Sextuplet phenyl embrace in a metal-organic Kagomé lattice

A novel Kagomé lattice that demonstrates the modular nature of metal-organic networks has been prepared and is to our knowledge the first example of a metal-organic coordination polymer that incorporates the sextuplet phenyl embrace as a supramolecular synthon.     

A dual chemosensor for Cu2+ and Fe3+ based on π-extend tetrathiafulvalene derivative

A new dual chemosensor (TTF-PBA) for Fe³⁺ and Cu²⁺ in different signal pathways was designed and synthesized. The absorption spectrum, fluorescence spectrum and cyclic voltammograms changed in the presence of Cu²⁺ and Fe³⁺. The optical color changed within 5 s from yellow to orange upon the addition of Cu²⁺, and it changed to dark yellow when Fe³⁺ existed. The cyclic voltammogram of Cu²⁺/TTF-PBA changed from E_ox = 0.50 V, E_red = 0.32 V to E_ox = 0.64 V, E_red = 0.80 V (vs Ag/AgCl) upon the addition of 2.0 equiv. Cu²⁺. As for Fe³⁺/TTF-PBA, its oxidation wave disappeared, and its reduction wave appeared at E_red = ?0.59 V (vs Ag/AgCl) upon the addition of 4.0 equv. Fe³⁺. The sensor displayed high selectivity for Cu²⁺ and Fe³⁺ over other ions including Pb²⁺, Zn²⁺, Ni²⁺, Ag⁺, Cr³⁺, Mn²⁺, Al³⁺, Co²⁺, Pd²⁺, Hg²⁺, Fe^2+, Cd²⁺, Ce³⁺, Bi³⁺ and Au³⁺, the detection limits for Cu²⁺ and Fe³⁺ ion reached as low as 5.33 × 10^?7 mol/L and 5.34 × 10^?7 mol/L, respectively. Furthermore, when Fe³⁺ existed, Cu²⁺ can be detected sequentially by the sensor through the absorption spectrum and the color change observed by naked-eyes.     

A new Kagomé lattice coordination polymer based on bismuth and pyridine-2,5-dicarboxylate: structure and photoluminescent properties

A new Kagomé lattice topology assembled from ML(4) metal-organic polyhedra prepared using bismuth nitrate and pyridine-2,5-dicarboxylate has been obtained via a solvo-thermal reaction. Bi(pydc)(2)·(H(3)O(+))(H(2)O)(0.83) is, to the best of our knowledge, the first example of a bismuth-based coordination polymer to form with a Kagomé topology. Its structure and photoluminescence properties are reported.     

Stability prediction of Cu2+, Ni2+ and Zn2+ N-salicylidene-aminoacidato complexes by models based on connectivity index 3 χ v

This paper presents models for the estimation of stability constants (K ₁ and β ₂) of nickel(II), copper(II) and zinc(II) mono- and bis-complexes with 5 Schiff bases (salicylideneglycine, salicylidenealanine, salicylideneserine, salicylidenephenylalanine, and salicylidenetyrosine). The models were based on the molecular-graph theory and valence molecular connectivity index of the 3^rd order, ³χ ^v , derived from it. Univariate linear models were developed for each metal separately, while in the common models for two and three metals, the indicator variable, In, was introduced. The standard error of models for the log K ₁ constant was less than 0.12, while for log β ₂ models, the S.E. did not exceed 0.14.      

Supramolecular engineering of a 2D Kagomé lattice: synthesis, structures, and magnetic properties

Two 2D Mn (II) complexes, [Mn3(TzDC)2(phen)3] x 2 H2O (1; H3TzDC = 1,2,3-triazole-4,5-dicarboxylic acid, phen = 1,10-phenanthroline) and [Mn3(TzDC)2(bipy)3] x 4 H2O (2; bipy = 2,2'-bipyridine), were synthesized by hydrothermal reactions and characterized magnetically, and complex 1 was the first example of the chiral complex with a Kagomé lattice connectivity obtained through spontaneous resolution.     

