Presence Of ClO4 Research Articles

1D, 3D supramolecular assemblies of a series of cyclometalated platinum(II) complexes with deep-red aggregation-induced phosphorescent emission and anion turn-on sensing via Pt-Pt interaction

Controlling the size and morphology of supramolecular assemblies is still an enormous challenge for the development of novel functional materials. Herein, cyclometalated platinum(II) complexes were designed and used as effective theragnostic supramolecular nano agents. Benzoquinoline was used as the main C^N ligand, and the increased number of aromatic rings in the N^N ligand of Pt complexes could greatly improve lipophilicity and cytotoxicity towards cancer cells over normal cells. Moreover, the morphology of nanoparticles formed by self-assembly of Pta-d could change from one to three-dimensional (1-3D), which can form nanowires and nanospheres. Besides, complexes of Pta-c, the number of aromatic rings in the N^N ligand of which does not exceed 4, all exhibit significant aggregation-induced phosphorescent emission (AIPE) with 100 - 200-fold enhancement in red phosphoresce intensity recorded in the solvent of Pta-1 and Ptb. Pt-Pt interaction induced by coordination and electrostatic interaction between complex and anions, and a new deep red emission improvement was observed in aqueous solution of Pta and Ptb with the presence of ClO4−, and two similar deep red emissions induced by two different interactions can be told by new emerging MMLCT absorption band. Ptd of dppz ligand exhibits the highest efficiency in inducing apoptosis of HeLa and its anticancer mechanism was studied. Our work aims to promote the fundamental comprehension of the self-assembly behavior of cyclometalated platinum complex with AIPE in vitro and living cells.

Impact of some inorganic anions on the corrosion of nickel in a solution containing Na2SO4 and NaClO4

Potentiodynamic study was carried out on nickel in Na2SO4 solution in the presence of ClO4–, WO42–, MoO42–, NO2– and NO3– ions. The anodic excursion spans of the metal nickel in a solution of Na2SO4 are marked by the appearance of clearly defined anodic peak, passive region, and transpassive shoulder. According to the data, the anodic peak current density (IPAI) rise from 1.82 to 8.12 mA cm–2 as the concentration of the Na2SO4 solution rises from 0.2 to 1.0 M. It is clear that as scan rate increases, the IPAI rises reaching to 11.8 mA cm–2. The apparent activation energy of nickel corrosion in Na2SO4 is 33.25 kJ mol–1. ClO4– anion addition speeds up nickel’s active dissolution, as well tends to break down the passive layer, and causes pitting penetration. It was found that, the pitting potential (Epit) of nickel in solutions containing the two anions ClO4– and SO42– shifts to the positive direction by addition of WO42–, MoO42–, NO2– anions and shifts to the negative direction by addition NO3- anion. Epit increased by 0.67, 0.37 and 0.15 V in the presence of WO42–, MoO42– and NO2–, respectively. WO42– > MoO42– > NO2– was the order in which the inhibitors were most effective.

A mono-nuclear Cu(II) complex of an unsymmetrical Schiff base ligand and its use to synthesise trinuclear CuII2MnII complexes showing anion dependent SMM behaviour

The effort for synthesis complexes of unsymmetrical Schiff base ligands derived from 2,2-dimethyl-1,3-propanediamine, o-hydroxyacetophenone and salicylaldehyde by modified Edler's method resulted in the isolation of mononuclear [CuL]·CH3OH (1), where H2L = N-(α-methylsalicylidene)-N′-(salicylidene)-2,2-dimethyl-1,3-propanediamine. Complex 1 on reaction with Mn(II) ion in presence of ClO4−, N(CN)2−, or N3− yielded three tri-nuclear complexes [(CuL)2Mn(CH3OH)2](ClO4)2·3H2O (2) [(CuL)2Mn(N(CN)2)2] (3) and [(CuL)2Mn(N3)2]∙2H2O (4), respectively. X-ray crystallography revealed square planar geometry of Cu(II) and distorted octahedral geometry of Mn(II) in the complexes. Temperature dependent molar magnetic susceptibility measurements illustrated overall anti-ferromagnetic coupling between the Cu(II) and Mn(II) centres in complexes 2–4 with exchange coupling parameters, J = −16.82 cm−1 and g = 2.06 for 2, J = −19.40 cm−1 and g = 2.10 for 3 and J = −18.98 cm−1 and g = 2.11 for 4. Among these hetero-metallic complexes only the azide derivative (4) presented prominent ac signals under an applied dc bias field. Cyclic voltammetry measurements showed reversible Cu(II)/Cu(I) couple for complex 1 whereas complexes 2–4 showed irreversible reduction of Cu(II).

