Metal chelates with some cellulose derivatives. Part III. Synthesis and structural chemistry of nickel (II) and copper (II) complexes with carboxymethyl cellulose

Cu(II) and Ni(II) complexes with three grades of carboxymethyl cellulose (CMC) with different degrees of substitution have been synthesized and characterized. Probable structures of the metal complexes are inferred from the electronic and IR spectra, elemental analysis data and magnetic moment measurements. CMC coordinates with cu(II) and Ni(II) via the carboxymethyl and hydroxyl groups. The effect of the degree of substition of the CMC on the mode of chelation is discussed. Ni(II) complexes show an octahedral geometry around the metal ion and exhibit the formula [NiL · 4H₂O]Cl. Cu(II) complexes exist in the square planar form and have the formula Cu(L)₂, where L is uninegatively charged bidentate CMC ligand. The ligand field parameters of Ni(II) complexes are also evaluated.     

Metal chelates with some cellulose derivatives. Part I. Preparation and characterization of chromium (III)–carboxymethyl cellulose complexes

A systematic spectrophotometric study on the complexation of chromium (III) ion with sodium carboxymethyl cellulose (CMC) was carried out. The effects of the degree of substitution (DS) of the polymer, the concentrations of Cr(III) and CMC solutions, the pH and temperature on the complex formation were studied in the aqueous state. CMC complexes with Cr(III) were characterized by elemental analysis, magnetic moment and spectral (Vis and IR) data. The results showed that CMC (L) chelated to the metal ion according to the formula CrL₂ · 2H₂O. The ligand field parameters, namely D_q, B and β were calculated; the β-values indicate strong covalency in the ligand σ bond. The IR spectra revealed that the chelating sites of CMC are not only the carboxymethyl groups, via the ether- and the carboxyl-oxygen atoms, but also the secondary hydroxyl groups.     

Some Semiconductor Properties of Carboxymethyl Cellulose-Copper Complexes

Metal chelates of three grades of carboxymethyl cellulose (CMC) (LI-L3) with Cu(II) ions, either originating from CuCl₂ or CuSO₄, were prepared and characterized by elemental analysis, infrared spectra, and electrical conductivity studies. The results showed that the degree of substitution of CMCs and the origin of the Cu(II) ion have a profound effect on the amount of metal included in the polymer complexes and the structure and the electrical conductivity of the prepared complexes. CMC acts as a uninegatively charged bidentate ligand when it is chelated with Cu(II) of CuCl₂ via the carboxymethyl group and exhibits the formula Cu(L)₂, whereas it acts as a binegatively charged bitentate ligand when it is chelated with CuSO₄ via the carboxymethyl and secondary hydroxyl groups and exhibits the formula CuL.2H₂O. The investigation revealed that the electrical conductivity depends on the temperature and has two maximum peaks. The values of the activation energy for the conductivity of CMC and their complexes indicated that the samples changed from a low-semiconductor to a high-semiconductor property with heating. It is found that CMC-Cu(II) complexes formed from CuSO₄ exhibit a high-semiconductor property compared to complexes derived from CuCl₂.     

Syntheses,structures, and magnetic properties of ethoxy-bridged dinuclear iron(III) complexes containing tetradentate ligands

Dinuclear iron(III) complexes, [(phenO)Fe(SO₄)]₂·2CH₃OH (1) and [(bpmapO)Fe(NO₃)]₂(NO₃)₂·3CH₃OH (2) have been prepared by the reaction of phenOH/bpmapOH and FeSO₄·7H₂O/Fe(NO₃)₃·9H₂O in methanol, respectively (phenOH = N-(2-pyridylmethyl)-N′-(2-hydroxyethyl)ethylenediamine, bpmapOH = N-(bis(2-pyridylmethyl)amino)-2-methylpropan-2-ol). Both complexes are ethoxy-bridged dinuclear species and the iron(III) ions in 1 and 2 have distorted octahedral geometries. Both complexes show strong antiferromagnetic interactions through the bridged ethoxy groups within the dimeric units.     

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.     

Two bimetallic tetranuclear three-blade propeller shaped complexes with helical water chains: Crystal structures, second-order nonlinear optical (NLO) properties and thermal decomposition mechanisms

Two isostructural bimetallic tetranuclear chiral complexes, [K(18-crown-6)]₃[Fe(ox)₃] · 9H₂O and [K(18-crown-6)]₃[Cr(ox)₃] · 9H₂O, crystallize in rhombohedral R3 space group, the tetranuclear cluster is respectively built from one [Fe(ox)₃]³⁻ or [Cr(ox)₃]³⁻ species with three K(18-crown-6 ether) supramolecular cations linked by oxalate groups, and lattice water molecules form the double helical chains. Two complexes are second-harmonic-generation (SHG) active with the SHG response about 0.5 times that of urea.     

