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1.
Mater Sci Eng C Mater Biol Appl ; 104: 109922, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31499936

RESUMO

Synthesis of monodisperse carboxylic acid-functionalized magnetic mesoporous silica nanoparticles is performed by either two-step sol-gel process or post-grafting using citric acid modified isocyanate silane coupling agent (MMSN-NCO-CA) or succinic anhydride modified magnetic mesoporous silica (MMSN-NH-SA). Morphology, structure and magnetic properties of bare and mesoporous silica coated Fe3O4 core were studied using various techniques such as FTIR, VSM, TEM, FESEM, XRD and N2 adsorption-desorption isotherms (BET). Cisplatin (cis-Pt) adsorption isotherms and its release profile in various media were investigated by ICP-OES. MMSN-NCO-CA with mean particle size 107 nm had lower surface area (87.5 m2/g) and larger pore size (6.9 nm) in comparison with MMSN-NH-SA (respective values of 151.2 m2/g and 3.5 nm). cis-Pt loading into particles followed a saturable adsorption with respect to the drug to particle mass ratios. More sustained release of cis-Pt was observed for MMSN-NCO-CA, though both nanoparticles exhibited a pH- and saline concentration-dependent drug release. In addition, general and cis-Pt specific cytotoxicity were examined by MTT assay in MDA-MB-231 breast cancer cell line, and to further detect apoptosis, acridine orange/ethidium bromide dual cell staining was investigated by fluorescence microscopy. In-vitro anti-tumor efficiency of cis-Pt loaded MMSN-NCO-CA and MMSN-NH-SA were similarly enhanced in comparison to free cis-Pt; however, more specific apoptotic death occurred for cis-Pt loaded MMSN-NCO-CA. Therefore, the as-synthesized citric acid functionalized core-shell magnetic mesoporous hybrid nanoparticles could be used as a promising drug carriers for cancer therapy in-vivo.


Assuntos
Cisplatino/administração & dosagem , Ácido Cítrico/química , Sistemas de Liberação de Medicamentos , Compostos Férricos/química , Nanopartículas/química , Salinidade , Silanos/química , Dióxido de Silício/química , Adsorção , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Ácido Cítrico/síntese química , Liberação Controlada de Fármacos , Compostos Férricos/síntese química , Hemólise , Humanos , Hidrodinâmica , Concentração de Íons de Hidrogênio , Cinética , Magnetometria , Nanopartículas/ultraestrutura , Porosidade , Silanos/síntese química , Dióxido de Silício/síntese química , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Propriedades de Superfície , Difração de Raios X
2.
Colloids Surf B Biointerfaces ; 181: 166-173, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31132608

RESUMO

Amino-terminated surfaces can be effectively obtained by means of silanizing agents, realizing surfaces suitable for the purification of biomarkers of several pathologies. Since the level of biomarkers, such as microRNAs and cell-free DNA, into circulation may be extremely low, new and ameliorated capturing molecules and protocols are highly required. In this work, a new silane, acetone-imine propyl trimethoxysilane (AIPTMS), is synthesized with a simple and elegant reaction, via the nucleophilic addition of the primary amino group to the carbonyl group of acetone. AIPTMS and APTMS were used to silanize silicon oxide surfaces, which were characterized chemically (XPS) and morphologically (AFM). The two types of surfaces were chemically similar, but behaved very differently both for surface morphology and functional properties. The AIPTMS-modified surface was indeed very smooth and homogeneous with respect to the APTMS-modified surface. Moreover, the AIPTMS surface captured larger amounts of nucleic acids almost immediately after preparation, while APTMS-based functional surfaces needed longer time to reach comparable efficiency. AIPTMS shows several advantages over standard aminosilanes, as it realizes a more homogeneous surface coverage that, in turn, produces an improved response towards the capture of nucleic acids. AIPTMS is a very promising reagent for the reliable and reproducible preparation of active biofunctional surfaces for the purification and analysis of circulating biomarkers.


