Synthesis, Structure and Characterization of Two 1D Chain-like Cadmium Terephthalate Complexes: [Cd(tp)(H2O)3]?·?4H2O and [Ph4P][Cd(tp)0.5Cl2]?·?H2O

Abstract  Two new compounds, [Cd(tp)(H₂O)₃] · 4H₂O (1) and [Ph₄P][Cd (tp)_0.5Cl₂] · H₂O (2) (tp = terephthalate, [Ph₄P] = tetraphenylphosphonium), are metal-polycarboxylate coordination polymers prepared by similar hydrothermal synthesis techniques. Both compounds crystallize in the 1D chain-like architectures. 1 (C₈H₁₈CdO₁₁) is orthorhombic Pcca, Z = 4 (a = 7.3018(1) ?, b = 9.9975(3) ?, c = 19.9695(5) ?, V = 1457.77(6) ?³). 2 (C₂₈H₂₄CdCl₂O₃P) is triclinic P−1, Z = 2 (a = 9.5028(4) ?, b = 12.3130(5) ?, c = 12.7343(6) ?, α = 68.380(1)°, β = 73.723(1)°, γ = 89.624(1)°, V = 1321.8(1) ?³). Transition metal cadmium centers bridged by rigid linear tp ligands give rise to a 1D infinite zigzag chain polymer for 1 and a simple 1D infinite stepped chain polymer for 2. 1 presents an interesting plywood-like packing network while 2 shows a simple parallel rod-like stacking network. An intense fluorescent emission at 412 nm (λ_exc = 338 nm) for 1 in the solid state at room temperature is observed. Index Abstract  Polymeric compounds [Cd(tp)(H₂O)₃] · 4H₂O (1) and [Ph₄P][Cd (tp)_0.5Cl₂] · H₂O (2) crystallize in two remarkable 1D chain-like architectures prepared by similar hydrothermal synthesis techniques, showing an interesting plywood-like packing network in 1 and a simple parallel rod-like stacking network in 2, respectively. An intense fluorescent emission at 412 nm (λ_exc = 338 nm) for 1 in the solid state at room temperature is observed.      

Antimony-film electrode for the determination of trace metals by sequential-injection analysis/anodic stripping voltammetry

The possibility of applying antimony-film modified glassy carbon electrode in sequential-injection analysis (SIA) was investigated with the objective of determining Pb(II) and Cd(II) by anodic stripping voltammetry (ASV). The conditions of antimony-film deposition concerning composition of the plating/carrier solutions, concentrations of Sb(III) and hydrochloric acid, effects of different supporting electrolyte salts, and plating potential were optimized. It was found that the antimony-film deposition on glassy carbon substrate in a sample solution consisting of 750 μg L⁻¹ Sb(III), 0.5 mol L⁻¹ HCl at −1.5 V (vs. Ag/AgCl/3 mol L⁻¹ KCl) yielded a modified electrode suitable for the determination of Pb(II) and Cd(II) at the μg L⁻¹ level. The reproducibility of the analytical signals was characterized by a relative standard deviation lower than 2.8%, and the calculated values of detection limits were 1.2 μg L⁻¹ for Pb(II) and 1.4 μg L⁻¹ for Cd(II). The presence of KSCN in the sample solution offers the possibility of detecting ions with more negative oxidation potentials like Zn(II), Mn(II) or Cr(III). The developed SIA-ASV procedure was compared with the commonly used batch method, and its applicability was tested on a spiked tap water sample.     

Coordination polymers of cadmium with (4-carbomethoxy-naphthalen-1-yloxy) acetic acid derivatives

Three cadmium coordination polymers derived from the dianions of (4-carboxymethoxy-naphthalen-1-yloxy) acetic acid (LH₂) and (4-carboxymethoxy-2,3-bis-arylsulfanyl naphthalene-1-yloxy) acetic acid (L₁H₂), in which the dianions of the corresponding acids act as a spacer to cadmium nodes, have been prepared and characterized. The coordination polymer of the dianion of (4-carboxy-methoxy-2,3-bis-arylsulfanylnaphthalene-1-yloxy) acetic acid with cadmium is a 3-D coordination polymer, whereas the dimensionality of the coordination polymer of the dianion of (4-carboxymethoxy-naphthalen-1-yloxy) acetic acid is dependent on the ancillary ligand. The presence of the chelating ligand 1,10-phenanthroline gave a 1-D polymer of the dicarboxylate anion L, but in the absence of a chelating ligand a 2-D coordination polymer encapsulating hexa–aquacadmium(II) ions was obtained. The latter two coordination polymers show fluorescence emission in the solid state.     

Reduction of the dislocation density in molecular beam epitaxial CdTe(2 1 1)B on Ge(2 1 1)

The high dislocation density (2×10⁷/cm² for a thickness of 7 μm) in CdTe(2 1 1)B on Ge(2 1 1) has become a roadblock for the technological exploitation of this material. We present a systematic study of in situ and post-growth annealing cycles aimed at reducing it. An etch pit density of 2×10⁶/cm² was achieved by optimizing the growth conditions and annealing the samples in situ. This finding was corroborated by high-resolution X-ray diffraction, atomic force microscopy, photoluminescence and ellipsometry measurements.     

