Wydział Chemii

Jerzy Lisowski

2011

Inorganic Chemistry

50

5567-5576

10.1021/ic2001909

Naukowa

Angielski

Artykuł

The controlled formation of lanthanide(III) dinuclear μ-hydroxo-bridged [Ln₂L₂(μ-OH)₂X₂]ⁿ⁺ complexes (where X = H₂O, NO₃^–, or Cl^–) of the enantiopure chiral macrocycle L is reported. The ¹H and ¹³C NMR resonances of these complexes have been assigned on the basis of COSY, NOESY, TOCSY, and HMQC spectra. The observed NOE connectivities confirm that the dimeric solid-state structure is retained in solution. The enantiomeric nature of the obtained chiral complexes and binding of hydroxide anions are reflected in their CD spectra. The formation of the dimeric complexes is accompanied by a complete enantiomeric self-recognition of the chiral macrocyclic units. The reaction of NaOH with a mixture of two different mononuclear lanthanide(III) complexes, [Ln¹L]³⁺ and [Ln²L]³⁺, results in formation of the heterodinuclear [Ln¹Ln²L₂(μ-OH)₂X₂]ⁿ⁺ complexes as well as the corresponding homodinuclear complexes. The formation of the heterodinuclear complex is directly confirmed by the NOESY spectra of [EuLuL₂(μ-OH)₂(H₂O)₂]⁴⁺, which reveal close contacts between the macrocyclic unit containing the Eu(III) ion and the macrocyclic unit containing the Lu(III) ion. While the relative amounts of homo- and heterodinuclear complexes are statistical for the two lanthanide(III) ions of similar radii, a clear preference for the formation of heterodinuclear species is observed when the two mononuclear complexes contain lanthanide(III) ions of markedly different sizes, e.g., La(III) and Yb(III). The formation of heterodinuclear complexes is accompanied by the self-sorting of the chiral macrocyclic units based on their chirality. The reactions of NaOH with a pair of homochiral or racemic mononuclear complexes, [Ln¹L^RRRR]³⁺/[Ln²L^RRRR]³⁺, [Ln¹L^SSSS]³⁺/[Ln²L^SSSS]³⁺, or [Ln¹L^rac]³⁺/[Ln²L^rac]³⁺, results in mixtures of homochiral, homodinuclear and homochiral, heterodinuclear complexes. On the contrary, no heterochiral, heterodinuclear complexes [Ln¹L^RRRRLn²L^SSSS(μ-OH)₂X₂]ⁿ⁺ are formed in the reactions of two different mononuclear complexes of opposite chirality.

https://doi.org/10.1021/ic2001909

https://www.acs.org/content/acs/en.html