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).     

Association behaviors between carboxymethyl cellulose and polylactic acid revealed by resonance light scattering spectra

Resonance light scattering (RLS) spectra were used to study the formation of complexes of carboxymethyl cellulose (CMC) and polylactic acid (PLA) in a mixed solvent of 10% DMSO/90% H₂O(V/V). The RLS results showed that the CMC and PLA could form a steady homogeneous complex due to the interaction of hydrogen bonding. With the increasing of CMC mass fraction in the complex, the observed durative enhancement RLS signal with two inflexion points indicated the forming of complexes and aggregation of complexes. The aggregation equilibrium and thermo stability of the complexes were also investigated based on RLS values.     

Micro/nano-structured SnS2 negative electrodes using chitosan derivatives as water-soluble binders for Li-ion batteries

Micro/nano-structured SnS₂ was prepared by a hydrothermal method using biomolecular l-cysteine and SnCl₄·5H₂O as sulfur source and tin source, respectively. The electrochemical performances of SnS₂ electrodes were investigated using water-soluble binders of carboxymethyl chitosan (C-chitosan) and chitosan lactate, and compared with the conventional water-soluble sodium carboxymethyl cellulose (CMC) and non-aqueous polyvinylidene difluoride (PVDF). SnS₂ electrode using the water-soluble binders (C-chitosan, chitosan lactate, and CMC) showed higher initial coulombic efficiency, larger reversible capacity, and better rate capabilities than that of PVDF. In addition, SnS₂ electrode using C-chitosan binder exhibited somewhat worse cycling stability, but better rate capability at a high rate of 5C than CMC.     

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.     

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.     

From tetranuclear cluster with single-molecule-magnet behavior to 1D alternating spin-canting chain in a Fe(III)–Mn(III) bimetallic system

A tetranuclear cluster and an alternating zigzag chain were synthesized via rational assembly of the same cyanometalate building blocks with different Mn(III) Schiff bases possessing varying proportions of sterically hindered groups causing steric hindrances. The tetranuclear cluster [(Tp*)Fe(CN)₃]₂[Mn(salen)]₂·H₂O [1; [(Tp*)Fe(CN)₃]⁻ [Tp* = hydrotris(3,5-dimethylpyrazol-1-yl) borate], salen = N,N′-ethylenebis(salicylideneiminato) dianion] was formed with Schiff bases possessing smaller steric hindrances, whereas the one-dimensional alternating zigzag chain {[(Tp*)Fe(CN)₃Mn(salcyen)]·2CH₃OH·H₂O}_n [2; salcyen = N,N′-(1,2-cyclohexanediylethylene)bis(salicylideneiminato) dianion] was formed with Schiff bases possessing larger steric hindrances. Magnetic measurements revealed that 1 exhibits single-molecule-magnet behavior with dominant ferromagnetic interactions, whereas 2 exhibits spin-canting behavior with dominant antiferromagnetic interactions.     

Seven Coordinated Metal Complexes derived from (3-Carboxymethoxy-Naphthalen-2-yloxy)-Acetic Acid and Coordination Polymers

A design principle for seven coordinated metal carboxylate complexes and coordination polymers of Mn(II), Cd(II) and Na(I) derived from (3-carboxymethoxy-naphthalen-2-yloxy)-acetic acid (LH2) is presented. The complexes/coordination polymer [Mn(L)(H₂O)₃]·3H₂O (1), [{Cd(L)(H₂O)₂}·H₂O]_n (2); [Cd(L)(py)₃]·3H₂O (3) have metal ions in pentagonal bipyramid environments (py = pyridine). The coordination polymer [{Cd(L)(H₂O)₂}·H₂O]_n (2) may be considered to be the self-assembly of hexacoordinated [Cd(L)(H₂O)₂] units; it reacts with pyridine to form mono-nuclear complex 3. Depending on the reaction conditions, Ni-coordination polymers of L adopt different compositions. From the reaction carried out with NiCl₂ and NaOH in quinoline and water, a hetero bimetallic coordination polymer; namely, [[NaL(H₂O)]₂Ni(H₂O)₄]_n (4) is obtained. A similar reaction in pyridine-water solvent led to [{Ni(L)(py)₃}.py]_n (5). The coordination polymer 5 has pyridine in its interstices held by C–H···π interactions.     

