Novel anion receptors: hybrid materials based on quaternary ammonium salts for selective extraction of dichromate ions

Disiloxanes and Functionalized Silica Gels: One Route, Two Complementary Outcomes—Guanidinium and Pyridinium Ion-Exchangers

“…No single method can be applied to both materials and compounds and provide directly comparable, quantitative information about their ion-exchange properties. However, as we have shown before, certain tendencies evidenced by compounds in their selective extraction of ions (from the solid phase to the apolar solvent) can indeed be transferrable to materials bearing similar organic moieties (used in extraction of those ions from a polar medium to the solid phase)[ 18 – 19 ]. This is especially interesting since the change of solvent has been known to dramatically impact both the effectiveness and selectivity of a molecular receptor.…”

“…Siloxanes, however, are mainly encountered in polymer science, and the usefulness of smaller compounds comprising siloxane bridges remains fairly unexplored, with few notable exceptions in supramolecular chemistry of metal complexes [ 16 – 17 ]. Recently, we focused our attention on studying the differences between simple organic salts and silica gels with analogous, ionized moieties grafted on their surfaces; we concluded that ion-exchange selectivity can be well-defined even for uncomplicated ligands, and those tendencies can be further reinforced by preorganization of such ligands on rigid matrix [ 18 – 19 ]. Now, taking this approach a step further, we theorized that one synthetic pathway can lead to both novel disiloxane compounds and correspondingly functionalized siliceous materials, with potentially complementary properties.…”