Di-μ-hydroxy macrocyclic ytterbium(III) complex

The mononuclear [YbracL]Cl₃·2H₂O and dinuclear [Yb₂(OH)₂Cl₂(racL)₂]Cl₂·4CH₃OH·2H₂O complexes of the macrocyclic ligand L derived from trans-1,2-diaminocyclohexane and 2,6-diformylpyridine have been obtained. The formation of the dinuclear species upon addition of hydroxide to the [YbracL]Cl₃·2H₂O or the enantiopure [YbrrrrL(NO₃)₂](NO₃) has been followed using ¹H NMR spectroscopy. The X-ray crystal structure of [Yb₂(OH)₂Cl₂(racL)₂]Cl₂·4CH₃OH·2H₂O complex has been determined. The complex is a dimer consisting of two macrocyclic units. The Yb(III) ion is coordinated by six nitrogen atoms of the macrocyclic ligand, two bridging OH groups and chloride anions. The chiral macrocycle L in this complex exhibits twist-bent conformation of approximate C₂ symmetry.     

New dinuclear cobalt (ΙΙ, ΙΙΙ) and tetranuclear manganese (ΙΙΙ) complexes assembled by a polydentate Schiff-base ligand: synthesis,structure and magnetic properties

The reactions of 2-(((2-hydroxy-3-methoxyphenyl)methylene)amino)-2-(hydroxymethyl)-1,3-propanediol (H₄L) and Mn(ClO₄)₂·6H₂O or Co(SCN)₂·3H₂O in the presence of triethylamine in methanol led to the formation of two new complexes [Mn^ΙΙΙ₄(HL)₂(H₂L)₂(CH₃OH)₄]·4CH₃OH·(ClO₄)₂ (1) and [Co^ΙΙCo^ΙΙΙ(H₂L)₂(CH₃OH)(SCN)]·1.5CH₃OH·1.5H₂O (2), respectively. According to structural data and magnetic properties tetranuclear complex 1 contains four homo-valence manganese (ΙΙΙ) atoms, while in the binuclear complex 2 composed of hetero-valence bi- and trivalent cobalt (ΙΙ, ΙΙΙ) atoms. Weak antiferromagnetic exchange interactions between neighboring manganese ions in 1 have place. χ_MT for 2 was fitted using a model of isolated cobalt (ΙΙ) ion with zero-field splitting parameters and the study confirms its mixed valence Co^ΙΙ/Co^ΙΙΙ nature. No slow magnetic relaxation effects were observed for both complexes in the absence of an applied dc magnetic field.     

A new cyano-bridged Ca(II)–Fe(III) complex containing both molecular square and linear trimetallic species

A new cyano-bridged Ca(II)–Fe(III) complex, [Ca₂(phen)₄(H₂O)₆Fe(CN)₆][{Ca(phen)₂(H₂O)₂Fe(CN)₆}₂]·3(phen)·(phenH)·14H₂O·CH₃OH (where phen=1,10-phenanthroline) 1 has been synthesized and structurally characterized. It contains a cyano-bridged trimetallic cationic species [Ca₂(phen)₄(H₂O)₆Fe(CN)₆]⁺ 1a with a nearly linear Ca–Fe–Ca arrangement, and an anionic species [{Ca(phen)₂(H₂O)₂Fe(CN)₆}₂]²⁻ 1b which has a cyano-bridged tetrametallic Ca–Fe–Ca–Fe molecular square framework. In both the species, the Ca atoms are eight coordinated with distorted anti-squareprismatic geometry and the Fe atoms have six coordinated octahedral geometry. The charge is balanced by the protonation of one phen molecule in the lattice.     

Enhanced catalytic oxidation of monoterpenes by zeolite-Y entrapped iron complex: spectral studies and mechanistic vision

[Fe(L)₂(H₂O)₂]–Y complex (where, L?=?(Z)-2-((4-hydroxybenzylidene)-amino)benzoic acid) has been synthesized by Flexible Ligand (FL) method and characterized by chemical analysis (CHN, ICP-OES, TGA, AAS), diffraction method (XRD), absorption spectroscopy (FTIR, UV–Vis), BET and SEM techniques. To investigate the catalytic performance (activity, stability, and reusability), [Fe(L)₂(H₂O)₂]–Y was employed as heterogeneous catalyst in the liquid phase oxidation of α-pinene and limonene with H₂O₂ oxidant. [Fe(L)₂(H₂O)₂]–Y catalyzed the oxidation of α-pinene via free radical formation as confirmed by in-situ IR and DR UV–Vis spectroscopy. [Fe(L)₂(H₂O)₂]–Y showed conversion of α-pinene (67%) and limonene (79%) with better TONs, which is far better performance than neat iron complex.     

