Synthesis, structural characterization and solvent effect of copper(II) complexes with a variational multidentate Salen-type ligand with bisoxime groups

Intercalation of salicylaldoxime into layered double hydroxide: ultrafast and highly selective uptake of uranium from different water systems via versatile binding modes

We report the first example of MgAl layered double hydroxide intercalated with salicylaldoxime (SA-LDH) which exhibits excellent uranium (U(VI)) capture performance. In U(VI) aqueous solutions, the SA-LDH shows a tremendous maximum U(VI) sorption capacity (q_m^U) of 502 mg·g^-1, surpassing most known sorbents. For the aqueous solution with an initial U(VI) concentration (C₀^U) of ∼ 10 ppm, ≥99.99 % uptake is achieved in a wide pH range of 3-10. At C₀^U ∼ 20 ppm, >99 % uptake is reached within only 5 min, and pseudo-second-order kinetics rate constant (k₂) of 44.9 g·mg^-1·min^-1 reaches the record value, placing the SA-LDH amongst the fastest U adsorbing materials reported to date. In contaminated seawater with 35 ppm of U while highly concentrated metal ions of Na⁺, Mg²⁺, Ca²⁺, and K⁺, the SA-LDH still displays exceptionally high selectivity and ultrafast extraction for UO₂²⁺, giving >95 % uptake of U(VI) within 5 min, and the k₂ value of 0.308 g·mg^-1·min^-1 for seawater surpasses most reported values for aqueous solutions. Versatile binding modes toward U by SA-LDH, including complexation (UO₂²⁺ with SA^- and/or CO₃^2-), ion exchange and precipitation, contribute to the preferable uptake of U at different concentrations. X-ray absorption fine structure (XAFS) analyses demonstrate that one uranyl ion (UO₂²⁺) binds to two SA^- anions and two H₂O molecules forming 8-coordinated configuration. The U coordinates with O atom of the phenolic hydroxyl group and N atom of the -CN-O^- group of SA^-, forming a stable six-membered ring motif, which endows the fast and robust capture of U. The wonderful uranium trapping ability makes the SA-LDH among the best adsorbent used for uranium extraction from various solution systems including seawater.

Influence of the Lewis basicity hardness of crystallization solvents on the coordination sphere of the complex [Co(3,5-dinitrobenzoate-O,O′)2]: crystallographic and theoretical analysis

Crystal growth of [Co(DNB)2] in different solvents is a thermodynamic process favored by ΔErecrys (kcal mol−1) where mono/trinuclear molecules are obtained. Closeness of HOMO orbitals of solvents to the SOMOs orbitals of Co(ii) ions guide the process.

Synthesis, crystal structure, luminescence and electrochemical properties of a Salamo-type trinuclear cobalt(II) complex

A trinuclear Co(II) complex, [{CoL(C4H9OH)}2-(OAc)2Co]·C3H7NO, was synthesized by the reaction of a Salamo-type chelating ligand (H2L=4,42′-dinitro-2,2′-[1,2-ethylenedioxybis(nitrilomethylidyne)]diphenol) with cobalt(II) acetate tetrahydrate in n-butanol, and characterized by elemental analyses, X-ray crystallography, FT-IR and UV/Vis spectra. In the Co(II) complex, there are two ligand L2− units, two μ 2-acetate ions, two coordinated n-butanol molecules and one non-coordinated N,N-dimethylformamide molecule. The Co(II) atoms in the structure of the Co(II) complex adopt slightly distorted octahedra geometries. Furthermore, through intermolecular C–H···O, O–H···O and C–H···π interactions, infinite layer-like, plane-like and 3D supramolecular structures are constructed. The fluorescence and electrochemical properties of the Co(II) complex have also been investigated.

Crystal structure of tetrakis(methanol-κO)bis{3-((4-methoxy-2-oxidobenzylidene)amino)-2-oxo-2H-chromen-4-olato-κ3 O,N,O′}bicobalt(II), C38H38Co2N2O14

C38H38Co2N2O14, monoclinic, P21/n (no. 14), a = 9.7459(5) Å, b = 7.9026(7) Å, c = 24.0622(15) Å, β = 100.260(5)°, Z = 2, V = 1823.6(2) Å3, R gt(F) = 0.0576, wR ref(F 2) = 0.1201, T = 293(2) K.

A new azine derivative colorimetric and fluorescent dual-channel probe for cyanide detection

A novel azine derivative colorimetric and fluorescent dual-channel probe salicylaldehyde hydrazine-3,5-dibromosalicylaldehyde (1) has been designed, synthesized and characterized. The probe 1 is confirmed to have especial selectivity and good sensitivity on detecting CN^- via UV-vis absorption and fluorescence spectrum in aqueous solution (H₂O/DMSO, 1:4, v/v). This colorimetric and fluorescent dual-channel probe response to CN^- owed to the deprotonation process and established the mechanism by using ¹H NMR spectroscopy. Further researches showed that the detection limit of the probe 1 to CN^- anions is 8.01×10^-9M, significantly lower than the maximum level 1.9×10^-6M in potable water from WHO guidelines.