Assuntos
Propilaminas/química , Silanos/química , Dióxido de Silício/química , Estrutura Molecular , Tamanho da Partícula , Propilaminas/síntese química , Silanos/síntese química , Propriedades de Superfície
3.
Colloids Surf B Biointerfaces ; 181: 125-133, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31128512

RESUMO

One of the events occurring when a biomaterial is implanted in an host is the protein deposition onto its surface, which might regulate cell responses. When a biomaterial displays a compromised biocompatibility, distinct complement pathways can be activated to produce a foreign body reaction. In this article, we have designed different types of biomaterial surfaces to study the inflammation process. Here, we used different concentrations of (3-glycidoxypropyl)-trimethoxysilane (GPTMS), an organically-modified alkoxysilane as a precursor for the synthesis of various types of sol-gel materials functionalizing coatings for titanium implants to regulate biological responses. Our results showed that greater GPTMS surface concentrations induced greater secretion of TNF-α and IL-10 on RAW 264.7 macrophages. When implanted into rabbit tibia, osseointegration decreased with higher GPTMS concentrations. Interestingly, higher deposition of complement-related proteins C-reactive protein (CRP) and ficolin-2 (FCN2), two main activators of distinct complement pathways, was observed. Taking all together, inflammatory potential increase seems to be GPTMS concentration-dependent. Our results show that a greater adsorption of complement proteins can condition macrophage polarization.


Assuntos
Materiais Biocompatíveis/farmacologia , Proteínas do Sistema Complemento/metabolismo , Macrófagos/efeitos dos fármacos , Silanos/farmacologia , Titânio/farmacologia , Animais , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Interleucina-10/biossíntese , Macrófagos/metabolismo , Camundongos , Tamanho da Partícula , Células RAW 264.7 , Coelhos , Silanos/síntese química , Silanos/química , Propriedades de Superfície , Tíbia/efeitos dos fármacos , Tíbia/metabolismo , Titânio/química , Fator de Necrose Tumoral alfa/biossíntese
4.
Int J Mol Sci ; 20(8)2019 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-31003413

RESUMO

Gamma-ray radiation was used as a clean and easy method for turning the physicochemical properties of graphene oxide (GO) in this study. Silane functionalized-GO were synthesized by chemically grafting 3-aminopropyltriethoxysilane (APTES) and 3-glycidyloxypropyltrimethoxysilane (GPTES) onto GO surface using gamma-ray irradiation. This established non-contact process is used to create a reductive medium which is deemed simpler, purer and less harmful compared conventional chemical reduction. The resulting functionalized-GO were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), and Raman spectroscopy. The chemical interaction of silane with the GO surface was confirmed by FT-IR. X-ray diffraction reveals the change in the crystalline phases was due to surface functionalization. Surface defects of the GO due to the introduction of silane mioties was revealed by Raman spectroscopy. Thermogravimetric analysis of the functionalized-GO exhibits a multiple peaks in the temperature range of 200-650 °C which corresponds to the degradation of chemically grafted silane on the GO surface.


Assuntos
Grafite/química , Compostos de Organossilício/química , Propilaminas/química , Silanos/química , Compostos de Epóxi/síntese química , Compostos de Epóxi/química , Compostos de Epóxi/efeitos da radiação , Raios gama , Grafite/síntese química , Grafite/efeitos da radiação , Microscopia Eletrônica de Varredura , Compostos de Organossilício/efeitos da radiação , Propilaminas/síntese química , Propilaminas/efeitos da radiação , Silanos/síntese química , Silanos/efeitos da radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Propriedades de Superfície/efeitos da radiação , Temperatura Ambiente , Termogravimetria , Difração de Raios X
5.
Molecules ; 24(3)2019 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-30709033

RESUMO

A series of disilane-linked donor‒acceptor‒donor triads (D‒Si‒Si‒A‒Si‒Si‒D) was synthesized to investigate the effects of substituents on the photophysical properties. The triads were prepared by metal-catalyzed diiodosilylation of aryl iodides using a Pd(P(t-Bu)3)2/(i-Pr)2EtN/toluene system that we previously developed. Optical measurements, X-ray diffraction analysis, and density functional theory calculations revealed relationships between the photophysical properties and molecular structures of these triads in solution and in the solid state. The compounds emitted blue to green fluorescence in CH2Cl2 solution and in the solid state. Notably, compound 2 showed fluorescence with an absolute quantum yield of 0.17 in the solid state but showed no fluorescence in CH2Cl2. Our findings confirmed that the substituent adjacent to the disilane moiety affects the conformations and emission efficiencies of compounds in solution and in the solid state.