Salen Type Homo-multinuclear Yb3 and Yb4 Complexes and Their NIR Luminescence

Two discrete salen type homo-multinuclear Yb₃ and Yb₄ complexes, namely, [Yb₃L₃(OAc)₃]·3CH₃OH·H₂O (1) and [Yb₄L₂(OAc)₄(μ₃-OH)₂(H₂O)₂](ZnCl₄)·3CH₃OH (2) (H₂L = N,N′-bis(2-oxy-3-methoxybenzylidene)-1,2-phenylenediamine) have been synthesized by reactions of H₂L and different ytterbium salts. X-ray crystallographic analysis reveals that complex 1 exhibits a triple-decker Yb₃ sandwich structure with a ratio of H₂L:Yb = 1:1, while complex 2 exhibits a defect-dicubane Yb₄ core with a ratio of H₂L:Yb = 1:2. The NIR luminescence of complexes 1 and 2 have been investigated and discussed.     

A novel cyano-bridged Sr(II)–Fe(III) polymer containing alternating octanuclear and tetranuclear cores

A novel cyano-bridged Sr(II)–Fe(III) polymeric complex ([Sr₃(phen)₆(H₂O)₆{Fe(CN)₆}₂]·phen·6.5H₂O)_n (1) has been synthesized and structurally characterized. The complex contains alternating octanuclear 24-membered and tetranuclear 12-membered metallocycles, which are repeated to form a polymeric chain. The Sr(II) centres are eight coordinated with distorted bicapped trigonal prismatic geometry while the Fe(III) centres have six coordinate octahedral geometry.     

Hetero-bimetallic 2D coordination network constructed by azacrown ether carboxylic acid with lanthanide(III) and sodium ions

Two lanthanide-based coordination polymers [Na₃La(L)Cl·(H₂O)₆]·NO₃ (La-L) and [Na₃Eu(L)Cl·(H₂O)₆]·NO₃ (Eu-L) were newly synthesized by reaction of an azacrown ether carboxylic acid ligand H₄L (4,7,13,16-tetracarboxymethyl-1,10-dioxa-4,7,13,16-tetraazacyclooctadecane) with La(III)/Eu(III). Complexes La-L and Eu-L exhibited two-dimensional (2D) coordination architectures built up by Ln–L coordinating subunits and one-dimensional (1D) Na–O bridging chains. Four versatile coordination modes of carboxyl groups and Na–O coordination bi-chains linked by novel μ-O bridges (μ2-O and μ3-O) were demonstrated in the structure. Photoluminescence spectra of Eu-L were investigated to reveal characteristic emissions of Eu(III). This is the first example of hetero-bimetallic complex of the tetraazacrown ether ligand with lanthanide and sodium ions.     

Copper(II) and cadmium(II) complexes with an imide tethered imidazole and a copper(II) coordination polymer through ring opening reaction

The reactions of 2-(3-(1H-imidazol-1-yl)propyl)isoindoline-1,3-dione (L) with copper (II) chloride or copper(II) nitrate resulted in mononuclear complexes [CuL₄Cl₂]·12H₂O (1) or [CuL₄(H₂O)NO₃]NO₃·2H₂O (2) respectively; whereas the copper(II) acetate reacted with L to give a three dimensional coordination polymer {[Cu(L′)₂]·4H₂O}n (3), (where L′ = 2-(3-(1H-imidazol-1-yl)propylcarbamoyl)benzoate). The reaction of cadmium(II) acetate with L led to the formation of a seven-coordinated complex [CdL₃(O₂CCH₃)₂]·2H₂O (4).     

Copper(II) and cadmium(II) complexes derived from Strandberg-type polyoxometalate clusters: Synthesis,crystal structures,spectroscopy and biological activities

Three Strandberg-type polyoxometalate compounds [Cu(L)₂(H₂O)₂]₂H₂[P₂Mo₅O₂₃]·2CH₃OH (1), [Cu(L)₂(H₂O)]H₂[Cu(L)₂(P₂Mo₅O₂₃)]·4H₂O (2), [Cd(L)₂(H₂O)₂]₂H₂[P₂Mo₅O₂₃]·2CH₃OH (3), (L = pyridine-2-carboxamide) have been synthesized and structurally characterized by elemental analysis, spectroscopic methods (IR and UV–vis) as well as single crystal X-ray diffraction. Single-crystal X-ray structural analyses indicate that 1 and 3 are isostructural and crystallized in monoclinic, space group I2/a. Biological studies have indicated that compounds 1–3 exhibit broad and effective activities against the tested cells. A synergistic effect involving L, metal and P₂Mo₅ could probably explain the improved growth-inhibiting properties. Both coordination mode and the type of metal ion play significant roles in these compounds cytotoxicity.     

