New acrylamide‐based monomer containing metal chelating units: Homopolymer grafted magnetite nanoparticles via ATRP for the magnetic removal of Co(II) ions

In this research, we synthesized and characterized a new acrylamide‐based monomer containing pyridine and 1,3,4‐oxadiazole moieties, N‐(4‐(5‐(pyridin‐2‐yl)‐1,3,4‐oxadiazol‐2‐yl)phenyl)acrylamide (POPA). Poly(POPA)‐grafted magnetite nanoparticles were then obtained via surface‐initiated atom transfer radical polymerization. The grafted nanoparticles were characterized by Fourier transform infrared analysis, scanning electron microscopy, wide angle X‐ray diffraction, and vibrating sample magnetometry. The amount of the grafted polymer was 126 mg/g, as calculated from thermo gravimetric analysis experiment. The capability of poly(POPA)‐g‐magnetite nanoparticles (MNPs) to remove Co(II) cations, under optimal time period, pH and adsorbent mass, was shown by atomic absorption. The adsorption kinetics obeyed the pseudo–second‐order kinetic equation, and the adsorption isotherm was best described by the Freundlich model with a maximum adsorption capacity of 59.90 mg/g. In addition, the poly(POPA)‐g‐MNPs were regenerated by simply washing with an aqueous 0.1M HCl solution, and no considerable decrease was observed in the extraction efficiency following the test of up to 7 cycles. These findings suggest that poly(POPA)‐g‐MNPs are stable and reusable adsorbent, and they could be potentially applied to water treatments for an efficient removal of Co(II) cations.     

Preparation of a chitosan-coated C18-functionalized magnetite nanoparticle sorbent for extraction of phthalate ester compounds from environmental water samples

Novel superparamagnetic chitosan-coated C₁₈-functionalized magnetite nanoparticles (MNPs) were successfully synthesized and applied as an effective sorbent for the preconcentration of several typical phthalate ester compounds from environmental water samples. The MNPs were 20 nm in diameter and had a high magnetic saturation value (52 emu g⁻¹), which endowed the sorbent with a large surface area and the convenience of isolation from water samples. Phthalate esters could be extracted by the interior octadecyl groups through hydrophobic interaction. The hydrophilic porous chitosan polymer coating promoted the dispersion of MNPs in water samples, and improved the anti-interference ability of the sorbent without influencing the adsorption of analytes. The main factors affecting the adsorption of phthalate esters, including the pH of the solution, humic acid, sample loading volume, adsorption time, and desorption conditions, were investigated and optimized. Under the conditions selected (pH 11, adsorption time 20 min, elution with 10 mL of acetonitrile, and concentration to 0.5 mL), concentration factors of 1,000 were achieved by extracting 500 mL of several environmental water samples with 0.1 g of MNP sorbent. The method detection limits obtained for di-n-propyl phthalate, di-n-butyl phthalate, dicyclohexyl phthalate, and di-n-octyl phthalate were 12.3, 18.7, 36.4, and 15.6 ng L⁻¹, respectively. The recoveries of spiked samples ranged from 60 to 100%, with a low relative standard deviation (1–8%), which indicated good method precision.     

Poly(N‐phenylmaleimide‐co‐acrylic acid)–copper(II) and poly(N‐phenylmaleimide‐co‐acrylic acid)–cobalt(II) complexes: Synthesis,characterization, and thermal behavior

The free‐radical copolymerization of N‐phenylmaleimide (N‐PhMI) with acrylic acid was studied in the range of 25–75 mol % in the feed. The interactions of these copolymers with Cu(II) and Co(II) ions were investigated as a function of the pH and copolymer composition by the use of the ultrafiltration technique. The maximum retention capacity of the copolymers for Co(II) and Cu(II) ions varied from 200 to 250 mg/g and from 210 to 300 mg/g, respectively. The copolymers and polymer–metal complexes of divalent transition‐metal ions were characterized by elemental analysis, Fourier transform infrared, ¹H NMR spectroscopy, and cyclic voltammetry. The thermal behavior was investigated with differential scanning calorimetry (DSC) and thermogravimetry (TG). The TG and DSC measurements showed an increase in the glass‐transition temperature (T_g) and the thermal stability with an increase in the N‐PhMI concentration in the copolymers. T_g of poly(N‐PhMI‐co‐AA) with copolymer composition 46.5:53.5 mol % was found at 251 °C, and it decreased when the complexes of Co(II) and Cu(II) at pHs 3–7 were formed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4933–4941, 2005     

