Synthesis,structures and properties of cobalt(II) and copper(I) complexes of 2,6-diamino-3-[(2-carboxymethyl)phenylazo]-pyridine

The reaction of methyl anthranilate, sodium nitrite, and 2,6-diamino-pyridine affords a new compound, 2,6-diamino-3-[(2-carboxymethyl) phenylazo]-pyridine (L), which has been characterized with X-ray crystallography and NMR spectrum. The reaction of L and CoCl₂? 6H₂O or Cu(ClO₄)₂? 6H₂O gives a dinuclear cobalt(II) complex [Co₂L₂Cl₃]Cl (1), and a copper(I) complex [CuL₂]ClO₄ (2),respectively. They are characterized by X-ray crystallography, X-ray photoelectron spectroscopy, NMR spectra, magnetic measurement and emission spectra. Magnetic behavior of 1 denotes the occurrence of intramolecular antiferromagnetic interactions (J = ? 141.8 cm^? 1). Complex 2 exhibits photoluminescence at 557 nm.     

Synthesis,luminescence, and structural characterization of Zn and Cd coordination polymers of flexible bis(imidazolyl) derivatives

Coordination polymers [Zn(imc)(L¹)] · H₂O, (1, imc = iminodiacetate, L¹ = bis(N-imidazolyl)methane) [Zn(hba)₂(L²)]₂ · EtOH · 3H₂O, (2, hba = p-hydroxybenzoate, L² = bis(N-benzimidazolyl)methane), [Cd(mal)(H₂O)(L³)](3, L³ = 1,4-bis(N-imidazolyl)butane, mal = maleate) have been prepared and structurally characterized. Complex 1 consists of hexa-coordinated central Zn ions and exhibits 2D network structure. The Zn atoms in 2 have tetrahedral coordination geometry, and are linked by bis(imidazolyl) ligands into 1D chain structure. The cadmium ions in 3 are hepta-coordinated with pentagonal bipyramidal geometry. Complex 3 displays 2D grid structure. The TGA showed that the coordination polymers are stable up to 200 °C. All the three complexes are emissive at room temperature in their solid state.     

Structural diversity in coordination polymers with angular ditetrazole ligands

Three new coordination polymers with angular bis(1-tetrazol)diphenyl ligands as bridges, {[Ag(L¹)₂](NO₃) ? 2H₂O}_∞ [L¹ = 4,4'-bis(1-tetrazolyl)diphenyl methane], 1, [Ag(L²)₂(NO₃)]_∞ [L² = 4,4'-bis(1-tetrazolyl)diphenyl sulfone], 2, and [CuBr(L³)_0.5]_∞ [L³ = 4,4'-bis(1-tetrazolyl)diphenyl ether], 3, are reported, which show unique 2D structural types. Complex 1 forms 1D double-stranded helical chains where the cavities are threaded by linear hydrogen bondings formed by the co-crystallized water molecules and nitrate anions and complex 2 shows 2D grids involving M₄L₄ 64-membered metallocycles composed of helical chains, while complex 3 exhibits a 2D pleated net comprising 1D channels linked by the double-chain CuBr ribbons.     

Solvothermal in situ synthesis of (Schiff-base)-containing dinuclear cobalt compound

A new dinuclear cobalt compound, namely Co₂(L)(H₂O)Cl₂ (1, H₂L = N,N′-o-phenylenebis(salicylide-neimine) was obtained by one-pot solvothermal self-assembly of CoCl₂, 1,2-phenylenediamine, and salicylaldehyde in C₂H₅OH. The magnetic studies suggest weak antiferromagnetic behavior and the magnetic data were interpreted by means of a dinuclear cobalt model with the parameters of g = 2.12, J = ?1.25 cm^?1, θ = ?3.12 K.     