Two-dimensional assembling of 4,4′-bipyridine and 4,4′-azopyridine bridged iron (II) linear coordination polymers via hydrogen bond

Novel two-dimensional polymers, [Fe(L¹)(H₂O)₂(NCX)₂] · L¹ (L¹ = 4,4′-bipyridine (bipy)) (1, 2) and [Fe(L²)(CH₃OH)₂-(NCX)₂] · L² (L² = 4,4′-azopyridine (azpy)) (3) and X = S (1,3),Se (2), have been synthesized and characterized by X-ray crystallography. The structures reveal the formation of trans-L-bridged [Fe(NCX)₂(Y)₂] where Y = H₂O, CH₃OH linear chains assembled into two-dimensional networks by hydrogen bonds between the uncoordinated ligand L and the coordinated solvent molecules.     

Structures and magnetism of bimetallic octacyanometallates: honeycomb-like [Mo(CN)8Ni2(pn)4]n·4nH2O and binuclear [Mo(CN)8Ni(en)2(H2O)][Ni(en)3]·2H2O (pn=1,3-diaminopropane,en=1,2-diaminoethane)

Bimetallic octacyanometallates [Mo(CN)₈Ni₂(pn)₄]_n·4nH₂O (1) and [Mo(CN)₈Ni(en)₂(H₂O)][Ni(en)₃]·2H₂O (2) based on [Mo(CN)₈]⁴⁻ were synthesized in aqueous solution, and their crystal and molecular structures have been determined. The complex [Mo(CN)₈Ni₂(pn)₄]_n·4nH₂O (1) consists of novel two-dimensional honeycomb-like layers. The complex [Mo(CN)₈Ni(en)₂(H₂O)][Ni(en)₃]·2H₂O (2) contains a binuclear anion [Mo(CN)₈Ni(en)₂(H₂O)]²⁻,[Ni(en)₃]²⁺ cation and two lattice water molecules. Magnetic studies suggest a possible weak antiferromagnetic interaction between Ni²⁺ ions in 1.     

Bis-boron-capped tris(dioxime) cage complexes with terminal carbonyl groups

Three clathrochelate complexes, [(p-OHCC₆H₄B)₂(chdd)₃Fe^II]·0.5CH₂Cl₂ (1·0.5CH₂Cl₂, H₂chdd = 1,2-cyclohexanedione-1,2-dioxime), [(p-OHCC₆H₄B)₂(hmbd)₃Mn^II₂]}·Et₃NH·0.5CH₃OH·0.5H₂O (2·0.5CH₃OH·0.5H₂O, H₃hmbd = 2-hydroxy-5-methyl-1,3-benzenedicarboxaldehyde-1,3-dioxime), and [(p-OHCC₆H₄B)₂(hmbd)₃Co^II₂]·Et₃NH·H₂O (3·H₂O), were synthesized through template macrobicyclization using metal-oximates as building blocks. These complexes contained reactive apical formyl substituents. Fe^II in mononuclear complex 1 was wrapped in the cavity formed by condensation of H₂chdd with 4-formylphenylboron acid. The organic frameworks of anion unit of binuclear Mn^II complex 2 and that of binuclear Co^II complex 3 were combined by H₃hmbd with 4-formylphenylboronic acid. Spectroscopic, electrochemical characterizations of complexes 1–3 were exploited. DFT calculation of 1 and 2 was also done for better understanding of the electronic property and charge carrier mobility.     