A conceptual model of hydrogeological function and perchlorate transfer in the unconfined Champagne Chalk aquifer (NE France)

Abstract Groundwater of the unconfined Chalk aquifer in Champagne-Ardenne (NE France) is contaminated by perchlorate ( ClO 4 − ), a persistent water-soluble anion. The Chalk aquifer is a crucial water resource of the region, with complex hydraulic properties. The presence of ClO 4 − is of concern due to its potential adverse human health effects. In France, three sources of ClO 4 − contamination are suspected: industrial, military and agricultural. Both a comprehensive understanding of hydrogeological characteristics of the aquifer, and a sound knowledge of sources and behaviour of ClO 4 − in groundwater are required to allow the sustainable use of this groundwater resource. From data acquired during hydrogeological, geochemical, isotopic ( ClO 4 − ) and groundwater age (CFCs and SF 6 ) studies, and historical investigations in a study area located east of Reims, a conceptual model of Chalk aquifer function and ClO 4 − transfer has been established. High spatio-temporal heterogeneities in the unconfined Chalk aquifer are discussed. Different correlations between ClO 4 − , major ions and groundwater-level fluctuations are shown and interpreted, highlighting main factors governing the Chalk groundwater geochemistry and ClO 4 − transfer mechanisms, including water-level fluctuation, groundwater residence time, thickness of the unsaturated zone, superficial formations, distribution of fissure networks, aquifer–river relationships, origin and location of ClO 4 − in soil and human activity.

Hetero-Tetranuclear Cu2+ /Ca2+ /Ca2+ /Cu2+ Architectures Based On Malten Ligand: Scaffold for Anion Binding.

The hetero-tetranuclear Cu2+ /Ca2+ /Ca2+ /Cu2+ complex obtained with the N,N'-bis((3-hydroxy-4-pyron-2-yl)methyl)-N,N'-dimethylethylendiamine (Malten) ligand has been studied in solid and solution states as scaffold to bind anions. Three crystal structures showing the same metal ions sequence have been examined; they display a tetracharged complex cation neutralized by four monocharged anions. The anions play two different roles: as coordinated (two ClO4- , Cl- or NO3- ) or ancillary (two ClO4- ) guests. The tetranuclear scaffold hosts two anions also in aqueous and ethanol solutions. Spectrophotometric studies in ethanol allowed to determine the addition constant values for Cl- and Br- (Log K1-2 =4.43(4), 4.39(3) for Cl- , 3.80(3), 3.54(2) for Br- ) while the others, although bound, showed lower affinity for the scaffold. Both the crystals and the solutions change their color depending on the added anion, namely pink, dark green or blue in the presence of ClO4- , Cl- or NO3- , respectively, thus the presence of the different anions is visible to the naked eye. The hetero-tetranuclear Cu2+ /Ca2+ /Ca2+ /Cu2+ complex is a versatile architecture to be used as scaffold for anion binding.

Pseudo[1]Catenane-Type Pillar[5]thiacrown Whose Planar Chiral Inversion is Triggered by Metal Cation and Controlled by Anion.

