Sulfoethylated polyethylenimine: synthesis in gel and sorption properties

Using the gel synthesis approach of polymer-analogous transformations, N-sulfoethylation of polyethylenimine was carried out by treating the polymer with sodium vinyl sulfonate. The compositions and structures of the products were characterized by elemental analysis, FT-IR spectroscopy, and ¹H NMR spectroscopy. At pH 3.0–4.5 sulfoethylated polyethylenimine can selectively extract Ag^I and Cu^II from an ammonia—acetate buffer solution in the presence of a series of transition and alkaline-earth metals. At pH > 6.5 the sorbent can be used for the group extraction of a number of transition metal ions. The structural feature of the obtained derivative eliminates the selectivity of sorption of Ag^I ions compared to Cu^II ions, which has previously been revealed for the sulfoethylated derivatives of chitosan and polyaminostyrene.

     

Complexing properties of N-[1,1-bis(hydroxymethyl)ethyl]-and N-[tris(hydroxymethyl)methyl]-β-alanine

Russian Chemical Bulletin - Protolytic and complexing properties of N-[1,1-bis(hydroxymethyl)ethyl]- and N-[tris-(hydroxymethyl)methyl]-β-alanine were estimated using the potentiometry. Values...     

Synthesis and surface structural characteristics of new polysiloxane xerogel

Pyridylethylaminopropylpolysiloxane xerogel (PEAPPSX) was synthesized by sol-gel technology. The composition of the substance was determined via elemental analysis and 1H NMR spectroscopy. The surface structural characteristics of the xerogel were determined by electron microscopy and low-temperature nitrogen sorption; thermal analysis was also performed. It was established that the content of functional groups in PEAPPSX was 2.43 mmol/g, and that xerogel is a mesoporous substance with a developed surface (121.71 m²/g).     

Effect of the nature of ions on the position of the absorption bands of water OH bonds in diffuse reflection spectra in the near-infrared region

The effect of the nature of anions and cations on the position of the absorption bands of free and crystallization water in inorganic salts in the near-infrared region (7400–4000 cm⁻¹) was systematically studied. It was shown experimentally that the shift of the absorption bands of free water to the high-frequency region is 100 cm⁻¹ in the region of 6900 and 62.1 cm⁻¹ in the region of 5160 cm⁻¹. It was concluded that the results on the shift of the water absorption bands in moisture-containing solid-state compounds with respect to those of pure liquid water can serve for a qualitative estimate of the bond energy of water with the substance under study and can be used to choose the wavelength for measuring the humidity of these objects and those more complicated in composition by means of near-infrared spectroscopy.     

Complexes of mono- and bis(2-carboxyethyl)-2-picolylamine: Synthesis and crystal and molecular structures

N-(2-Pyridylmethyl)iminodipropionic (I) and N-(2-pyridylmethyl)-3-aminopropionic acids (II) were obtained. A reaction of acid I with a Cu(II) salt gave a 2: 2 complex (III); a reaction of acid II with a Ni(II) salt yielded a 1 : 2 complex (IV). The crystal structures of these complexes were determined by X-ray diffraction. The abilities of compounds I and II to form complexes were compared with the literature data for other ligands containing the N-(2-pyridylmethyl)amino fragment. The structural features of the chelate complexes with 2-aminomethylpyridine derivatives were revealed, depending on the other substituents and the metal center.     

Acceptor doping of single-walled carbon nanotubes by encapsulation of zinc halogenides

To modify the electronic properties of single-walled carbon nanotubes (SWCNTs), ZnX₂@SWCNT (X = Cl, Br, I) nanostructures were prepared by capillary filling of 1.4–1.6 nm single-walled carbon nanotubes (SWCNT) with zinc halogenide melts. The loading factor is estimated as 30% for ZnCl₂ and approximately 60% for ZnBr₂ and ZnI₂. Well-ordered 1D crystals were observed by TEM only for ZnI₂@SWCNT. We propose two possible atomic structures of the 1D crystals, (Zn₄I₇) _n and less stable (Zn₄I₉) _n . According to the optical absorption and photoemission data, there is a charge transfer from the nanotube to the filler for all ZnX₂@SWCNT nanostructures. The results of the DFT PW-GGA modeling indicate that the acceptor properties correspond to (Zn₄I₉) _n only.     

