Extraction of tributyltin by magnetic molecularly imprinted polymers

We have prepared core-shell magnetic molecularly imprinted polymer nanoparticles for recognition and extraction of tributyl tin (TBT). The use of particles strongly improves the imprinting effect and leads to fast adsorption kinetics and high adsorption capacities. The functional monomer acrylamide was grafted to the surface of Fe₃O₄ nanospheres in two steps, and MIP layers were then formed on the surface by creating a MIP layer on the surface consisting of poly(ethyleneglycol dimethacrylate) with a TBT template. The particles were characterized in terms of morphological, magnetic, adsorption, and recognition properties. We then have developed a method for the extraction of TBT from spiked mussel (Mytilidae), and its determination by liquid chromatography-tandem mass spectrometry. The method has a limit of detection of 1.0 ng?g^?1 (n?=?5) of TBT, with a linear response between 5.0 and 1,000 ng?g^?1. The proposed method was successfully applied to the determination of trace TBT in marine food samples with recoveries in the range of 78.3–95.6 %.

基于磁性分子印迹聚合物的电化学传感器的研究进展

分子印迹聚合物与磁性纳米材料结合,制备成磁性分子印迹纳米敏感膜,这样做不仅可以发挥分子印迹聚合材料的优势,而且磁性纳米粒子可有效提高电化学传感器的灵敏度、稳定性以及生物相容性等。近年来将磁性分子印迹纳米敏感膜应用于电化学传感器制备成的磁性分子印迹电化学传感器得到了较快的发展。本文就近5年来磁性分子印迹电化学传感器敏感膜所用的磁性材料、敏感膜制备方法以及磁性分子印迹电化学传感器在环境、食品以及临床方面的应用进行了综述总结。     

New magnetic nanomaterials based on soluble ferrocene-containing polymers

Russian Chemical Bulletin - New magnetic nanomaterials based on soluble ferrocene-containing polyphenylenes were synthesized at 20–80 °C both under normal conditions and under ultrasonic...     

ESR and magnetic properties of electrically conducting metallophthalocyanine polymers

Polymeric metallophthalocyanines of Cu, Ni, Co in which benzene rings are shared in common with the macrocyclic phthalocyanine rings containing peripheral carboxylic groups have been synthesized and their electrical conductivities are shown to increase from 5 to 8 orders of magnitude by thermal treatment. The cobalt polymer exhibits greater conductivity than its nickel or copper analogs. The heated polymers show very broad electron spin resonance (ESR) signals and large paramagnetic susceptibilities. The bulk magnetic susceptibility of these polymers shows Curie-like behavior when the samples are heated from room temperature to 473 K. This is explained on the basis of coexistence of fixed mobile and conduction electron spins in the system and the interaction of the soliton type defects present in these polymers with the polymeric network to give dipolar charge carriers. This is also supported by the decrease in ESR intensity with increasing temperature when the samples are heated in the ESR cavity. The effect of the presence of unpaired electrons on the d shell of the central metal atoms on the line width and the line shape of the ESR spectra is also explained. © 1994 John Wiley & Sons, Inc.     

三聚氰胺磁性分子印迹聚合物材料的制备及性能表征

利用溶剂热法通过控制反应时间和温度制得了分散性好和磁性强的Fe3O4,并利用溶胶凝胶法制备得到包覆SiO2的磁性微球(Fe3O4@SiO2)。以三聚氰胺为模板分子,甲基丙烯酸(MAA)为单体,采用本体聚合法制备了磁性分子印迹聚合物(MMIPs)。通过静态吸附实验表明,MMIPs对三聚氰胺的饱和吸附量高达10.22μg/mg,是磁性非印迹聚合物(MNIPs)的1.62倍。粒子扩散模型、Elovich模型和动态吸附实验表明所制得的MMIPs有较好的吸附性能。     

A series of manganese-carboxylate coordination polymers exhibiting diverse magnetic properties

The hydrothermal reactions of an asymmetrical 4-(4-carboxyphenylamino)-3,5-dinitrobenzoic acid (H2cpdba), MnCl2.4H2O, or together with 2,2'-bipyridine (2,2'-bpy) or 4,4'-bipyridine (4,4'-bpy) afford three novel molecule-based magnetic coordination polymers [Mn(cpdba)]n (1), ([Mn2(cpdba)2(2,2'-bpy)2(H2O)2].H2O)n (2) and ([Mn2(cpdba)2(4,4'-bpy)].2H2O)n (3). Compound 1 has a 3D acentric coordination network containing carboxylate-bridged 1D ladder-like manganese chains with spin-canted antiferromagnetism (J = -3.51 cm(-1) for the coupling along the ladder legs, and zJ' = 0.22 cm(-1) for coupling along the ladder rungs), whereas compounds 2 and 3 crystallize in the centrosymmetric space groups P1 and C2/c, respectively. 2 exhibits a 1D chain structure, which is extended into a 3D supramolecular network by pi-pi stacking interactions, while 3 features a quite complex 3D network built up from the cpdba(2-) and 4,4'-bpy spacers as well as the carboxylate-bridged Mn(II) chains. Both 2 and 3 show weak antiferromagnetic coupling interactions (J = -0.55 cm(-1) for 2), and a field-induced spin-flop magnetic transition can also be observed in 2 at ca. 3.2 T at 2 K.     

