Immobilization of palladium nanoparticles on ionic liquid-triethylammonium chloride functionalized magnetic nanoparticles: As a magnetically separable,stable and recyclable catalyst for Suzuki-Miyaura cross-coupling reactions

A facile procedure was applied to successfully synthesize novel Pd nanoparticles immobilized on triethanolamine-functionalized magnetic nanoparticles [Fe₃O₄/IL/Pd]. Diverse characterizations (HR-TEM, XRD, FT-IR, TGA, EDX, FE-SEM, ICP, XPS and VSM) were carried out to identify intrinsic traits of the nanoparticles. At room temperature, Fe₃O₄/IL/Pd demonstrated high catalytic activity toward Suzuki-Miyaura cross-coupling reactions in aqueous solution. Based on the results, Fe₃O₄/IL/Pd acted as zwitterionic IL-type heterogeneous catalyst, which could be separated from the reaction mixture, conveniently. Moreover, it exhibited excellent recyclability for at least eight cycles without considerable loss of its activity.     

Fluorescence and DNA-binding spectral studies of neodymium(III) complex containing 2,2′-bipyridine, [Nd(bpy)2Cl3·OH2]

The interaction of [Nd(bpy)₂Cl₃·OH₂], where bipy is 2,2′-bipyridine, with DNA has been studied by absorption, emission, and viscosity measurements. [Nd(bpy)₂Cl₃·OH₂] showed absorption decreasing in charge transfer band with increasing of DNA. The binding constant, K_b has been determined by absorption measurement and found to be (1.5 ± 0.1) × 10⁵ M^?1. The fluorescent of [Nd(bpy)₂Cl₃·OH₂] has been investigated in detail. The interaction was also studied by fluorescence quenching technique. The results of fluorescence titration revealed that DNA had the strong ability to quenching the intrinsic fluorescence of Nd(III) complex at 327 nm. The binding site number n, apparent binding constant K_b and the Stern–Volmer quenching constant K_SV have been determined. Thermodynamic parameters have been calculated according to relevant fluorescent data and Van’t Hoff equation. Characterization of bonding mode has been studied. The results suggested that the major interaction mode between [Nd(bpy)₂Cl₃·OH₂] and DNA was groove binding.     

A nanosized cadmium(II)-imprinted polymer for use in selective trace determination of cadmium in complex matrices

We describe a nanosized Cd(II)-imprinted polymer that was prepared from 4-vinyl pyridine (the functional monomer), ethyleneglycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the radical initiator), neocuproine (the ligand), and Cd(II) (the template ion) by precipitation polymerization in acetonitrile as the solvent. The imprinted polymer was characterized by X-ray diffraction, thermogravimetric analysis, differential thermal analysis, and scanning electron microscopy. The maximum adsorption capacity of the nanosized sorbent was calculated to be 64 mg g^?1. Cadmium(II) was then quantified by FAAS. The relative standard deviation and limit of detection are 4.2 % and 0.2 μg L^?1, respectively. The imprinted polymer displays improve selectivity for Cd(II) ions over a range of competing metal ions with the same charge and similar ionic radius. This nanosized sorbent is an efficient solid phase for selective extraction and preconcentration of Cd(II) in complex matrices. The method was successfully applied to the trace determination of Cd(II) in food and water samples.

Facile synthesis of 4-nitro-N-substituted-1,8-naphthalimide derivatives using ultrasound in aqueous media

This study describes the ultrasound-assisted synthesis of 4-nitro-N-substituted-1,8-naphthalimide derivatives from 4-nitro-1,8-naphthalic anhydride and related amines by irradiating at 35 KHz in a sonic bath in aqueous media at room temperature. The results obtained by this method are comparable to those obtained by a common reflux method. The imidation reaction under ultrasound irradiation preceded 8 and 20 times faster than the common method and produced higher yields.     

How far the substituent effects in disubstituted cyclohexa-1,3-diene derivatives differ from those in bicyclo[2.2.2]octane and benzene?

Structural Chemistry - Substituents effects in cyclic diene derivatives are studied using quantum chemical modeling and compared to the corresponding effects in aromatic (benzene) and fully...     