Hydrothermal synthesis,crystal structure,and thermal stability of a novel 3D cadmium phosphonate with double-stranded helical channels

In the presence of ethylenediamine template agents, a novel 3D cadmium phosphonate with double-stranded helical channels, [enH₂]_0.5[Cd₂(HL)(L)] 1(H₃L =  2-hydroxyphosphonoacetic acid; en = ethylenediamine) has been synthesized by hydrothermal reaction at 140 °C and characterized by single-crystal X-ray diffraction as well as by infrared spectroscopy, elemental and thermogravimetric analysis. The structure of compound 1 comprises right-handed double-stranded helical channels, left-handed double-stranded helical channels and achiral channels that are connected through cadmium atoms and L³⁻ligands to form a meso compound, and the protonated ethylenediamine cations are located inside the achiral channels.     

Hetero-trinuclear near-infrared (NIR) luminescent ZnLn2 (Ln = Nd,Yb or Er) complexes based on monomer ZnL Schiff-base precursor and o-vanillin

With the monomer [Zn(L¹)(H₂O)] (1) complex in situ formed by the deprotonated hexadentate Salen-type Schiff-base ligand H₂L¹ (H₂L¹ = N,N′-bis(3-methoxy-salicylidene)cyclohexane-1,2-diamine) and Zn(NO₃)₂ as the precursor, series of the hetero-trinuclear ZnLn₂ complexes [ZnLn₂(L¹)₂(L²)(NO₃)₂Cl] (Ln = Nd, 2; Ln = Yb, 3; Ln = Er, 4 or Ln = Gd, 5) were obtained from the further reaction with LnCl₃ (Ln = Nd, Yb Er or Gd) and the second o-vanillin (HL²) ligand, respectively. The photophysical properties of complexes 2–4 showed that the characteristic near-infrared (NIR) luminescence of Ln^3 + ions with two emission centers and emissive lifetimes in microsecond ranges, was sensitized from the excited state (both ¹LC and ³LC) of mixed H₂L¹–HL² ligands.     

Selective adenine/cytosine cations in one-dimensional coordination polymers of manganese (II) and copper (II) 2,3-pyridinedicarboxylates

One-dimensional coordination polymer {[1H,9H-ade]₂[MnL₂]?4H₂O}_n (1) and {[1H,3H-cyt]₂[CuL₂]?6H₂O}_n (2) (ade = adenine, cyt = cytosine, L = dianion of 2,3-pyridinedicarboxylic acid) are selectively synthesized and variable-temperature magnetic susceptibility measurements revealed weak antiferromagnetic interactions within the chains of 1 and 2 (J = ? 0.29 cm^? 1 for 1 and J = ?0.03 cm^? 1 for 2, according to the ? 2J_ijS_iS_j HDvV Hamiltonian formalism).     

1D and 3D arrays of isomeric cadmium(II) diphosphonates constructed from N,N-dimethylaminomethane-1,1-diphosphonate ligand

Two isomeric cadmium(II) diphosphonates built up from corner-sharing CdO₆ octahedra and CPO₃ tetrahedra, with the same formula of [Cd(H₃L)₂] (H₄L = (CH₃)₂N–CH(PO₃H₂)₂), have been synthesized and structurally characterized. Compound 1 shows a 1D chain structure in which the adjacent Cd²⁺ ions are doubly bridged by two equivalent H₃L^? anions, whereas compound 2 exhibits a novel non-centrosymmetric 3D framework which is formed by a pillared-layer array, with one type of H₃L^? anions participating in the construction of a 2₁-symmetry layer and the other type of H₃L^? anions acting as pillars.     

Synthesis,crystal structures and NIR luminescence properties of binuclear lanthanide Schiff Base complexes

Three binuclear lanthanide complexes [Nd₂(L¹)₃(MeOH)]·MeOH·H₂O (1) and [Ln₂(H₂L²)₂(OAc)₄]·2(CF₃SO₃)·MeOH·EtOH (Ln = Nd (2) and Ho (3)) were prepared using two Schiff base ligands. Interestingly, 1 has a triple-decker structure with two lanthanide ions enclosed by three rigid conjugated Schiff base ligands (H₂L¹), while 2 and 3 show nanoscale ring structures (8 × 12 × 12 Å) formed by flexible long-chain Schiff base ligands (H₂L², ~ 23 Å) with the lanthanide ions located in the center. Upon excitation of the ligand-centered absorption bands, 1–2 and 3 show typical NIR emission spectra for Nd^3 + and Ho^3 + ions, respectively. In 1, the Nd(III) centers are shielded within the decker-like structure and surrounded by chromogenic Schiff base ligands (energy transfer donors). Luminescence studies show that the NIR emission lifetime of 1 is longer than that of 2 in solution.     