Synthesis and characterization of magnetic poly(acrylic acid) hydrogel fabricated with cobalt nanoparticles for adsorption and catalytic applications

The present study aimed to synthesize poly(acrylic acid) hydrogel embedded with magnetic cobalt (Co) nanoparticles and to investigate their potential in adsorption and catalysis. The hydrogel was prepared by facile free radical polymerization reaction and Co nanoparticles were fabricated within hydrogel by reducing Co (II) ions using NaBH₄ as reducing agent. Co nanoparticles within hydrogel system imparted magnetic properties to the resulting composite gel and also increased the adsorption capacity. The swelling study of hydrogel was carried out by gravimetric analysis. Different functional groups were identified by Fourier Transform Infrared Spectroscopy and Transmission Electron Microscopy analysis was done to investigate dispersion of Co nanoparticles in hydrogel. The bare hydrogel along with Co nanoparticles loaded gel were tested as adsorbent systems for the removal of a cationic dye (methylene blue) from aqueous solution. 95% removal of methylene blue was achieved with a highest adsorption capacity of 836.5 mg/g of adsorbent. The famous adsorption isotherms were used to evaluate adsorption data. Results showed that Freundlich isotherm model was followed with R² value of 0.95. The hydrogel was also used for catalytic reduction in a toxic pollutant, i.e., 4-nitrophenol. Experimental data for 4-nitrophenol reduction followed pseudo first order kinetics model. Activation energy and apparent rate constant were calculated as 9.24 kJ/mol and 0.24 min⁻¹, respectively. Recycling of the magnetic poly(acrylic acid) hydrogel fabricated with Cobalt nanoparticles was carried out for four consecutive cycles and no significant loss in catalytic activity was observed.

     

一步法制备PNIPAAm-g-PAN/PSt载银复合微球及其抗菌性能研究

以AgNO3为金属源,通过乙醇将与聚N-异丙基丙烯酰胺接枝聚丙烯腈/聚苯乙烯（PNIPAAm-g-PAN/PSt）聚合物微球表面酰胺基团配位的银离子（Ag+）还原,一步法制备了PNIPAAm-g-PAN/PSt载银复合微球。通过傅立叶变换红外（FTIR）和紫外-可见光光谱表征发现,由Ag+还原所得的Ag纳米颗粒被成功地固载在PNIPAAm-g-PAN/PSt 微球上;用透射电子显微镜（TEM）对载银微球的大小和形态进行了表征;热重分析（TGA）结果表明,固载在微球表面的银纳米颗粒的含量（质量分数）为12%;抗菌实验结果表明,所制备的载银微球具有抗革兰氏阴性菌的活性。     

Synthesis and investigation of dual pH‐ and temperature‐responsive behaviour of poly[2‐(dimethylamino)ethyl methacrylate]‐grafted gold nanoparticles