Magnetic studies on ScyU1−yO2+x solid solutions

Magnetic susceptibilities of Sc_yU_1−yO_2+x solid solutions have been measured from 2.7 K to room temperature. The magnetic moment and Weiss constant have been determined in the temperature range in which the Curie-Weiss law holds. For the solid solutions showing antiferromagnetic transition, the Néel temperature has also been determined. The substitution of Sc³⁺ for U⁴⁺ was found to effect not only magnetic dilution of UO₂, but also oxidation of U⁴⁺ to U⁵⁺. Excess oxygen ions which entered the interstitial sites, weakened the antiferromagnetic interaction between uranium ions and oxidized U⁴⁺ to U⁵⁺. The effect of oxygen vacancies on the antiferromagnetic interaction was small in the concentration range of this experiment (0.8 a/o).     

The synthesis and study of the fluorescent probe for sensing Cu2＋ based on a novel coumarin Schiff-base

A novel, fluorescent probe was synthesized from 2,4-dihydroxybenzaldehyde and 8-hydroxyquinoline for sensing Cu2+by the naked eye. The structure was confirmed by IR, MS,1H NMR,13 C NMR and the spectral properties of the probe were investigated. It exhibited strong fluorescence responses toward Cu2+and high selectivity over other metal ions. The binding constant between the probe and Cu2+was calculated using Benesi–Hildebrand equation.     

New type polyrotaxanes based on polyethyleneimine and α-cyclodextrin

Functional polyrotaxanes of N-alkanoylpolyethyleneimine@ α-cyclodextrin type are synthesized by acylation of the polypseudorotaxane precursor, namely, a polyethylenimine@ α-cyclodextrin inclusion complex, with excess of carboxylic acid anhydrides. In the course of the processing, α-cyclo-dextrin moieties are also fully O-acylated. The introduction of acyl moieties into polyethyleneimine backbone prevents the expulsion of α-cyclodextrin rings from this backbone.     

A rapid selective colorimetric and ‘On–Off’ fluorimetric sensor for detecting Cu2+ ions in aqueous media based on a simple bis-schiff-base derivative

A simple colorimetric and fluorimetric ‘On–Off’ sensor L (3,3′-dimethyl -[1,1′-biphenyl]-4,4′-diyl)bis(azanylylidene)bis(methanylylidene)bis(naphthalen-2-ol) for Cu²⁺ ions bearing o-tolidine substituents has been designed and synthesised, and exhibits significant fluorimetric and colorimetric response for Cu²⁺ in DMSO/H₂O (8:2, v/v) HEPES buffer (pH 7.2) solution. The detection limit of the sensor towards Cu²⁺ is 7.25 × 10^? 8 M and the association constant K_a of 9.86 × 10⁴ M^? 1 was determined. Furthermore, other anions, including Fe³⁺, Hg²⁺, Ag⁺, Ca²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Cr³⁺ and Mg²⁺ have almost no influence on the probe's behaviour. Test strips based on the sensor L were fabricated, which could act as convenient and efficient Cu²⁺ test kits.     

Fabrication of a Kagomé-type MOF Membrane by Seeded Growth on Amino-functionalized Porous Al2O3 Substrate

In this study, we report an efficient fabrication method for the membrane of a metal-organic framework (MOF) (Kgm−OEt) which is one kind of kagomé-type MOF with a two-dimensional (2D) sheet structure having one-dimensional (1D) channels suitable for separation of H₂ from other larger gases. The Kgm−OEt seed layer was created on an Al₂O₃ substrate using layer-by-layer (LBL) growth, then a membrane was fabricated by secondary growth. The membrane on a 3-aminopropyltriethoxysilane (APTEs)-treated substrate obtained in this method was continuous and defect-free with the crystal orientation suitable for gas transportation, while the membrane grown on an unmodified substrate was loosely packed with unfavorable crystal orientation.     

Synthesis of a model photosynthetic system of the “covered” type based on mesoporphyrin II

The synthesis of a porphyrinquinone compound of the covered type based on mesoporphyrin II was accomplished. Spectral investigations of the compound obtained were carried out.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1419–1423, October, 1991.     