Ferromagnetic dinuclear nickel(II) complexes bridged by azide ions

Dinuclear nickel(II) complexes, [Ni₂(mpapOH)₂(CH₃CO₂)(N₃)₃] (1) and [Ni₂(mpapOH)₂(N₃)₄]·CH₃OH (2) were synthesized by treating Ni(CH₃CO₂)₂·4H₂O and Ni(NO₃)₂·6H₂O in methanol, respectively, with mpapOH (= 2-methyl-2-[(2-pyridinylmethyl)amino]-1-propanol) and sodium azide; both 1 and 2 were characterized by elemental analysis, IR spectroscopy, X-ray diffraction, and magnetic susceptibility measurement. 1 was shown an asymmetric dinuclear structure, whereas 2 was displayed a symmetric dimeric one. 1 and 2 were exhibited end-on azido-bridged nickel(II) dinuclear units; corresponding ferromagnetic interactions through the bridged end-on azido ligands within the dimeric units were observed.     

A Ladder-like Coordination Polymer [Sr(H2O)4(CuL)2]·(CuL)·2.25H2O Constructed From Metallo-Ligand Na[CuL] and Sr(NO3)2: Crystal Structure and ESR Study

Ligand L (H₃L = Glycylglycine, N-[1-(2-hydroxy,5-bromophenyl)propylidene]) has been prepared which contain flexible dipeptide group and substituted phenol group. The ligand react with Cu(NO₃)₂ to give the metallo-ligand [CuL]⁻, in which L acting as quadridentate ONNO chelate, coordinate to Cu(II) ion. The metallo-ligand [CuL]⁻ is rigid and has multifunctional groups. Reaction of metallo-ligand with Sr(NO₃)₂ leads to the formation of the title complexes [Sr(H₂O)₄(CuL)₂]· (CuL)·2.25H₂O (1). This heteronuclear compound has been characterized by elemental analyses, spectroscopic analyses, and single crystal diffraction. Structural analyses reveal that the complex was crystallized in triclinic space group P-1 and has intricate 2D net-structure, which contain an infinite 1D [Sr(H₂O)₄(CuL)₂]⁺ ladder-like structure. In addition ESR (electron spin resonance) property and thermogravimetric analysis of 1 are discussed in detail.     

Synthesis and characterization of a rare hemiacetalate bridged incomplete Cu4II dicubane cluster

Reaction of 2-pyridinecarboxaldehyde [(Py)CHO] with Cu(NO₃)₂·2.5H₂O in the presence of 4-aminopyridine and NaN₃ in MeOH lead to an incomplete double-cubane [Cu₄{PyCH(O)(OMe)}₄(N₃)₄] (1) in 87% isolated yield, representing a rare type of metal cluster containing bridging hemiacetalate ligand [pyCH(O)(OMe)]^?1 which was characterized by single crystal structure analysis and variable temperature magnetic behavior.     

Synthesis,characterization and immobilization of iron (III) pyridoxinato complex within Al-MCM-41 as catalyst for cycloalkanes oxidation

Biomimetic [Fe(pyridoxinato)₂OH·(H₂O)₃] non-hem complex designated as [Fe(L)₂OH·(H₂O)₃] was synthesized with basic solution of pyridoxine (Vitamin B₆) and FeCl₃ in methanol under reflux condition. It was then immobilized within the Al-MCM-41. Characterizations were carried out by powder X-ray diffraction, nitrogen adsorption desorption, FTIR and UV–Vis spectroscopy. It was found that pore volume, surface area, and pore diameter of Al-MCM-41 decreases after immobilization of iron complex. Density functional theory studies confirmed the experimental results of [Fe(L)₂OH·(H₂O)₃] complex. Fe-complex/Al-MCM-41 was found to successfully catalyze the oxidation of cyclohexane, cyclooctane and adamantane using H₂O₂ as oxidant with 45–90 % conversion toward the corresponding alcohols and ketones is considerable.     

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.     

Heteropolynuclear Schiff-base complexes Cu–Ln–Fe (Ln = Sm & Pr) with magnetic property

Two new complexes [{CuL}Sm(H₂O)₃{Fe(CN)₆}]₂·6H₂O (1) [{CuL}₂Pr(H₂O){Fe(CN)₆}]₂·4H₂O (2) (H₂L = N,N′-ethylenebis(3-methoxysalicylideneimine)) have been prepared by reactions of acyclic compartmental Schiff-base heterodinuclear 3d–4f compound [{CuL}Ln(NO₃)₃] (Ln = Sm & Pr) with K₃[Fe(CN)₆]. Crystal structures of both 1 and 2 reveal unique topology structures. 1 shows a dimeric heterotrinuclear [{CuL}Sm(H₂O)₃{Fe(CN)₆}]₂ while 2 displays a dimeric heterotetranuclear [{CuL}₂Pr(H₂O){Fe(CN)₆}] with distorted sandwich moieties [{CuL}₂Pr]. Both 1 and 2 form similar 1D ladder-like structure through the intermolecular double bridges of Cu–N bonds. The measurement of variable-temperature magnetic susceptibility reveals that both complexes 1 and 2 exhibit antiferromagnetic interaction between spin carriers.