Solid-phase iodine as an oxidant in flow injection analysis: determination of ascorbic acid in pharmaceuticals and foods by background correction

A flow injection analysis (FIA)-background correction method comprising two solid-phase reactors and spectrophotometry for determination of ascorbic acid (AsA) is proposed. A polyethylene mini-column filled with solid iodine (30% m/m suspended on silica gel beads), reactor 1, and other column filled only with silica gel, reactor 2, which are then incorporated in a flow system so that solid iodine reagent in reactor 1 is affected as the sample passes through the column. The sample blank is produced by the oxidation of the AsA by iodine to form dehydroascorbic acid, insensitive to ultraviolet at 267 nm. AsA in samples is determined after injected in reactor 2; the difference in two analytical signal observed is related to amount of AsA. The linear range of the system is up to 50 μg ml⁻¹ with a detection limit of 0.08 μg ml⁻¹, R.S.D. of better than 1.0% and sampling frequency of 110 sample h⁻¹. The method is successfully applied to the determination of AsA in pharmaceuticals and foods.     

Computational and experimental study on the interaction of three novel rare earth complexes containing 2,9-dimethyl-1,10-phenanthroline with human serum albumin

In this paper, several rare earth [terbium(III), ytterbium(III) and yttrium(III)] complexes containing 2,9-dimethyl-1,10-phenanthroline (Me₂Phen) were successfully synthesized and characterized by means of elemental analysis (CHN), infrared spectroscopy (FT-IR), UV–vis absorption spectroscopy and ¹HNMR. To explore the potential medicinal value of these complexes (MMe₂Phen), their binding interactions with human serum albumin (HSA) were investigated through UV–vis and fluorescence spectroscopies and also molecular docking examinations. The thermodynamic parameters, binding forces and Förster resonance distance between these complexes and Trp-214 of HSA were estimated from the analysis of fluorescence measurements. The values of estimated binding constants (K_b) ranging for the formation of MMe₂Phen:HSA complex were in the order of 10⁵ M^?1. The thermodynamic parameters determined by van’t Hoff analysis of K_b (ΔH°?<?0 and ΔS°?<?0) clearly indicate the major rules of hydrogen bonds and van der Waals interactions in the formation process of MMe₂Phen:HSA. The values of Stern–Volmer constant and the evaluation of dynamic quenching constant at various temperatures provided good evidences for static quenching mechanism. Furthermore, the results of molecular docking calculation and competitive binding experiments represent the binding of these complexes to site 3 of HSA located in subdomain IB, containing both polar and apolar residues. The consistency of computational and experimental results, according to the binding sites and the order of binding affinities (TbMe₂Phen?>?YbMe₂Phen?>?YMe₂Phen), supports the accuracy of docking calculation.     

Reaction of dimethylplatinum(II) complexes with PhCH2CH2Br: Comparative reactivity with CH3CH2Br and PhCH2Br and synthesis of Pt(IV) complexes

Oxidative addition of 2‐phenylethylbromide (PhCH₂CH₂Br) to dimethylplatinum(II) complexes [PtMe₂(NN)] ( 1a , NN = 2,2′‐bipyridine (bpy); 1b , NN = 1,10‐phenanthroline (phen)) afforded the new organoplatinum(IV) complexes [PtMe₂(Br)(PhCH₂CH₂)(bpy)], as a mixture of trans ( 2a ) and cis ( 3a ) isomers, and [PtMe₂(Br)(PhCH₂CH₂)(phen)], as a mixture of trans ( 2b ) and cis ( 3b ) isomers, respectively. The new Pt(IV) complexes were readily characterized using multinuclear (¹H and ¹³C) NMR spectroscopy and elemental microanalysis. The crystal structure of 2a was further determined using X‐ray crystallography indicating an octahedral geometry around the platinum centre. A comparison of reactivity of RCH₂Br reagents (R = CH₃, Ph or PhCH₂) in their oxidative addition reactions with complex 1a , with an emphasis on the effects of the R groups of alkyl halides, was also conducted using density functional theory.