Chiral inversion of single molecules has been a challenging task because chirality information controls structures and functions of various molecules, artificial nanostructures, DNA, and proteins. Herein we present a pseudo[1]catenane-type molecule whose planar chiral inversion is driven by a metal ion under the control of anions for the first time. Considering an in-out equilibrium of a fused thiacrown and the soft metal binding, pillar[5]thiacrown ( rac-L) was synthesized. Two planar-chiral enantiomers of rac-L ( in-pS-L and in-pR-L) were isolated and the absolute configuration was determined by circular dichroism and single crystal X-ray analysis. The in-pS-L recognizes Hg2+ to trigger the chiral inversion to out-pR-L, to our surprise; it takes place only in the presence of ClO4- or NO3- among the anions used. In the mercury(II) perchlorate complex solution, anion-exchange from ClO4- to I- or removal of Hg2+ by addition of S2- makes the system reversible. The crystallographic approach reveals that the anions act as coordination mode-directing species ( endo- or exo-coordination) which play a decisive role on the chiral inversion. For instance, the week coordinating ClO4- allows Hg2+ to locate inside the thiacrown ( endo-coordination) which causes the chiral inversion from in-pS-L to out-pR-L due to the expansion of the thiacrown unit upon endo-mode complexation. Oppositely, the strong coordinating I- takes Hg2+ out of the thiacrown ( exo-coordination) without large conformational changes of the thiacrown, resulting in no chiral inversion. A series of experimental works was also accomplished with the other enantiomer in-pR-L, which afforded identical results. Consequently, the chiral inversion is governed by steric factors that arise from the coordination modes depending on the coordinating ability of anions. This work demonstrates the first chiral inversion induced by combination of metal ion and anion and presents a new perspective on the supramolecular coordination chemistry of pillar[ n]arenes.

A water–soluble cationic Ir(III) complex for turn–on sensing of ClO4− based on aggregation–induced emission

A water–soluble Ir(III) complex has been developed for the first time as a turn–on luminescence probe of ClO4− based on aggregation–induced emission (AIE). The probe showed an unprecedented 250–fold emission enhancement in the presence of ClO4− in water. Formation of nanoparticles due to ClO4−–induced aggregation was confirmed by transmission electron microscope (TEM), scanning electron microscope (SEM), dynamic light scattering (DLS) and confocal laser scanning microscope (CLSM). The Ir(III) complex was further successfully applied in cell–imaging.

Temperature-Dependent Transport Properties of Poly[2-(methacryloyloxy)ethyl]trimethylammonium Chloride Brushes Resulting from Ion Specific Effects

Combined use of electrochemical techniques (electrochemical impedance spectroscopy and cyclic voltammetry) and quartz crystal microbalance with dissipation allowed to resolve separately the thermal effects on diffusion and electron-transfer steps of the electrochemical reaction of the [Fe(CN)6]3–/4– redox couple at a Au electrode modified with poly[2-(methacryloyloxy)ethyl]trimethylammonium chloride (PMETAC) brushes. Arrhenius-type dependences of the kinetic constant and the diffusion coefficient with temperature were observed in different electrolytes. Ion-paired collapsed polyelectrolyte brushes in NaClO4 result in compact stiff structures with less amount of entrapped water and markedly different from the same brushes with a collapse driven by pure Coulombic screening in NaCl. A remarkable difference related to the type of counterion is the occurrence of a thermal transition for the polyelectrolyte brush in the presence of ClO4– ions at near-ambient temperature (∼17 °C). Activation energies for electro...

Surface Prevalence of Perchlorate Anions at the Air/Aqueous Interface.

Air/aqueous interfaces provide a unique environment for many chemical, environmental, and biological processes. To gain insight, molecular-level understanding of the interfacial water organization and ion distributions at these interfaces is required. Here, the air/aqueous interface of NaClO4 salt solutions was investigated by means of conventional and heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectroscopy. It is found that perchlorate (ClO4(-)) ions exist in the interfacial region and prefer to reside on average above their counterions. This finding is inferred from the average orientation of the OH transition dipole moment of interfacial water molecules governed by the direction of the net electric field arising from the interfacial ion distributions. At the air/aqueous interface of NaClO4 salt solutions, the net dipole moments of hydrogen-bonded water molecules are oriented preferentially toward the vapor phase. Contrary to some other salts (e.g., sulfates), the presence of ClO4(-) may cause a full reversal in the direction of the interfacial electric field at a higher concentration (≥1.7 M). Another interpretation for the positive Im χ((2)) spectra of NaClO4 salt solutions could be an increase in the population of water species contributing positively to the net OH transition dipole moment. Regardless of the mechanism, this effect becomes even more pronounced with increasing salt concentration.

