Polystyrene Support Research Articles

Thermal behaviour of DVB-crosslinked polystyrene-supported dithiocarbamate-metal complexes

Thermogravimetric studies of the Cu(II) and Ni(II) complexes of dithiocarbamate functions supported on 2% divinylbenzene (DVB)-crosslinked polystyrenes are described. The relative thermal stabilities, decomposition patterns and the kinetic parameters of decompositions of the different metal complexes were followed. The thermal stabilities of the Ni(II) complexes are higher than the Cu(II) complexes. Among the different types of complex, the thermal stability depends on the mode of attachment of the ligand functions to the crosslinked polystyrene support.

Asymmetric catalytic dihydroxylation of alkenes on polymer support: Scope and limitation

Osmium catalyzed asymmetric dihydroxylation of alkenes has been reported using dihydroquinidine (DHQD) and dihydroquinine (DHQ) on a polystyrene support. Effect of other oxidants and additives has been examined.

Photografting of acrylic monomers on polystyrene support

AbstractPolystyrene xanthates, prepared through the reaction of chloromethylated polystyrene resins with potassium O‐ethyl xanthate, have been used for the photografting of acrylic monomers. Monomers such as acrylamide, acrylic acid, methacrylic acid, and methyl methacrylate were grafted onto the xanthate polymers on irradiation with a 450 W medium‐pressure mercury lamp (Hanovia). Among these monomers, the maximum graft efficiency was obtained for methyl methacrylate. The effect of cross‐link density of the xanthate polymer on the percentage graft yield was also studied. Scanning electron microscopic studies have shown that appreciable grafting has taken place on the surface of the polymer in a uniform manner. © 1992 John Wiley & Sons, Inc.

Évaluation du pouvoir adhérant du Lactobacillus helveticus au polystyrène expansé

We measured the surface tension of a three-phase (solid–solid–liquid) system consisting of the bacterium Lactobacillus helveticus in a culture medium containing an expanded polystyrene support, to determine the adherence capacity of the bacteria to the support. The surface tension of the expanded polystyrene and the L. helveticus cells was evaluated by measuring contact angles. The Wilhelmy's microslide method was used to measure the surface tension of the liquid phase. The values obtained showed that the adherence capacity of the L. helveticus cells to expanded polystyrene pellets was not facilitated under the experimental thermodynamic conditions. The pellet surfaces and adhering bacterial cells were examined with a scanning electron microscope. The pellets exhibited several grooves in which microbial cells preferentially accumulated. Key words: Lactobacillus helveticus, adherence, surface tension, expanded polystyrene. [Translated by the journal]

Polymer-supported Mo and V cyclohexene epoxidation catalysts: Activation, activity, and stability

The immobilisation of MoO 2acac 2 and VOacac 2 on a polystyrene support carrying a hydroxypropylated aminomethylpyridine ligand occurs via a ligand exchange reaction involving displacement of the acetylacetonate (acac) groups. In the case of the molybdenum species, the resulting blue polymer complex contains both MoO and MoOMo groups and immobilised ligand-metal bonds. Activation of the resulting complexes to form bright yellow species by pretreatment with excess t-butyl hydroperoxide is required before the supported complexes can become active catalysts for the epoxidation of cyclohexene by t-butyl hydroperoxide. In situ activation does not occur. It is believed that in the case of molybdenum activation involves oxidation of Mo(V) to new supported Mo(VI) species and that this is inhibited in the presence of alkene. Both polymer-immobilised Mo and V systems are catalysts of the epoxidation reaction, but the Mo-based system is considerably more active. Epoxidation reactions are characterised by an induction period followed by a relatively long linear conversion/time relationship. The induction period is probably associated with formation of the reactive intermediate which constitutes the true catalytic species, and this probably involves the reaction of the immobilised Mo(VI) complex with cyclohexene or traces of its epoxide. Polymer complexes subjected to more severe activation conditions display shorter induction periods and faster rates of epoxidation as a result of formation of more Mo(VI) centres. Additional Mo(VI) centres do not appear to be generated during epoxidation reactions. Mo and V are leached from their supports during activation. More severe activation conditions cause more metal leaching but the amounts lost are small (always < 1.6%). The supported Mo complex remains an active catalyst when recycled up to nine times. Apart from an initial small drop, the activity remains essentially constant on reuse. Mo is also leached during epoxidations but the leached species make no significant contribution as catalyst-immobilised complexes are the active catalysts. The amounts of Mo leached are small (<0.4% per cycle) and fall progressively to essentially zero after nine cycles. The immobilised Mo complex offers the prospect of a technologically useful alkene epoxidation catalyst for continuous liquid phase oxidations using t-butyl hydroperoxide.

