Dioxidomolybdenum(VI) complexes of allyl N'-2-hydroxy-3-methoxybenzylidenecarbamohydrazonothioate: synthesis,spectral, and theoretical investigations

The new dibasic NNO ligand H₂L (H₂L = allyl N′-2-hydroxy-3-methoxybenzylidenecarbamohydrazonothioate) was synthesized by condensation of 2-hydroxy-3-methoxybenzaldehyde with the product resulting from the reaction of thiosemicarbazide with allyl bromide. Four dioxidomolybdenum(VI) complexes with the general formula [MoO₂L(S)] (S=MeOH, EtOH, DMSO, and 1-methylimidazole) were synthesized and characterized by elemental analysis, FT-IR, EI-MS and UV-Vis spectroscopy, and by X-ray crystallography. Spectroscopic evidence indicates that the cis-MoO₂ chelates have octahedral geometry in which H₂L coordinates via the phenolate oxygen, azomethine nitrogen and deprotonated thioamide nitrogen. The other sites are occupied by two oxido and an additional ligand (S). Density functional theory calculations of spectral parameters were also carried out for these systems.     

Simultaneous voltammetric determination of uric acid and ascorbic acid using carbon paste/cobalt Schiff base composite electrode

Differential pulse and cyclic voltammetry were applied for the oxidation of mixture of uric acid and ascorbic acid at the surface of carbon paste/cobalt Schiff base composite electrode. The electrooxidation of these compounds at bare electrode is sluggish, and there is no suitable peak separation between them. However, using cobalt methyl salophen as modifier, two well-defined anodic waves with a considerable enhancement in the peak current and a remarkable peak potential separation near 315 mV are obtained. It can improve the kinetics of electron transfer for both compounds remarkably. All these improvements are created because of the electrocatalytic property of cobalt Schiff base complex. The effect of some parameters such as pH and scan rates were studied. All the anodic peak currents for the oxidation of ascorbic acid and uric acid shifted toward more negative potential with an increase in pH, revealing that protons have taken part in their electrode reaction processes. The best peak separation with appropriate current was obtained for pH 4.0. A linear range of 5.0?×?10^?4 to 1.0?×?10^?8 and 1.0?×?10^?3 to 1.0?×?10^?8 M with detection limit of 8.0?×?10^?9 and 8.0?×?10^?9 M was obtained for ascorbic acid and uric acid using differential pulse voltammetry at the surface of modified electrode, respectively. Analytical utility of the modified electrode has been examined successfully using human urine samples and vitamin C commercial tablets.     

Small signal gain and saturation intensity of a Yb:Silica fiber MOPA system

In this work, the small signal gain (γ₀) and signal saturation power (P_sat) of a continuous wave (CW) single-frequency ytterbium-doped (YD) double-clad (DC) fiber master oscillator power amplifier (MOPA) array has been determined in the optimum length. At first, we have obtained output versus input signal powers in the amplifier, using the coupled steady-state rate equations for the various end diode pumping such as co/counter propagation and bidirectional modes. On the other hand, the steady-state amplification relation was employed at a presumed γ₀ and P_sat as initial guess, to generate output signals. Then, using the least square method (LSM), those input/output signal powers were fitted by the best regression curve obtained from the amplification relation to determine the converged γ₀ and P_sat values. The analytical formulae for γ₀ and P_sat were derived using the rate equations as well.     

Optimization of Raman gain spectrum using Lagrangian multiplier method

Based on Lagrangian multiplier method (LMM), the gain spectrum of distributed multi-pump Raman amplifier (DMRA) is optimized. Beside of governing rate equations in Raman amplifiers, we consider two applicable constrains on cost function for optimizing the gain spectrum. Because of more accurate and controllable designing of DMRAs, a maximum power for each input pump wave is considered as well as average gain value as two constrains. LMM reduces the optimization problem with constrains to solve a two-point boundary value problem for each solution. This method is applied to minimizing gain ripple of full bandwidth (60 nm) a 100 Km Raman amplifier for different number of pumps.     

