A chemosensor for dihydrogenphosphate based on an oxoazamacrocycle possessing three thiourea arms

We report a new H-bond macrocyclic chromogenic chemosensor in organic media, H3L, which displayed drastic changes in its UV–vis spectra revealing selectivity for dihydrogenphosphate over other inorganic anions, such as acetate or fluoride. The X-ray crystal structures of the [H4L⋯NO3]·(CH3CN)4 and [H4L⋯CF3CO2]·(CH3CN)2 salt complexes are also reportedR. B. thanks the Xunta de Galicia (Spain), Projects PGIDI10PXIB209028PR and INCITE09E1R209058ES. M. V. L. thanks the Directorate-General for Research and Development of the Xunta of Galicia (INCITE09 209 084 PR) and the Ministry for Science and Innovation of Spain (CTQ2009-14431/BQU) for financial supportS

A novel zinc(II) complex with the ligand 2,2′,2′′-(1,4,7-triazanonane-1,4,7-triyl)triacetate (NOTA)

The zinc(II) complex with NOTA [2,2′,2′′-(1,4,7-triazanonane-1,4,7-triyl)triacetate] has previously been synthesized and studied in solution, but was not isolated. The corresponding title ZnII complex penta­sodium(I) bis­{[2,2′,2′′-(1,4,7-triazanonane-1,4,7-triyl)triacetato]zinc(II)} tris­(perchlorate) methanol solvate, Na5[Zn(C12H18N3O6)]2(ClO4)3·CH3OH, was crystallized as a sodium perchlorate double salt in methano­l solution. The asymmetric unit contains two independent [Zn(NOTA)]− complex anion entities, five sodium cations, three perchlorate anions and a methanol solvent mol­ecule. The two ZnII cations exhibit a distorted trigonal-prismatic N3O3 coordination with a bifacial arrangement of the donor atoms. Neither the methanol solvent mol­ecule nor the perchlorate anions appear to be coordinated to the Zn centres. The crystal structure shows a layer arrangement parallel to (001) generated by inter­actions between the [Zn(NOTA)]− units, the Na+ cations, two ClO4 − units and the methanole mol­ecule, leading to an overall layer composition of [Na5[Zn(C12H18N3O6)]2(ClO4)2 .CH3OH]+. The third ClO4 anion is isolated and situated between the layers without any significant inter­actions

Copper complexes with new oxaaza-pendant-armed macrocyclic ligands: X-ray crystal structure of a macrocyclic copper(II) complex

The synthesis of new oxaaza macrocyclic ligands (2-4) derived from O1,O7-bis(2-formylphenyl)-1,4,7-trioxaheptane and functionalized tris(2-aminoethyl)amine are described. Mononuclear copper(II) complexes were isolated in the reaction of the corresponding macrocyclic ligand and copper(II) perchlorate. The structure of the [Cu(2)](ClO4)2 complex was determined by X-ray diffraction analysis. The copper(II) ion is five-coordinated by all N5 donor atoms, efficiently encapsulated by the amine terminal pendant-arm, with a trigonal-bipyramidal geometry. The complexes are further characterized by UV-Vis, IR and EPR studies. The electronic reflectance spectra evidence that the coordination geometry for the Cu(II) complexes is trigonal-bipyramidal with the ligands 1 and 2 or distorted square-pyramidal with the ligands 3 and 4. The electronic spectra in MeCN solutions are different from those in the solid state, which suggest that some structural modification may occur in solution. The EPR spectrum of powder samples of the copper complex with 2 presents axial symmetry with hyperfine split at g// with the copper nuclei (I = 3/2), which is characteristic of weakly exchange coupled extended systems. The EPR parameters (g// = 2.230, A// = 156 × 10-4 cm-1 and g[perpendicular] = 2.085) indicate a dx2-y2 ground state. The EPR spectra of the complexes with ligands 3and 4 show EPR spectra with a poorly resolved hyperfine structure at g//. In contrast, the complex with ligand 2 shows no hyperfine split and a line shape which was simulated assuming rhombic g-tensor (g1 = 2.030, g2 = 2.115 and g3 = 2.190).http://www.sciencedirect.com/science/article/B6TG5-4F02M3R-B/1/9fb378e69c125e05e7458b03422aeec

Lanthanide(III) Complexation with an Amide Derived Pyridinophane

Herein we report a detailed investigation of the solid state and solution structures of lanthanide­(III) complexes with the 18-membered pyridinophane ligand containing acetamide pendant arms TPPTAM (TPPTAM = 2,2′,2″-(3,7,11-triaza-1,5,9­(2,6)-tripyridinacyclododecaphane-3,7,11-triyl)­triacetamide). The ligand crystallizes in the form of a clathrated hydrate, where the clathrated water molecule establishes hydrogen-bonding interactions with the amide NH groups and two N atoms of the macrocycle. The X-ray structures of 13 different Ln³⁺ complexes obtained as the nitrate salts (Ln³⁺ = La³⁺–Yb³⁺, except Pm³⁺) have been determined. Additionally, the X-ray structure of the La³⁺ complex obtained as the triflate salt was also obtained. In all cases the ligand provides 9-fold coordination to the Ln³⁺ ion, ten coordination being completed by an oxygen atom of a coordinated water molecule or a nitrate or triflate anion. The bond distances of the metal coordination environment show a quadratic change along the lanthanide series, as expected for isostructural series of Ln³⁺ complexes. Luminescence lifetime measurements obtained from solutions of the Eu³⁺ and Tb³⁺ complexes in H₂O and D₂O point to the presence of a water molecule coordinated to the metal ion in aqueous solutions. The analysis of the Ln³⁺-induced paramagnetic shifts indicates that the complexes are ten-coordinated throughout the lanthanide series from Ce³⁺ to Yb³⁺, and that the solution structure is very similar to the structures observed in the solid state. The complexes of the light Ln³⁺ ions are fluxional due to a fast Δ­(λλλλλλ) ↔ Λ­(δδδδδδ) interconversion that involves the inversion of the macrocyclic ligand and the rotation of the acetamide pendant arms. The complexes of the small Ln³⁺ ions are considerably more rigid, the activation free energy determined from VT ¹H NMR for the Lu³⁺ complex being Δ<i>G</i>^⧧₂₉₈ = 72.4 ± 5.1 kJ mol^–1

The first substituted macrocyclic ligand Py2N4S2 containing four naphthylmethylene pendant-armed groups: Synthesis and photophysical properties

The synthesis of a pendant donor emissive macrocyclic ligand Py2N4S2 with up to four naphthylmethylene arms (L) has been achieved. Their derivative solid metal complexes (Co2 +, Ni2 +, Cu2 +, Zn2 +, Cd2 +, Hg2 + and Ag+) have been isolated and characterized. The photophysical properties of the free ligand L and their complexation behaviour have been investigated in solution. In dichloromethane, the free ligand presents two emission bands which are related to the monomer naphthalene emission and a red-shifted band attributable to ground state dimers (interaction between two naphthalene chromophores), which was further validated from time-resolved data, with bi-exponential decay with absence of dynamic components. UV–Vis spectroscopy has revealed a 2:1 binding stoichiometry for Co2 +, Cu2 +, Zn2 +, Hg2 + and Ag+