Chemical modification of zinc hydroxide nitrate and Zn-Al-layered double hydroxide with dicarboxylic acids

A zinc hydroxide nitrate (ZHN), Zn5(OH)8(NO3)2.2H2O, and a layered double hydroxide (LDH), Zn/Al-NO3 were doped with 0.2 mol% of Cu2+ during alkaline chemical precipitation. Both compounds were intercalated with adipate ((-)OOC(CH2)4COO(-)), azelate ((-)OOC(CH2)7COO(-)), and benzoate (C6H5COO(-)) ions through ion exchange reactions. Solid state 13C nuclear magnetic resonance spectroscopy showed only one signal of carboxylic carbon for adipate and azelate intercalated into LDH, indicating that the carboxylic ends of both acids were equivalent, whereas the signal split when the intercalation was into the ZHN matrix. The electron paramagnetic resonance (EPR) spectrum of copper in octahedral cation sites of LDH layers showed a Hamiltonian parameter ratio g ||/A ||=170 cm and, after intercalation of adipate, the change was not significant: g ||/A ||=174 cm. This result indicates that the carboxylate ions did not coordinate with copper centers. Nonetheless, the intercalation of azelate increased the ratio to g ||/A ||=194 cm, similar to the spectra of ZHN modified with adipate, g ||/A ||=199 cm, and azelate, g ||/A ||=183 and 190 cm, which are associated with the coordination of copper by weak carboxylate anion ligands. Copper occupies octahedral or tetrahedral sites in ZHN layers, and the EPR spectra indicate that the dicarboxylate anions reacted preferentially with octahedral sites, whereas benzoate reacted with both sites.     

Synthesis, crystal structure, EPR spectra of Cu2+ doped [Zn(methylisonicotinate)2(H2O)4]·(sac)2 single crystal

The tetraaquabis(methylisonicotinate)zinc(II) disaccharinate [hereafter, [Zn(mein)2(H2O)4]·(sac)2], complex has been synthesized and characterized by spectroscopic IR, EPR and X-ray diffraction technique. The octahedral Zn(II) ion, which rides on a crystallographic centre of symmetry, is coordinated by two monodentate mein ligands through the ring nitrogen and four aqua ligands to form discrete [Zn(mein)2(H2O)4] unit, which captures two saccharinate ions in up and down positions, each through intermolecular hydrogen bonds. The magnetic environments of Cu2+ doped [Zn(mein)2(H2O)4]·(sac)2 complex have been identified by electron paramagnetic resonance (EPR) technique. EPR spectra of Cu2+ doped [Zn(mein)2(H2O)4]·(sac)2 single crystals have been studied between 113 and 300 K in three mutually perpendicular planes. The calculated results of the Cu2+ doped [Zn(mein)2(H2O)4]·(sac)2 indicate that Cu2+ ion contains two different complexes and each complexes are located in different chemical environments and each environment contains two magnetically inequivalent Cu2+ sites in distinct orientations occupying substitutional positions in the lattice. The vibrational spectra of this compound were discussed in relation to other compounds containing methyl isonicotinate and saccharinate complexes. The assignments of the observed bands were discussed.     

Intercalation and functionalization of zinc hydroxide nitrate with mono- and dicarboxylic acids

The intercalation of ions derived from succinic, glutaric, and adipic acid into layered zinc hydroxide nitrate by ionic exchange reaction is reported. Different reaction conditions are investigated and the materials are characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis (simultaneous thermogravimetry and differential scanning calorimetry) and elemental analysis. The dicarboxylic acids can be grafted to the matrix slab by one carboxylate group and the second hydrated carboxylate group is hanging between the layers. Benzoate ions have also been intercalated by both ionic exchange reaction and stirring in acetonitrile. The two benzoate-intercalated materials exchange the organic moiety by sulfate ions if stirred in magnesium sulfate solution, but the sample obtained by anion exchange also allows the unusual incorporation of neutral magnesium sulfate in addition to free solvated sulfate ion. A schematic arrangement of the intercalated species between the layers is presented.     

