- Enhancing the Efficacy of Photodynamic Therapy through a Porphyrin/POSS Alternating Copolymer
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Aggregation-induced quenching (AIQ) of photosensitizers greatly reduces the quantum yield of singlet oxygen generation and mitigates the efficacy of photodynamic therapy (PDT). We have prepared an alternating copolymer starting from 4-vinylbenzyl-terminated tetraphenylporphyrin (VBTPP) and maleimide isobutyl polyhedral oligomeric silsesquioxane (MIPOSS), via alternating reversible addition–fragmentation chain transfer (RAFT) polymerization. Porphyrin and POSS are installed on the amphiphilic block copolymers backbone in an alternating fashion and POSS completely inhibits the aggregation of porphyrin units via stacking. The amphiphilic block copolymer can self-assemble into nanoparticles and its application in PDT treatment was tested. These porphyrin-containing polymeric nanoparticles display high photochemical yield and phototoxicity in vitro and in vivo, providing a novel strategy to enhance the PDT efficacy.
- Jin, Jianqiu,Zhu, Yucheng,Zhang, Zhenghe,Zhang, Weian
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- Cooperative catalysis with block copolymer micelles: A combinatorial approach
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A rapid approach to identifying complementary catalytic groups using combinations of functional polymers is presented. Amphiphilic polymers with "clickable" hydrophobic blocks were used to create a library of functional polymers, each bearing a single functionality. The polymers were combined in water, yielding mixed micelles. As the functional groups were colocalized in the hydrophobic microphase, they could act cooperatively, giving rise to new modes of catalysis. The multipolymer "clumps" were screened for catalytic activity, both in the presence and absence of metal ions. A number of catalyst candidates were identified across a wide range of model reaction types. One of the catalytic systems discovered was used to perform a number of preparative-scale syntheses. Our approach provides easy access to a range of enzyme-inspired cooperative catalysts.
- Bukhryakov, Konstantin V.,Desyatkin, Victor G.,O'Shea, John-Paul,Almahdali, Sarah R.,Solovyeva, Vera,Rodionov, Valentin O.
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- Solid supported 9-amino-9-deoxy-epi-quinine as efficient organocatalyst for stereoselective reactions in batch and under continuous flow conditions
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Polystyrene-supported 9-amino-9-deoxy-epi-quinine was synthesized through co-polymerization of an ad hoc-designed chiral monomer with divinylbenzene, in the presence of azobis(isobutyronitile) (AIBN) as radical initiator and toluene and 1-dodecanol as porogenic solvents. The heterogenized catalyst efficiently promoted the reaction of isobutyric aldehyde with b-nitrostyrene, in very high yield and enantioselectivity, comparable or even higher than that of the homogeneous counterpart (up to 95% ee). The recyclability of the catalyst, its general applicability and its successful application to other reactions was also demonstrated. Finally, for the first time, a 9-amino- epi-quinine derivative was employed to perform an enantioselective Michael reaction under continuous-flow conditions; by using a home-made, packed-bed catalytic reactor, the aldehyde addition to nitrostyrene was successfully realized in flow mode, leading to the product in up to 93% ee.
- Porta, Riccardo,Benaglia, Maurizio,Coccia, Francesca,Cozzi, Franco,Puglisi, Alessandra
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- New acetylacetone-polymer modified nanoparticles as magnetically separable complexing agents
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In this paper, we present two methods of synthesis of new bifunctional polymeric nanohybrids and their full characterization. These nanohybrids consist of a magnetic nanoparticle core and polymeric shell which possess the ability to complex metal ions and organic compounds. Synthesized materials exhibit superparamagnetic properties and can thus be easily separated from complex mixtures by using an external magnetic field (facile separation, purification and recyclability). Herein, the syntheses of three bifunctional monomers are presented. Each of them was used to prepare the homopolymeric shell and two types of copolymeric shells (using styrene as a comonomer) around the magnetite nanoparticles. A surface initiated RAFT/MADIX polymerization technique was employed to prepare polymeric shells. Afterwards, post-modification of azide functionalized polymeric shells using the Huisgen "click" reaction was performed. Finally, twelve types of nanohybrids were prepared and their physicochemical properties were investigated. Additionally, the ability of nanohybrids to complex lanthanides and spectroscopic properties of obtained materials were studied.
