Poly(neutral red): Electrosynthesis,Characterization, and Application as a Redox Mediator

The synthesis by electropolymerization, the characterization, and applications of poly(neutral red) (PNR), including as a redox mediator, are reviewed. PNR's high electrical conductivity and its redox characteristics have led to special applications of the polymer, and it has been used for the development of electrochemical and optical sensors. Moreover, the attractive properties of PNR allow it to be applied in the development of electrochemical biosensors. Future perspectives are indicated.     

氟喹诺酮类抗生素与钴(II)和刚果红三元配合物的共振瑞利散射光谱研究及其分析应用

在pH 4.5～6.5的Britton-Robinson缓冲溶液中, 钴(II)与环丙沙星(CIP)、诺氟沙星(NOR)、氧氟沙星(OF)和左氧氟沙星(LEV)等氟喹诺酮类抗生素(FLQs)能形成螯合阳离子, 它们能通过静电引力和疏水作用与刚果红(CR)阴离子反应, 形成1∶2∶1 (Co^2＋∶FLQs∶CR)三元离子缔合配合物. 此时将引起溶液的共振瑞利散射(RRS)显著增强, 并出现新的RRS光谱. 不同抗生素具有相似的光谱特征, 其最大散射波长均位于560 nm处, 并在382和278 nm处有2个较小的散射峰. 一定浓度的抗生素与散射增强(ΔI)成正比, 对不同氟喹诺酮类药物的线性范围和检出限(3s)分别是0.026～2.64 μg•mL^－1和7.68 ng•mL^－1 (CIP), 0.045～3.20 μg•mL^－1和13.00 ng• mL^－1 (NOR), 0.037～4.00 μg•mL^－1和11.24 ng• mL^－1 (OF), 0.039～4.00 μg•mL^－1和11.80 ng•mL^－1 (LEV), 据此提出了一种以RRS技术测定氟喹诺酮抗生素的新方法. 方法不仅灵敏度高, 而且简单、快速, 并有良好的选择性和重复性, 可用于片剂、针剂、滴眼液和人尿液中氟喹诺酮类药物的测定. 文中还对反应机理和RRS增强的原因作了讨论.     

荷移反应分光光度法测定苯巴比妥钠

采用分光光度法研究了电子给体苯巴比妥钠与π电子受体茜素红的荷移反应,建立了荷移分光光度法测定苯巴比妥钠的方法。在水溶液中,苯巴比妥钠与茜素红荷移络合物的最大吸收波长为530 nm,该络合物的组成为1∶1,表观摩尔吸光系数ε为4.43×103L.mol-1.cm-1,稳定常数为2.30×105。药物质量浓度在5~40 mg/L范围内符合比尔定律,相关系数为0.9996。当苯巴比妥钠浓度为20 mg/L时,10次测定结果的相对标准偏差为1.3%。测定了针剂中的苯巴比妥钠,加标回收率在98.9%~105%之间。     

薄层色谱-紫外可见分光光度法测定食品中的苏丹红Ⅰ号

建立了测定食品中苏丹红Ⅰ号新方法:薄层色谱-紫外可见分光光度法.方法的线性回归方程为:A=0.00583 0.15105ρ,在0.50～10.0 μg/mL之间苏丹红Ⅰ号的浓度与吸光度之间呈线性关系,相关系数R=0.9992,检出限为0.05 μg/mL.测定结果与国家标准HPLC法对照,令人满意.可用于食品中苏丹红Ⅰ号的测定.     

荷移光度法测定依诺沙星

依诺沙星与茜素红在水-乙醇介质中发生电荷转移反应,其中依诺沙星是电子给予体,茜素红是电子接受体,依据此荷移反应建立了一种快速测定依诺沙星的荷移分光光度法.荷移络合物在 546 nm 波长处有最大吸收,表观摩尔吸光率为 8.04×103L·mol-1·cm-1,相关系数为0.999 9.该络合物的组成为 1:1,表观稳定常数为 2.84×104.依诺沙星的质量浓度在 0～40 mg·L-1范围内服从比耳定律.当依诺沙星的质量浓度为 20 mg·L-1时,测定结果的相对标准偏差(n=6)为 1.2%,回收率在 99%以上.测定了依诺沙星制剂中有效成分的含量,与文献[1]方法结果基本吻合.     

Simple Chemical Route Synthesis of Fe2O3 Nanoparticles and its Application for Adsorptive Removal of Congo Red from Aqueous Media: Artificial Neural Network Modeling

Nanocrystalline Fe₂O₃ powder was synthesized by a simple chemical route involving FeCl₃ and NaOH. The Fe₂O₃ powder thus prepared was characterized using x-ray diffraction study, scanning electron microscopy, and Fourier transform infrared spectroscopy. The adsorption properties of crystalline Fe₂O₃ powder have been investigated with an aim to explore a possible low cost and efficient way to remove Congo red (CR) from waste water. Fe₂O₃ powder was found as an excellent adsorbent for CR from aqueous medium. Adsorption capacity as much as 203.66 mg g^?1 is reported at room temperature. Effect of different experimental parameters such as reaction pH, initial CR dye concentration, adsorbent dose, and reaction temperature were studied on adsorption capacity of Fe₂O₃ powder and modeled by artificial neural network (ANN). Optimal ANN structure (4–5–1) shows minimum mean squared error (MSE) of 0.00235 and determination coefficient (R²) of 0.991 with Levenberg–Marquardt algorithm. Isotherm analysis of experimental data exhibited better fit to the Langmuir isotherm. The adsorption process was found to follow second-order kinetics as depicted by the analysis of experimental results. Thermodynamic study shows that the adsorption process is endothermic, spontaneous, and thermodynamically favorable in the temperature range of 27°C to 60°C.     