柱撑阴离子粘土的合成、表征及催化性能研究(V)

Organic-anion-pillared layered double hydrotalcites such as Zn2AlTA(TA=terephthalate) are easily synthesized by using coprecipitation reaction of Zn2+ and Al3+ ions with terephthalic acid in NaOH solution. Exchange of this material under mild acidic conditions with the heteropolyanions proceeds smoothly to yield Zn2AlSiW11Co and Zn2Al-BW11Cu. Characterization has been carried out by elemental chemical analysis, powder X-ray diffraction and IR spectra. The results indicated that these materials possess exceptionally well-ordered gallery height of 0.98nm. It was found that this kind of pillared layered catalyst has high activity and selectivity for the oxidation of benzaldehyde to benzoic acid using H2O2 as oxidant in liquid-solid phase system.     

Synthesis, physico-chemical and DNA interaction studies of homo- and hetero-trinuclear complexes

Synthesis and characterization of three new trinuclear metal complexes of type Cu3, Cu2Zn and Cu2Ni have been achieved by assembling simple mononuclear complexes, namely 2,2'-bipyridyl 3,4-dihydroxo benzaldehyde copper(II) complex and diethylenetriamine complexes of copper(II), nickel(II) and zinc(II) ions, through the reaction of coordinated ligands. The FAB mass spectra for the complexes show fragmentation pattern in accordance with the molecular formula. The frozen electron paramagnetic resonance (EPR) spectrum of tricopper complex shows two sets of parallel lines with approximately 2:1 ratio. The simulation has been carried out by considering dipolar interaction between the two types of copper ions present in the complex. The trimetallic complexes, Cu3, Cu2Ni and Cu2Zn show strong intercalation type of interaction with Calf thymus DNA in 0.02 mol L(-1) of phosphate buffer containing 60 mmol sodium chloride at pH 7.0 at room temperature. The binding constant is found to be in the order Cu3相似文献   

ESR and photoluminescence properties of Cu doped ZnS nanoparticles

Nanoparticles of Zn1-xCuxS with Cu concentrations of x=0.0, 0.1, 0.2, 0.3 and 0.4 were prepared by a co-precipitation reaction method from homogeneous solutions of zinc and copper salts. Both the ZnS and ZnS:Cu nanoparticles excited at about 370 nm exhibits a broad green emission band peaking around 491 nm, which confirms the characteristic feature of Zn2+ as well as Cu2+ ions as luminescent centers in the lattice. The TEM micrographs showed spherical morphology for ZnS nanocrystals and the average size of the particles was estimated to be around 8.5 nm. At liquid nitrogen temperature, ESR signal characteristic of Cu2+ ions was observed in samples of all concentrations. ESR spectra analysis also indicated that Cu2+ ions enter the host lattice by replacing Zn2+ ions with distorted tetrahedral site symmetry.     

新型层柱微孔材料-XW11Co柱撑Zn-Al型层柱化合物的合成、表征及催化活性研究

采用水热合成与离子交换方法, 将中心原子不同的过渡金属(Co^2^+)取代型Keggin结构杂多阴离子XW11O39Co(H2O)^n^-(X=Ge^4^+, B^3^+和Co^2^+)嵌入Zn-Al型阴离子粘土层间, 合成了底面间距(d001)为1.46±0.01nm的新型层柱化合物Zn2Al-GeW11Co, Zn2Al-BW11Co和Zn2Al-CoW11Co; 通过XRD, IR, XPS和DTA等手段, 研究了它们的结构与性质, 推测了这些杂多阴离子(XW11Co)在层间的空间取向; 考察了这些新型层柱化合物对乙酸与n-丁醇酯化反应的催化活性; 吡啶吸附IR光谱研究结果表明, 它们同时具有B酸与L酸两种酸中心。     

Neocuproine-extended porphyrin coordination complexes. 2. Spectroscopic properties of the metalloporphyrin derivatives and investigations into the HOMO ordering

The synthesis of a porphyrin compound, 1, containing a 2,9-dimethyl-1,10-phenanthroline moiety that is fused at the beta-pyrrole positions is reported. The absorption spectra of the free-base, copper(II), and zinc(II) derivatives have been studied. On the basis of absorption band intensities, the HOMO of the free base (H21) and its copper and zinc complexes (Cu1 and Zn1) was determined to be of a1u symmetry. Relative to H21, compounds Cul and Znl show enhanced spectral changes upon external metal ion binding. Although the HOMO is the same in all three compounds, the energy gap between the two highest occupied orbitals is greater for Cu1 and Zn1 than it is for the free-base compound. Several metal ions (Ni2+, Cu+, Cu2+, Zn2+, Li+) were examined in their binding to the phenanthrolinic group by measuring the resulting changes in the absorption spectra. It is shown that the observed changes in the absorption spectra are insensitive to the nature of the metal ion coordinated by the phenanthroline moiety. Significant differences in the absorption and emission spectra between Zn1 and [Zn(Zn1)2]2+ clearly demonstrate that the porphyrin pi-system is strongly affected by the binding of metal ions at the fused phenanthrolinic moiety.     

