Binding and removal of sulfate, phosphate, arsenate, tetrachloromercurate, and chromate in aqueous solution by means of an activated carbon functionalized with a pyrimidine-based anion receptor (HL). Crystal structures of [H3L(HgCl4)]·H2O and [H3L(HgBr4)]·H2O showing anion-π interactions.

Binding of anions of great environmental concern such as SO(4)(2-), PO(4)(3-), AsO(4)(3-), HgCl(4)(2-), and CrO(4)(2-) by the protonated forms of a tren-like (tren = tris(2-aminoethyl)amine) ligand (HL) functionalized with a pyrimidine residue was studied by means of potentiometric measurements and isothermal titration calorimetry (ITC) affording log K, ΔH°, and TΔS° values for the formation of the relevant complexes. The complexes show high to very high stability due to the particular topology and electronic properties of the ligand which is able to use two separated coordination environments to host the anions, the protonated tren site where electrostatic and hydrogen bond interactions are operating, and the pyrimidine ring which may act via anion-π interaction. A contribution of -8.9 ± 0.4 kJ/mol for pyrimidine-anion interaction in water was derived for SO(4)(2-) binding. The crystal structures of [H(3)L(HgCl(4))]·H(2)O (1), [H(3)L(HgBr(4))]·H(2)O (2), and that previously reported for [H(3)L(CdI(4))], clearly show these binding features in the solid state. A hybrid AC-HL material obtained by adsorption of HL on commercial activated carbon (AC) was used to study the removal of these anions from water. AC-HL shows enhanced adsorption capacity toward all the anions studied with respect to AC. This behavior is ascribed to the stronger interaction of anions with the HL function of AC-HL than with the Cπ-H(3)O(+) sites of the unfunctionalized AC.

catena-Poly[[[aquachloridocopper(II)]-mu-N-(6-amino-3-methyl-5-nitroso-4-oxo-3,4-dihydropyrimidin-2-yl)glycinato] monohydrate] redetermined at 120 K: a highly polarized ligand within coordination polymer chains linked by hydrogen bonds.

In the title compound, {[Cu(C(7)H(8)N(5)O(4))Cl(H(2)O)].H(2)O}(n), the bond lengths in the N-pyrimidinylglycinate unit provide evidence for a strongly polarized electronic structure. This ligand is coordinated to three Cu(II) centres, resulting in the formation of a coordination polymer in the form of a chain containing two types of centrosymmetric ring. These chains are linked by an extensive series of hydrogen bonds, including O-H...O, N-H...O, O-H...Cl and N-H...Cl types, into a continuous three-dimensional structure.

Bis[mu-6-amino-3-methyl-5-nitrosopyrimidine-2,4(1H,3H)-dionato-kappa3O4,N5:O5]-di-micro-aqua-bis[diaqua[6-amino-3-methyl-5-nitrosopyrimidine-2,4(1H,3H)-dionato-kappa2N1,O2]strontium(II)]: centrosymmetric dimers containing nine-coordinate Sr, linked by multiple hydrogen bonds into a three-dimensional framework.

The title complex, [Sr(2)(C(5)H(5)N(4)O(3))(4)(H(2)O)(6)], forms centrosymmetric dimers in which one water ligand bridges two Sr centres and in which one of the anionic ligands is bidentate and bonded to just one Sr atom, and the other is tridentate and bridges the two Sr centres within the dimer. The dimeric units are linked by an extensive series of O-H...O, O-H...N and N-H...O hydrogen bonds to form a complex three-dimensional framework.