Assemblies of cucurbit[6]uril-based coordination complexes with disulfonate ligands: from discrete complexes to one- and two-dimensional polymers

Nine assemblies of Q[6]-based coordination complexes incorporating disulfonate ligands were obtained and two of them were found to have the ability to sense Fe³⁺via a fluorescence quenching effect.

Encapsulation-Controlled Photoisomerization of a Styryl Derivative: Stereoselective Formation of the Anti Z-Isomer in the Cucurbit[7]uril Cavity

The photochemical isomerization of a styrylpyridinium dye (SP) bearing an unsymmetrically attached benzo-15-crown-5 ether has been studied in aqueous solution in the absence and presence of cucurbit[7]uril (CB[7]). The detailed analysis of the UV/Vis and NMR spectra showes that the isomeric composition of the photostationary mixtures of SP can be modulated by the host-guest complexation with CB[7]. It was found that steric hindrance caused by encapsulation of SP in the host cavity induces the exclusive formation of the anti conformer of Z-SP in contrast with the mixture of both anti and syn conformers obtained during photoisomerization of the dye without CB[7]. Remarkably, the displacement of anti Z-SP from CB[7] does not lead to the transformation of the anti Z-isomer into the syn Z-isomer pointing out the conformational memory of the system. The results provide an interesting example of the supramolecular stereorecognition by the achiral CB[7] host.

The lanthanide contraction effect and organic additives impact the coordination structures of lanthanide ions with symmetrical octamethyl-substituted cucurbit[6]uril ligands

Two facts, the lanthanide contraction effect and the “bridge” role of organic additives, impact the coordination structures of lanthanide ions with OMeQ[6] ligands.

Adducts of aqua complexes of Ln3+ with a di-hydroxylated symmetrical octamethyl-substituted cucurbituril: potential applications for isolation of heavier lanthanides

In the present work, we have demonstrated that t(OH)₂OMeQ[6] could be used for isolating heavy lanthanides from their lighter counterparts.

Interaction of a symmetrical α,α′,δ,δ′-tetramethyl-cucurbit[6]uril with Ln3+: potential applications for isolation of lanthanides

Interaction of a symmetrical α,α′,δ,δ′-tetramethyl-cucurbit[6]uril (TMeQ[6]) with a series of lanthanide cations (Ln³⁺) was investigated in neutral water and acidic solution.

Interaction of Ln3+ with Methyl-Substituted Cucurbit[n]urils (n=5,6) Derived from 3α-Methyl Glycoluril

The interactions between a series of lanthanide cations (Ln³⁺ ) and methyl-substituted cucurbiturils (SPMeQ[5] and SHMeQ[6]) derived from a 3α-methyl glycoluril have been investigated. Single-crystal X-ray diffraction analysis revealed that both SPMeQ[5] and SHMeQ[6] selectively interact with certain lanthanide ions. SPMeQ[5] forms coordination capsules in the presence of [CdCl₄ ]^2- . The Ln³⁺ cations that interact are the four light lanthanides, La³⁺ , Ce³⁺ , Pr³⁺ , and Nd³⁺ , whereas the remaining lanthanide cations remain in solution. SHMeQ[6] formed adducts of SHMeQ[6] with aqua complexes of lanthanide cations ([Ln(H₂ O)₈ ]³⁺ ); for SHMeQ[6]-Ln(NO₃ )₃ -CdCl₂ -HCl systems (Ln=Gd-Lu), no solid crystals were obtained from systems that contained La, Ce, Pr, Nd, Sm, or Eu. Whereas solid crystals of adducts of SHMeQ[6] with aqua complexes of lanthanide cations (Ln=Sm-Lu) formed SHMeQ[6]-Ln(NO₃ )₃ systems in neutral solution, no solid crystals were obtained from systems that contained La, Ce, Pr, or Nd. These results suggest that SPMeQ[5]- and SHMeQ[6]-Ln(NO₃ )₃ systems could be useful for the selective isolation of these lighter or heavier lanthanide cations from mixtures. Energy-dispersive spectrometry indicated that the lighter or heavier lanthanide cations could be isolated from their heavier or lighter counterparts through interaction with SPMeQ[5] and SHMeQ[6].