Conservation of order, disorder, and "crystallinity" during anion-exchange reactions among layered double hydroxides (LDHs) of Zn with Al

Carbonate and chloride ions mediate an ordered stacking of metal hydroxide slabs to yield ordered layered double hydroxides (LDHs) of Zn with Al, by virtue of their ability to occupy crystallographically well-defined interlayer sites. Other anions such as ClO(4)- (T(d)), BrO(3)- (C(3v)), and NO(3)- (coordination symmetry C(2v)) whose symmetry does not match the symmetry of the interlayer sites (D(3h) or O(h)) introduce a significant number of stacking faults, leading to turbostratic disorder. SO(4)(2-) ions (coordination symmetry C(3v)) alter the long-range stacking of the metal hydroxide slabs to nucleate a different polytype. The degree of disorder is also affected by the method of synthesis. Anion-exchange reactions yield a solid with a greater degree of order if the incoming ion is a CO3(2-) or Cl-. Incoming NO(3)- ions yield an interstratified phase, whereas incoming SO(4)(2-) ions generate turbostratic disorder. Conservation or its converse, elimination, of stacking disorders during anion exchange is the net result of several competing factors such as (i) the orientation of the hydroxyl groups in the interlayer region, (ii) the symmetry of the interlayer sites, (iii) the symmetry of the incoming ion, and (iv) the configuration of the anion. These short-range interactions ultimately affect the long-range stacking order or "crystallinity" of the LDH.     

Electron Paramagnetic Resonance and optical absorption spectra of Cr3+ in zinc maleate tetrahydrate single crystals

Electron Paramagnetic Resonance (EPR) and optical absorption spectra of Cr³⁺ ions doped in single crystals of zinc maleate tetrahydrate (ZMTH) have been studied at room temperature (300 K). The EPR spectra exhibit a group of three fine structure transitions, characteristic of the Cr³⁺ ion. From the observed EPR spectra, the spin-Hamiltonian and zero-field splitting parameters have been determined. The optical absorption spectrum exhibits two broad bands characteristic of Cr³⁺ ions in octahedral symmetry. From the observed spectrum, the crystal field parameters have been evaluated.     

EPR and optical absorption studies of Cu2+ doped L-arginine phosphate monohydrate single crystals--part II

The EPR spectra of Cu2+ ion in L-Arginine phosphate monohydrate (LAP) at X-band frequencies at room temperature reveal the presence of two magnetically inequivalent interstitial Cu2+ sites in the lattice. The principal values of the g- and A-tensors indicate rhombic symmetry around the Cu2+ ion. From the direction cosines of the principal values of the g- and A- tensors, the orientations of the sites in the lattice have been identified. The bonding parameters were evaluated and the ground state wave function of Cu2+ ion was constructed. The ground state is found to be an admixture of [x2 - y2> and [3z2 - r2> orbitals. The optical absorption studies show four bands centered at 9803, 10753, 15748 and 16666 cm(-1) confirming the rhombic symmetry around the Cu2+ ion. Using the observed bands the crystal field parameters have been evaluated.     

Dicopper(II) trihydroxide cyanoureate dihydrate

The title compound, poly[[μ‐cyanoureato‐tri‐μ‐hydroxido‐dicopper(II)] dihydrate], {[Cu₂(C₂H₂N₃O)(OH)₃]·2H₂O}_n, is a new layered copper(II) hydroxide salt (LHS) with cyanoureate ions and water molecules in the interlayer space. The three distinct copper(II) ions have distorted octahedral geometry: one Cu (symmetry ) is coordinated to six hydroxide groups (4OH + 2OH), whilst the other two Cu atoms (symmetries and 1) are coordinated to four hydroxides and two N atoms from nitrile groups of the cyanoureate ions (4OH + 2N). The structure is held together by hydrogen‐bonding interactions between the terminal –NH₂ groups and the central cyanamide N atoms of organic anions associated with neighbouring layers.     