A unique 3-D 3d–4f heterometallic coordination polymer with double betaine ligand: Crystal structure and magnetic properties

A unique 3d–4f heterometallic coordination polymer with double betaine ligand, [GdCu₂(L¹)₄(H₂O)₂](ClO₄)₇ · 6H₂O 1 (L¹ = 1,3-bis(pyridinio-4-carboxylato)-propane), has been synthesized by the self-assembly of Cu(ClO₄)₂ and Gd(ClO₄)₃ with flexible double betaine ligand L¹, and structurally characterized by single-crystal X-ray diffraction. The structure of 1 can be regarded as being constructed by the cross-linkage of the vertex-sharing double-paddle-wheel-like trinuclear [Cu(COO)₄Gd(COO)₄Cu] units and L¹ ligands to produce an interesting cationic NaCl-like framework with a 4¹²6³ topology, which is counter-balanced by the perchlorate ions located in the interspaces of the framework. Variable-temperature magnetic susceptibilities of 1 show there is no magnetic interaction between the Cu(II) and Gd(III) ions.     

A 3D Cu(II) coordination polymer constructed from BIBP (BIBP = 5,5′-bis(1H-imidazol-1-yl)-2,2′-bithiophene) ligand with semiconductive property

Hydrothermal reaction of Cu(NO₃)₂·3H₂O with BIBP and H₂hfipbb at 105 °C yielded a novel 3D Cu(II) coordination polymer, {[Cu₂(BIBP)_0.5(hfipbb)₂(CH₃CN)]·5H₂O}_n (1) [BIBP = 5,5′-bis(1H-imidazol-1-yl)-2,2′-bithiophene, H₂hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid)]. Compound 1 displays a 3D 2-fold interpenetrating framework with {4⁴.6⁶} sqp topology, containing interesting ⋯LRLR⋯ double helical chains. The compound 1 was characterized by IR spectra, elemental analysis, thermal analysis and single crystal X-ray diffraction. In addition, solid-state UV–vis spectra experiment shows that compound 1 exhibits semiconductive property with a band gap of 2.46 eV.     

Four-, six- and eight-coordinated lead(II) complexes with amine- or amide-type tripodal ligands

Three novel lead(II) complexes, [Pb(L¹)](ClO₄)₂ (1) (L¹ = tris(2-benzylaminoethyl)amine), [Pb(L²)₂](ClO₄)₂ (2) (L² = tris(4-phenyl-3-aza-2-oxobutyl)amine) and [Pb₂(L³)₂](ClO₄)₄ (3) (L³ = tris[3-aza-2-oxo-4-(2-pyridyl)butyl]amine) were synthesized and structurally characterized. All three complexes show different stoichiometries as well as coordination numbers of four in 1, eight in 2 and six in 3, respectively. Complex 1 displays a typical tripodal-type 1:1 (M:L) structure and 2 shows a sandwich-type 1:2 structure. The octa-dentate lead(II) ion in 2 is at the center of a dicapped trigonal prism. Complex 3 is revealed as a unique dinuclear 2:2 complex, in which two hexa-dentate lead(II) ions are linked by two carbonyl μ–O atoms forming a Pb₂(μ–O)₂ parallelogram-type moiety.     

