Preparation of novel cross-linked fluoroalkyl end-capped adamantane cooligomer/copper nanocomposites

Copper(II) oxide reacted with hydrazine in the presence of fluoroalkyl end-capped oxime-blocked isocyanato cooligomer containing adamantyl segments at 90 °C for 30 min in ethylene glycol, and the deprotecting reaction of the cooligomer in the resulting product at 120 °C for 15 min was found to afford the colloidal red-brown colored cross-linked fluorinated cooligomer/Cu nanocomposites, which were stabilized by fluoroalkyl end-capped cooligomer containing benzotriazole segments. On the other hand, the corresponding cross-linked fluorinated cooligomer possessing no adamantyl segments could not afford the copper nanocomposites under similar conditions. Dynamic light scattering measurements and TEM photography of these cross-linked fluorinated cooligomer/Cu composites showed that these composites are nanometer size-controlled very fine nanoparticles. These fluorinated Cu nanocomposites have a good dispersibility and stability in mixed solvents of ethylene glycol and methanol for two weeks under air atmosphere conditions. In addition, these fluorinated Cu nanocomposite powders have been found to be stable for more than three months.     

Arrangement of fullerene above the poly(methyl methacrylate) surface with fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide polymers

Fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide polymers were found to be a convenient tool for the arrangements of fullerenes above the poly(methyl methacrylate) [PMMA] surface, and the higher fluorescent intensity of fullerene was obtained in the modified PMMA surface, although the reverse side of this modified film surface afforded an extremely weak fluorescent intensity.     

Solubilization of cytochrome c in organic media with fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer: a new approach to fluorinated biocatalyst in organic media

Self-assembled molecular aggregates of fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer can solubilize cytochrome c in organic media such as methanol, although the corresponding non-fluorinated polymer cannot solubilize cytochrome c in organic media. Interestingly, the resulting fluorinated oligomer-cytochrome c aggregate was found to act effectively as a new fluorinated biocatalyst for the oxidation of pinacyanol chloride with hydrogen peroxide in the non-aqueous methanol.     

Facile one-pot preparation of gold nanoparticles in the presence of fluoroalkyl end-capped oligomers,fluoroalkyl end-capped oligomers/silica nanocomposites,and fluoroalkyl end-capped oligomers/polyaniline nanocomposites

A variety of fluoroalkyl end-capped oligomers, such as fluoroalkyl end-capped acrylic acid oligomer [R_F-(ACA) _n -R_F], acryloylmorpholine oligomer [R_F-(ACMO) _n -R_F], 2-acrylamido-2-methylpropanesulfonic acid oligomer [R_F-(AMPS) _n -R_F], 2-(methacryloyloxy)ethanesulfonic acid oligomer [R_F-(MES) _n -R_F], and N,N-dimethylacrylamide oligomer [R_F-(DMAA) _n -R_F], were applied to the autoreduction of gold ions to give the corresponding oligomers/gold nanocomposites, of whose sharp plasmon absorption bands are observed around 535 nm. In these fluorinated oligomers, R_F-(ACA) _n -R_F oligomer and R_F-(ACMO) _n -R_F were effective for the one-pot preparation of the gold nanoparticles under very mild conditions; although the other fluorinated oligomers and the corresponding non-fluorinated–(ACMO) _n -oligomer were unable to afford the gold nanoparticles. R_F-(ACA) _n -R_F/SiO₂ nanocomposites and R_F-(ACMO) _n -R_F/SiO₂ nanocomposites, which were prepared by the sol–gel reactions of tetraethoxysilane in the presence of silica nanoparticles and the corresponding oligomers under alkaline conditions, were also applied to the encapsulation of gold nanoparticles into these fluorinated nanocomposite cores through the autoreduction of gold ions at room temperature. Interestingly, these fluorinated oligomers/silica nanocomposite-encapsulated gold nanocomposites before and after calcination at 800 °C were found to exhibit the same plasmon absorption band around 525 nm. R_F-(MES) _n -R_F oligomer and R_F-(AMPS) _n -R_F oligomer are not suitable for the autoreduction of gold ions; however, R_F-(MES)_n-R_F[or R_F-(AMPS) _n -R_F]/polyaniline [PAn] nanocomposites, which were prepared by the polymerization of aniline initiated by ammonium persulfate in the presence of the corresponding oligomer, enabled the formation of gold nanoparticles through the oxidation of PAn in the composites at room temperature. The reversible conformational change of PAn in the nanocomposites from the polyemeraldine salt to the oxidized pernigraniline base was observed during such oxidation process. Graphical abstract

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Preparation and polymerization of N-(1,1-dimethyl-3-hydroxybutyl) acrylamide and N-(1,1-dimethyl-3-hydroxybutyl)methacrylamide

The syntheses of N-(1,1-dimethyl-3-hydroxybutyl)acrylamide and the corresponding methacrylamide by reduction of the oxobutyl acrylamides are described. These monomers are colorless liquids which are soluble in water and many organic solvents. They polymerize readily to form homopolymers and copolymers with other vinyl monomers. The preparation of polymers containing these repeating units by reduction of polymers of diacetone acrylamide and diacetone methacrylamide is also described.     