Luminescent properties of heterotrinuclear 3d-4f complexes constructed from a naphthalenediol-based acyclic bis(salamo)-type ligand

Heterotrinuclear 3d-4f complexes with a naphthalenediol-based acyclic bis(salamo)-type ligand have been synthesized and structurally characterized. Spectral titrations clearly show that the heterotrinuclear complexes [Zn₂(L)La(OAc)₃] (1), [Zn₂(L)Ce(OAc)₃] (2) and [Zn₂(L)Dy(OAc)₃(CH₃OH)]·CH₂Cl₂ (3) are acquired by the substitution reaction of the obtained homotrinuclear Zn(II) complex with 1 equiv. of Ln(NO₃)₃ (Ln³⁺=La³⁺, Ce³⁺ and Dy³⁺). Two Zn(II) ions are penta- and hexa-coordinated with geometries of distorted tetragonal pyramid and octahedron. La(III) ion is deca-coordinated, adopting a distorted bicapped square antiprism geometry. Ce(III) ion is nona-coordinated with geometry of distorted capped square antiprism as well as Dy(III) ion. The different coordination modes of acetate ions in complexes 1, 2 and 3 lead to different coordination numbers of the lanthanide(III) ions. Furthermore, the structures and fluorescence properties have been discussed.

Two Supramolecular Cobalt(II) Complexes: Syntheses, Crystal Structures, Spectroscopic Behaviors, and Counter Anion Effects

Two new Co(II) complexes, [{Co(L)}2{Co(Pic)2(CH3OH)2}] (1) and [{CoL(μ-OAc)}2Co] (2), where H2L = 2,2′-[Ethylenedioxybis(nitrilomethylidyne)]dinaphthol, were designed, synthesized and characterized by elemental analysis, FT-IR spectra, UV-Vis spectra, and X-ray crystallography. Complex 1 consists of two [CoL] and one [Co(Pic)2(CH3OH)2] (Pic = picrate) units and in the [CoL] unit, the Co(II) atom is tetra-coordinated with a slightly distorted square-planar geometry. In the [Co(Pic)2(CH3OH)2] unit, the Co(II) atom is hexa-coordinated with a slightly distorted octahedral geometry. Meanwhile in complex 2, two acetate ions coordinate to three Co(II) atoms through Co-O-C-O-Co bridges and four μ-naphthoxo oxygen atoms from two [CoL] units also coordinated to the central Co(II) atom. Thus, complex 2 has two distorted square pyramidal coordination geometries around the terminal Co(II) atom and an octahedral geometry around the central Co(II) atom. The supramolecular structures of complex 1 is a 3D-network supramolecular structure linked by C-H···O hydrogen bonds and π···π stacking interaction, but complex 2 possesses a self-assembled 2D-layer supramolecular structure linked by C-H···π and π···π stacking interactions. The structure determinations show that the coordination anions are important factors influencing the crystalline array.

A dinuclear nickel(II) complex derived from an asymmetric Salamo-type N2O2 chelate ligand: synthesis, structure and optical properties

A new dinuclear Ni(II) complex, [{Ni(L)(C5H5N)}2], has been synthesized with 4-chloro-4′,6′-dibromo-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol (H2L), and characterized by elemental analyses, FT-IR, UV/Vis, molar conductance and X-ray crystallographic analysis. Each Ni(II) atom is located at a N2O2 coordination site of a completely deprotonated (L)2− unit. Two μ-phenoxo oxygen atoms from two [Ni(L)] units and two pyridine nitrogen atoms coordinate with two Ni(II) atoms. The two hexa-coordinated Ni(II) atoms have slightly distorted octahedral geometries. The μ-phenoxo bridges play important roles in assembling Ni2+ and (L)2− units. This 2:2 (Ni2+:(L)2−) structure is different from that of other Salamo-type Ni(II) complexes reported earlier.

Crystal structure of 4-bromo-2-(8-(3-ethoxy-2-hydroxyphenyl)-3,6-dioxa-2,7-diazaocta-1,7-dien-1-yl)phenol, C18H19BrN2O5

C18H19BrN2O5, triclinic, P1̅ (no. 2), a = 9.0429(7) Å, b = 9.5752(11) Å, c = 11.8422(15) Å, α = 70.954(11)°, β = 72.691(8)°, γ = 84.794(8)°, V = 925.33(18) Å3, Z = 2, R gt (F) = 0.0511, wR ref (F 2 ) = 0.0876, T = 173 K.

