The Pfeiffer effect, outer-sphere complexation, and the absolute configuration of dissymmetric coordination compounds

Abstract

Abstract

Importance of hydrogen‐bonding sites in the chiral recognition mechanism between racemic D3 terbium(III) complexes and amino acids

“…tartrate substrates, amino acids, or sugar derivatives) 26-28. The added chiral species may perturb the racemic equilibrium resulting in a nonracemic ground state (this is often referred to as the “Pfeiffer effect”,29-32 a term originated from a work on the enhancement of optical rotation of optically active alkaloids in the presence of labile racemic transition-metal complexes) 33,34. These differences can be detected by measurement of the circular polarization in the luminescence.…”

Localizing Perturbations of the Racemic Equilibria Involving Dipicolinate‐Derived Lanthanide(III) Complexes

“…It has been suggested that molecules associating to [LnL 3 ] n− complexes interact with the π*orbitals of the pyridine rings, 8 in analogy to phenanthroline complexes of transition metals; 46 however, we are not convinced that these interactions govern this effect. Consider that when the carboxylate groups of dipicolinate are transformed into chiral amide groups, the resulting complexes of lanthanides self-assemble in solution as enantiopure Λ or Δ complexes.…”

“…5,34,35 When the mixture of enantiomers is racemic, the emitted light is not circularly polarized; however, perturbing the equilibrium between the Λ and Δ forms generates an excess of one enantiomer and the luminescence from this mixture is circularly polarized. 31, 44,46 …”

“…7–15 This perturbation of a racemic equilibrium has been termed the “Pfeiffer effect”, after its discoverer. 6,16,17 …”

Outer sphere complexes as intermediates in coordination chemistry

“…Many of the earlier results, which concentrated more on equilibrium studies, were based on UV spectroscopy. Other methods, such as the use of the Pfeiffer effect [22], have also been employed.…”