Novel fluoroalkyl end-capped amphiphilic diblock copolymers with pH/temperature response and self-assembly behavior

A series of fluoroalkyl end-capped diblock copolymers of poly[2-(N,N-dimethylamino)ethyl methacrylate] (PDMAEMA or PDMA) and poly[2-(N,N-diethylamino)ethyl methacrylate] (PDEAEMA or PDEA) have been synthesized via oxyanion-initiated polymerization, in which a potassium alcoholate of 4,4,5,5,6,6,7,7,7-nonafluoro-1-heptanol (NFHOK) was used as an initiator. The chemical structures of the NFHO-PDMA-b-PDEA and NFHO-PDEA-b-PDMA depended on the addition sequence of the two monomers and the feeding molar ratios of [DMA] to [DEA] during the polymerization process. These copolymers have been characterized by (1)H NMR and (19)F NMR spectroscopy and gel permeation chromatography (GPC). The aggregation behavior of these copolymers in aqueous solutions at different pH media was studied using a combination of surface tension, fluorescence probe, and transmission electron microscopy (TEM). Both diblock copolymers exhibited distinct pH/temperature-responsive properties. The critical aggregation concentrations (cacs) of these copolymers have been investigated, and the results showed that these copolymers possess excellent surface activity. Besides, these fluoroalkyl end-capped diblock copolymers showed pH-induced lower critical solution temperatures (LCSTs) in water. TEM analysis indicated that the NFHO-PDMA(30)-b-PDEA(10) diblock copolymers can self-assemble into the multicompartment micelles in aqueous solutions under basic conditions, in which the pH value is higher than the pKa values of both PDMA and PDEA homopolymers, while the NFHO-PDEA(10)-b-PDMA(30) diblock copolymers can form flowerlike micelles in basic aqueous solution.     

Photooxidation of Co-thiolato complexes in protic and aprotic solvents

Protic solvents decrease the susceptibility of the thiolate ligand in Co(III) thiolato complexes toward attack by singlet oxygen, but greatly increase the conversion of the peroxidic intermediate to the sulfenato product.     

Photochemistry of 5-aminoquinoline in protic and aprotic solvents

Photophysical properties of 5-aminoquinoline (5AQ) have been investigated in various non-polar and polar (protic and aprotic) solvents using steady state and time resolved fluorescence. In aprotic solvents, the spectral maxima depend on the polarity. However, in protic solvents both the fluorescence intensity as well decay time show decrease depending on the hydrogen bonding ability of the solvent. The results suggest that photochemistry 5AQ is quite sensitive towards the polarity as well as protic character of the solvent.     

Preparation and applications of novel fluoroalkyl end-capped acrylamide oligomers/polythiophene nanocomposites

Thiophene monomer reacted with ferric chloride in the presence of a variety of fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomers [R_F-(DOBAA)_x-R_F] to afford nanometer size-controlled R_F-(DOBAA)_x-R_F oligomers-polythiophene composites [R_F-(DOBAA)_x-R_F/PTh]. R_F-(DOBAA)_x-R_F/PTh nanocomposites thus obtained were demonstrated to have a good dispersibility and stability in methanol to give a transparent brown solution. In addition, these fluorinated nanocomposites were applied to the surface modification of common organic polymers such as poly(methyl methacrylate), and were dispersed regularly above the polymer surface.     

Preparation and applications of novel fluoroalkyl end-capped oligomers/calcium carbonate nanocomposites