Gold nanoparticles (AuNPs) were synthesized by reduction of chloroauric acid (HAuCl₄) aqueous solution with hydrazine monohydrate. The AuNPs were immediately treated with cysteamine to obtain amine‐functionalized nanoparticles (Au‐NH₂). The reaction of Au‐NH₂ with epichlorohydrin and subsequent treatment with sodium hydroxide gave epoxidized AuNPs (Au‐EP). Then, thiol‐capped AuNPs (Au‐SH) were synthesized by reaction of Au‐EP with cysteamine. A ‘grafting to’ approach was utilized to graft bromine‐terminated poly(N ,N ′‐dimethylaminoethyl methacrylate), synthesized via aqueous atom transfer radical polymerization, with various molecular weights (6280, 25 800, 64 200 and 87 600 g mol⁻¹) onto Au‐SH to obtain Au‐P1, Au‐P2, Au‐P3 and Au‐P4 samples, respectively. All samples were exposed to temperature and pH variations, and Z‐average diameter was monitored using dynamic light scattering. According to the results, polymer‐grafted nanoparticles collapsed at lower temperatures with increasing solution pH for all molecular weight ranges due to deprotonation of tertiary amine groups. However, higher molecular weight polymers were more sensitive to pH variation especially in alkaline media. Also, a high degree of agglomeration was observed for Au‐P4 nanoparticles in alkaline media on increasing the temperature to 55 and 65 °C.     

Low‐dimensional compounds containing bioactive ligands. IV. Unusual ionic forms of 5‐chloroquinolin‐8‐ol

Bis(5‐chloro‐8‐hydroxyquinolinium) tetrachloridopalladate(II), (C₉H₇ClNO)₂[PdCl₄], (I), catena‐poly[dimethylammonium [[dichloridopalladate(II)]‐μ‐chlorido]], {(C₂H₈N)[PdCl₃]}_n, (II), ethylenediammonium bis(5‐chloroquinolin‐8‐olate), C₂H₁₀N₂²⁺·2C₉H₅ClNO⁻, (III), and 5‐chloro‐8‐hydroxyquinolinium chloride, C₉H₇ClNO⁺·Cl⁻, (IV), were synthesized with the aim of preparing biologically active complexes of Pd^II and Ni^II with 5‐chloroquinolin‐8‐ol (ClQ). Compounds (I) and (II) contain Pd^II atoms which are coordinated in a square‐planar manner by four chloride ligands. In the structure of (I), there is an isolated [PdCl₄]²⁻ anion, while in the structure of (II) the anion consists of Pd^II atoms, lying on centres of inversion, bonded to a combination of two terminal and two bridging Cl⁻ ligands, lying on twofold rotation axes, forming an infinite [–μ₂‐Cl–PdCl₂–]_n chain. The negative charges of these anions are balanced by two crystallographically independent protonated HClQ⁺ cations in (I) and by dimethylammonium cations in (II), with the N atoms lying on twofold rotation axes. The structure of (III) consists of ClQ⁻ anions, with the hydroxy groups deprotonated, and centrosymmetric ethylenediammonium cations. On the other hand, the structure of (IV) consists of a protonated HClQ⁺ cation with the positive charge balanced by a chloride anion. All four structures are stabilized by systems of hydrogen bonds which occur between the anions and cations. π–π interactions were observed between the HClQ⁺ cations in the structures of (I) and (IV).     

Amphiphilic silica/fluoropolymer nanoparticles: Synthesis,tem‐responsive and surface properties as protein‐resistance coatings