Immobilization of anionic iron(III) porphyrins into ordered macroporous layered double hydroxides and investigation of catalytic activity in oxidation reactions

The first generation anionic iron(III) porphyrin [Fe(TSPP)] and the second generation anionic complexes [Fe(TDFSPP)], [Fe(TCFSPP)], and [Fe(TDCSPP)] were immobilized into three-dimensionally macroporous layered double hydroxide (3DM-LDH), using the direct reconstruction of 3DM-LDH from macroporous mixed oxides MOX or the anionic exchange on DDS intercalated 3DM-LDH. The macroporous layered double hydroxides were obtained at the surface of nanometric polystyrene spheres, which were synthesized by an inverse opal method. Polystyrene was removed after calcination in oxidizing atmosphere, nanostructured mixed oxides (3DM-MOX) were obtained, which after reconstruction give origin to macroporous layered double hydroxide (3DM-LDH). Following metalloporphyrin immobilization, the resulting materials were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), UV–vis (glycerin mull) spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FTIR), and electron paramagnetic resonance (EPR). Results revealed that the complexes are either immobilized at the surface of the macroporous layered double hydroxide or intercalated between the layers, displacing some dodecylsufate anions. The obtained materials were investigated as catalysts for oxidation reactions, to find out whether they function as cytochrome P-450 models.     

New insights into the intercalation chemistry of Al(OH)3

This paper reports a number of recent developments in the intercalation chemistry of Al(OH)(3). From Rietveld refinement and solid-state NMR, it has been possible to develop a structural model for the recently reported [M(II)Al(4)(OH)(12)](NO(3))(2)·yH(2)O family of layered double hydroxides (LDHs). The M(2+) cations occupy half of the octahedral holes in the Al(OH)(3) layers, and it is thought that there is complete ordering of the metal ions while the interlayer nitrate anions are highly disordered. Filling the remainder of the octahedral holes in the layers proved impossible. While the intercalation of Li salts into Al(OH)(3) is facile, it was found that the intercalation of M(II) salts is much more capricious. Only with Co, Ni, Cu, and Zn nitrates and Zn sulfate were phase-pure LDHs produced. In other cases, there is either no reaction or a phase believed to be an LDH forms concomitantly with impurity phases. Reacting Al(OH)(3) with mixtures of M(II) salts can lead to the production of three-metal M(II)-M(II)'-Al LDHs, but it is necessary to control precisely the starting ratios of the two M(II) salts in the reaction gel because Al(OH)(3) displays selective intercalation of M nitrate (Li > Ni > Co ≈ Zn). The three-metal M(II)-M(II)'-Al LDHs exhibit facile ion exchange intercalation, which has been investigated in the first energy dispersive X-ray diffraction study of a chemical reaction system performed on Beamline I12 of the Diamond Light Source.     

VO2+ ions in zinc lead borate glasses studied by EPR and optical absorption techniques

Electron paramagnetic resonance (EPR) and optical absorption spectra of vanadyl ions in zinc lead borate (ZnO-PbO-B2O3) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO2+ ions. The values of spin-Hamiltonian parameters indicate that the VO2+ ions in zinc lead borate glasses were present in octahedral sites with tetragonal compression and belong to C4V symmetry. The spin-Hamiltonian parameters g and A are found to be independent of V2O5 content and temperature but changing with ZnO content. The decrease in Deltag( parallel)/Deltag( perpendicular) value with increase in ZnO content indicates that the symmetry around VO2+ ions is more octahedral. The decrease in intensity of EPR signal above 10 mol% of V2O5 is attributed to a fall in the ratio of the number of V4+ ions (N4) to the number of V5+ ions (N5). The number of spins (N) participating in resonance was calculated as a function of temperature for VO2+ doped zinc lead borate glass sample and the activation energy was calculated. From the EPR data, the paramagnetic susceptibility was calculated at various temperatures and the Curie constant was evaluated from the 1/chi-T graph. The optical absorption spectra show single absorption band due to VO2+ ions in tetragonally distorted octahedral sites.     