Calcium chloride reacted with sodium carbonate in the presence of a variety of self-assembled molecular aggregates formed by fluoroalkyl end-capped acrylic acid, 2-methacryloyloxyethane sulfonic acid, dimethylacrylamide, and acryloylmorpholine oligomers in aqueous solutions to afford the corresponding fluorinated oligomers/calcium carbonate composites in excellent to moderate isolated yields. These fluorinated calcium carbonate composites thus obtained were shown to have a good dispersibility not only in water but also in traditional organic media including fluorinated solvents. Dynamic light scattering measurements (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that these fluorinated composites are nanometer-size-controlled particles and well dispersed in these media. Cross-linked fluoroalkyl end-capped acrylic acid co-oligomer containing poly(oxyethylene) units was also applied to the preparation of new cross-linked fluorinated calcium carbonate nanocomposites under similar conditions. The obtained cross-linked fluorinated calcium carbonate nanocomposites were found to have an extremely higher dispersibility in aqueous and organic media including fluorinated solvents, compared to that of the corresponding fluoroalkyl end-capped oligomer nanocomposites. In particular, it was verified that these fluorinated calcium carbonate nanocomposites are applicable to the dispersion above poly(methyl methacrylate) (PMMA) film surface. Interestingly, field-emission SEM (FE-SEM) images of the cross-section of the modified PMMA films showed that calcium carbonate particles dispersed into these PMMA films could be arranged regularly above the modified film surface. More interestingly, cross-linked fluorinated oligomeric aggregates were able to provide suitable host moieties for the crystallization of calcium carbonate.     

Selective recognition of alkyl pyranosides in protic and aprotic solvents

The design and synthesis of receptors capable of selective, noncovalent recognition of carbohydrates continues to be a signature challenge in bioorganic chemistry. We report a new generation of tripodal receptors incorporating three pyridine (compound 2) or quinoline (compound 3) rings around a central cyclohexane core for use in molecular recognition of monosaccharides in apolar and polar protic solvents. These tripodal receptors were investigated using (1)H NMR, UV, and fluorescence titrations in order to determine their binding abilities toward a set of octyl glycosides. Receptor 2 displayed the highest binding affinity reported to date for noncovalent 1:1 binding of an alpha-glucopyranoside in chloroform (Ka = 212,000 +/- 27,000 M(-1)) and an approximately 8-fold selectivity for the alpha anomer over the beta anomer of the glucopyranoside. Most importantly, 2 retained its micromolar range of affinities toward monosaccharides in a polar and highly competitive solvent (methanol). The quinoline variant 3 also displayed micromolar binding affinities for selected monosaccharides in methanol (as measured by fluorescence) that were generally smaller than those of 2. Compound 3 was found to follow a selectivity pattern similar to that of 2, displaying higher affinities for glucopyranosides than for other monosaccharides. The binding stoichiometry was estimated to be 1:1 for the complexes formed by both 2 and 3 with glucopyranosides, as determined by Job plots. Nuclear Overhauser effect spectroscopy allowed for the derivation of a binding model consistent with the observed selectivities.     

Preparation of fluoroalkyl end-capped oligomers/magnetite nanocomposites possessing a good dispersibility and stability

Fluoroalkyl end-capped vinylphosphonic acid cooligomers-encapsulated magnetite nanocomposites were prepared by the magnetization of aqueous ferric and ferrous ions in the presence of the corresponding fluorinated cooligomers and magnetic nanoparticles under alkaline conditions. These fluorinated cooligomers magnetic composites are nanometer size-controlled very fine particles and have a good dispersibility and stability in water and traditional organic solvents. These fluorinated nanocomposites were also applied to the surface modification of poly(methyl methacrylate) to exhibit a good oleophobicity imparted by fluorine on their surface. Fluoroalkyl end-capped 2-methacryloyloxyethanesulfonic acid oligomer-encapsulated magnetite nanocomposites and fluoroalkyl end-capped 2-acrylamide-2-methylpropanesulfonic acid oligomer-encapsulated magnetite nanocomposites were prepared in good isolated yields by the magnetization of iron chlorides in the presence of the corresponding oligomers and magnetic nanoparticles under similar conditions. Colloidal stability of these fluorinated nanocomposites thus obtained in water was demonstrated to become extremely higher than that of fluorinated vinylphosphonic acid cooligomers/magnetic nanocomposites.     

Polymerization and copolymerization of an isocyanate blocking agent. N-(1,1′-dimethyl-3-oxobutyl) acrylamide oxime. Mechanical and thermal properties

The bulk polymerization and copolymerization of N-(1,1′-dimethyl-3-oxobutyl) acrylamide oxime have been studied. Polymerization of diacetone acrylamide oxime was carried out with different initiating systems. The rate of polymerization of diacetone acrylamide oxime with azoisobutyronitrile as the initiating system was much higher than with peroxides. However, in the case of perester initiating systems (t-butyl perbenzoate and t-butyl per ethyl-2-hexanoate), cobalt salt promoted the polymerization rate markedly. Diacetone acrylamide oxime readily formed copolymers with a variety of comonomers (crosslinking agents and reactive diluents). Gel permeation chromatography has shown a higher reactivity of diacetone acrylamide oxime with trimethylol propane trimethacrylate as crosslinking agent and N-vinyl-pyrrolidone as reactive diluent. Therefore, the dynamic mechanical analyses presented an increase in T_g with trimethylolpropane trimethacrylate and N-vinyl-pyrrolidone as comonomers. The terpolymer formed with diacetone acrylamide oxime, trinethylolpropane trimethacrylate, and N-vinyl-pyrrolidone exhibited interesting mechanical properties and high temperature behavior.     