Six isostructural lanthanide-containing MOFs built on a semi-rigid tripodal organic ligand

By using a semi-rigid tripodal ligand 1,1′,1′′-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tripyridinium-4-olate) (L), six isomorphous lanthanum metal-organic frameworks (MOFs), namely, [Pr(L)₂(Cl)₂]·(Cl)(DMF)_0.5·(H₂O)·(1), [Nd(L)₂(Cl)₂]·(Cl)(2), [Tb(L)₂(Cl)₂]·(Cl)·(DMF)·(H₂O)(3), [Eu(L)₂(Cl)₂]·(Cl)(DMF)·(H₂O)(4), [La(L)₂(Cl)₂]·(Cl)(5), [Sm(L)₂(Cl)₂]·(Cl) (DMF)·(H₂O) (6), were obtained and characterized by single crystal X-ray diffraction, IR and elemental analysis. Six compounds are isostructural with Ln^3 + (Ln = Pr, Nd, Tb, Eu, La, Sm) and in which the Ln^3 + is considered as a 6-connecting node and the L ligand is a 3-connecting node to afford a (3,6)-connected 2D layer with kgd topology, which further stacks into 3D supramolecular networks through C-H^…O weak interactions. Luminescent properties of these lanthanide MOFs have also been assessed at ambient temperature, in which the Pr^3 +-1 and the La^3 +-5 are slightly blue-shifted with respect to the ligand. Series of sharp peaks characteristic of the Eu^3 +-4, the Tb^3 +-3 and Sm^3 + − 6 metal-centered luminescence appear. The Nd^3 +-2 has no emission.     

Syntheses,magnetic properties,and reactivity of dinuclear oxovanadium (IV) and copper (II) complexes with (μ-diphenylphosphinato)-bridges

Novel dinuclear oxovanadium (IV) complexes having the formula [(VO)₂(dpp)₃(bpy)₂]NO₃·2H₂O (1), [(VO)₂(dpp)₃(phen)₂]-NO₃·H₂O (2), [(VO)₂(bmp)₃(bpy)₂]NO₃·H₂O (3), and [(VO)₂(bmp)₃(phen)₂]NO₃·H₂O (4), and copper (II) complexes having the formula [Cu₂(bmp)₂(phen)₂](NO₃)₂·MeOH·H₂O (5), and [Cu₂(bmp)₂(bpy)₂](NO₃)₂ (6) (where Hdpp=diphenylphosphinic acid, Hbmp=bis(4-methoxyphenyl)phosphinic acid, bpy=2,2^′-bipyridine, and phen=1,10-phenanthroline) with (μ-phosphinato)-bridges, 1–6, have been prepared and characterized. Crystal structure of complex 2 reveals that two vanadium ions are linked by tris(μ-phosphinato)-bridges. The magnetic susceptibility data for 1–3, and 6 conform to the usual dimer equation with −2J values of 16–24 cm⁻¹, indicating a weak antiferromagnetic interaction between vanadium(IV) ions.The oxidation of cinnamyl alcohol was studied using complexes 1–6 as catalyst and molecular oxygen as an oxidant. In the presence of complex 3 as a catalyst, cinnamyl alcohol was oxidized to cinnamaldehyde 61% yield in 7 h. Consequently, complex 3 activates oxygen, and then alcohol was quite efficiently oxidized by activated oxygen.     

Syntheses and characterizations of two-dimensional polymers based on tetraimidazole tetraphenylethylene ligand with aggregation-induced emission property

Two new coordination polymers [Co(TIPE)(H₂O)₂]·Hbtc·CH₃CN·3H₂O (1) and [Cd(TIPE)_0.5(m-bdc)(H₂O)]·CH₃OH·H₂O (2) (TIPE = tetra(3-imidazoylphenyl)ethylene, H₃btc = 1,3,5-benzenetricarboxylate, m-H₂bdc = 1,3-benzenedicarboxylate) have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, elemental analysis, IR, TGA, and PXRD. Furthermore, the luminescent properties of complexes 1, 2 and TIPE ligand have also been investigated in the solid at room temperature.     

Polyoxometalate chain-like polymer: the synthesis and crystal structure of a 1D compound, [Mo36O108(NO)4(MoO)2La2(H2O)28]n·56nH2O

Reaction of {Mo₃₆(NO)₄} with LaCl₃ in the presence of NH₂OH·HCl results in the formation of a novel chain-like polymer, [Mo₃₆O₁₀₈(NO)₄(MoO)₂La₂(H₂O)₂₈]_n·56nH₂O, in which the {Mo₃₆(NO)₄} units are linked to each other by two parallel La atoms.     