N-Substituted-3-aminopropylsilsesquioxanes: synthesis,physicochemical properties,and application

Russian Chemical Bulletin - Synthesis and study of the physicochemical properties of silsesquioxanes modified with 3-aminopropyl, 2-aminoethyl-3-aminopropyl, and dithiooxamide groups was carried...     

Preparation of a chelating sorbent based on pyridylethylated polyethylenimine for recovering transition metal ions

A method was developed for preparing a chelating amino polymer, pyridylethylpolyethylenimine with maximal degree of substitution, by polymer-analogous transformations of branched polyethylenimine in reaction with 2-vinylpyridine. The ability of cross-linked pyridylethylpolyethylenimine with the degree of substitution of 0.32 to sorb Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺, Cd²⁺, Mn²⁺, and Pb²⁺ ions present simultaneously in solution was evaluated. In an ammonium acetate sorption system (pH 3.5–4.0), the sorbent selectively interacts with Cu(II) ions.     

Chemical properties of N-2-Sulfoethylchitosan with a medium degree of substitution

A method was developed for the preparation of N-2-sulfoethylchitosan (SECH) via synthesis in a gel with the use of the reaction of chitosan and sodium 2-bromoethanesulfonate. This method makes it possible to conduct a polymer-like transformation without any acid or base. The structures of the obtained polymers were confirmed via IR and ¹H NMR spectroscopy. The study of the sorption of Ag⁺, Cu²⁺, Zn²⁺, Ni²⁺, Co²⁺, Cd²⁺, Pb²⁺, Mn²⁺, Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺ ions that were crosslinked by SECH during their joint presence in an ammonia-acetate buffer solution showed high values of selectivity in relation to those of silver(I) and copper(II). The selectivity of the sorption of silver(I) ions with respect to copper(II) ions increased with an increase in the degree of substitution of SECH.     

Synthesis, XRD structure and properties of diaqua(p-toluidine-N,N-di-3-propionato)copper(II) dihydrate [Cu(p-Tdp)(H2O)2]·2H2O

The copper(II) complex [Cu(p-Tdp)(H₂O)₂]·2H₂O, where p-Tdp is the anion of p-toluidine-N,N-di-3-propionic acid (or N,N-di(2-carboxyethyl)-p-toluidine), has been synthesized and characterized by X-ray diffraction. Three crystallographically independent [Cu(p-Tdp)(H₂O)₂] molecules have a similar structure. The Cu atoms have a square pyramidal environment (4+1) with a small trigonal bipyramidal distortion. The ortho-H atom of the benzene ring blocks up the sixth coordination position of the Cu polyhedron. The basal plane is formed by the donor atoms of the tridentate ligand and by the water molecule (average bond length Cu---N 2.03, Cu---O 1.93, Cu---O_w 2.00 Å), the apex is occupied by another water molecule (Cu---O_w 2.27 Å). The Cu atoms are located 0.20–0.30 Å out of the mean planes of the four basal atoms towards the apical O_w atom. The IR and electronic absorption spectra of p-Tdp and the title compound have been described. UV–Vis reflectance spectra shows that the complex has the same square pyramidal geometry in the crystal state and in solution. The protonation constants of the ligand log K₁=6.87(2), log K₂=3.75(2), log K₃=2.57(2) and stability constants log K_CuH(p-Tdp)=2.13(5), log K_Cu(p-Tdp)=6.38(3) were determined by pH-titration at 25.0 °C and I=0.1 M KNO₃.