Optical activity induced in terbium(III) tris(pyridine-2,6-dicarboxylate) through association with certain chiral amino acids

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

“…Studies into the outer-sphere association of chiral molecules to [Ln(ADPA) 3 ] 3− were performed with [Tb(ADPA) 3 ] 3− because the CPL of the 5 D 4 → 7 F 5 transition of Tb(III) tends to be especially sensitive to the helicity of the complex, 8 Tb(III) is known to cause a powerful NMR shift, 48 and the related dipicolinate derivatives have been well characterized. 8–11,40 Lanthanide cations tend to have very similar coordination chemistry, 5 so was assumed that 5.5 equivalents of ADPA 2− and a pH of at least 12.0 was sufficient to form the tris Tb(III) complex, as it was for Eu(III) (vide supra).…”

“…8–11,40 Lanthanide cations tend to have very similar coordination chemistry, 5 so was assumed that 5.5 equivalents of ADPA 2− and a pH of at least 12.0 was sufficient to form the tris Tb(III) complex, as it was for Eu(III) (vide supra). Furthermore, the tris Tb(III) complexes of ADPA, CDA and DPA have been previously reported, including the stability constants for the formation of the tris Tb(III) complexes from additional ligand and the bis [TbL 2 ] n− species.…”

“…The association of proline to [LnL 3 ] n− (L = CDA or DPA) complexes has been well characterized, 8,40 so we studied the effect of proline on the racemic equilibrium of [Ln(ADPA) 3 ] 3− in some detail prior to studying the association of other small chiral molecules. The addition of 40 equivalents of L-proline to a 1 mM solution of [Ln(ADPA) 3 ] 3− resulted in a significant and measurable CPL signal for the 5 D 4 → 7 F 5 transition (fig.…”

“…This suggests that chiral recognition is localized on the lanthanide complex, perhaps to the carboxylate groups of ADPA 2− , although the π* system of DPA has been suggested as the site of binding (vide infra). 8 …”

Transition metal-based chiroptical switches for nanoscale electronics and sensors

“…Pfeiffer phenomena have now been observed in other systems such as lanthanide and titanium complexes [29,30]. Many environment substances have now been studied, including amino acids [31], tartrates [32], and others. A very interesting example involving a chiral phosphate anion was reported [33].…”