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Abstract: Immobilization of Pd(II) ions on magnetite nanoparticle (MNP) has been simply achieved through a surface modification of Fe3O4 nanoparticle with a biguanide. This surface-modified nanoparticle was characterized by various techniques such as TEM, XRD, VSM, TGA, elemental analyzer, atomic absorption spectroscopy, N2 adsorption–desorption (BET and BJH), and FT-IR. This nanosolid exhibits excellent catalytic activity for heterogeneous Suzuki reaction in aqueous media, and could be easily separated by an external magnet and reused for several times. TEM study of the recovered catalyst showed the preservation of the support core–shell structure and the good dispersion of the produced palladium nanoparticles. [Copyright &y& Elsevier]

Abstract: A proton transfer compound L, (MetH)2(dipic), (dipicH2 =2,6-pyridinedicarboxylic acid and Met=Metformin (N,N-dimethylebiguanidine), was synthesized and characterized by IR, 1H and 13C NMR spectroscopy. The reaction of L with PdCl2 in water results in the formation of novel tetracoordinated PdII complex [Pd(dipic)(Met)]·2H2O indicating the participation of both dipic2− and Met as chelating ligands. This complex was characterized by single crystal X-ray analysis. The crystal system is monoclinic with space group P21/c. The unit cell dimensions for PdII complex 1 is a =8.8619(14)Å, b =9.5072(9)Å, c =19.153(3)Å. [Copyright &y& Elsevier]

Abstract: The solution chemistry and solid-state structures of two new uraniumVI metal–organic compounds, (tataH)2[(UO2)2(pdtc)2(μ-OH)2]·2H2O (1) and (AcrH)2[(UO2)(pydc)2] (2), [where tata=1,3,5-triazine-2,4,6-triamine, Acr=acridine, pydc=pyridine-2,6-dicarboxylate and pdtc=pyridine-2,6-bis(monothiocarboxylate)] have been investigated. These compounds were obtained via proton-transfer methodology by reacting UO2 2+ with the preformed proton-transfer systems (tataH)2(pdtc) and (AcrH)2(pydc), respectively, in aqueous solution, after evaporation of the solvent. Our results show that noncovalent interactions such as hydrogen bonds, sulfur···sulfur, and π···π interactions, when acting cooperatively, are driving forces for the selection of different structures. The protonation constants of Acr, tata, pdtcH2, and pydcH2, the building blocks of the proton-transfer systems (tataH)2(pdtc) and (AcrH)2(pydc), and the stability constants of these systems were determined by potentiometric studies in a dioxane/H2O (1:1 v/v) mixture. The stoichiometry and the formation stability constants of complexes formed on reacting pydcH2/Acr or pdtcH2/tata 1:1molar mixtures with the UO2 2+ ion in dioxane/H2O (1:1 v/v) were investigated by potentiometric pH titration methods. The stoichiometries of the complex species formed in solution were compared with those observed for the crystalline metal ion complexes 1 and 2. [Copyright &y& Elsevier]

The process of mechanically stirred membrane reactor containing the suspension of horseradish peroxidase (HRP) immobilized on synthesized nanocomposite (Tau-SiO 2 @Fe 3 O 4 -GO) was designed for continuous degradation of tetracycline. The immobilized HRP was characterized in terms of kinetic parameters and catalytic activities as these parameters were improved highly through immobilization. The stability indices including pH and temperature were investigated in parallel. The immobilized HRP was more tolerable to pH changes as compared to free HRP and the optimum temperature obtained at 40 °C. The reusability of HRP was promoted by immobilization as far as 70% of initial activity after ten cycles. The enzymatic degradation of optimum concentration of tetracycline was carried out in batch condition and 100% of tetracycline removed after 30 min. The results also showed that higher concentration of H 2 O 2 exhibited more oxidation of tetracycline. The optimal ratio of HRP/H 2 O 2 was also obtained at 0.005. The simultaneous process including separation and the biocatalytic degradation established in the membrane stirrer reactor concluded that no amount of tetracycline was observed in the permeate stream coming from the membrane after 30 min of operation., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Novel magnetic molecularly imprinted nanoparticles (MMIPs) using N,N-p-phenylene bismethacryl amide as a cross linker and super paramagnetic core-shell nanoparticle as a supporter for use in controlled release were prepared by precipitation polymerization. Novel cross-linking agents were synthesized by the reaction of methacryloyl chloride with p-phenylenediamine. Then, the Fe3O4 nanoparticles were encapsulated with a SiO2 shell and functionalized with -CH=CH2 and MMIPs were further prepared by using methacrylic acid as a functional monomer, N,N-p-phenylene bismethacryl amide as a cross-linking agent and betamethasone as template. Magnetic non-MIPs were also prepared with the same synthesis procedure as with MMIPs only without the presence of the template. The obtained MMIPs were characterized by using transmission electron microscopy, Fourier transform infrared spectrum, X-ray diffraction, energy-dispersive X-ray spectroscopy, and the vibrating sample magnetometer. The performance of the MMIPs for the controlled release of betamethasone was assessed and results indicated that the magnetic MIPs also had potential applications in drug controlled release.

The novel magnetic molecularly imprinted polymers (MMIPs) had been synthesized using N,N-bis methacryloyl ethylenediamine as a cross-linker for the controlled release of meloxicam at a pH of 1.0 (simulated gastric fluid), at a pH of 6.8 (simulated intestinal fluid) and at a pH of 7.4 (simulated biological fluids). The MMIPs were prepared via precipitation polymerization, using Fe3O4 as a magnetic component, meloxicam as a template molecule, methacrylic acid (MAA) as a functional monomer and N,N-bis methacryloyl ethylenediamine as a new cross-linker in acetonitrile/dimethyl sulfoxide porogen. Magnetic non-molecularly imprinted polymers (MNIPs) were also prepared with the same synthesis procedure as with MMIPs only without the presence of the template. The obtained MMIPs were characterized using transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR), dynamic light scattering (DLS), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM). The performance of the MMIPs for the controlled release of meloxicam was assessed, and the results indicated that the magnetic MIPs also had potential applications in drug controlled release.

In the present work, gold electrode modified with novel aldehyde-terminated self-assembled monolayers (SAMs) was used for controllable load and release of dopamine molecules by pH triggering. Electrochemical techniques including cyclic voltammetry (CV) and electrochemcial impedance spectroscopy (EIS) were employed to investigate the SAMs characteristic on the gold electrode surface. The electrochemical experiments indicated Faradaic behavior for the electrode surface after its modification with dopamine. Notably, it was observed that decreasing the conditioning pH, results in a decrease of peak currents, presumably due to the hydrolysis of the terminal imine bonds and releasing the dopamine moiety into the solution. Moreover, the preliminary kinetics studies were done for dopamine release from the SAMs surface as a model to design future drug delivery systems. Finally, the rate constant of dopamine release from the SAMs modified surface estimated to be 0.167 day(-1) at pH=3., (© 2013.)