An optimized polystyrene support for rapid, efficient oligonucleotide synthesis

An optimized type of polystyrene has been developed as a solid support for automated oligonucleotide synthesis. The non-swelling, rigid beads possess the attractive features of rapid reaction kinetics, efficient washing with organic solvents, and mechanical stability. Pore size, particle size, and polymerization formula and conditions have been optimized. The support material is derivatized to give primary amino functionality, which is near quantitatively coupled to 3′ p-nitrophenyl succinate nucleosides. Loading of the nucleosides can be precisely controlled in a range of 5 to 70 μmole per gram. The high yield synthesis of oligonucleotides, by phosphoramidite chemistry has been demonstrated up to 120 bases in length. Side reactions, such as extraneous chain growth, are minimized due to the lack of reactive functionality on the new support surface.

Synthesis of substance P partial sequential peptides on a photolytically removable 4-aminomethyl-3-nitrobenzoylaminomethyl polystyrene support

Sequential peptides corresponding to substance P (6–11) were synthesised on a photocleavable 4-aminomethyl-3-nitrobenzoylaminomethyl polystyrene resin. This photoremovable polymeric support, useful for the synthesis of C-terminal peptide amides, was prepared from 4-bromomethyl-3-nitrobenzoylaminomethyl polystyrene by treatment with potassium phthalimide followed by hydrazinolysis. Amino acid residues were incorporated onto this support following the standard solid-phase methodology of peptide synthesis. The protected peptide amides were cleaved from the resin by photolysis with light of wavelength 350 nm. The resin was used for the synthesis of peptides including the partial sequence corresponding to substance P (9–11) which was further subjected to stepwise synthesis to prepare substance P (6–11) in an overall yield of 88%. This approach combines the advantages of the photochemical deprotection of the 4-aminomethyl-3-nitro carboxyl protecting group, the polymer-supported peptide synthesis and the polymer-analogous functionalisation procedure to obtain the C-terminal peptide amide under mild conditions.

Solid-phase synthesis of N-methyl- and N-ethylamides of peptides using photolytically detachable [(3-nitro-4-[(alkylamino)methyl]benzamido]methyl]polystyrene resin

A convenient method for the solid-phase synthesis of C-terminal peptide N-alkylamides using a photolytically detachable ((3-nitro-4-((alkylamino)methyl)benzamido)methyl) polystyrene support is described

ChemInform Abstract: Investigation of Phase‐Transfer Reactions Catalyzed by Polyethylene Glycol Bound to Macroporous Polystyrene Supports.

Preparation de differents systemes catalytiques constitues de PEG sur un support de polystyrene macroporeux et microporeux. Etude comparative de l'activite catalytique avec ces deux types de catalyseurs

Synthesis of unsymmetrical disulfides with thiolsulfonates immobilised on a polystyrene support

Polystyrene sodium sulfinate reacted with thionitrites gave polystyrene thiolsulfonates. These immobilised thioalkylation reagents were used for an effective synthesis of mixed disulfides.

Glycolamidic ester handle used with polystyrene supports. Application to the synthesis of tp 5

Glycolamidic ester linkage of a peptide chain to a polystyrene resin can be easily cleaved under smooth alkaline conditions.

Affinity chromatography of fibroblast growth factors on substituted polystyrene

The heparin-binding growth factors aFGF and bFGF (acidic and basic fibroblast growth factor) from crude bovine brain extract were co-eluted with purified [ 125I]aFGF and/or [ 125I]bFGF as tracers from heparin-Sepharose and from several insoluble substituted polystyrenes used as stationary phases in low-pressure affinity chromatography. The ability of the resins to isolate FGFs was determined by measuring the eluted radioactivity. It was demonstrated that the various substituted polystyrene resins retain [ 125I]aFGF and [ 125I]bFGF with different specificities according to the chemical nature of the substituted groups bound to the polystyrene support. Bifunctional resins substituted with sulphonate and phenylalanine sulphamide groups adsorbed both [ 125I]aFGF and [ 125I]bFGF whereas bifunctional resins substituted with sulphonate and sulphamide serine adsorbed only [ 125I]bFGF. These stationary phases could be adapted to high-performance affinity chromatography and used to isolate growth factors of the FGF family.