Safer Pyrotechnic Obscurants Based on Phosphorus(V) Nitride

The potential of phosphorus(V) nitride, P₃N₅ , as a replacement for red phosphorus, P_R, in pyrotechnic obscurants has been theoretically and experimentally investigated. P₃N₅ can be safely mixed with KNO₃ and even KClO₃ and KClO₄ . The corresponding formulations are surprisingly insensitive to friction and only mildly impact‐sensitive. P₃N₅ /KNO₃ pyrolants with ξ=20–80 wt % P₃N₅ burn 200 times faster than the corresponding mixtures based on P_R and generate a dense smoke. Hence obscurants based on P₃N₅ /KNO₃ have a figure of merit that by far exceeds that of current state‐of‐the‐art P_R‐based obscurants. Furthermore, unlike P_R, which slowly degrades in moist air to phosphoric acids and phosphine (PH₃), P₃N₅ is stable under these conditions and does not produce any acids or PH₃ . P₃N₅ is hence a safe, stable, and powerful replacement for P_R for use in insensitive munitions.     

Determination of allura red using composites of water-dispersible reduced graphene oxide-loaded Au nanoparticles based on ionic liquid

A facile route for producing reduced graphene oxide (RGO)-loaded Au nanoparticles based on ionic liquids (IL) has been proposed, in which the as-prepared RGO can be dispersed stably in water. With the assistance of IL, Au nanoparticles were uniformly and densely absorbed on the surfaces of the IL functionalised reduced graphene oxide (IRGO), forming a new composite of IRGO/Au with high dispersibility. This IRGO/Au composite enhanced its electrochemical signal obviously in the measurement of allura red in foods and exhibited a wider linear response ranging from 0.297 (0.0006 μmol L^?1) to 99.3 μg L^?1 (0.2 μmol L^?1) with lower detection limit of 0.213 μg L^?1 (0.00043 μmol L^?1) at a signal-to-noise ratio of 3. To further study the practical applicability of the proposed sensor, the modified electrode was successfully applied to detect allura red in five kinds of common foods and the assay results were in a good agreement with the reference values detected by HPLC.     

New red-luminescent cadmium coordination polymers with 4-amino-2,1,3-benzothiadiazole

New polymeric cadmium complexes, α-[CdLCl₂]_n (1), [CdL₂Cl₂]_n (2) and β-[CdLCl₂]_n (3) (L = 4-amino-2,1,3-benzothiadiazole), were obtained as products of the reaction of CdCl₂ with L. The synthetic procedures allowing isolation of pure 1–3 were optimized. The structures of 1–3 were established by single-crystal X-ray diffraction and the compounds were characterized by UV–Vis and IR spectroscopy. In these compounds, L is either μ-bridging (1) or terminal (2 and 3). The UV–Vis spectra of the complexes in the solid state resemble that of free L. However, coordination of L leads to a significant shift of emission in photoluminescence spectra from yellow (free L) to red (1–3).     

A wine red copper(II) complex of a tetradentate nitrogen donor showing two-electron oxidation. Generation of a copper(II)-phosphine bond

Using the 1 : 2 condensate of benzil and 2-hydrazinopyridine as the ligand LH₂ (H: dissociable NH proton), the red complex Cu(LH₂)(ClO₄)₂ (1) was synthesized. The ligand also afforded the orange [Zn(LH₂)(OH₂)₂](ClO₄)₂ (2). The X-ray crystal structures of the ligand, 1 and 2 have been determined. The metals in 1 and 2 have octahedral N₄O₂ environments. 1 is paramagnetic with μ_eff of one unpaired electron (1.63 μ_B and displays an axial EPR spectrum in the solid state with <g> = 2.07, characteristic of a (d_x2_?y2)¹ ground state (g_|| > g_⊥; A_|| = 16 mT). In cyclic voltammetry, 1 displays a two-electron oxidation around 0.9 V versus NHE. The two-electron oxidized (coulometrically) solution of 1 (golden yellow) gives an EPR spectrum with <g> = 2.17 and g_|| < g_⊥. The reaction of PPh₃ with 1 yields the orange complex [Cu(LH₂)(PPh₃)](ClO₄)₂ (4). With the assumed chemical formula, the effective magnetization of 4 corresponds to one electron. Its EPR spectrum in the solid state is isotropic with g = 2.07. This g value yields a theoretical μ_eff of 1.80 μ_B at 298 K from Curie’s law, which matches very well with the experimental value of 1.89 μ_B at room temperature. Since single crystals of 4 could not be obtained, DFT calculations at the UBP86/6–311G(2d,p) level have been carried out and indicate that the cation in 4 is square pyramidal with the phosphine at the apex. The ease of the oxidation of the metal in 1 leads to the stabilization of the rare Cu(II)-P bond in 4.