Layered copper hydroxide n-alkylsulfonate salts: synthesis, characterization, and magnetic behaviors in relation to the basal spacing

A series of hybrid inorganic-organic copper(II) hydroxy n-alkylsulfonate with a triangular lattice, Cu(2)(OH)(3)(C(n)H(2)(n)(+1)SO(3)) (n = 6, 8, 10), are prepared by anion exchange, starting from copper hydroxy nitrate Cu(2)(OH)(3)NO(3). These compounds show a layered structure as determined by X-ray diffraction, with interlayer distances of 14.3-34.8 A in alternation with interdigitated bilayer packing. Magnetic properties have been investigated by means of dc and ac measurements. All the compounds show similar metamagnet behaviors, with a Neel temperature of about 11 K. A subtle difference in the ac magnetic susceptibility among the compounds is understood by the existence of hydrogen bonding between the sulfonate headgroup and the hydroxide anion. A detailed molecular structure of the alkyl chains incorporated to the inorganic copper hydroxide layer is also discussed from the FTIR data.     

EPR spectra of Cu(2+) doped [Zn(sac)2(dmen)] and [Zn(sac)2(paen)] single crystals

Cu(2+) doped single crystals of [Zn(sac)2(dmen)] (sac: saccharinate, dmen: N,N'-dimethylethylendiamine) and [Zn(sac)2(paen)], (paen: N,N'-bis(3-propylamine)ethylendiamine) complexes have been investigated by electron paramagnetic resonance (EPR) technique. Detailed investigations of the EPR spectra indicate that Cu(2+) ion substitute with Zn(2+) ion and forms tetrahedral complex in [Zn(sac)2(dmen)] and octahedral complex in [Zn(sac)2(paen)] hosts. Principal values of the g and hyperfine tensors are determined and the ground state wave functions of Cu(2+) ions are obtained using EPR parameters.     

Pillaring of Zn2Al Layered Double Hydroxide by Dawson Polyoxometalate Anions

Zn2Al layered double hydroxide pillared with Dawson polyoxometalates, P₂W₁₇ZO₆₁^8-(Z=Mn²⁺, Co ²⁺, Ni²⁺, Cu²⁺, Zn²⁺) was prepared. A basal space of ca. 16 nm indicates the intercalated Dawson ions to be oriented with their C₂ axis perpendicular to the double hydroxide layers(with the exception of P₂W₁₇Zn-LDH). The IR and¹³P MASNMR spectral reveal that the Dawson ions retain their integrity in the interlayer space of LDH. A preliminary study shows that these compounds are highly active catalysts for the oxidation of cyclohexene with molecular oxygen.     

Single crystal EPR and optical absorption studies of Cu2+ ion in L-arginine sulphophosphate monohydrate--a nonlinear optical crystal

The EPR spectra of Cu2+ ion in L-arginine sulphophosphate monohydrate (LASP), a nonlinear optical material (NLO) have been studied at room temperature. Two magnetically inequivalent interstitial Cu2+ sites in the lattice were identified. The principal values of g- and A-tensors indicate that the symmetry of the electrostatic field around the Cu2+ ion is rhombic. Bonding parameters have been evaluated and the ground state wave function of Cu2+ ion is constructed. The ground state is found to be an admixure of x2 - y2 and 3z2 - r2 orbitals. By correlating EPR and optical absorption spectra the crystal field parameters have been evaluated.     

双金属复合氧化物的结构与紫外阻隔性能

双金属复合氧化物（ＣＬＤＨ）是一类发展迅速的无机层状材料的煅烧产物,在催化、吸附等领域已获长足进展［１］,但作为紫外阻隔材料的性能研究尚鲜见报道．本文研究了不同双金属复合氧化物的紫外阻隔性能,结果发现二价金属离子为锌离子的ＣＬＤＨ具有良好的紫外阻隔性能．实验所用试剂均为分析纯．ＣＬＤＨ由ＮａＯＨ,Ｎａ２ＣＯ３,ＭｇＳＯ４·７Ｈ２Ｏ,ＺｎＳＯ４·７Ｈ２Ｏ,Ａｌ２（ＳＯ４）３·１８Ｈ２Ｏ为原料,按文献［２］方法制备．ＺｎＯ＋Ａｌ２Ｏ３复配物是按一定比例机械混合后,研磨,并在与ＣＬＤＨ相同的条件下煅烧…