A new rigid ligand anthraquinone-1,4,5,8-tetracarboxylic acid (H4AQTC) and its two new porous metal-organic frameworks: Syntheses, structures and properties

A new rigid multicarboxylates anthraquinone-1,4,5,8-tetracarboxylic acid (H₄AQTC) was synthesized based on a modified synthetic procedure from 2,5-dimethylfuran and maleic anhydride. This rigid ligand can be widely utilized to construct rigid porous MOFs which may be candidates of porous materials. Two new rigid porous MOFs {[Cd(AQTC)_0.5(H₂O)₃]·H₂O}_n (1) and {[Ni(AQTC)_0.5(BPY)_0.5(H₂O)₃]·2H₂O}_n (2) based on this rigid ligand are reported (BPY = 4,4'-bpy). The adsorption properties of complexes 1 and 2 are investigated, and the Langmuir surface areas are measured to be 43.25 m²/g and 389.14 m²/g.     

A new 3D coordination framework with helical chains in mixed ligands system: Preparation,crystal structure and magnetic property

A new 3D coordination polymer [Ni₂(L)₂(bpp)₂(μ₂-H₂O)] (1) (H₂L = 2,4-dibenzoylisophthalic acid and bpp = 1,3-bis(4-pyridyl)propane) has been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectra, and thermogravimetric analysis. Further, it was determined by single crystal X-ray diffraction analysis. Compound 1 is a 3D network with (3⁶·4⁸·5⁷) topology, which comprises of two kinds of helical chains. Additionally, compound 1 shows ferromagnetic interactions among metal ions.     

Design,synthesis, structure and magnetic behavior of a high spin binuclear Fe(III) complex of N-(1-ethanol)-N,N-bis(3-tert-butyl-5-methyl-2-hydroxybenxyl) amine

The Mannich reaction of 2-aminoethanol, 2-tert-butyl-4-methylphenol, and formaldehyde at the ratio sets of 1:2:2 provided a new ligand, N-(1-ethanol)-N,N-bis(3-tert-butyl-5-methyl-2-hydroxybenxyl)amine (H₃L). In the presence of base, H₃L reacted with FeCl₃·6H₂O to form a dinuclear Fe(III) complex [Fe₂L₂] 1. The value of μ_eff at room temperature (5.95 μ_B), is much less than the expected spin-only value (8.37 μ_B) of two high spin (hs) Fe³⁺ (S = 5/2) ions [μ = g[∑ ZS(S + 1)]^1/2], indicating there were strong interactions between Fe³⁺ ions. The effective magnetic moment (μ_eff) decreased abruptly with cooling to a minimum value of 0.1 μ_B at 2 K. It was worth noting that Fe³⁺ ions of 1 exhibited thermally induced quartet ? doublet spin transitions, and these transitions were abrupt. The magnetic behaviors of 1 denoted the occurrence of intramolecular anti-ferromagnetic interactions. J (? 13.58 cm^? 1) agrees with the result from Gorun–Lippard equation, ? J (cm^? 1) = Aexp(BP(Å) = 12.9).     

Squarato-metal(II) complexes: Part 6. Synthesis,structure and magnetic characterization of an usual squarate-based 1D copper(II) coordination polymer composed of hexanuclear entities and a trinucleating ligand scaffold

The reaction of the polynucleating ligand 1,3,5-tris[bis(2-pyridylmethyl)aminomethyl]benzene (L^TDPA) with Cu(ClO₄)₂ · 6H₂O afforded the trinuclear complex [Cu₃(T^TDPA)(H₂O)₇](ClO₄)₆ · 5H₂O (1). When the reaction was performed in the presence of the squarate dianion, C₄O₄^2-, the compound {[Cu₆(L^TDPA)₂(μ_1,3-C₄O₄)₃](ClO₄)₆ · 12H₂O}_n (2) was obtained. Both compounds have been characterized by X-ray crystallography, showing a trinuclear and a 1D polymeric structures for 1 and 2, respectively. Complex 2 is composed of unusual hexametallic building blocks. Magnetic susceptibility measurements (SQUID) reveal essentially uncoupled copper(II) ions in complex 1, whereas complex 2 shows weak antiferromagnetic coupling via the squarato bridges within magnetically isolated dicopper(II) subunits of the 1D chain.     