Electrochemical, Photochemical, and Photoelectrochemical Treatment of Sodium p-Cumenesulfonate

The degradation of sodium p-cumenesulfonate (SCS) by electrochemical, photochemical, and photoelectrochemical methods in aqueous solution of NaClO4, NaCl, and NaClO has been studied. It was found that as a result of NaClO4 electroreduction and photodecomposition, the ions Cl− and ClO3 − are formed. These ions undergo transformations into radicals, mainly Cl•, Cl2 •−, ClO•−, ClO2 •−, and ClO3 •−, due to electrochemical and photochemical reactions. It was shown that the interpretation of results of the studies over mineralization processes carried out in the presence of ClO4 − cannot be adequate without taking into consideration the reduction of ClO4 − to Cl− and ClO3 −. Therefore, previous works presented in the literature should be rediscussed on the basis of the new data. Photoelectrochemical mineralization of substrate in NaCl solution at the concentration of 16 mmol L−1 is comparable with the efficiency of the reaction in NaClO4 solution containing more than 8 mmol L−1 of NaClO. Total SCS mineralization was obtained in the photoelectrochemical reactor with a UV immersion lamp with a power 15 W in the period of 135 min and current intensity of 350 mA. In such conditions, the power consumption was about 1.2 kWh per g of TOC removed.

Copper nanoparticles/poly-3-methylthiophene composite: Synthesis, characterization and catalytic application to enzyme-less glucose detecting

The present work describes the preparation and the characterization of a composite nanomaterial obtained by the electrochemical deposition of copper nanoparticles (CuNPs) on an electrosynthesized film of poly-3-methylthiophene (P3MT). Copper electrodeposition was achieved by applying a potential pulse program both on Pt and on screen-printed electrodes (SPEs). The microscopic characterization of the composite film by scanning electron microscopy (SEM) suggested that the applied pulse width is correlated to the amount of the deposited particles but it does not influence CuNPs size. The nanocomposite was analyzed also by X-ray Photoelectron Spectroscopy (XPS) confirming the influence of the pulse width on the amount of electrodeposited copper and evidencing the presence of Cu(I) and Cu(II) species in each sample. For a comparison, CuNPs were prepared from solutions of both CuCl2 and Cu(ClO4)2. XPS analysis evidenced the stabilizing effect of Cl− ions on CuNPs promoting their entrapment in P3MT film also when the composite film is exposed to carrier solution in a flow system, contrarily to what observed in the presence of ClO4− ions. Performed electrochemical tests showed that CuNPs/P3MT exhibited a remarkable electrocatalytic activity for glucose oxidation. The composite film deposited on SPEs was successfully used for glucose electrochemical detection in a flow system. The effect of the applied potential and of the flow rate of carrier stream was evaluated: under the selected optimal condition the composite film exhibited a satisfactory response in terms of detection limit, linear range and repeatability. The sensitivity of CuNPs/P3MT to other compounds (ascorbic acid, uric acid, sorbitol, fructose, dopamine) was verified evidencing that the proposed system could be effectively used as an electrochemical detector coupled to a chromatographic system for the simultaneous detection of biomolecules.

Investigation of anomalous diffusion and multifractal dimensions in polypyrrole film

The fractal dimensions of polypyrrole (PPy) film electrodeposited on the glassy carbon (GC) electrode formed in the presence of ClO4- is obtained by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods in different film thicknesses and various synthesis temperatures. Atomic force microscopy (AFM) technique was employed to analyze fractal structure of film. Anomalous diffusion through the film in which mean squared displacement of particles has not a linear dependence with time (〈x2〉∝tγ) has been discussed and values of γ that is the characteristic of anomalous diffusion is obtained by EIS method and then the relation between fractal dimension and anomalous diffusion has been investigated.

