PMR of complexes of organohalostannanes with N-vinyl-N-ethylimidazole

The chemical shifts and spin-spin coupling constants of the protons of the vinyl and ethyl groups and of the imidazole ring in the PMR spectra of complexes R_4–n·SnX_n · mB, where R=C₂H₅, C₄H₉;X=Cl, Br, I; B is N-vinylimidazole or N-ethylimidazole; and n=1 (m=1) and 2 (m=2), are compared. The electronic and geometrical structures of these complexes are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 391–394, March, 1973.     

Conformational study of N-vinyl-2-isopropyl- and N-vinyl-2-cyclopropylpyrroles by1H and13C NMR

In N-vinyl-2-isopropylpyrrole the isopropyl group is in a conformation with the CH₃ group in an anti position to the vinyl group. On introducing a substituent at the 3 position of the ring the isopropyl group passes into a gauche and (or) a syn conformation, leading to an increase in the dihedral angle between the plane of the vinyl group and the pyrrole ring. In N-vinyl-2-cyclo-propylpyrrole the cyclopropyl group is 80% in the gauche form, which is attributed to the repulsion between the electrons of the -shells of the cyclopropyl and pyrrole fragments.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1031–1038, May, 1991.     

Halocuprate(II) complexes with isoxazolium and imidazolium derivatives

Summary We have synthesized and characterized halocuprate(II) complexes with isoxazolium and imidazolium derivatives. The compounds are of three types: a) Cu(LH)X₃ · n H₂O where L=isoxazole (isox), 3,5-diMeisox, or 5-amino-3,4-diMeisox (5-ADI); X=Cl or Br; n=1–2; b) (LH)₂CuCl₄ where L=5-ADI, N-ethylimidazole (N-EtIm) or N-PropIm; c) (3-AMIH)₂Cu₂X₆ where 3-AMI=3-amino-5-methylisox; X= Cl or Br.Complexes (a) seem to be zwitterions with an oxygenbonded ligand and approximately tetrahedral structure; compounds (b) are distorted tetrahedral, nearly square planar; derivatives (c) are polymeric or dimeric with near square planar geometry.     

Blends of poly(n-vinyl-2-pyrrolidone)/poly(monoitaconates) II. The coefficient of linear expansion

Blends of poly(monoitaconates)^b) containing different side chain structures with poly(N-vinyl-2-pyrrolidone) (PVP) of three different weight-average molecular weights (M̄_w) were studied by thermomechanical analysis. Blends containing PVP of M̄_w =10000 shows a monotonous variation of the coefficient of linear expansion α against composition but PVP samples of higher molecular weights present a minimum which is attributed to polymer-polymer complex due to strong specific interactions.     

Synthesis and Characterization of Poly[N-Vinyl-2-Pyrrolidone-Polyethylene Glycol Diacrylate] Copolymeric Hydrogels for Drug Delivery

Abstract

Novel polymeric biodegradable and biocompatible copolymeric hydrogels based on N-vinyl-2-pyrrolidone (NVP) and polyethylene glycol diacrylate (PAC) were designed and synthesized. PAC macromonomer was synthesized by a modified procedure and characterized. Poly[N-vinyl-2-pyrrolidone-polyethylene glycol diacrylate] (Poly[NVP-PAC]) hydrogels were synthesized by varying the concentration of PAC. Azobisisobutyronitrile (AIBN) was used as the free radical initiator and N,N¹-methylene bis(acryl-amide) (BIS) was employed as the crosslinking agent. These hydrogels were characterized by various spectroscopic techniques. Fourier transform-infrared spectroscopy (FT-IR) confirms the formation of copolymer. Thermogravimetric analysis (TGA) curves obtained were continuous indicating the formation of copolymer. The glass transition temperature (T_g) of the copolymer was measured using differential scanning calorimetry (DSC). The equilibrium swelling measurements were carried out in simulated gastric and intestinal fluids (SGF & SIF). These swelling studies indicated that these gels had a higher sorption capacity in SIF when compared to that in SGF. 5-Fuorouracil (5-FU), an anti-cancer drug was entrapped in these hydrogels and the in-vitro release profiles were established in a sequential manner in SGF and SIF. About 50–56% of the drug entrapped was released in a period of 10 days.     