Quantitative nuclear magnetic resonance imaging of liquids in swelling polymers

The variation of nuclear magnetic resonance (NMR) relaxation parameters (T₁, T₂) within a polymer during swelling, limits the absolute accuracy with which liquid concentration profiles can be obtained using NMR imaging. In this article a study of the diffusion of decalin into ultra-high molecular weight polyethylene (UHMWPE) is reported. The study illustrates the use of a method of analysis whereby quantitative solvent profiles can be obtained from data influenced by both T₁ and T₂ contrast effects. A T₁ and T₂ map are obtained at a point in the uptake of liquid where the greatest range in liquid concentration is obtained at a point in the uptake of liquid where the greatest range in liquid concentration is observed. The intensity of signal corresponding to liquid in the polymer is compared to that of pure liquid in a reference sample, and correlations for T₁ and T₂ values versus signal intensity are used to deconvolve relaxation contrast, to yield the true liquid concentration. The technique was used to study the effect of degree of crosslinking of UHMWPE on the swelling kinetics and decalin transport within the polymer. A spin-echo imaging technique was used with a recycle delay approximately equal to the average spin-lattice relaxation time of the liquid, and an echo time approximately half the average spin-spin relaxation time. Under these conditions the relaxation contrast was significant, yet the mass uptake data derived from the concentration profiles obtained, using the method of analysis described, agreed well with gravimetric data. © 1995 John Wiley & Sons, Inc.     

Electric and magnetic characteristics of metal-free polymers containing azaporphine macrocycles

The electric and magnetic characteristics of metal-free polymers with azaporphine macrocycles in varying regular series were compared with the structural parameters of macromolecules, such as the macromolecule size, the length of conjugation regions, and the concentration of free peripheral CN groups. It was found that the array of the test polymers in general exhibits an average statistical tendency characteristic of organic semiconductors: as the molecular mass of macromolecules and, correspondingly, the conjugation chain length increase, the conductivity increases and the ESR signal narrows. For the revealed case of an abnormal drop in conductivity with an increase in the molecular mass, unequivocal evidence was obtained as to which of two possible factors responsible for the abnormality (breaking the continuous π-conjugation chain in the macromolecule or the emergence of intermolecular barriers) takes place in each particular series of such polymers.     

From high-spin organic molecules to organic polymers with magnetic ordering

This concept paper outlines the design of the first pi-conjugated organic polymer with magnetic ordering. This rational, "bottom-up" macromolecular design is based on synthesis and study of polyarylmethyl polyradicals with increasing number of exchange-coupled unpaired electron spins. The prospects for attaining organic polymer magnets with stability at ambient temperature and/or higher magnetic ordering temperatures will be discussed.     

ESR studies on polymers with particular electronic and magnetic properties

Measurements on insulating and conducting polymers from the polyaniline (PANI) family and investigations on semiconducting poly(tetrathiafulvalenes) (PTTF) have been used for illustration and discussion of some methodical questions of electron spin resonance (ESR). This concerns especially the new possibilities of the recently developed high-resolution ESR in the 2 mm wave band. It was applied for the study of the nature and dynamics of paramagnetic centres (PC) and charge carriers in PANI and PTTF. The rate of the quasi-one-dimensional (1D) intrachain electron motion and of the three-dimensional (3D) interchain electron hopping has been estimated separately. In iodine - doped PTTF the maximum electrical conductivity is 10⁻⁴ S ·cm⁻¹. It is almost identical with the 3D-conductivity estimated by ESR and shows the typical temperature dependence of a semiconductor. The quasi-1D-conductivity is several orders of magnitude higher and shows in its dependence on temperature similarities with a metal. The PANI samples show in the highly doped form a maximum conductivity of about 10 S ·cm⁻¹ and relativly small differences between the 1D- and 3D-conductivity, supporting the model of metallic islands.     