Ion-induced hydrophobic collapse of surface-confined polyelectrolyte brushes measured by total internal reflection microscopy

Cationic poly(2-(methacryloyloxy)ethyl trimethylammonium chloride) (PMETAC) brushes are grown from glass slides via surface-initiated atom transfer radical polymerization (SI-ATRP). The interaction potential energy between the surface-grown polyelectrolyte brushes and a 5 μm diameter polystyrene (PS) particle in different electrolyte environments (NaCl and NaClO4) has been directly measured using total internal reflection microscopy (TIRM). At a NaCl concentration of 0.05 mM, the measured interaction potential energy profiles show a long-range repulsion, arising from an electrical double layer interaction between the positively charged PS particle and the charges from the PMETAC layers. Upon addition of 1 mM NaCl, screening effects reduce the separation distance (h) between the PS particle and the surface, accompanied by the collapse of the PMETAC brushes. However, when the sample solution is replaced with a low concentration NaCl (0.05 mM) solution, h returns to the original values, indicating that the brushes resume the extended conformation. A remarkable difference is observed when similar TIRM experiments are carried out in the presence of NaClO4 solution. At the same concentration or ionic strength, NaClO4 causes a much more abrupt decrease in h between the particle and surface than that with NaCl solution. Conversely, flushing the sample cell with highly diluted NaClO4 or pure water cannot restore the original interaction potentials, thus implying an irreversible collapse of the PMETAC brushes in the presence of ClO4− anions. This apparent change in the PMETAC brush characteristics can be associated with the strong ion-pairing interaction between the ClO4− anions and the quaternary ammonium group in the PMETAC brushes, which experiences not only pure charge screening, but also a sharp hydrophilic-to-hydrophobic change of the brush layer. Using TIRM, we have directly measured such an ion-pairing induced collapse transition of surface-confined polyelectrolyte brushes, even at very low specific anion concentrations.

Perchlorate Depositional History as Recorded in North American Ice Cores from the Eclipse Icefield, Canada, and the Upper Fremont Glacier, USA

Temporal depositional rates are important in order to understand the production and occurrence of perchlorate (ClO 4 − ) as limited information exists regarding the impact of anthropogenic production or atmospheric pollution on ClO 4 − deposition. Perchlorate concentrations in discrete ice core samples from the Eclipse Icefield (Yukon Territory, Canada) and Upper Fremont Glacier (Wyoming, USA) were analyzed using ion chromatography tandem mass spectrometry to evaluate temporal changes in the deposition of ClO4 − in North America. The ice core samples cover a time period from 1726 to 1993 and 1970 to 2002 for the Upper Fremont Glacier (UFG) and Eclipse ice cores, respectively. The average ClO4 − concentration in the Eclipse ice core for the time period from 1970 to 1973 was 0.6 ± 0.3 ng L−1, with higher values of 2.3 ± 1.7 and 2.2 ± 2.0 ng L−1 for the periods 1982–1986 and 1999–2002, respectively. All pre-1980 ice core samples from the UFG had ClO4 − concentrations <0.2 ng L−1, and the post-1980 samples ranged from <0.2 ng L−1 to a maximum of 2.6 ng L−1 for the year 1992. A significant positive correlation (R = 0.75, N = 15, p < 0.001) of ClO 4 − with SO 4 2− was found for the annual UFG ice core layers and of ClO4 − with SO 4 2− and NO 3 − in sub-annual Eclipse ice samples (R > 0.3, N = 121, p < 0.002). The estimated yearly ClO 4 − depositional flux for the Eclipse ice core ranged from 0.6 (1970) to 4.7 μg m−2 year−1 (1982) and the UFG from <0.1 (pre-1980) to 1.4 μg m−2 year−1 (1992). There was no consistent seasonal variation in the ClO 4 − depositional flux for the Eclipse ice core, in contrast to a previous study on the Arctic region. The presence of ClO 4 − in these ice cores might correspond to an intermittent source such as volcanic eruptions and/or any anthropogenic forcing that may directly or indirectly aid in atmospheric ClO 4 − formation.