A series of amphiphilic silica/fluoropolymer nanoparticles of SiO₂‐g‐P(PEGMA)‐b‐P(12FMA) were prepared by silica surface‐initiating atom transfer radical polymerization (SI‐ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA) and poly dodecafluoroheptyl methacrylate (P12FMA). Their amphiphilic behavior, lower critical solution temperature (LCST), and surface properties as protein‐resistance coatings were characterized. The introduction of hydrophobic P(12FMA) block leads SiO₂‐g‐P(PEGMA)‐b‐P(12FMA) to form individual spherical nanoparticles (～150 nm in water and ～170 nm in THF solution) as P(PEGMA)‐b‐P(12FMA) shell grafted on SiO₂ core (～130 nm), to gain obvious lower LCST at 36–52 °C and higher thermostability at 290–320 °C than SiO₂‐g‐P(PEGMA) (LCST = 78–90 °C, T_d = 220 °C). The water‐casted SiO₂‐g‐P(PEGMA)‐b‐P(12FMA) films obtain much rougher surface (125.3–178.4 nm) than THF‐casted films (11.5–16.9 nm) and all SiO₂‐g‐P(PEGMA) films (26.8–31.3 nm). Therefore, the water‐casted surfaces exhibit obvious higher water adsorption amount (Δf = ?494 ～ ?426 Hz) and harder adsorbed layer (viscoelasticity of ΔD/Δf = ?0.28 ～ ?0.36 × 10^?6/Hz) than SiO₂‐g‐P(PEGMA) films, but present loser adsorbed layer than THF‐casted films (ΔD/Δf = ?0.29 ～ ?0.63 × 10^?6/Hz). While, the introduction of P(12FMA) segments does not show obviously reduce in the protein‐repelling adsorption of SiO₂‐g‐P(PEGMA)‐b‐P(12FMA) films (△f = ?15.7 ～ ?22.3 Hz) compared with SiO₂‐g‐P(PEGMA) films (△f = ?8.3 ～ ?11.3 Hz) and no obvious influence on water adsorption of ancient stone. Therefore, SiO₂‐g‐P(PEGMA)‐b‐P(12FMA) is suggested to be used as protein‐resistance coatings. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 381–393     

Preparation of poly(vinylalcohol)/poly(acrylamide‐co‐vinyl imidazole)/γ‐Fe2O3 semi‐IPN nanocomposite and their application for removal of heavy metal ions from water

A series of magnetic semi‐interpenetrating polymer network (semi‐IPN) hydrogels was prepared in one‐stage strategy composed of linear poly(vinyl alcohol) (PVA) chains and magnetic γ‐Fe₂O₃ nanoparticles entrapped within the cross‐linked poly(acrylamide‐co‐vinylimidazole) (poly(AAm‐co‐VI)) network. The influence of PVA, weight ratio of AAm:VI, γ‐Fe₂O₃, and MBA on the swelling properties of the obtained nanocomposite hydrogels was evaluated. The prepared magnetic semi‐IPN hydrogels were fully characterized and used as absorbent for removal of Pb(II) and Cd(II) from water. Factors that influence the metal ion adsorption such as solution pH, contact time, initial metal ion concentration, and temperature were studied in details. The experimental results were reliably described by Langmuir adsorption isotherms. The adsorption capacity of semi‐IPN nanocomposite for Pb(II) and Cd(II) were175.80 and 149.76 mg g^?1, respectively. The kinetic experimental data indicated that the chemical sorption is the rate‐determining step. According to thermodynamic studies, Pb(II) and Cd(II) adsorption on the hydrogels was endothermic and also chemical in nature. The prepared magnetic PVA/poly(AAm‐co‐VI) semi‐IPN hydrogels could be employed as efficient and low‐cost adsorbents of heavy metal ions from water. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis of polybutadiene‐graft‐poly(dimethylsiloxane) and polyethylene‐graft‐poly(dimethylsiloxane) copolymers with hydrosilylation reactions

We report preliminary results for the synthesis of polyethylene‐graft‐poly(dimethylsiloxane) copolymers obtained by catalytic hydrogenation of polybutadiene‐graft‐poly(dimethylsiloxane) copolymers (PB‐g‐PDMS). These last copolymers were synthesized by hydrosilylation reactions between commercial polybutadiene and ω‐silane poly(dimethylsiloxane). The reaction was carried in solution catalyzed by cis‐dichloro bis(diethylsufide) platinum(II) salt. The PB‐g‐PDMS copolymers were analyzed by ¹H and ¹³C NMR spectroscopies, and the relative weight percentages of the grafted poly(dimethylsiloxane) macromonomer were determined from the integrated peak areas of the spectra. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2920–2930, 2004     

Biodegradable polyester/modified mesoporous silica composites for effective bone repair with self‐reinforced properties

