Synthesis, molecular structure and spectral properties of quaternary ammonium derivatives of 1,1-dimethyl-1,3-propylenediamine

1,1-Dimethyl-3-oxo-1,4-diazepan-1-ium chloride (1) and 1,1-dimethyl-1-carboxymethyl-3-aminopropyl ammonium hydrochloride (2) have been obtained by the reactions of 1,1-dimethyl-1,3-propylenediamine with ethyl chloroacetate and chloroacetic acid, respectively. The products have been characterized by FTIR, Raman and NMR spectroscopy. B3LYP calculations have also been carried out. The screening constants for (13)C- and (1)H- atoms have been calculated by the GIAO/B3LYP/6-31G(d,p) approach and analyzed. The FTIR and NMR spectra of the investigated compounds 1 and 2 are in excellent agreement with the structures optimized by Density Functional Theory (DFT) calculations.     

Double deposition/accumulation and double stripping steps system as a new way of decreasing the detection limit and elimination of interferences in stripping voltammetry of inorganic ions: A review

The article reviews an application of double deposition/accumulation and stripping steps as a new and beneficial manner of decreasing a detection limit and/or interferences elimination in stripping voltammetric determination of inorganic ions: Pb(II), Cd(II), Tl(I), U(VI), Au(III), As(III), Se(IV), In(III), Co(II), Cu(II), Bi(III) and Ga(III). A simple design of four-electrodes system, containing two working electrodes differing in their surface area, allows for conducting two preconcentration and two stripping steps in one measurement cycle and in one voltammetric cell. Considerable analytes preconcentration and, consequently, an increase of sensitivity of determinations was obtained by conducting the first stripping step in a small volume of a solution near the microelectrode surface. An appropriate selection of the conditions of the first deposition/accumulation and the first stripping steps allowed for a minimization/elimination of interference effects. The proposed procedures allows for ultra-trace levels determinations of mentioned inorganic ions (often impossible to determine by means of traditional three-electrodes systems) without additional preconcentration outside the electrochemical cell and with the use of mercury-free electrodes.     

Kinetics of the CCl2 + Br2 and CCl2 + NO2 reactions in the temperature range 266−365 K and reactivity of the CCl2 biradical

The kinetics of the CCl₂ + Br₂ and CCl₂ + NO₂ reactions have been studied at temperatures between 266 and 365 K using laser photolysis/photoionization mass spectrometry. Dichloromethylene biradicals were produced by the pulsed laser photolysis of CCl₄. The bimolecular rate coefficients of the CCl₂ + Br₂ reaction can be described by the Arrhenius expression k₁ = (7.05 ± 1.75) × 10⁻¹² exp[(3.52 ± 0.63) kJ mol⁻¹/RT] cm³ molecule⁻¹ s⁻¹. CCl₂Br was observed as a primary product of this reaction. Interestingly, the bimolecular rate coefficients of the CCl₂ + NO₂ reaction were observed to depend weakly on the bath gas density and to possess a negative temperature dependence.     

Biologically Active Heteroglycoclusters Constructed on a Pillar[5]arene‐Containing [2]Rotaxane Scaffold

A synthetic approach combining recent concepts for the preparation of multifunctional nanomolecules (click chemistry on multifunctional scaffolds) with supramolecular chemistry (self‐assembly to prepare rotaxanes) gave easy access to a large variety of sophisticated [2]rotaxane heteroglycoclusters. Specifically, compounds combining galactose and fucose have been prepared to target the two bacterial lectins (LecA and LecB) from the opportunistic pathogen Pseudomonas aeruginosa.     

Effect of carbon nanotube modification on poly(butylene terephthalate)-based composites

The influence of the chemical modification of carbon nanotubes on the mechanical, thermal and electrical properties of poly(butylene terephthalate)-based composites was investigated. Polymer composites based on poly(butylene terephthalate) were obtained via in situ polymerisation or extrusion. Commercially available multi-walled carbon nanotubes (Nanocyl NC7000) at different loadings (mass %: 0.05, 0.25, 1, 2) were used as fillers. The functionalisation process took place under a chlorine atmosphere followed by a reaction with sodium hydroxide. The effect of carbon nanotube modification was analysed according to the changes in the polymer thermal and mechanical properties. An addition of modified carbon nanotubes in the amount of 0.05 mass % improved the mechanical properties of the composites in terms of both Young’s modulus and tensile strength by 5–10 % and 17–30 % compared with composites with unmodified carbon nanotubes and neat poly(butylene terephthalate), respectively. The in situ method of composite preparation was a more effective technique for enhancing the matrix-filler interactions, although a significantly lower amount of fillers were used than in the extrusion method.     