Microcantilevers Modified with Ferrocene-Terminated Self-Assembled Monolayers: Effect of Molecular Structure and Electrolyte Anion on the Redox-Induced Surface Stress

The redox-activated deflection of microcantilevers has attracted interest for chemical sensing and nanoactuation. However, the development and optimization of this type of microcantilever transduction requires a better understanding of the effect of the particular system parameters on the surface stress changes that cause the measured bending response. We investigate here the effects of the adsorbate structure and electrolyte anion on the surface stress generated by the electrochemical oxidation of ferrocene-terminated self-assembled monolayers (SAMs) chemisorbed to the surface of gold-coated microcantilevers. Ferrocenylalkanethiolate-modified cantilevers are an interesting system for study as the electroactive monolayer can induce charge-normalized surface stress changes that are at least 10-fold greater than those generated by multilayers of the conducting polymers commonly used for electroactuation. The resonance angle shifts measured by surface plasmon resonance spectroscopy in the presence of ClO4− suggest that the extent of the oxidation-induced SAM reorganization is the same for short (n = 6) and long (n = 12) chain ferrocenylalkanethiolate (FcCnSAu) SAMs and for a long chain carbonyl derivative (Fc(CO)C11SAu). The magnitude of the measured cantilever deflection is however not the same for the different SAMs, reflecting differences in the tensile contributions to the overall surface stress of the SAM elasticity and wettability versus the compressive lateral pressure generated by the collective molecular reorientations induced by the pairing of anions to the surface-confined, oxidized ferrocenium cations. The hydrophobic anions PF6− and ClO4−, which form 1:1 contact ion pairs with the SAM-bound ferrocenium cations, give reversible cantilever deflections and the largest compressive surface stress changes. By contrast, oxidation of the FcC11SAu SAM in NO3− and F−, which exhibit the poorest ion-pairing abilities of the anions investigated, results in an irreversible deformation of the cantilever bending and smaller stress changes. The surface phenomena that give rise to the observed differences in the surface stress as a function of the ion pairing ability are discussed.

Synthesis, Characterization and Crystal Structure of Gallosilicate Perchlorate Sodalite

Perchlorate enclathrated sodalite with gallosilicate host framework has been synthesized under low temperature (100 o C) hydrothermal technique and characterized by X-ray powder diffraction, IR, Raman spectroscopy, UV DRS, SEM, MAS NMR spectroscopy and thermogravimetry. The structural features were investigated by IR, MAS NMR spectroscopy of 29 Si and 23 Na nuclei and by Reitveld refinement of X-ray powder diffraction data. IR and Raman spectroscopy confirms formation of framework and presence of ClO4 - group. The tetrahedral framework T-atoms are completely ordered and the chloride atoms are located at the centre of the sodalite cages. The crystal structure of this new sodalite was refined in the space group P 4 3n with a = 9.15788 A, V = 768.5 A, Z =1, Rwp = 0.0611, Rp = 0.1079 and Si-O-Ga is 144.036 o . The surface area of single entity with stoichiometry Na8[GaSiO4]6(ClO4)2 was found to be 8.385x10 -15 cm 2 /g. 29 Si MAS NMR study confirms complete ordering of Si and Ga in the gallosilicate framework. Thermo gravimetric analysis has provided information on the extent of perchlorate entrapment, stability within the cage and decomposition properties.

Synthesis and X‐ray Crystal Structure of Bis[oxamide dioximato‐κ2N,N′](oxamide dioxime‐κ2N,N′)cobalt(III) Perchlorate Hexahydrate

AbstractCo(OAc)2 reacts with oxamide dioxime (H2oxado) in water in the presence of ClO4– ions to produce [Co(Hoxado)2(H2oxado)]ClO4·6H2O (1), where Hoxado– is the anion of H2oxado, derived from the deprotonation of one of the two hydroximinic groups, and in which oxidation of CoII to CoIII (in air) had occurred. 1 is the first example of a salt in which the cation, [Co(H2oxado)3]3+, is doubly deprotonated to generate the chiral cation, [Co(Hoxado)2(H2oxado)]+. The central cobalt cation is pseudo‐octahedrally coordinated by six nitrogen atoms. In the solid state, the complex cations form centro‐symmetric dimers via O–H···O bridges. The bulk structure is consolidated by an extended three‐dimensional network of O–H···O and N–H···O bridges that interconnect the ionic constituents and the water molecules.