A series novel composites based on poly(_L‐lactide) (PLLA) oligomer modified mesoporous silica (MCM41) homogeneous dispersed into poly(_L‐lactide‐co‐trimethylene carbonate‐co‐glycolide) (PLTG) terpolymer has been successfully prepared. The structure of PLTG terpolymer was characterized by ¹H NMR. The structure and properties of modified and unmodified MCM41 were attested by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyzer (TGA), X‐ray diffraction (XRD), N₂ adsorption–desorption, scanning electron microscope (SEM), and transmission electron microscope (TEM), which demonstrated that the MCM41 was successfully grafted by the PLLA oligomer. The effect of different concentration of modified MCM41 in PLTG matrix on thermal properties, mechanical properties, and hydrophilicity was investigated by TGA, differential scanning calorimetry (DSC), mechanical testing, contact angle measurement, and SEM. The results of mechanical tests showed that 5 wt% of modified MCM41 nanoparticles gave rise to optimal reinforcing effect. The tensile strength, Young's modulus, and elongation at break of the PLTG/PLLA‐MCM41 (5%) composites were 33.2 Mpa, 1.58 Gpa, and 268.7%, respectively, which were all higher than the PLTG/MCM41 (5%) composites and pristine PLTG matrix, which were due to good interfacial adhesion between the PLTG matrix and MCM41 nanoparticles. TGA and DSC have shown that 5% modified MCM41 in the PLTG increased the temperature of composite degradation and T_g. Water contact angle measurement showed the hydrophilicity of the composites increases with the increase of modified MCM41 content. The live/dead assay showed that the modified MCM41 existing on the PLTG matrix presents very excellent cytocompatibility. Therefore, the novel composite material represents promising way for bone tissue engineering application.     

Synthesis and characterization of CoFe2O4@SiO2-polyethyleneimine magnetic nanoparticle and its application for ultrasonic-assisted removal of disulfine blue dye from aqueous solution

In the present work, a simple synthesis approach was applied for the fabrication of CoFe₂O₄@SiO₂-polyethyleneimine magnetic nanoparticles as an effective sorbent for ultrasonic-assisted removal of disulfine blue dye from an aqueous solution. For identification and characterization of prepared sorbent, different analysis including Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM), Vibrating sample magnetometer (VSM), Energy dispersive X-ray analysis (EDX) and Transmission electron microscopy (TEM) were applied. The effect of effective parameters on the removal of disulfine blue such as pH, sorbent mass, ultrasonic time and disulfine blue concentration were also assessed. The optimum values for investigated parameters were achieved to be as follows: pH of 5.0, sorbent mass of 0.015 g, ultrasonic time of 5.0 min and disulfine blue concentration of 10.0 mg L⁻¹. Different isotherm and kinetic models were used for the evaluation of isotherm and kinetic of adsorption. Results showed that the Langmuir isotherm model was better than other isotherm models as well as the second-order equation model was selected as a kinetic model. The maximum adsorption capacity of the proposed magnetic sorbent was achieved to be 110.0 mg g⁻¹ which shows the applicability of proposed sorbent for removal of disulfine blue dye from aqueous solution.     

SBA‐15‐supported N‐coordinate ruthenium(II) materials bearing sulfonamide‐type ligands: Effect of ligand backbones on catalytic transfer hydrogenation of ketones and aldehydes

[RuLCl(p ‐cymene)] (L = N ‐arylsulfonylphenylenediamine) complexes ( 2 _{a – d} ) were synthesized from the reaction between [Ru(p ‐cymene)Cl₂]₂ and ligand. Additionally, SBA‐15–[RuLCl(p ‐cymene)] derived catalysts ( 3 _{a – d} ) were successfully immobilized onto mesoporous silica (SBA‐15) by an easily accessible approach. The structural elucidations of 2 _{a – d} and 3 _{a – d} were carried out with various methods such as ¹H NMR, ¹³C NMR and infrared spectroscopies, elemental analysis, thermogravimetric/differential thermal analysis, nitrogen adsorption–desorption and scanning electron microscopy/energy‐dispersive X‐ray analysis. The Ru(II) complexes and materials were found to be highly active and selective catalysts for the transfer hydrogenation (TH) reaction of aldehydes and ketones. The influence of various 1,2‐phenylenediamines on the reactivity of the catalysts (complexes or materials) was studied and the catalysts ( 2 _d and 3 _d ) with a 4,5‐dichlorophenylenediamine substituent showed the best activity (the maximum turnover frequencies are 2916 and 2154 h⁻¹ for TH of 4‐fluoroacetophenone, and 6000 and 4956 h⁻¹ for TH of 4‐chlorobenzaldehyde).     