Poly(styrene) coating of monodispersed colloidal metal oxides by grafting to hydrophilic macromer adsorbed on the surface

Poly(styrene) (PST) coatings of monodispersed colloidal metal oxide particles by surface grafting to poly(N-vinyl-2-pyrrolidone) (ST–PVP) or quaternized poly(4-vinylpyridine) (ST-PVPy(Me)) macromer, having a vinylphenylene end group, were investigated. Radical polymerization of styrene (ST) in ethanolic silica colloid in the presence of ST-PVP successfully led to the formation of monodispersed PST/PVP copolymer/SiO₂composites. The addition of divinylbenzene (DVB) to the reaction system gave SiO₂ composites coated with crosslinked PST. Graft-polymerization of ST to ST-PVP also took place on TiO₂, CeO₂ and Al(OH)₃ colloidal particles in ethanolic solution. However, ST-PVPy(Me) adsorbed on colloidal silica did not effectively graft PST.     

Synthesis of pyrrole-2-carboxylic acids and their N-vinyl derivatives

Haloform cleavage of 2-trifluoroacetyl- and N-vinyl-2-trifluoroacetylpyrroles gives pyrrole-2-carboxylic acids and their N-vinyl derivatives in good yields; most of these compounds do not melt between 120–190C, but rather decompose with CO₂ evolution.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 612–616, May, 1990.     

Synthesis and characterization of Pd-poly(N-vinyl-2-pyrrolidone)/KIT-5 nanocomposite as a polymer–inorganic hybrid catalyst for the Suzuki–Miyaura cross-coupling reaction

Composite poly(N-vinyl-2-pyrrolidone)/KIT-5 (PVP/KIT-5) was prepared by in situ polymerization method and used as a support for palladium nanoparticles obtained through the reduction of Pd(OAc)₂ by hydrazine hydrate. The physical and chemical properties of the catalyst were investigated by XRD, FT-IR, UV–vis, TG, BET, SEM, and TEM techniques. The catalytic performance of this novel heterogeneous catalyst was determined for the Suzuki–Miyaura cross-coupling reaction between aryl halides and phenylboronic acid in the presence of water at room temperature. The stability of the nanocomposite catalyst was excellent and could be reused 8 times without much loss of activity in the Suzuki–Miyaura cross-coupling reaction.     

Synthesis and PMR spectra of vinyl derivatives of 2-hydroxylepidine

The reaction of 2-hydroxylepidine with acetylene under pressure in various catalytic systems was investigated. 2-(Vinyloxy)lepidine and N-vinyl-2-lepidone were obtained, and their IR and PMR spectra were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 798–800, June, 1971.The PMR spectra were recorded at room temperature with a JNM-4H-100 spectrometer. The solvent was CCl₄, and the Internal standard was hexamethyldisiloxane ( scale).     

VINYLTRIMETHYLSILANE-CO-METHYLMETHACRYLATE COPOLYMERS. SYNTHESIS AND REACTIVITY RATIOS

In order to obtain information about the copolymerization process of vinyltrimethyl silane with comonomers of different chemical structure, copolymers containing vinyltrimethylsilane and methyl methacrylate at different compositions were synthesized and characterized. Comparison of the reactivity ratios of the resulting copolymers with those containing N-vinyl-2-pyrro-lidone and 2-vinylpyridine previously reported and other related comonomers with different chemical structure allows us to establish some reactivity structure relationship and a generalization for these systems. The monomer reactivity ratios r₁ and r₂ (MRR) were estimated by using the classical linear fitting procedures and also through a computer program based on a nonlinear minimization algorithm, starting from the r₁ and r₂ values obtained by the former procedures.     