Specific ζ-Potential Response of Layer-by-Layer Coated Colloidal Particles Triggered by Polyelectrolyte Ion Interactions

The zeta-potential of PSS/PAH and PSS/PDADMAC coated silica particles was studied in the presence of ClO4(-) and H2PO4(-) salts. In the presence of ClO4(-), layer-by-layer (LbL) coated silica particles with PDADMAC as the top layer show a reversal in the surface charge with increasing salt concentration but remain positive in phosphate solutions. LbL particles with PAH as the top layer become, however, negative in the presence of H2PO4(-) but retain their positive charge in the presence of ClO4(-). Charge reversal was explained by specific interaction of ClO4(-) ions with the quaternary amine groups and of H2PO4(-) with the primary amines through hydrogen bonding. Atomic force microscopy (AFM) and quartz crystal microbalance with dissipation (QCM-D) were employed to study the corresponding layer stability on planar surfaces.

Organic derivatives of the layered perovskite HLaNb2O7·xH2O with polyether chains on the interlayer surface: characterization, intercalation of LiClO4, and ionic conductivity

Polyether chains have been successfully grafted onto the interlayer surface of a Dion–Jacobson-type layered perovskite, HLaNb2O7·xH2O, by a reaction between an n-decoxy-derivative of HLaNb2O7·xH2O and CH3(OCH2CH2)mOH (1 ≤ m ≤ 4). After the reaction, the interlayer distance decreases from 2.73 nm to 1.58 (m = 1), 2.07 (m = 2), 2.28 (m = 3), and 2.69 (m = 4) nm. Solid-state 13C CP/MAS NMR spectroscopy indicates that the CH3(OCH2CH2)mO– groups are bound to the interlayer surface of HLaNb2O7·xH2O. The n-decoxy groups are completely removed by the reaction with CH3(OCH2CH2)mOH (m = 2 and 3), while a part of the n-decoxy groups remain after the reaction with CH3(OCH2CH2)mOH (m = 1 and 4). Upon treatment of the CH3(OCH2CH2)mO-grafted HLaNb2O7·xH2O (m = 2 or 3) with a CH3(OCH2CH2)mOH solution of LiClO4, the interlayer distance decreases further to 1.78 (m = 2) and 2.01 (m = 3) nm. Inductively coupled plasma emission spectrometry reveals the presence of lithium (0.22 (m = 2) and 0.24 (m = 3) per [LaNb2O7]). The presence of ClO4− ions is demonstrated by Raman spectroscopy, and the position of the ν1(A1) band indicates the presence of isolated ClO4− ions in the interlayer space. After treatment with a LiClO4 solution, CH3(OCH2CH2)mO-grafted HLaNb2O7·xH2O (m = 2 and 3) exhibits ionic conductivity, and no clear temperature dependence is observed.

Mixed‐Valence Cobalt(II/III) Carboxylate Clusters: CoII4CoIII2 and CoIICoIII2 Complexes from the Use of 2‐(Hydroxymethyl)pyridine

AbstractAerobic reactions of Co(O2CR)2 with 2‐(hydroxymethyl)pyridine (hmpH), in the presence of ClO4– counterions give the hexanuclear, mixed‐valence clusters [CoII4CoIII2(O2CR)4(hmp)8](ClO4)2 [R = Me (1), Ph (2)] which possess the unprecedented [CoII4CoIII2(μ3‐OR′)4(μ‐OR′)4]6+ [R′ = (2‐pyridyl)CH2‐] core. Replacement of ClO4– by N3– in the reaction mixture that gives 1 leads to the linear complex [CoIII,II,III3(O2CMe)2(N3)2(hmp)4] (3). Q‐band EPR spectra and variable‐temperature magnetic susceptibility studies for 1 and 2 provide strong evidence that the CoII ions are antiferromagnetically coupled.(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2007)