Crystal structure of (E)-1-(4-(((E)-3,5-dibromo-2-hydroxybenzylidene)amino)phenyl)ethan-1-one O-methyl oxime, C17H16Br2N2O2

C17H16Br2N2O2, monoclinic, P21/c (no. 14), a = 9.2648(14) Å, b = 13.3034(16) Å, c = 14.510(2) Å, β = 105.261(15)°, V = 1725.4(4) Å3, Z = 4, R gt (F) = 0.0679, wR ref (F 2) = 0.1657, T = 293(2) K.

Crystal structure of (E)-1-(2-chlorophenyl)-N-(4-chlorophenyl)methanimine, C13H9Cl2N

C13H9Cl2N, monoclinic, P21/c (no. 14), a = 3.9518(18) Å, b = 10.495(5) Å, c = 27.875(15) Å, β = 91.224(8)°, V = 1155.8(10) Å3, Z = 4, R gt (F) = 0.0719, wR ref (F 2 ) = 0.1862, T = 293 K.

Crystal structure of (Z)-1-(((3-acetyl-2-hydroxyphenyl)amino)methylene)naphthalen-2(1H)-one, C19H15NO3

C19H15NO3, monoclinic, P21/n, a = 9.1811(4) Å, b = 16.0396(6) Å, c = 10.1330(5) Å, β = 98.640(5)° V = 1475.27(11) Å3, Z = 4, R gt (F) = 0.0539, wR ref (F 2 ) = 0.1373, T = 294.29(10) K.

Nine self-assembled nickel(ii)–lanthanide(iii) heterometallic complexes constructed from a Salamo-type bisoxime and bearing a N- or O-donor auxiliary ligand: syntheses, structures and magnetic properties

Nine Ni(ii)–Ln(iii) complexes were prepared using 3-MeOsalamo and structurally characterized, and their magnetic properties were studied.

A novel trinuclear cobalt(II) complex derived from an asymmetric Salamo-type N2O3 bisoxime chelate ligand: synthesis, structure and optical properties

A novel trinuclear Co(II) complex, {[CoL(PrOH)]2Co(H2O)}·PrOH, has been synthesized with 6-ethoxy-6'-hydroxy-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol (H3L), and characterized by elemental analyses, FT-IR, UV-Vis, molar conductance and X-ray crystallographic analysis. Two n-propanol molecules and one water molecule coordinate to three Co(II) ions and four μ-phenoxo oxygen atoms from two [CoL(CH3CH2CH2OH)] units also coordinating to Co(II) ion. All the penta-coordinated Co(II) ions of the Co(II) complex have a slightly distorted trigonal bipyramidal coordinated polyhedron. Meanwhile, the μ-phenoxo bridges play important roles in assembling Co(II) ions and L(3-) units, which is different from the normal trinuclear Co(II) complexes with the Salamo-type ligands reported early.

Synthesis, crystal structure and spectral properties of a supramolecular trinuclear nickel(II) complex with 5-methoxy-4'-bromo-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol

A novel trinuclear Ni(II) complex [{NiL(n-PrOH)(μ-OAc)}2Ni]·n-PrOH·H2O with an asymmetric Salamo-type ligand, 5-methoxy-4'-bromo-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol (H2L), has been synthesized and characterized by elemental analyses, IR, UV/Vis and fluorescence spectra and molar conductance measurement. The crystal structure of the Ni(II) complex has been determined by single-crystal X-ray diffraction. Two acetate groups coordinating to three Ni(II) ions through NiOCONi bridges and four μ-phenoxo oxygen atoms from two [NiL(n-PrOH)] units also coordinating to Ni(II) ions. In the Ni(II) complex, two n-propanol molecules are coordinated to the two terminal Ni(II) ions having slightly distorted octahedral coordination geometries and form a trinuclear structure, There are also one non-coordinated n-propanol and one non-coordinated water molecule. In the crystal structure, the Ni(II) complex is linked by intermolecular hydrogen bonds into an infinite 1D supramolecular chain-like structure.

Synthesis, crystal structure and spectroscopic properties of a supramolecular zinc(II) complex with N2O2 coordination sphere

A new hexa-coordinated zinc(II) complex, namely [ZnL(H2O)2]n, with N2O2 coordination sphere (H2L=4,4'-dibromo-6,6'-dichloro-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol) has been synthesized and structurally characterized by elemental analyses, IR, UV-vis spectra and TG-DTA analyses, etc. Crystallographic data are monoclinic, space group P2(1)/c, a=24.634(2)Å, b=10.144(1)Å, c=7.9351(6)Å, β=91.371(2)°, V=1982.4(3)Å(3), Dc=2.099 g/cm(3), Z=4. The zinc(II) complex exhibits a slightly distorted octahedral geometry with halogen-substituted Salen-type bisoxime forming the basal N2O2 coordination sphere and two oxygen atoms from two coordinated water molecules in the axial position. The hydrogen-bonding and π-π stacking interactions have stabilized the zinc(II) complex molecules to form a self-assembling infinite dual metal-water chain-like structure with the nearest Zn⋯Zn distance of 4.954(4)Å.