Controlling the water content of never dried and reswollen bacterial cellulose by the addition of water-soluble polymers to the culture medium

For the modification of medically useful biomaterials from bacterially synthesized cellulose, fleeces of Acetobacter xylinum have been produced in the presence of 0.5, 1.0, and 2.0% (m/v) carboxymethylcellulose (CMC), methylcellulose (MC), and poly(vinyl alcohol) (PVA), respectively, in the Hestrin-Schramm culture medium. The incorporation of the water-soluble polymers into cellulose and their influence on the structure, crystal modifications, and material properties are described. With IR and solid-state ¹³C NMR spectroscopy of the fleeces, the presence of the cellulose ethers and an increase in the amorphous parts of the cellulose modifications (NMR results) have been detected. The incorporation is represented by a higher product yield, too. As demonstrated by scanning electron microscopy, a porelike cellulose network structure forms in the presence of CMC and MC. This modified structure increases the water retention ability (expressed as the water content), the ion absorption capacity, and the remaining nitrogen-containing residues from the culture medium or bacteria cells. The water content of bacterial cellulose (BC) in the never dried state and the freeze-dried, reswollen state can be controlled by the CMC concentration in the culture solution. The freeze-dried, reswollen BC-CMC (2.0%) contains 96% water after centrifugation, whereas standard BC has only 73%. About 98% water is included in a BC-MC composite in the wet state, and about 93% is included in the reswollen state synthesized in the presence of 0.5, 1.0, or 2.0% MC. These biomaterial composites can be stored in the dried state and reswollen before use, reaching a higher water absorption than pure, never dried BC. The copper ion capacity of BC-CMC composites increases proportionally with the added amount of CMC. BC-CMC (0.5%) can absorb 3 times more copper ions than original BC. In the case of 0.5 and 1.0% PVA additions to the culture solution, this polymer cannot be detected in the cellulose fleeces after they are washed. Nevertheless the presence of PVA in the culture medium effects a decreased product yield, a retention of nitrogen-containing residues in the material during purification, a reduced water absorption ability, and a slightly higher copper ion capacity in comparison with original BC. The water content of freeze-dried, reswollen BC-PVA (0.5%) is only 62%. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 463–470, 2004     

Novel polycationic biocides: Synthesis and antibacterial activity of polymeric phosphonium salts

Various polymeric phosphonium salts and the corresponding low-molecular-weight model compounds were prepared and their antibacterial activities against Staphylococcus aureus and Escherichia coli were explored by the viable cell counting method in sterile distilled water. Antibacterial activity of the polymers was found to be higher than that of the corresponding model compounds, particularly against S. aureus. Furthermore, the polymeric phosphonium salt exhibited a higher activity by 2 orders of magnitude than the polymeric quaternary ammonium salt with the same structure except the cationic part. Compounds with the longest alkyl chain (octyl) studied were found to exhibit particularly high activity, and this finding may be ascribed to the contribution of the increased hydrophobicity of the compounds to the cidal activity. © 1993 John Wiley & Sons, Inc.     

Diallylacylhydrazines as monomers for polyfunctional water-soluble polymers

Allylation of acetohydrazide afforded the corresponding diallylacylhydrazine, which can be used for syntheses of water-soluble polyfunctional polymers.     

Selectivity of catalytic systems RhCl3 · Polycation in hydroformylation of hex-1-ene under conditions of biphase catalysis

Approaches to increasing the selectivity of water-soluble catalytic systems based on RhCl₃ and polycation in hydroformylation of hex- 1-ene were studied. The introduction of a long-chain alkyl radical into the polycation or the use of a higher fatty acid anion results in an increase in the selectivity of the catalytic system at pH > 7 with respect to n-aldehyde to 60 %. This effect is presumably associated with the suppression of isomerization processes due to steric hindrances.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1968–1971, August, 1996.     

Studies on novel cyclodextrans: Inclusion of C60 and C70

Cycloisomalto-heptaose (CI-7) and cycloisomalto-octaose (CI-8) are two novel cyclodextrans. Treatment with C₆₀ or C₇₀ by kneading leads to the formation of four distinct water-soluble inclusion complexes: CI-7/C₆₀ (2: 1), CI-8/C₆₀ (2: 1), CI-7/C₇₀ (2: 1) and CI-8/C₇₀ (2: 1). Their formation and structures have been examined by UV vis spectroscopy, X-ray powder diffraction and fluorescence spectral studies. The reaction is a reversible process.     