Tuning the structural and magnetic properties of thermally robust coordination polymers

Thermally robust materials of the M(5-X-pyrimidin-2-olate)2 type [M = Co, X = Cl (1(Cl)), X = Br (1(Br)), X = I (1(I)); M = Zn, X = Cl (2(Cl)), X = Br (2(Br)), X = I (2(I))] have been synthesized. Their X-ray powder diffraction structural characterization has revealed that they crystallize as I2d diamondoid frameworks, isomorphous to those of the pristine [M(pyrimidin-2-olate)2]n analogues (1(H), M = Co; 2(H), M = Zn). The magnetic measurements of the 1(X) series at magnetic fields of 100, 300, and 5000 Oe reveal a weak ferromagnetic ordering taking place below the Néel temperature (T(N) approximately 20 K), arising from spin canting phenomena of the antiferromagnetically coupled cobalt centers. Moreover, magnetic hysteresis studies carried out on the 1(X) series at 2 K reveal a strong dependence of both the coercive field H(coer) (2500, 1000, 775, and 500 Oe for 1(Br), 1(Cl), 1(I), and 1(H), respectively) and the remnant magnetization M(rem) (0.0501 mu(B) for 1(Br) and 1(Cl), 0.0457 mu(B) for 1(I), and 0.0358 mu(B) for 1(H)) on the 5-substituent of the pyrimidin-2-olates. The molecular alloys [Co(5-Y-pyrimidin-2-olate)2] (Y = Cl/Br, 1(Cl/Br)) and [Co(5-Y'-pyrimidin-2-olate)2] (Y' = Br/I, 1(Br/I)) have also been prepared and characterized, proving that they have intermediate properties. These materials combine interesting functional properties, such as chemical inertness, magnetism, photoluminescence, and (although weak) SHG activity.     

Selective recognition of sesamol using molecularly imprinted polymers containing magnetic wollastonite

The magnetic molecularly imprinted polymers (MMIPs) have been synthesized using piperonal molecules as dummy template and magnetic wollastonite composites as support. The resulting composites were applied to selective recognition of sesamol from aqueous solution. MMIPs were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) analysis, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). MMIPs were demonstrated with an imprinted polymer film (90-100 nm) and exhibited magnetic property (M(s) =8.60 emu/g) and thermal stability. The effective average diameter of the Fe(3) O(4) nanoparticles was about 10 nm and the thickness of magnetic film was about 160 nm. Batch mode adsorption studies were carried out to investigate the specific adsorption equilibrium, kinetics and selective recognition. The Langmuir isotherm model was fitted to the equilibrium data better than the Freundlich model, and the kinetic properties were well described by the pseudo-second-order equation. The value of E(a) in this study was 5.35 kJ/mol for MMIPs. In addition, the selective recognition experiments demonstrated that MMIPs have specific recognition ability toward sesamol.     

The effect of magnetic field on the band structure of polymers Part 1. Static magnetic field

The Hartree-Fock equations for a periodic polymer chain in the presence of a static magnetic field are formulated. The cases of homogeneous and inhomogeneous static field are treated separately. In the case where the magnetic field strength is dependent on the coordinate z (the direction of the main axis of the polymer), the periodic symmetry of the polymer breaks down. For the case of weak z dependence of the magnetic field the chain can be divided into segments, each one characterized by an averge field, and the interface of these segments can be treated with the help of two Dyson equations (one for each segment at the interface).     

New magnetic nanomaterials based on ferrocene-containing polymers synthesized under ultrasonic irradiation

Russian Chemical Bulletin - A new magnetic nanomaterial was obtained based on soluble ferrocene-containing poly-phenylene synthesized under ultrasonic irradiation at room temperature. The maximum...     

核壳结构的萘夫西林磁性分子印迹聚合物微球的制备及性能

以表面修饰双键的Fe₃O₄@SiO₂纳米颗粒为基体,以萘夫西林(nafcillin)为模板,甲基丙烯酸(MAA)为单体,乙二醇二甲基丙烯酸酯(EGDMA)为交联剂,偶氮二异丁腈(AIBN)为引发剂,采用三步升温聚合法合成了核壳结构的萘夫西林磁性分子印迹聚合物。采用傅里叶变换红外光谱仪(FT-IR)、透射电子显微镜(TEM)、X射线衍射仪(XRD)和振动样品磁强计(VSM)对制备的印迹聚合物微球进行了表征,得到的磁性印迹聚合物微球的粒径在320 nm左右,大小均匀,分散性较好,可以在外加磁场下与溶剂实现快速分离。对磁性印迹和非印迹聚合物进行了吸附性能研究,结果表明该印迹聚合物微球对模板分子具有很高的吸附容量(50.7 mg/g),特异性识别性能良好(印迹因子为2.46),有望应用于实际样品中萘夫西林残留量的富集分析。