Photolysis of acetyl esters of 2,2′-dinitrodiphenyl-carbinols in protic and aprotic solvents

Irradiation ofacetyl esters of 2,2′-dinitrodiphenyl-carbinols (1a-d) in aprotic medium like 2-propanol yielded dibenzol [c,f]-[1,2]diazepin-11-one-5-oxides (5a-d) as the major product. Dibenzoi[c,f]-[1,2]diazepin-11-one (2a-d), 2,2′-dinitrobenzophenones (3a-d), 2-amino-2′-nitrobenzophenones (4a-d), and N-hydroxyacridones (6a-d) were also formed in varying amounts. Irradiation of 1a-d in an aprotic medium like benzene yielded the above products along with benzisoxazoles (7a-d) also. When triethylamine was used as the solvent the major product obtained was N-hydroxyacridones (6a-d). Plausible mechanisms for the formation of the products are discussed     

Preparation and applications of novel fluoroalkyl end-capped 2-acrylamido-2-methylpropanesulfonic acid oligomer/clay nanocomposites

New fluoroalkyl end-capped 2-acrylamido-2-methylpropanesulfonic acid oligomers/clay composites were prepared by reaction of fluoroalkanoyl peroxide with the corresponding monomer in the presence of clay in aqueous solutions. These obtained fluorinated composites were nanometer size-controlled and were found to exhibit a good dispersibility in water and polar organic solvents such as methanol. The contents of clay in these nanocomposites were estimated to be 3～19% by the thermogravimetric analysis measurements. X-ray diffraction spectra showed the successful intercalation of fluorinated oligomers into the interlayer spaces of clay. These fluorinated clay nanocomposites were applied to the surface modification of poly(vinyl alcohol). In addition, these fluorinated nanocomposites were found to interact with methylene blue effectively to afford the fluorinated oligomers/clay/methylene blue nanocomposites.     

A fluoroalkyl end-capped <Emphasis Type="Italic">N</Emphasis>-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer/silica gel nanocomposite with no weight loss even at 800 °C equal to an original silica gel

Fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer [R_F-(DOBAA)_n-R_F]/silica gel nanocomposite, which was prepared by reaction of the corresponding fluorinated oligomer with tetraethoxysilane and silica gel nanoparticles under alkaline conditions, exhibited no weight loss even at 800 °C equal to the original silica gel, although the corresponding parent R_F-(DOBAA)_n-R_F oligomer was completely degraded at 600 °C. Thermogravimetric analyses/mass spectra of fluorinated nanocomposite showed that this nanocomposite decomposed around 280 °C to afford CO₂ and H₂O as the major evolved gaseous products including some minor fluoro- and hydrocarbons. X-ray photoelectron spectroscopy analyses also showed that the contents of C, F, and Si atoms in R_F-(DOBAA)_n-R_F/SiO₂ nanocomposite after the calcination at 800 °C were similar to those before the calcination. These findings suggest that the evolved gaseous products should be encapsulated quantitatively into nanometer-size-controlled silica matrices to give the fluorinated silica gel nanocomposite with no weight loss even at 800 °C equal to the original silica gel.     

Diffusion of symmetrical and spherical solutes in protic,aprotic, and hydrocarbon solvents

The diffusion coefficients of a series of symmetrical tetraalkyltins (tetramethyltin, tetraethyltin, tetrapropyltin, tetrabutyltin, tetradodecyltin) of the gases argon, krypton, xenon, methane, and tetramethylmethane and of carbon tetrachloride and tetraethylmethane in hexane, decane, and tetradecane at 25°C have been determined using the Taylor dispersion technique. Diffusion coefficients for the gases in acetone, 2-propanol, 1-butanol, and 1-octanol were also determined. Deviations from the predictions of Stokes' law were found to be large, and the magnitude of the deviation can be directly related to solute size. The predictions of the Hubbard-Onsager equation were tested using the diffusion data.     

Decomposition of hydrogen peroxide in protic and polar aprotic solvents on TS-1 heterogeneous catalyst

Kinetic parameters of H₂O₂ decomposition in methanol, propanol-1, propanol-2, acetone, and acetonitrile at 30–55°C on a TS-1 heterogeneous catalyst were determined. Recommendations are given on choice of solvents in oxidation of organic compounds with hydrogen peroxide.