Azacrown Ether Pillared Layered Zirconium Phosphonates and the Crystal Structure of N,N‘-Bis(phosphonomethyl)-1,10-diaza-18-crown-6

Abstract

The synthesis of N,N‘-bis(phosphonomethyl)-1,10-diaza-18-crown-6 tetrahydrate (6) from the corresponding diazacrown ether is described and the crystal structure of this diphosphonic acid determined. The crystals are triclinic, P1̄ with a = 8.1829(8), b = 8.3092(10), c = 9.1429(10) Å, α = 85.286(9)°, β = 84.736(9)°, γ = 73.158(7)°, and Z = 1. The center of the azacrown ether ring coincides with the center of symmetry, requiring that the CH2PO3H groups lie trans to each other. One of the acid protons of each phosphonic acid group resides on the aza nitrogens, resulting in a zwitterion arrangement. There are four water molecules per unit cell that participate in an extensive system of hydrogen bonding. An important feature of the H-bonding is that between adjacent phosphonic acid groups to form linear chains along the unit cell diagonal. Reaction of 6 with Zr(IV) in the presence of H3PO4 yields zirconium phosphate-type layers cross-linked by the crown ether groups. The types of layers formed were deduced by a combination of 31P NMR and X-ray data. Affixing phosphonic acid groups onto the aza crown ether results in a more rectangular shape to the ring, which is further distorted by the cross-linking of the layers.

Hybrid Organic-Inorganic Materials Based on Organophosphorus Derivatives

“…Mixed zirconium phosphate/phosphonate may be prepared by the classical way (which leads to a-ZrP type compounds), or from g-ZrP, by exchange of O 2 PR(OH) phosphonate groups for O 2 P(OH) 2 phosphate groups [54][55][56]. Recently a third type has been obtained by co-precipitation, depending on the phosphoric acid relative amount, where both PO 4 bridging orthophosphate sites (g-ZrP type) and O 3 PR bridging phosphonate sites (a-ZrP type) are present [44,57,58] (Fig. 8).…”

“…Immobilization of crown ethers and diaza crown ethers has been carried out with the bisphosphonate pillars strategy by using the co-precipitation synthesis [44,58]. Exchange re- [64,65] actions on g-ZrP led to pillared layered ion exchangers showing selective recognition [69].…”

Nanomaterials for Environmental Remediation

“…The presence of an acidic, exchangeable phosphate proton in the immediate proximity of a chemoselective macrocyclic ligand is of obvious value for ion-exchange applications. Bridging diphosphonic acid crown ether complexes have also been prepared, and shown to have anion exchange capability (these azacrowns were protonated and could serve as anion hosts) [56]. Changing the metal from Zr to Cu(ii) has a profound impact on the structure of these complexes [57], with the Cu(ii) ion chelated within the macrocycle, and wrapped up by the phosphonate ''arms''.…”

Specific capture of phosphopeptides by Zr4+‐modified monolithic capillary column

“…The development of new efficient methods for highly specific enrichment of phosphopeptides still is one of the most active research fields in phosphoproteome analysis. Self-assembling monolayer and multilayer thin films of phosphate-containing organic molecules have been prepared for immobilization of oligonucleotides based on the strong interaction between Zr 4+ and phosphate groups [11][12][13][14][15][16]. Taking advantage of the strong interaction, we have developed a zirconium phosphate (ZrP)-modified porous silicon wafer and IMAC adsorbent through Zr 4+ chelating to the phosphate-modified poly(glycidyl methacrylate-co-ethylene dimethacrylate) polymer beads for highly specific capture of phosphopeptides [17][18].…”