- Misztalewska,Wilczewska,Wojtasik,Markiewicz,Kuchlewski,Majcher
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p. 100281 - 100289
(2015)
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- Synthesis of azide-functionalized nanoparticles by microemulsion polymerization and surface modification by click chemistry in aqueous medium
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Stable translucent aqueous suspensions of azide-functionalized cross-linked nanoparticles (NPs), with diameters in the 15-20 nm range, were prepared using two synthetic approaches. Copolymerization of azidomethylstyrene (VBN 3), styrene, and di
- Ouadahi, Karima,Allard, Emmanuel,Oberleitner, Birgit,Larpent, Chantal
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- Preparation of functional monomers as precursors of bioprobes from a common styrene derivative and polymer synthesis
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CM-Str (4-(Chloromethyl)styrene) was used as a useful starting material for the construction of a series of functional monomers. Substitution of the chlorine to the corresponding azide was performed, and the reduction of the azide proceeded smoothly to afford an aminostyrene, which was used as a common precursor for the preparation of functional monomers. Condensation of the amine with a fluorophore, biotin and carbohydrate was accomplished. Among the monomers, a carbohydrate monomer was polymerized with or without acrylamide as a model polymerization to yield the corresponding water-soluble glycopolymers, and biological evaluations of the glycopolymers for a lectin, and wheat germ agglutinin (WGA), were carried out on the basis of the fluorescence change of tryptophan in the WGA.
- Hayama, Riho,Koyama, Tetsuo,Matsushita, Takahiko,Hatano, Ken,Matsuoka, Koji
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- Catalytic Staudinger Reduction at Room Temperature
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We report an efficient catalytic Staudinger reduction at room temperature that enables the preparation of a structurally diverse set of amines from azides in excellent yields. The reaction is based on the use of catalytic amounts of triphenylphosphine as a phosphine source and diphenyldisiloxane as a reducing agent. Our catalytic Staudinger reduction exhibits a high chemoselectivity, as exemplified by reduction of azides over other common functionalities, including nitriles, alkenes, alkynes, esters, and ketones.
- Lenstra, Danny C.,Wolf, Joris J.,Mecinovi?, Jasmin
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p. 6536 - 6545
(2019/05/24)
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- Carcarinic acid-1, 2, 3- based triazole compound as well as preparation method and application thereof (by machine translation)
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The method comprises the following steps: firstly 1, 2, 3 - oxidizing and opening the carbon- carbon double bond of the, carcarinic acid into methylene to, obtain carcarinic acid (not shown, in the technical field of, organic 3 - synthesis), Wolf - Kishner - 1, 2, 3 - 1, 2, 3 - 1, 2, 3 - 3 . (by machine translation)
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Paragraph 0208-0210
(2019/12/25)
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- Reactive polymer zwitterions: Sulfonium sulfonates
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Sulfonium sulfonate, or sulfothetin, zwitterionic monomers were synthesized by ring-opening of 1,3-propanesultone with dialkyl sulfides containing styrenic or methacrylic moieties. Reversible addition-fragmentation chain-transfer polymerization of these m
- Santa Chalarca, Cristiam F.,Emrick, Todd
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- Structurally Defined Molecular Hypervalent Iodine Catalysts for Intermolecular Enantioselective Reactions
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Molecular structures of the most prominent chiral non-racemic hypervalent iodine(III) reagents to date have been elucidated for the first time. The formation of a chirally induced supramolecular scaffold based on a selective hydrogen-bonding arrangement provides an explanation for the consistently high asymmetric induction with these reagents. As an exploratory example, their scope as chiral catalysts was extended to the enantioselective dioxygenation of alkenes. A series of terminal styrenes are converted into the corresponding vicinal diacetoxylation products under mild conditions and provide the proof of principle for a truly intermolecular asymmetric alkene oxidation under iodine(I/III) catalysis.
- Haubenreisser, Stefan,W?ste, Thorsten H.,Martnez, Claudio,Ishihara, Kazuaki,Muiz, Kilian
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supporting information
p. 413 - 417
(2016/01/25)
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- Organocatalytic Enantioselective Continuous-Flow Cyclopropanation
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A set of six solid-supported diarylprolinol catalysts (varying on the anchoring strategy and the type of polymeric support) has been prepared and applied to the enantioselective cyclopropanation reaction. The selected candidate allows implementation of a long flow experiment (48 h) and generates a library of 12 cyclopropanes by sequential flow experiments. The mildness and utility of the method have enabled a telescoped process in which the outstream is directly used in a Wittig flow reaction.
- Llanes, Patricia,Rodríguez-Escrich, Carles,Sayalero, Sonia,Pericàs, Miquel A.
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supporting information
p. 6292 - 6295
(2016/12/23)
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- Carbon black functionalized with hyperbranched polymers: Synthesis, characterization, and application in reversible CO2 capture
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The functionalization of carbon black by grafting of hyperbranched polymers from the surface via self-condensing atom transfer radical polymerization (SC-ATRP) is reported. The surfaces of the pristine carbon black were modified with ATRP initiators using two different methods. The first method uses acid oxidation to place COOH groups on the carbon black surface, followed by the esterification to give ATRP initiators bound to the carbon black surface. Alternatively, ATRP initiators bearing both azido and bromine groups were placed directly on the carbon black surface by nitrene chemistry. The hyperbranched poly(p-chloromethylstyrene) (PCMS) was grafted from the ATRP initiator modified carbon black surfaces using the inimer of p-chloromethylstyrene, and CuCl/CuCl2/N,N,N′,N″,N″- pentamethyldiethylenetriamine (PMDETA) as the catalytic system in N,N-dimethylformamide (DMF). In addition, a one-pot two-step method was developed to graft crosslinked polymers from the carbon black surfaces. The polymerization process was well controlled and the fraction of the grafted polymers on carbon black could be adjusted by changing the polymerization time. The resulting samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The hyperbranched polymers on the carbon black surfaces were quaternized to give an ammonium group on the polymer, and a chloride counterion was subsequently exchanged to give a hydroxide counterion. Under these basic conditions, the ATRP initiators should be attached to the surface using nitrene chemistry rather than acid oxidation, to avoid the hydrolysis of the ester groups that link the grafted polymers to the carbon black surface. The ammonium hydroxide functionalized carbon black materials were utilized for the reversible absorption and desorption of CO2 from ambient air, providing improved absorption/desorption kinetics compared with the commercially available Excellion membrane.