Quasi-classical trajectory study of the H + CO2 → HO + CO reaction on a new ab initio based potential energy surface

A detailed quasi-classical trajectory study of the H + CO(2) → HO + CO reaction is reported on an accurate potential energy surface based on ab initio data. The influence of the vibrational and rotational excitations of CO(2) was investigated up to the collision energy of 2.35 eV. It was found that the total reaction integral cross section increases monotonically with the collision energy, consistent with experimental results. The excitation of the CO(2) bending vibration enhances the reaction, while the excitation in its asymmetric stretching vibration inhibits the reaction. The calculated thermal rate constants are in excellent agreement with experiment. At the state-to-state level, the rotational state distributions of the HO product are in good agreement with experimental results, while those for the CO product are much hotter than measurements. The calculated differential cross sections are dominated by forward scattering, suggesting that the lifetime of the HOCO intermediate may not be sufficiently long to render the reaction completely statistical.     

Quasi-classical trajectory study of the HO + CO → H + CO2 reaction on a new ab initio based potential energy surface

We report extensive quasi-classical trajectory calculations of the HO + CO → H + CO(2) reaction on a newly developed potential energy surface based on a large number of UCCSD(T)-F12/AVTZ calculations. This complex-forming reaction is known for its unusual kinetics and dynamics because of its unique potential energy surface, which is dominated by the HOCO wells flanked by an entrance channel bottleneck and a transition state leading to the H + CO(2) products. It was found that the thermal rate coefficients are in reasonably good agreement with known experimental data in both low and high pressure limits. Excitation of the OH vibration is shown to enhance reactivity, due apparently to its promoting effect over the transition state between the HOCO intermediate and the H + CO(2) product. On the other hand, neither CO vibrational excitation nor rotational excitation in either CO or OH has a significant effect on reactivity, in agreement with experiment. However, significant discrepancies have been found between theory and the available molecular beam experiments. For example, the calculated translational energy distribution of the products substantially underestimates the experiment. In addition, the forward bias in the differential cross section observed in the experiment was not reproduced theoretically. While the origin of the discrepancies is still not clear, it is argued that a quantum mechanical treatment of the dynamics might be needed.     

Cu2+-壳聚糖螯合物及壳聚糖吸附Cu2+机理的XPS研究

吸附机理;XPS;Cu2+-壳聚糖螯合物及壳聚糖吸附Cu2+机理的XPS研究     

The effect of Cu2+ doping in β-tricalcium phosphate on the hydration mechanism of a brushite cement

Brushite cements show excellent biocompatibility and are therefore an often-used material for bone repair. However, methods to prevent inflammations after surgery are needed. As Cu²⁺ was proven to provide antibacterial properties, as well as other application relevant features, it is a promising additive. Concerning these factors, a brushite cement containing Cu²⁺-doped β-tricalcium phosphate, monocalcium phosphate monohydrate, and phytic acid as setting retarder was investigated with powder and in situ X-ray diffraction, isothermal heat flow calorimetry, in situ ¹H-time domain – nuclear magnet resonance, and pore solution analysis. The influence of Cu²⁺ ions on the hydration kinetics of the brushite cement and the locations of the Cu²⁺ ions after completion of the hydration were the main questions of interest. Heat flow calorimetry showed a significant retardation and deceleration of the hydration with increasing Cu²⁺ content in β-tricalcium phosphate. This effect can be directly correlated to the Cu²⁺ ions, as it was also shown for cements without phytic acid. X-ray diffraction showed brushite as main hydrate phase. Additionally, Cu²⁺-doped cements formed a hydrate phase not assignable by X-ray diffraction, which is assumed to be Cu²⁺ containing. Furthermore, Cu²⁺ was detected in the pore solution after the hydration, and no signs of Cu²⁺ incorporation in the crystal structure of brushite were found.     

