Carbon Dioxide Fixation and Sulfate Sequestration by a Supramolecular Trigonal Bipyramid

Abstract

The subcomponent self-assembly of ab ent dialdehyde ligand and different cationic and anionic templates led to the formation of two new metallosupramolecular architectures:aFe II 4 L 6 molecular rectangle was isolated following reaction of the ligand with iron(II) tetrafluoroborate,a nd aM 5 L 6 trigonal bipyramidal structure was constructed from either zinc(II) tetrafluoroborate or cadmium(II) trifluoromethanesulfonate.T he spatially constrained arrangement of the three equatorial metal ions in the M 5 L 6 structures was found to induce small-molecule transformations.Atmospheric carbon dioxide was fixeda sc arbonate and bound to the equatorial metal centers in both the Zn 5 L 6 and Cd 5 L 6 assemblies,a nd sulfur dioxide was hydrated and bound as the sulfite dianion in the Zn 5 L 6 structure.S ubsequent in situ oxidation of the sulfite dianion resulted in as ulfate dianion bound within the supramolecular pocket.

Functional Capsules via Subcomponent Self-Assembly

“…The self-assembly of a bent dialdehyde subcomponent with 4methoxyaniline and Cd(OTf)2 or Zn(BF4)2 led to the formation of M5L6 trigonal bipyramidal structures 25 or 26, containing two apical and three equatorial metal ions (Figure 12). 34 The X-ray structure of 25 revealed a CO3 2anion, arising from the atmospheric CO2, coordinated to the three equatorial cadmium centers in addition to two TfOanions occupying binding pockets in the structure. Exposure of the zinc analog 26, initially formed under a N2 atmosphere, to air also led to the formation of its CO3 2adduct.…”