Some observations on monomer reactivity ratios in aqueous and non-aqueous media

Reactivity ratios have been determined for free radical copolymerization of n.butyl acrylate (BA) with N-vinyl-2-pyrrolidone (VP) at 65°C in bulk and in the presence of water. For 0 to 30% by weight of water in the feed, the value of r_VP was sensibly constant (∼ 0.03 ± 0.03). The value of r_BA also underwent virtually no change (∼ 0.90 ± 0.05) at water contents from 0 to 22% by weight but increased to 3.7 at 25% water and to 6.3 at 30% water. These findings are not amenable to satisfactory explanation but one aspect of possible relevance is proposed tentatively.     

Structural effects of amphiphilic block copolymers on the gold nanoplates synthesis. Experimental and theoretical study

Geometric and multi-arms gold nanoplates were synthesized by direct reaction between two different amphiphilic block copolymers and KAuCl₄ in aqueous solution. Amphiphilic copolymers containing blocks of ε-caprolactone and N-vinyl-2-pyrrolidone were used. The block copolymer structures and concentration play a key role on the morphology and size of gold nanoparticles. Copolymers have a dual function as reductant and stabilizer agent. The gold nanoparticles obtained were characterized by transmission electron microscopy (TEM), UV–visible spectroscopy (UV–vis) and dynamic light scattering (DLS). On the other hand, electronic structure calculations, based on density functional theory were performed to support the experimental results. The simple models built with small clusters of gold and co-monomer units provide planar structures complexes with higher stabilization energies. These results agree with the nanoplates obtained experimentally. Moreover, the reactivity analysis based on monoelectronic properties suggests that the formation of aggregates between complexes is favored.     

Colloidal metal dispersions as catalysts for selective surface hydrogenation of biomembranes, 1. Preparation and characterization of palladium catalysts

Paliadium sols containing largely uniform, nanosize metallic, particles stabilized by poly(N-vinyl-2-pyrrolidone) were found to be active microheterogeneous catalysts for hydrogenation of water soluble olefinic substrates as well as of unsaturated lipid dispersions. The same metallic particles were supported on the surface of crosslinked insoluble poly(N-vinyl-2-pyrrolidone) and served as easily removable macroheterogeneous hydrogenation catalysts.     

Study of the stereochemistry of N-H and N-vinyl-4,5,7-trimethyi-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridines and their nitro derivatives by the method of 1H and 13C NMR

The configurations and conformational features of N-H and N-vinyl-4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridines and their nitro derivatives were established by the method of ¹H and ¹³C NMR spectroscopy. It was shown that the conformational uniformity of the piperideine ring in the compounds studied is strongly dependent on the character of the substituents in the pyrrole ring. A method for the determination of the orientation of the substituent at the -position to the nitrogen atom of the piperideine ring, according to the direct ¹J_CH SSCC, was proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 75–81, January, 1993.     

Conformational analysis of N-vinyl-2-phenylpyrrole

A conformational analysis of N-vinyl-2-phenylpyrrole was undertaken according to the results from experimental measurements and nonempirical quantum-chemical calculation of the high-level ¹³C–¹H and ¹³C–¹³C spin-spin coupling constants. Angular relationships were established in the direct and vicinal J _C,C and J _C,H constants in the N-vinylpyrrole fragment, making it possible to use them in stereochemical investigations of the vinyl derivatives of pyrrole. Dedicated to Boris Aleksandrovich Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 35–42, January, 2009.     