- He, Hongkun,Zhong, Mingjiang,Konkolewicz, Dominik,Yacatto, Karin,Rappold, Timothy,Sugar, Glenn,David, Nathaniel E.,Matyjaszewski, Krzysztof
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p. 6810 - 6821
(2013/07/26)
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- Porous heterogeneous organic photocatalyst prepared by HIPE polymerization for oxidation of sulfides under visible light
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A porous heterogeneous photocatalyst was prepared by high internal phase emulsion (HIPE) polymerization. Such porous materials have interconnected pores and enough active moieties for photocatalysis. The material demonstrated a very high catalytic efficiency and can be reused for photocatalyzed oxidation of thioanisole under visible light.
- Li, Wenliang,Zhang, Wenjing,Dong, Xiaoqing,Yan, Lesan,Qi, Ruogu,Wang, Weicai,Xie, Zhigang,Jing, Xiabin
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scheme or table
p. 17445 - 17448
(2012/09/22)
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- Reactions of nitroalkenes with nitroalkanes or sulfur ylides catalyzed by amine-thiourea bifunctional polymeric organocatalysts
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Non-cross-linked and cross-linked bifunctional polystyrenes bearing both amine and thiourea groups have been synthesized and used as organocatalysts in reactions between nitroalkenes and nitroalkanes or sulfur ylides. Control experiments using monofunctional polymers with only either amine or thiourea groups attached indicated that both functional groups were essential for efficient catalysis of the reactions studied. The non-cross-linked polystyrene was soluble in typical organic solvents and was used as a homogeneous catalyst, while the cross-linked polystyrene was used as a heterogeneous catalyst. Georg Thieme Verlag Stuttgart · New York.
- Lu, Jinni,Toy, Patrick H.
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scheme or table
p. 2985 - 2990
(2012/01/07)
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- Polymeric ligands as homogeneous, reusable catalyst systems for copper assisted click chemistry
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Tris-(benzyltriazolylmethyl)amine (TBTA) has been immobilized onto a styrenic monomer and subsequently copolymerized with styrene to afford catalytically active and reusable copolymers for the CuAAC reaction. The Royal Society of Chemistry 2010.
- Lammens, Mieke,Skey, Jared,Wallyn, Sofie,O'Reilly, Rachel,Du Prez, Filip
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supporting information; experimental part
p. 8719 - 8721
(2011/02/24)
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- Iron-catalyzed aminohydroxylation of olefins
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We have discovered that N -sulfonyl oxaziridines react with a broad range of olefins in the presence of iron salts to afford 1,3-oxazolidines. This process provides access to 1,2-aminoalcohols with the opposite sense of regioselectivity produced from the copper-catalyzed oxyamination previously reported by our laboratories. Thus, either regioisomeric form of 1,2-aminoalcohols can easily be obtained from the reaction of oxaziridines with olefins, and the sense of regioselectivity can be controlled by the appropriate choice of inexpensive, nontoxic, first-row transition-metal catalyst.
- Williamson, Kevin S.,Yoon, Tehshik P.
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supporting information; experimental part
p. 4570 - 4571
(2010/06/12)
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- Immobilized iminophosphatranes useful for transesterification
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The present invention provides a method for transesterifying an ester, comprising combining the ester, a C1-C3 alcohol, and a heterogeneous catalyst of formula (I) or formula (II): wherein R′, R″ and R′″ are each H, (C1-C8)alkyl, (C6-C9)aryl, or (alk)3Si, wherein each alk is (C1-C4)alkyl; L is an organic linking moiety and X is a solid support material, and the salts thereof under conditions wherein the catalyst catalyzes the formation of the (C1-C3) ester of the acid portion of the ester and the corresponding free alcohol of the ester.
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Page/Page column sheet 4; 5
(2008/06/13)
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- Preparation of soluble polymeric supports with a functional group for liquid-phase organic synthesis
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Soluble copolymers of styrene with functional groups were prepared by radical co-polymerization of styrene with various substituted styrenes. They were characterized by NMR spectroscopy and their molecular weight was determined by size exclusion chromatography.
- Malagu, Karine,Guérin, Philippe,Guillemin, Jean-Claude
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p. 316 - 318
(2007/10/03)
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