Characterization and evaluation of commercial poly (vinylidene fluoride)‐g‐sulfonatedPolystyrene as proton exchange membrane

The possibility of developing low‐cost commercial grafted and sulfonated Poly(vinylidene fluoride) (PVDF‐g‐PSSA) membranes as proton exchange membranes for fuel cell applications have been investigated. PVDF‐g‐PSSA membranes were systematically prepared and examined with the focus of understanding how the polymer microstructure (degree of grafting and sulfonation, ion‐exchange capacity, etc) affects their methanol permeability, water uptake, and proton conductivity. Fourier transform infrared spectroscopy was used to characterize the changes of the membrane's microstructure after grafting and sulfonation. The results showed that the PVDF‐g‐PSSA membranes exhibited good thermal stability and lower methanol permeability. The proton conductivity of PVDF‐g‐PSSA membranes was also measured by the electrochemical impedance spectroscopy method. It was found that the proton conductivity of PVDF‐g‐PSSA membranes depends on the degree of sulfonation. All the sulfonated membranes show high proton conductivity at 92°C, in the range of 27 to 235 mScm⁻¹, which is much higher than that of Nafion212 (102 mScm⁻¹ at 80°C). The results indicated that the PVDF‐g‐PSSA membranes are particularly promising membranes to be used as polymer electrolyte membranes due to their excellent stability, low methanol permeability, and high proton conductivity.     

Poly(L‐Glutamic Acid)‐Drug Conjugates for Chemo‐ and Photodynamic Combination Therapy

Despite the polymeric vascular disrupting agent (poly(_L‐glutamic acid)‐graft‐methoxy poly(ethylene glycol)/combretastatin A4) nanoparticles can efficiently inhibit cancer growth, their further application is still a challenge owing to the tumor recurrence and metastasis after treatment. In this study, two poly(_L‐glutamic acid)‐drug conjugates for chemo‐and photodynamic combination therapy are fabricated. PLG‐g‐mPEG‐CA4 nanoparticles are prepared by combretastatin A4 (CA4) and poly(_L‐glutamic acid)‐graft‐methoxy poly(ethylene glycol) (PLG‐g‐mPEG) using the Yamaguchi esterification reaction. PLG‐g‐mPEG‐TPP (TPP: 5, 10, 15, 20‐tetraphenylporphyrin) nanoparticles are constructed using PLG‐g‐mPEG and amine porphyrin through condensation reaction between carboxyl group of PLG‐g‐mPEG and amino group of porphyrin. The results showed that PLG‐g‐mPEG‐CA4 nanoparticles have good antitumor ability. PLG‐g‐mPEG‐TPP nanoparticles can produce singlet oxygen under the laser irradiation. Moreover, the combined therapy of PLG‐g‐mPEG‐CA4 and PLG‐g‐mPEG‐TPP nanoparticles has higher antitumor effect than the single chemotherapy or the single photodynamic therapy in vitro. The combination of CA4 nondrug and photodynamic therapy provides a new insight for enhancing the tumor therapeutic effect with vascular disrupting agents and other therapy.     