Determination of trace Cd and Pb in environmental and biological samples by ETV-ICP-MS after single-drop microextraction

A method based on single-drop microextraction (SDME) combined with electrothermal vaporization (ETV)-ICP-MS was proposed for the determination of trace Cd and Pb. 8-Hydroxyquinoline (8-HQ) was employed as extractant dissolved in several microliters of chloroform and then an organic microdrop was formed at the tip of the microsyringe needle to extract the interest analytes. The vaporization behavior of the metal-8-HQ chelates in graphite furnace was investigated, and the ETV temperature program was optimized. The factors that influenced the extraction efficiency of target analytes (including pH value, flow rate of sample, extraction time and organic microdrop volume) were studied. Under the optimum conditions, the detection limits of the Cd and Pb were 4.6 and 2.9 pg mL⁻¹ with the enrichment factor of 140-fold for Cd and 190-fold for Pb, respectively. The proposed method was applied successfully to the determination of trace Cd and Pb in environmental and biological samples. In order to validate the developed method, a certified reference material of GBW 08501 peach leaves was analyzed and the determined values obtained were in a good agreement with the certified values.     

Simple procedure for the determination of Cd, Pb, As and Se in biological samples by electrothermal atomic absorption spectrometry using colloidal Pd modifier

Electrothermal atomic absorption spectrometry was used for the determination of Cd, Pb, As and Se in the whole blood, serum, hair reference standard materials and the samples of algae collected at the coastal Estonian regions of Baltik sea. Instead of tedious and time-consuming experimental comparison of various chemical modifiers, theoretical consideration of the problem was applied for choosing the most prospective one (colloidal Pd) for solution of the given task. The experimental data obtained proved correctness of the choice. Pure standard solutions in diluted nitric acid were used for construction of the calibration graphs. The same experimental conditions were applied for each analyte for calibration solutions and all samples studied. In spite of very limited optimization procedures used, all the values obtained agree well with the corresponding reference values. Accuracy of the analysis of the algae samples was checked by recoveries of the spikes that were in the region 91-109%. Detection limits reached are 0.021, 1.2, 0.62 and 1.1 ng ml⁻¹ for Cd, Pb, As and Se, respectively, in digests of biological samples.     

Naked eye detection of cadmium using inorganic–organic hybrid mesoporous material

A novel and low-cost optical sensor for the naked eye detection of Cd²⁺in aqueous media based on mesoporous silica containing 4-(2-pyridylazo)resorcinol (PAR) as a probe molecule anchored by N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TMAC) was prepared. The effects of various factors such as pH, solvent volume, temperature, reaction time, amount of the material, and the presence of various ions were studied in order to optimize operating conditions. The detection was based on the color change of PAR from orange-yellow to purple as a result of complexation with Cd²⁺. The intensity of the Cd-PAR complex varies linearly with the Cd²⁺concentration, from zero to 1.78×10⁻⁷ mol dm⁻³. The detection and quantification limits for the method when determining Cd²⁺ were 1.75×10⁻⁸ and 5.77×10⁻⁸ mol dm⁻³, respectively, with a correlation coefficient of 0.99. Good chemical stability of the material was observed for a period of five months. The developed sensor was applied to the analysis of various industrial effluents and tap water samples. Electronic supplementary material Supplementary material is available for this article at     

1-对偶氮苯基-3-(2-嘧啶)-三氮烯的合成及与镉(Ⅱ)的显色反应

报道了1-对偶氮苯基-3-(2-嘧啶)-三氮烯(APPMT)的合成及其与镉(Ⅱ)的显色反应。在非离子表面活性剂TritonX-100存在下,于pH11.4的Na2B4O7-NaOH缓冲介质中,镉(Ⅱ)与APPMT形成1∶3的红色配合物,试剂与配合物的最大吸收波长分别为430和520nm,表观摩尔吸光系数为1.99×105L.mol-1.cm-1,镉(Ⅱ)量在0~0.36μg/mL范围内符合比尔定律。     

Silver-Loaded Bio-Structured Carbon/Cadmium Sulfide Lamellar Composites with Enhanced Photocatalysis under Visible Light

A silver (Ag)-loaded biostructured carbon/cadmium sulfide (CdS) lamellar composite photocatalyst was synthesized using a hydrothermal and photodeposition method. Camellia petals functioned both as a biological layered template and as a source of carbon. The prepared composite photocatalyst demonstrated good absorption under visible light and exhibited excellent photocatalytic degradation performance. The photocatalytic degradation efficiency of the obtained composites substantially improved compared with pure CdS. The 5 wt.-% Ag-loaded C/CdS sample exhibited the highest photocatalytic activity, reaching 96.5 % after 180 min, which was 8.7 times that of pure CdS. Specifically, the biocarbon sheet enhanced the absorption of visible light. Furthermore, the high electrical conductivity of Ag can effectively transfer and separate photogenerated electrons and holes, thus enhancing both photocatalytic performance and stability.