Synthesis of silver nanoparticles in NMMO and their in situ doping into cellulose fibers

We present a method for synthesis of silver nanoparticles in N-methylmorpholine N-oxide (NMMO) and the associated mechanism, as well as their use for in situ volume modification of cellulose fibers. The synthesized particles had diameter of about 4 nm, and their colloid solution was stable for 1 year. The nanoparticles were stabilized using polyethylenimine, which apart from preventing nanoparticle agglomeration, also accelerated Ag⁺ ion reduction and prevented NMMO degradation. A mechanism for the nanoparticle synthesis is suggested based on the electrochemical potentials of all ions in solution, with perhydroxyl ions resulting from NMMO reducing the silver ions. We also created nanocomposites from fibers and silver nanoparticles, in which the latter showed very good dispersion in the fiber volume. Such spun fibers showed improved mechanical parameters in comparison with unmodified fibers.     

Structure,Physicochemical and Biological Properties of an Aqua (2,2′,2′′‐Nitrilotriacetato)‐oxidovanadium(IV) Salt with 4‐Methylpyridinium Cation

The crystal structure of a nitrilotriacetate (nta) oxidovanadium(IV) salt with 4‐methylpyridinium cation, [4‐Me(Py)H]⁺, of [4‐Me(Py)H][VO(nta)(H₂O)] stoichiometry was determined. The complex comprises a discrete mononuclear [VO(nta)(H₂O)]^– coordination entity that can be rarely found among other known compounds containing nitrilotriacetate oxidovanadium(IV) moieties. The complex was characterized by spectroscopic (IR and EPR) methods, magnetic measurements, and thermogravimetry (TG‐FTIR). The stability of the title compound in aqueous solutions was investigated by using the potentiometric titration method. Furthermore, spectrophotometric (UV/Vis) studies have revealed that the compound is capable to scavenge the superoxide free radicals (O₂ ^{? –}) as well as stable organic radicals i.e. 2,2′‐azinobis(3‐ethylbenzothiazoline‐6 sulfonic acid) cation radical (ABTS^{+ ?} ) and 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH ^? ). Finally, biological properties of the complex studied were investigated in relation to its cytoprotective activity against the oxidative damage generated exogenously by using hydrogen peroxide in the HT22 hippocampal neuronal cell line (the MTT assay). Additionally, the biological action of the compound towards two human osteosarcoma HOS and MG‐63 cell lines (the MTT and BrdU tests) as well as the untransformed human osteoblast hFOB 1.19 cell line was tested.     

Bonding interactions in oxydiacetate and thiodiacetate cobalt(II) and nickel(II) complexes

The influence of the central donor atom of the oxydiacetate and thiodiacetate ligands (oxygen and sulphur atoms, respectively) on the thermodynamic parameters for complexation reactions of the Co²⁺ and Ni²⁺ ions has been investigated using the isothermal titration calorimetry (ITC) technique and density functional theory (DFT) computations. The polarized continuum (PCM) - solvation model was employed to describe the structural factors that govern the coordination modes of the ligands (mer or fac) in the solution. The differences in the binding enthalpies of the investigated complexes were discussed based on the results obtained both from the natural bond orbital (NBO) analysis and the second-order perturbation theory.     

2-Methylthio-imidazolins: a rare case of different tautomeric forms in solid state and in solution

Structural Chemistry - The synthesis and structure elucidation of two new compounds, 2-(methylthio)-1,3-diazaspiro[4.4]non-2-ene-4-one (1) and 2-(methylthio)-1,3-diazaspiro[4.4]non-2-ene-4-thione...     

Macro- and micro- elements in some herbal drug raw materials and their water extracts consumed in Poland

The concentrations of seven macro- and microelements (K, Mg, Ca, Na, Fe, Zn, Mn) in 59 herbs (herbs, leaves, flowers, fruits, roots), which are commercially available and frequently used in Poland for medical purposes as well as in their water extracts (infusions and decoctions), were determined after microwave mineralization. The data obtained show that all herbal raw materials analysed contain macroelements in the range of mg g⁻¹ on d.w. whereas microelements in the range of mg kg⁻¹ on d.w. and that elemental concentrations varied widely. On the basis of a comparison of concentrations of elements in herbal raw materials examined and water extracts prepared from them, the extraction efficiency was expressed as a percent of the total content of each element present in the infusion or decoction. The percentages of macro- and micro- elements leaching from different morphological parts of plants into water extracts varied across a wide range of values, from 1% in the case of Na to 56% in the case of K. Real daily intake of the macro- and microelements elements through one cup of infusions or decoctions were shown that water extracts from herbal raw materials are not an important source of bioelements in human diet.