Assuntos
Luminescência , Silanos/química , Modelos Moleculares , Estrutura Molecular , Silanos/síntese química , Soluções , Análise Espectral
6.
Bioorg Med Chem ; 26(15): 4493-4501, 2018 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-30077610

RESUMO

Pregnane X receptor (PXR) is a ligand-dependent transcription factor that is considered to be a potential therapeutic target for multiple diseases. Herein, we report the development and structure-activity relationship studies of a new series of hPXR agonists. Focusing on our recently developed silanol-sulfonamide scaffold, we developed the potent hPXR agonist 28, which shows good selectivity over hLXRα and ß, hFXR, and hRORα and γ. Examination of the structure-activity relationship suggested a possible strategy to manipulate the selectivity. Docking simulation indicated the presence of an additional binding cavity and polar contacts in the ligand-binding pocket of hPXR. This information should be helpful for the future development of more potent and selective hPXR ligands.


Assuntos
Receptor de Pregnano X/agonistas , Silanos/química , Sítios de Ligação , Desenho de Drogas , Humanos , Receptores X do Fígado/agonistas , Receptores X do Fígado/metabolismo , Simulação de Acoplamento Molecular , Receptores Nucleares Órfãos/antagonistas & inibidores , Receptores Nucleares Órfãos/metabolismo , Receptor de Pregnano X/metabolismo , Estrutura Terciária de Proteína , Silanos/síntese química , Silanos/metabolismo , Relação Estrutura-Atividade
7.
Molecules ; 23(6)2018 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-29895798

RESUMO

The effective and straight-forward modification of nanostructured celluloses under aqueous conditions or as "never-dried" materials is challenging. We report a silanization protocol in water using catalytic amounts of hydrogen chloride and then sodium hydroxide in a two-step protocol. The acidic step hydrolyzes the alkoxysilane to obtain water-soluble silanols and the subsequent addition of catalytic amounts of NaOH induces a covalent reaction between cellulose surficial hydroxyl groups and the respective silanols. The developed protocol enables the incorporation of vinyl, thiol, and azido groups onto cellulose fibers and cellulose nanofibrils. In contrast to conventional methods, no curing or solvent-exchange is necessary, thereby the functionalized celluloses remain never-dried, and no agglomeration or hornification occurs in the process. The successful modification was proven by solid state NMR, ATR-IR, and EDX spectroscopy. In addition, the covalent nature of this bonding was shown by gel permeation chromatography of polyethylene glycol grafted nanofibrils. By varying the amount of silane agents or the reaction time, the silane loading could be tuned up to an amount of 1.2 mmol/g. Multifunctional materials were obtained either by prior carboxymethylation and subsequent silanization; or by simultaneously incorporating both vinyl and azido groups. The protocol reported here is an easy, general, and straight-forward avenue for introduction of anchor groups onto the surface of never-dried celluloses, ready for click chemistry post-modification, to obtain multifunctional cellulose substrates for high-value applications.


Assuntos
Celulose/química , Ácido Clorídrico/química , Silanos/síntese química , Hidróxido de Sódio/química , Catálise , Química Click , Nanofibras/química , Silanos/química , Compostos de Sulfidrila/síntese química , Compostos de Sulfidrila/química , Propriedades de Superfície , Compostos de Vinila/síntese química , Compostos de Vinila/química , Água/química
8.
J Org Chem ; 83(10): 5398-5409, 2018 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-29667397

RESUMO

Silanediol peptidomimetics have been prepared, designed to inhibit the serine protease enzyme Factor XIa (FXIa) for treatment of thrombosis without complete interruption of normal hemostasis. These Arg-[Si]-Ala analogues of the FXIa substrate (FIX) are the first silanediol dipeptide analogues to carry a basic guanidine group. Control of stereochemistry was accomplished using catalytic asymmetric hydrosilylation and addition of a silyllithium intermediate to the Davis-Ellman sulfinimine.