Spectroscopic and Thermal Studies of Mn(II), Fe(III), Cr(III) and Zn(II) Complexes Derived from the Ligand Resulted by the Reaction Between 4-Acetyl Pyridine and Thiosemicarbazide

Transition metal complexes of Mn(II), Fe(III), Cr(III) and Zn(II) metal ions with a general formulas [Mn(L)₂(Cl)₂]·4H₂O (I), [Fe(L)₂(Cl)₂]·Cl·6H₂O (II), [Cr(L)₂(Cl)₂]·Cl·6H₂O (III) and [Zn(L)₂(Cl)₂]·2H₂O (IV) where L = 4-acetylpyridine thiosemicarbazone, have been synthesized and interpreted using CHN elemental analysis, magnetic susceptibility measurements, molar conductance, thermal analysis and spectroscopic techniques; i.e., infrared, electronic UV/vis, ¹H-NMR and mass. The manganese(II), ferric(III), chromium(III) and zinc(II) complexes have octahedral geometry. The molar conductance measurements reveal that the Mn(II) and Zn(II) chelates are non-electrolytes but Fe(III) and Cr(III) have an electrolytic behavior. The IR spectra show that the 4-acetylpyridine thiosemicarbazone free ligand is coordinated to the metal(II) chlorides as a neutral bidentate ligand through both of the lone pair of electrons of the C=N azomethine group and C=S group. X-ray powder diffraction gives an impression that the resulting complexes are amorphous and different from the start materials. The thermogravimetric studies indicate that uncoordinated water molecules are lost in the first and second decomposition steps. The activation thermodynamic parameters E*, ΔH*, ΔS* and ΔG* are estimated from the differential thermogravimetric analysis (DTG) curves using Horowitz–Metzger (HM) and Coats–Redfern (CR) methods. The ligand and its complexes have been screened for antibacterial and antifungal activities against two bacteria; i.e., Escherichia coli (Gram −ve) and Bacillus subtilis (Gram +ve) and two fungi, i.e., tricoderma and penicillium activities).     

A novel three-dimensional 3d–4f heterometallic coordination polymer with unique (3,4)-connected topology and helical units: Synthesis,crystal structure and photoluminescence property

One new three-dimensional 3d–4f heterometallic coordination polymer, namely, {[EuZn₂(imdc)₂(C₂O₄)_0.5(H₂O)₄]·2H₂O}_n (1) (H₃imdc = imidazole-4,5-dicarboxylic acid), has been successfully synthesized by the hydrothermal reactions of Eu₂O₃, Zn(NO₃)₂·6H₂O, H₃imdc, H₂C₂O₄·2H₂O and H₂O. Single-crystal X-ray diffraction analysis reveals that complex 1 possesses 3D heterometallic framework containing 2D layer based on L–Zn2–L (L = imdc) helical chains and L–EuZn1–L chains. Complex 1 exhibits unprecedented (3,4)-connected four-nodal topology with Schläfli symbol (6·7·8) (6·7·9) (6·7²·8²·10) (7·8²). Moreover, the photoluminescence property of 1 was investigated in the solid-state at room temperature.     

Frequently used,but still unknown: Terbium(III) tris-hexafluoroacetylacetonate dihydrate

This work provides direct access to the complex [Tb(hfa)₃(H₂O)₂] with elucidation of the molecular and crystal structure. It has been shown that the interaction of Tb(OAc)₃·4H₂O with H-hfa·2H₂O in water gives {[Tb₂(hfa)₄(F₃CCO₂)₂(H₂O)₄][Tb(hfa)₃(H₂O)₂]₂·H₂O}, which can be used as a source of pure [Tb(hfa)₃(H₂O)₂]. This compound is a good quantitative precursor for the synthesis of various Tb(hfa)₃ complexes due to its good solubility in common organic solvents such as hexane, benzene, ether and acetone. Hence, it opens new possibilities in the field of molecular magnetism and design for photonic and optoelectronic applications.     

Temperature-controlled structural diversity of two Cd(II) coordination polymers based on a flexible tripodal multicarboxylate ligand

Two new 3-D Cd(II) coordination polymers (CPs) with 3,5-bi(4-carboxyphenoxy)-benzoic acid (H₃L), namely [Cd₃(L)₂(H₂O)₄]·4H₂O (1) and [Cd₃(L)₂(H₂O)₃]·2H₂O (2), were successfully synthesized under hydrothermal condition at 140 °C and 180 °C, respectively. Complex 1 is constructed from 1-D (–Cd–O–)_∞ rod-shaped SBUs (secondary building units) and ‘Y’-shaped L ligands. In complex 2, the 3-D network is mediated by 2-D [Cd(COO)₂]_n layered motifs and ‘T’ and ‘Y’-shaped L ligands. The results show that the reaction temperature plays a key role on the final structures of the complexes. The luminescent properties of the complexes have also been investigated.