Investigation of phase-transfer reactions catalyzed by polyethylene glycol bound to macroporous polystyrene supports

Preparation de differents systemes catalytiques constitues de PEG sur un support de polystyrene macroporeux et microporeux. Etude comparative de l'activite catalytique avec ces deux types de catalyseurs

Fully automatic simultaneous multiple peptide synthesis in micromolar scale - rapid synthesis of series of peptides for screening in biological assays.

A new method of simultaneous multiple peptide syntheses on polystyrene support in the wells of microtiterplates is illustrated by the syntheses of 31 overlapping segments of endothelin. All reagent and solvent handling is automatically performed by a freely programmable robotic sample processor.

Spectroscopic properties and photochemical behaviour of polymers with covalently bound tris(bipyridine)ruthenium(II) complex. Use of a hydrophilic chain as spacer

The synthesis of a tris(bipyridine)ruthenium(II) complex, covalently bound through a polyethoxylated chain to an insoluble polymer is described. The spectroscopic properties of several Ru(bpy) 3 2+ complexes anchored to insoluble polystyrene supports, and of the monomeric complex are compared and shown to be very similar. Methyl viologen luminescence quenching studies of the excited state of the polymer show behaviour different from that of monomeric Ru(bpy) 3 2+.

Transient behaviour and luminescence quenching of Rub(bpy) 32+ bound to an insoluble polymeric phase

The spectroscopic behaviour of Ru(bpy) 3 2+ bound to an insoluble polystyrene support is similar to that reported in homogeneous solution and in other heterogeneous media. Following pulsed excitation at 532 nm, emission from the MLCT complex is observed, the decay of which contains both unimolecular and bimolecular components. Weak transient absorption within the sample is also observed and *Ru(bpy) 3 2+ could be identified by its absorption maximum at 375 nm and depletion minimum at 430 nm. Experiments using methylviologen show that luminescence quenching is about forty times slower than in aqueous solution, indicating that the hydrophobic nature of the polymer impedes the approach of the quencher to the ruthenium complex. The inclusion of a hydrophilic sequence in the sample has little effect on improving the quenching efficiency.

Polymer-supported synthesis of protected peptide segments on a photosensitive o-nitro(a-methyl)bromobenzyl resin

The preparation of a new polystyrene support containing the photodetachable o -nitro(α -methyl)benzyl anchoring group and its application in the solid phase synthesis of fully protected C-terminal peptides are described, The preparation of the photosensitive resin involves a 4-step polymer-analogous reaction starting from 1 %-divinyl benzene crosslinked polystyrene. Amino acid units were incorporated into this resin following standard solid phase peptide synthetic methodology and the peptides were cleaved from the support by photolysis under neutral conditions at 350 nm, in 40–50 % overall yield. The attachment of the peptide through a secondary ester linkage In o -position to the nitro group is the factor permitting the photolytic cleavage of the peptides from the support.

Solid phase synthesis of oligoribonucleotides using [formula omitted]-nitrobenzyl protection of 2'-hydroxyl via a phosphotriester approach

Oligoribonucleotides with chain length of 6–9 were synthesized on a polystyrene support using o -nitrobenzyl protection of 2'-hydroxyls via phosphotriester method. The condensation reactions between N -acyl-5'- O -monomethoxytrityl-2'- O -( o -nitrobenzyl) nucleoside 3'-( o -chlorophenyl) phosphate and nucleoside bound to the resin using l-mesitylenesulfonyl-3-nitro-1 H -1,2,4-triazole (MSNT) as a condensing agent were examined. It was found that the condensation reaction using MSNT was promoted in the presence of 1-methylimidazole as a catalyst. A mixture of MSNT and 1-methylimidazole was also found to be effective in the condensation reaction involving a dinucleotide with 3'-phosphodiester. The fully protected oligomer were deblocked and purified by chromatography in total yields of 3–21 % based on initial nucleoside bound to the support.

Peptide synthesis by fragment condensation on a soluble polymer support. 8. Maximum peptide chain lengths of carboxyl component peptides for effective coupling reactions with amino component peptides anchored to soluble and cross-linked polystyrene supports

Peptide synthesis by fragment condensation on a soluble polymer support. 8. Maximum peptide chain lengths of carboxyl component peptides for effective coupling reactions with amino component peptides anchored to soluble and cross-linked polystyrene supports

Solid-phase synthesis of peptide amides on a polystyrene support using fluorenylmethoxycarbonyl protecting groups

Solid-phase synthesis of peptide amides on a polystyrene support using fluorenylmethoxycarbonyl protecting groups