La4Cu(3-x)Zn(x)MoO12: zinc-doped cuprates with Kagomé lattices

Two solid solutions, La4Cu(3-x)Zn(x)MoO12 (0.05 < or = x < or = 0.20, SS1) and La4Cu(3-x)Zn(x)MoO12 (0.30 < or = x < or = 2.40, SS2), were synthesized at ambient pressure and at temperatures from 1025 to 1200 degrees C by traditional solid-state reactions. Their structures were determined from X-ray powder diffraction with the help of electron and neutron diffraction. The atomic arrangements of SS1 and SS2 are similar, but their space groups are different, Pmnm for SS1 and P-1 for SS2, respectively. The copper, zinc, and molybdenum are coordinated by oxygen in corner-sharing trigonal bipyramids that are sandwiched between layers of lanthanum cations. In the transition metal cations layer of SS2, the copper and zinc cations order into a Kagomé-like lattice of triangular clusters. The magnetism has been measured from 2 to 300 K and is highly influenced by the geometric arrangement of the Cu(II) and Zn(II) cations. The number of free electrons per three Cu atoms is close to one for all samples in SS1 and SS2 indicating that the system can be well expressed by independent Cu(II)3 clusters. Spontaneous magnetization was observed in the system.     

Determination of Trace Copper by Fluorescence Spectrophotometry Based on Cu(DP)2+ and Cu‐4.0‐Generations Polyamidoamine Dendrimers Catalyze Cu2+ to Oxidize Fluorescein

Abstract

Fluorescein can emit strong and stable fluorescence. Cu²⁺ can oxidize fluorescein, which causes the fluorescence signal to diminish. Cu(DP)²⁺ (DP refers to α,α′‐dipyridyl) and Cu‐GPD‐4.0 (GPD‐4.0 refers to 4.0‐generations polyamidoamine dendrimers) both can catalyze Cu²⁺ to oxidize fluorescein, which causes the fluorescence signal to diminish sharply. The ΔF is directly proportional to the content of copper. Based on the facts above, a new catalytic fluorescence spectrophotometry for the determination of trace copper using Cu(DP)²⁺ and Cu‐GPD‐4.0 was established. The linear range of this method is 0.040–28 pg mL^?1. The regression equation for working curve is ΔF=209.5+14.39 C_Cu ²⁺ (pg mL^?1), n=7; correlation coefficient is 0.991. The detection limit of this method is 1.0×10^?14 g mL^?1. After replicate measurement times, RSDs are 3.1% and 4.2% for samples containing 0.040 and 28 pg mL^?1 Cu²⁺, respectively. This method is rapid and precise with high sensitivity and good repeatability. The method has been applied to the determination of trace copper in tea and human hair with satisfactory results. Meanwhile, the mechanism for the determination of trace copper by catalytic fluorescence spectrophotometry using Cu(DP)²⁺ and Cu‐GPD‐4.0 was also discussed.     

Cu2+–Mn2+-Co-doped CdO nanocrystallites: comprehensive research on phase,morphology and optoelectronic properties

In this study, firstly cadmium hydroxide nanopowder was evolved by cost-effective wet chemical co-precipitation method. The transformation of nanocrystalline Cu²⁺–Mn²⁺-co-doped CdO occurred via thermal decomposition of the obtained hydroxide at 750 °C. The structural, optical and electrical behavior of nanocrystallites was analyzed by different complementary measuring tools. DTA of the as-prepared sample exhibited an endothermic peak at 240 °C attributed to crystallization. XRD analysis depicted a multiphase structure in the as-prepared sample, and pure rocksalt structure was obtained after annealing. Cu²⁺–Mn²⁺-co-doped cubic CdO has been achieved first time which was further confirmed by FTIR with various stretching and bending vibrations of Cd–O at 720, 625 and 460 cm^?1. SEM–TEM images demonstrated the brain-like morphology of different hexagonal and spherical nanocrystallites with an average size of ~?35 nm. In addition, optical band gap energy was found in the range 2.14–2.44 eV by Tauc’s plot. In photoluminescence results, emission spectra have many bands at 420, 480, 550 nm originated from excitonic transition, structural defects and oxygen vacancies, while intense peak at 450, 520 nm may be ascribed to Cu²⁺ and Mn²⁺ dopants, respectively. Hall measurements demonstrated that the Cu²⁺–Mn²⁺-co-doped CdO with a pure cubic phase has superior semiconducting behavior. The homogeneous codoping of Cu²⁺–Mn²⁺ leads to efficient modification in structural, optical and electrical parameters of CdO which would make such materials attractive for semiconductor and photovoltaic industry, etc.