Synthesis and characterization of dinuclear copper(II) complexes, [Cu2([20]-DCHDC)(La)2] (La = N3−, NCS− or S2O32−) with tetraazadiphenol macrocyclic ligand having cyclohexane rings

The chiral dinuclear tetraazadiphenol macrocyclic copper(II) complexes [Cu₂([20]-DCHDC)(L_a)₂] {H₂[20]-DCHDC = 14,29-dimethyl-3,10,18,25-tetraazapentacyclo-[25,3,1,0^4,9,1^12,16,0^19,24]ditriacontane-2,10,12,14,16(32),17,27(31),28,30-decane-31,32-diol; L_a = N₃^? (II), NCS^? (IV) or S₂O₃^2? (V)} has been synthesized and structurally characterized by elemental analysis, conductance, electronic and IR spectra as well as FAB-MS method. Crystal structure of [Cu₂([20]-DCHDC)(N₃)₂]·2CH₃OH (III) determined by X-ray crystallography reveal the two square pyramidal copper centers bridged by the two phenoxide oxygen atoms, with large Cu–O–Cu angles {100.88(10)°}.     

Rhodium(III) complexes of N-{2-(arylseleno/telluro)ethyl} morpholine: Synthesis,structure and applications as efficient catalyst for transfer hydrogenation reaction of ketones

N-{2-(Arylseleno/telluro)ethyl}morpholine (L1/L2) synthesized by reacting PhSe^?/ArTe^? (generated insitu) with (2-chloroethyl)morpholine hydrochloride, reacts with RhCl₃·3H₂O resulting in complexes [RhCl₂(L1/L2)₄][ClO₄] (1/2). ¹H, ¹³C{¹H} and ⁷⁷Se{¹H}/¹²⁵Te{¹H} NMR spectra of L1, L2, 1 and 2 were found characteristic. The single crystal structure of 2 has been solved. The L2 binds with Rh in 2 as a monodentate ligand. The geometry around Rh is distorted octahedral. The Rh–Te distances are in the range 2.6509(9)–2.6688(8) ?. Both the complexes efficiently catalyze transfer hydrogenation reaction of acetophenone (TON/TOF up to 9.9 × 10⁴/9.9 × 10³ h^? 1) and benzophenone (TON up to 9.8 × 10⁴ and TOF up to 9.8 × 10³ h^? 1).     

A Michael-type reaction between acrylato ions and ethylenediamine coordinated to Ni(II). Synthesis,crystal structure and magnetic properties of [Ni2(EDDP)2(H2O)2] · 2H2O (H2EDDP = ethylenediamine-N,N-dipropionic acid)

The reaction between NiCO₃ · Ni(OH)₂, acrylic acid and ethylenediamine in a 2:4:1 molar ratio affords the binuclear complex, [Ni₂(EDDP)₂(H₂O)₂] · 2H₂O 1. The organic ligand, EDDP^2? (the dianion of the ethylenediamine-N,N-dipropionic acid ligand), results from the addition of one amine group to the carbon–carbon double bonds of two acrylato ions. The crystal structure of 1 consists of neutral centrosymmetric entities, with the nickel ions connected by two carboxylato groups, each one acting as a monoatomic bridge. The intramolecular Ni?Ni distance is 3.212 Å. The metal ions exhibit an octahedral geometry. The cryomagnetic investigation of 1 reveals an antiferromagnetic coupling of the nickel(II) ions (J = ?21.8 cm^?1, H = ?JS_Ni1S_Ni2).     

Novel 3-dimensional sixfold interpenetrating diamondoid networks of copper(I) coordination polymers of polypyridyl ligands – Syntheses,characterization and crystal structures

Two new coordination polymers [Cu(L¹)₂]_n(ClO₄)_n·2nH₂O (1), [Cu(L²)₂]_n(ClO₄)_n·2nH₂O (2) of polydentate imine/pyridyl ligands, L¹ and L² with Cu(I) ion have been synthesized and characterized by single crystal X-ray diffraction studies, elemental analyses, IR′ UV–vis and NMR spectroscopy. They represent 3-dimensional, sixfold interpenetrating diamondoid network structures having large pores of dimension, 35 × 21 Å² in 1 and 38 × 19 Å² in 2, respectively.