Synthesis,Crystal Structure,Spectroscopic, Electrochemical and Antimicrobial Properties of Cu(II) Complex with the Mixed Ligands of 2,9‐Dimethyl‐1,10‐phenanthroline and 4‐Hydroxypyridine‐2,6‐dicarboxylic Acid

A mononuclear Cu(II) complex with mixed ligands, formulated as [Cu(hypydc)(dmp)]·H₂O (hypydc=4‐hydroxypyridine‐2,6‐dicarboxylate, dmp=2,9‐dimethyl‐1,10‐phenanthroline), was synthesized and well characterized by single crystal X‐ray diffraction analysis, as well as spectroscopic (IR, UV‐Vis), and electrochemical methods. The Cu(II) atom exhibits a distorted square‐pyramidal geometry. Intermolecular O? H···O and C? H···O hydrogen bonds, π‐π stacking interactions and C? H···π interactions seem to be effective in the stabilization of the crystal structure. The complex was also evaluated for its antimicrobial activity using in vitro microdilution methods. Six standard bacteria and a strain of Candida albicans were used for the antimicrobial activities. There was a very strong activity against Candida albicans and significant activities against Enterococcus fecalis, Listeria monocytogenes, Bacillus cereus and Staphylococcus aureus, indicating important biological activities of the complex.     

Synthesis, characterization and electrochemical properties of two new calix[4]arene derivatives bearing two ferrocene imine or ferrocene amine units at the upper rim

A novel calix[4]arene derivative with two ferrocenyl Schiff-base groups at the upper rim 3 has been synthesized from 5,17-diformyl-25,27-dipropoxy-26,28-dihydroxy calix[4]arene and 4-ferrocenylaniline via condensation reaction. Reduction of 3 with sodium borohydride led to calix[4]arene derivative 4 with two amino ferrocenyl groups at the upper rim. The ferrocenyl Schiff-base calix[4]arene and its corresponding reduced amine have been purified and characterized by elemental analysis,¹H NMR, FTIR, Mass and UV-vis spectral data. Electrochemical properties of compounds 3 and 4 have been investigated. Cyclic voltammograms of 3 and 4 show reversible redox couples of ferrocene/ferrocinium at E_1/2=0.401 V and 0.346 V, respectively. Electrochemical studies show these redox active compounds electrochemically recognize trivalent lanthanides La³⁺ and Ce³⁺ and divalent Pb²⁺ and Cu²⁺cations. With ferrocenyl Schiff-base calix[4]arene 3 an anodic shift as large as 130 mV is observed on addition of one equivalent of Ce³⁺ ion. Also extraction properties of compound 4 towards some metal cations have been described. It has been observed that compound 4 has a good selectivity for metal cations Fe³⁺, Cu²⁺, Pb²⁺ and Cd²⁺ against Ni²⁺ and Co²⁺.     

One-pot synthesis of functionalized furamide derivatives via a three-component reaction between an amine, diketene and dibenzoylacetylene in the presence of triphenylphosphine

An effective route to functionalized furamide derivatives is described. This involves reaction of N-alkyl-3-oxobutanamides, derived from the addition of amines to the diketene, and dibenzoylacetylene in the presence of triphenylphosphoine. The reactive 1:1 intermediate obtained from the addition of triphenylphosphine to dibenzoylacetylene was trapped by OH-acids such as N-alkyl-3-oxobutanamide to produce functionalized furamide derivatives.     