Effect of crosslinker functionality on swelling and network parameters of copolymeric hydrogels

Crosslinked xerogels comprising N-vinyl-2-pyrrolidone (VP) and butyl acrylate (BA) with different weight fractions of BA ranging between 0.1 and 0.3 were prepared by γ-ray initiation copolymerization using different concentrations of either hexa- or tetrafunctional crosslinking agents. Methylene bisacrylamide (MBA) was selected as tetrafunctional crosslinker, while 1,1,1-trimethylolpropane trimethacrylate (TPT) was used as a hexafunctional crosslinker. The concentration of both crosslinkers ranged between 0.5% and 2%. Thin disks of the prepared copolymers were swollen in deionized water at 294 K. The final equilibrium water content, volume fraction of polymer and swelling capacity were determined. The effective crosslinking density V_e, the average molecular weight between the crosslinks M_c and the polymer–water interaction parameter were determined from stress–strain measurements. For different compositions of VP/BA, the linear relations between theoretical crosslinking densities V_t and V_e were established. The efficiencies of MBA and TPT crosslinking agents towards VP–BA copolymers were determined. © 1998 John Wiley & Sons, Ltd.     

A Novel Approach to Prepare Zn(II)-loaded Cotton Fibers with Antibacterial Property

This study is focused on investigating the feasibility of using poly(acrylamide-co-N-vinyl-2-pyrrolidone)-grafted cotton fibers for the release of Zn(II) ions under physiological conditions.

The optimum grafting conditions for ceric ammonium nitrate induced graft-copolymerization of acrylamide and N-vinyl-2-pyrrolidone onto cotton fibers was found to include initiator concentration of 35 mM, catalyst HNO₃concentration of 0.35 M and initiation time of 10 min. The Zn(II)-loaded grafted fibers released Zn(II) in the physiological fluid for nearly 72 h with first order diffusion constant 6.0× 10^?4 min^?1. The release was regulated by ion-exchange mechanism and less release was observed in protein solution. The Zn (II)—loaded fibers exhibit fair antibacterial activity.     

Synthesis,characterization, microstructure determination,thermal studies of poly (N-vinyl pyrrolidone-maleic anhydride-methyl methacrylate)

Synthesis of Poly (N-vinyl pyrrolidone-maleic anhydride-methyl methacrylate) terpolymer using azobisisobutyronitrile in 1,4-dioxan is described. The polymers with different composition were synthesized and characterized using FTIR, ¹HNMR, ¹³NMR, TGA and DSC techniques. The monomer-monomer interactions were studied using Finemann-Ross and Kelen-Tudos methods by calculating the reactivity ratio. The reactivity ratio r₁ and r₂ with respect to methyl methacrylate and N-vinylpyrrolidone-maleic anhydride complexomer are found to be 6.05 and 0.06 respectively. The study showed methyl methacrylate have higher reactivity than N-vinyl-2-pyrrolidone-maleic anhydride complex, i.e., the terpolymer contained methyl methacrylate in higher ratio. The thermal stability of poly (N-vinyl pyrrolidone-maleic anhydride-methyl methacrylate) was 165°C and the glass transition temperature was found to increase from 153°C to 182°C as MMA concentration increase. The studies indicate the activity of the polymer to inhibit bacterial growth is very poor.     

SYNTHESIS OF N-VINYL-2-OXAZOLIDONE: A COMMERCIALLY IMPORTANT INTERMEDIATE*

An improved synthesis of N-vinyl-2-oxazolidone starting from ethanolamine has been developed.

     

Interaction of 1-anilinonaphthalene-8-sulphonate with cross-linked poly (N-vinyl-2-pyrrolidone)

The interaction of 1-anilinonaphthalene-8-sulphonate (ANS) with cross-linked poly(N-vinyl-2-pyrrolidone) (CPVP) was studied by the adsorption technique at different temperatures and at two different pH values. Analysis by the Scatchard method and the study made in the presence of urea showed that the iceberg structure of water affects the sorption of ANS to CPVP, leading to cooperativity. The observed Giles sorption isotherms at both the pH values were of theL-type which indicated the interaction of ANS in flat configuration with the binding site in CPVP. The sorption of ANS to CPVP was enhanced considerably at acidic pH due to some structural factors which also resulted in multilayer sorption at this pH. Comparison of binding of ANS to CPVP and to linear poly(N-vinyl-2-pyrrolidone) demonstrated the greater contribution of hydrophobic interaction in CPVP than in the linear polymer.