riehl published a review of CPL in 1977 (Richardson and Riehl, 1977) and an updated review in 1986 (Riehl and Richardson, 1986). Brittain published a review of the use of CPL to study chiral lanthanide complexes in 1989 (Brittain, 1989). Several other recent articles describing various general aspects of CPL measurements and CPL theoretical principles are also available (Riehl and Richardson, 1993 Riehl, 1993, 2000 Maupin and Riehl, 2000). In this article we will review the various applications of CPL to the study of lanthanide complexes, as well as provide an up-to-date assessment of the state of theory and instramentatiorL We will emphasize both the qrralitative artd qrrarrtitative molecular information that has so far been obtained from this technique, and disctrss the future of CPL as a reliable probe of the molecular stereocherrristry of lanthanide complexes. 

Stable metal complexes can be favorably formed when a bidentate metal-binding site is available, such as a- and -diketone moieties which are the tautomeric forms of a- and /3-ketoenols. Some /S-diketonate complexes of paramagnetic lanthanides such as Pr(III), Eu(III) and Yb(III) have been extensively utilized as paramagnetic shift reagents for structural assignment of molecules with complicated stereochemistry prior to 2D techniques in NMR spectroscopy. Their syntheses and application are discussed in separate chapters in this volume. The examples below provide some dynamic and structural basis for better understanding of metal enolates in biomolecules and biochemical processes. 

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