Synthesis,characterization, cytotoxic activity and DNA-binding studies of cobalt (II) mixed-ligand complex containing pyridine-2,6-dicarboxylate ion and 2-aminopyrimidine

Treatment of pyridine-2,6-dicarboxylic acid and 2-aminopyrimidine with Co(NO₃)₂?6H₂O under hydrothermal conditions led to a new Co (II) complex [Co(amp)(pydc)(H₂O)₂]?H₂O (1), which was characterized by infrared spectroscopy, elemental analysis as well as X-ray diffraction studies. The DNA-binding behavior of the complex has been studied by UV–Vis absorption and fluorescence spectroscopic titration, viscosity measurements, thermal denaturation and circular dichroism (CD). The experimental results indicated that Co (II) complex was bound to DNA by an intercalative mode. The intrinsic binding constant of Co (II) complex with DNA was (3.80 ± 0.02) × 10⁴ M^?1. The biological effects of the Co (II) complex were also studied by MTT assay in MCF-7 and HT-29 cancer cell lines. Treatment of MCF-7 and HT-29 cells with Co (II) complex resulted in a concentration-dependent cell growth inhibition.     

Using synchrotron radiation inline phase‐contrast imaging computed tomography to visualize three‐dimensional printed hybrid constructs for cartilage tissue engineering

Synchrotron radiation inline phase‐contrast imaging combined with computed tomography (SR‐inline‐PCI‐CT) offers great potential for non‐invasive characterization and three‐dimensional visualization of fine features in weakly absorbing materials and tissues. For cartilage tissue engineering, the biomaterials and any associated cartilage extracellular matrix (ECM) that is secreted over time are difficult to image using conventional absorption‐based imaging techniques. For example, three‐dimensional printed polycaprolactone (PCL)/alginate/cell hybrid constructs have low, but different, refractive indices and thicknesses. This paper presents a study on the optimization and utilization of inline‐PCI‐CT for visualizing the components of three‐dimensional printed PCL/alginate/cell hybrid constructs for cartilage tissue engineering. First, histological analysis using Alcian blue staining and immunofluorescent staining assessed the secretion of sulfated glycosaminoglycan (GAGs) and collagen type II (Col2) in the cell‐laden hybrid constructs over time. Second, optimization of inline PCI‐CT was performed by investigating three sample‐to‐detector distances (SDD): 0.25, 1 and 3 m. Then, the optimal SDD was utilized to visualize structural changes in the constructs over a 42‐day culture period. The results showed that there was progressive secretion of cartilage‐specific ECM by ATDC5 cells in the hybrid constructs over time. An SDD of 3 m provided edge‐enhancement fringes that enabled simultaneous visualization of all components of hybrid constructs in aqueous solution. Structural changes that might reflect formation of ECM also were evident in SR‐inline‐PCI‐CT images. Summarily, SR‐inline‐PCI‐CT images captured at the optimized SDD enables visualization of the different components in hybrid cartilage constructs over a 42‐day culture period.     

Nanosized aptameric cavities imprinted on the surface of magnetic nanoparticles for high-throughput protein recognition

The authors introduce a new kind of surface artificial biomimetic receptor, referred to as aptameric imprinted polymer (AIP), for separation of biological macromolecules. Highly dispersed magnetic nanoparticles (MNPs) were coated with silica and then functionalized with methacrylate groups via silane chemistry. The aptamer was covalently immobilized on the surface of nanoparticles via a “thiol-ene” click reaction. Once the target analyte (bovine serum albumin; BSA) has bound to the aptamer, a polymer is created by 2-dimensional copolymerization of short-length poly(ethylene glycol) and (3-aminopropyl)triethoxysilane. Following removal of BSA from the polymer, the AIP-MNPs presented here can selectively capture BSA with a specific absorbance (κ) as high as 65. When using this AIP, the recovery of BSA from spiked real biological samples is >97%, and the adsorption capacity is as high as 146 mg g^?1. In our perception, this method has a wide scope in that it may be applied to the specific extraction of numerous other biomolecules.

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Graphical abstract Schematic presentation of the AIP (aptamer-imprinted polymer) introduced here. The surface of silica coated magnetic nanoparticles is modified with a polymer that is covalently modified with an aptamer against bovine serum albumin (BSA).