Acyclic Schiff base salts derived from 1,3‐diaminopropane and 1,3‐diamino‐2‐hydroxypropane

Two salts of acyclic Schiff base cationic ligands, namely N,N′‐bis(2‐nitrobenzyl)propane‐1,3‐diammonium dichloride monohydrate, C₁₇H₂₂N₄O₄²⁺·2Cl⁻·H₂O, (I), and 2‐hydroxy‐N,N′‐bis(2‐nitrobenzyl)propane‐1,3‐diammonium dichloride, C₁₇H₂₂N₄O₅²⁺·2Cl⁻, (II), were synthesized as precursors in order to obtain new acyclic and macrocyclic multidentate ligands and complexes. The cation conformations in compounds (I) and (II) are different in the solid state, although the cations are closely related chemically. Similarly, the hydrogen‐bonding networks involving ammonium cations, hydroxyl groups and chloride anions are also different. In the cation of compound (II), the hydroxyl group is disordered over two sets of sites, with occupancies of 0.785 (8) and 0.215 (8).     

Synthesis,crystal structure and magnetic properties of diaquabis(2,6‐diamino‐7H‐purin‐1‐ium‐κN9)bis(4,4′‐oxydibenzoato‐κO)cobalt(II) dihydrate

The title mononuclear Co^II complex, [Co(C₅H₇N₆)₂(C₁₄H₈O₅)₂(H₂O)₂]·2H₂O, has been synthesized and its crystal structure determined by X‐ray diffraction. The complex crystallizes in the triclinic space group P, with one formula unit per cell (Z = 1 and Z′ = ). It consists of a mononuclear unit with the Co^II ion on an inversion centre coordinated by two 2,6‐diamino‐7H‐purin‐1‐ium cations, two 4,4′‐oxydibenzoate anions (in a nonbridging κO‐monodentate coordination mode, which is less common for the anion in its Co^II complexes) and two water molecules, defining an octahedral environment around the metal atom. There is a rich assortment of nonbonding interactions, among which a strong N⁺—H…O⁻ bridge, with a short N…O distance of 2.5272 (18) Å, stands out, with the H atom ostensibly displaced away from its expected position at the donor side, towards the acceptor. The complex molecules assemble into a three‐dimensional hydrogen‐bonded network. A variable‐temperature magnetic study between 2 and 300 K reveals an orbital contribution to the magnetic moment and a weak antiferromagnetic interaction between Co^II centres as the temperature decreases. The model leads to the following values: A (crystal field strength) = 1.81, λ (spin‐orbit coupling) = −59.9 cm⁻¹, g (Landé factor) = 2.58 and zJ (exchange coupling) = −0.5 cm⁻¹.     

Synthesis of double‐hydrophilic block copolymers via combination of oxyanion‐initiated polymerization and polymer reaction for fabricating magnetic target gene carrier

In this work, we have synthesized a polycation and a polyanion via a combination of oxyanion‐initiated polymerization and polymer reaction, and then developed a novel approach to prepare a controlled magnetic target gene carrier with magnetic Fe₃O₄ nanoparticles as core and poly(ethylene glycol) (PEG) segment as corona via layer‐by‐layer (LbL) assembly and shell‐crosslinking. Magnetic nanoparticles (MNPs) were first modified by poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) via radical polymerization. The resulting MNPs were used to compact deoxyribonucleic acid (DNA) through LbL assembly, involving four steps: ( 1 ) the binding of DNA to the polycation PDMAEMA on the surface of MNPs; ( 2 ) the produced particles in Step 1 with negative charge interacting with additional polycation ethoxy group end‐capped PDMAEMA (EtO‐PDMAEMA) homopolymer, leading to a positive charge surface; ( 3 ) using carboxyl group (‐COO^‐) of poly(methacrylic acid) (PMAA) in a diblock copolymer (MePEG2000‐b‐PMAA_SH) as polyanion, which has partial mercapto groups (‐SH) in PMAA segment, to interact with the particles produced in Step 2; ( 4 ) the shell of the composite nanoparticle was crosslinked by oxidizing the ‐SH groups of the MePEG2000‐b‐PMAA_SH to form disulfide linkage (S? S). All the processes of LbL assembly were investigated by agarose gel retardation assay and zeta potential measurements. The in vitro cytotoxicity analysis proves that polyions/DNA MNPs have excellent properties and potential applications as gene carriers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011