Synthesis of the first kinetically stable dibenzosilafulvene

The first stable dibenzosilafulvene, 9-{[8-(dimethylaminomethyl)-1-naphthyl]phenylsil-1-ylium}fluoren-9-ide (7a), was obtained in one step from 9-fluorenyllithium and chloro[8-(dimethylaminomethyl)-1-naphthyl]phenylsilane as a stable solvate with THF. The structure of the zwitterionic compound7a was established by¹H,¹³C, and²⁹Si NMR in solution and in the solid state. The reactions of compound7a with crotonaldehyde, ethanol, and triethylethylidenephosphorane are described. The data on the synthesis of alkoxy- and alkylthiochloro-9-fluorenylsilanes and their phosphonium salts are given. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 486–491, March, 1998.     

The first structural characterization of a phosphonium amide: synthesis, isolation and molecular structure of (Ph3PEt)(NPh2)

The first isolation of a phosphonium amide, (Ph₃PEt)⁺(NPh₂)⁻, obtained via the deprotonation of a secondary amine (diphenylamine) with a phosphorus ylide (triphenylphosphonium ethylide), is described. An X-ray crystal structure provides the first observation of an essentially ion-separated Ph₂N⁻ anion in the solid state, though weak association with Ph₃PEt⁺ cations take plac through C---H…N hydrogen bonding. Cryoscopic and NMR spectroscopic data suggest that this association is not maintained in benzene solution.     

Ion/molecule reactions in a miniature RIT mass spectrometer

Ion/molecule reactions were explored in a newly developed miniature mass spectrometer fitted with a rectilinear ion trap (RIT) mass analyzer. The tandem mass spectrometry performance of this instrument is demonstrated using collision induced dissociation (CID) and ion/molecule reactions. The latter includes Eberlin transacetalization reactions and electrophilic additions. Selective detection of the chemical warfare simulant dimethyl methyl phosphonate (DMMP) was achieved through selective Eberlin reactions of its characteristic phosphonium fragment ion CH3OP(+)(O)CH3 (m/z 93), with 1,4-dioxane or 1,3-dioxolane. Efficient adduct formation as a result of electrophilic attack by the phosphonium ion on various nucleophilic reagents, including 1,1,3,3-tetramethyl urea, methanesulfonic acid methyl ester, dimethyl sulfoxide and methyl salicylate, was also observed using the RIT device. The product ions of these reactions were analyzed using CID and the characteristic fragmentation patterns of the ionic addition products were recorded using multiple-stage experiments in the miniature RIT instrument. This study clearly demonstrates that a small, home-built, miniature RIT mass spectrometer can be used to perform analytically useful ion/molecule reactions and also that instruments like this have the potential to provide a portable platform for in situ detection of organophosphorus esters and related compounds with high specificity using tandem mass spectrometry.     

Alkyl (C<Subscript>10</Subscript>, C<Subscript>12</Subscript>, C<Subscript>14</Subscript> and C<Subscript>16</Subscript>) triphenyl phosphonium bromide influenced cloud points of nonionic surfactants (Triton X 100, Brij 56 and Brij 97) and the polymer (Polyvinyl methyl ether)

The clouding points (CP) of the nonionic surfactants p-tert-octyl phenyl polyoxyethylene ether (Triton X 100), Brij-56 and Brij-97, and the water soluble polymer polyvinylmethylether (PVME) have been measured in the presence of the ionic surfactants alkyl (C₁₀, C₁₂, C₁₄ and C₁₆) triphenyl phosphonium bromides (ATPBs). The threshold additive concentrations required for efficient CP enhancement of the systems that were studied have been determined. Considering CP as the threshold state of phase separation, the energetics of the process at different additive concentrations has been evaluated. The spontaneity of free energy of the clouding process (G _c ⁰ ) at the transition concentrations followed the order PVME > TX 100  Bj 56 > Bj 97. The clouding process has been found to be energetically endothermic with fairly large enthalpy and entropy changes that nicely compensate each other. The compensation temperature has been evaluated and compared with different types of the clouding agents.This revised version was published online in January 2005 with corrections to the names of the authors.     

Polymeric phosphonium salts as a novel class of cationic biocides. V. Synthesis and antibacterial activity of polyesters releasing phosphonium biocides

Polyesters were prepared which retained phosphonium biocides as counter ions of sodium sulfonate moieties incorporated into the polymers, and surface antibacterial activity of the polyester films against Staphylococcus aureus and Escherichia coli was explored. These films exhibited a high surface antibacterial activity against S. aureus and E. coli, particularly against S. aureus, and the activity was affected by the structure and the compositional ratio of the phosphonium salts. Amount of the released phosphonium salts was very small, so that liberation of the phosphonium biocides can be expected to occur over a long period. Morphological changes of the cells of S. aureus and E. coli in contact with the polyester films were evaluated by scanning electron microscopy. It was found that the surface antibacterial activity of the polyester films was rather bacteriostatic than bactericidal as evidenced by no morphological changes of the bacterial cells in contact with the phosphonium biocides © 1993 John Wiley & Sons, Inc.