Assuntos
Fator XIa/antagonistas & inibidores , Inibidores de Serino Proteinase/farmacologia , Silanos/farmacologia , Fator XIa/metabolismo , Humanos , Conformação Molecular , Inibidores de Serino Proteinase/síntese química , Inibidores de Serino Proteinase/química , Silanos/síntese química , Silanos/química
9.
J Am Chem Soc ; 140(1): 139-142, 2018 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-29202243

RESUMO

An asymmetric Ni-catalyzed reductive cross-coupling has been developed to prepare enantioenriched allylic silanes. This enantioselective reductive alkenylation proceeds under mild conditions and exhibits good functional group tolerance. The chiral allylic silanes prepared here undergo a variety of stereospecific transformations, including intramolecular Hosomi-Sakurai reactions, to set vicinal stereogenic centers with excellent transfer of chirality.


Assuntos
Compostos Alílicos/síntese química , Níquel/química , Silanos/síntese química , Compostos Alílicos/química , Catálise , Estrutura Molecular , Oxirredução , Silanos/química , Estereoisomerismo
10.
Molecules ; 22(12)2017 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-29231894

RESUMO

Molecules containing catenated heavy group 14 atoms are known to exhibit the interesting property of σ-bond electron delocalization. While this is well studied for oligo- and polysilanes the current paper addresses the UV-absorption properties of small tin containing oligosilanes in order to evaluate the effects of Sn-Si and Sn-Sn bonds as well as the results of substituent exchange from methyl to phenyl groups. The new stannasilanes were compared to previously investigated oligosilanes of equal chain lengths and substituent pattern. Replacing the central SiMe2 group in a pentasilane by a SnMe2 unit caused a bathochromic shift of the low-energy band (λmax = 260 nm) of 14 nm in the UV spectrum. If, instead of a SnMe2, a SnPh2 unit is incorporated, the bathochromic shift of 33 nm is substantially larger. Keeping the SnMe2 unit and replacing the two central silicon with tin atoms causes shift of the respective band (λ = 286 nm) some 26 nm to the red. A similar approach for hexasilanes where the model oligosilane [(Me3Si)3Si]2(SiMe2)2 (λmax = 253 nm) was modified in a way that the central tetramethyldisilanylene unit was exchanged for a tetraphenyldistannanylene caused a 50 nm bathochromic shift to a low-energy band with λmax = 303 nm.


Assuntos
Compostos Orgânicos de Estanho/química , Polímeros/química , Silanos/química , Espectrofotometria Ultravioleta/métodos , Luz , Espectroscopia de Ressonância Magnética/métodos , Espectrometria de Massas/métodos , Modelos Moleculares , Estrutura Molecular , Compostos Orgânicos de Estanho/síntese química , Polímeros/síntese química , Silanos/síntese química , Relação Estrutura-Atividade , Estanho/química
11.
J Inorg Biochem ; 177: 211-218, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-29031179

RESUMO

A series of new organometallic carbosilane dendrimers functionalized with Copper(II) complex on the surface were synthesized and characterized as potential anticancer agents. These metallodendrimers were synthesized through the reaction of dendritic ligands containing N,N- and N,O- donor atoms able to act as chelating agents with CuCl2 as metallic ion precursor. The structural characterization of these complexes was addressed through the use of different analytical and spectroscopical techniques. Particularly, an electron paramagnetic resonance study was performed to corroborate the coordination properties of these dendritic ligands. A preliminary study was carried out to establish the cytotoxicity of the new synthesized compounds in human prostate (PC3) and human cervical (HeLa) cancer cell lines in order to evaluate their potential as anticancer agents and compare their activity with other copper or analogous ruthenium metallodendrimers.


Assuntos
Antineoplásicos/farmacologia , Complexos de Coordenação/farmacologia , Cobre/química , Dendrímeros/farmacologia , Silanos/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Dendrímeros/síntese química , Dendrímeros/química , Espectroscopia de Ressonância de Spin Eletrônica , Humanos , Ligantes , Silanos/síntese química , Silanos/química
12.
J Org Chem ; 82(18): 9487-9496, 2017 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-28809110

RESUMO

A method for the deprotonative silylation of aromatic C-H bonds has been developed using trifluoromethyltrimethylsilane (CF3SiMe3, Ruppert-Prakash reagent) and a catalytic amount of fluoride. In this reaction, CF3SiMe3 is considered to act as a base and a silicon electrophile. This process is highly tolerant to various functional groups on heteroarenes and benzenes. Furthermore, this method can be applied to the synthesis of trimethylsilyl group-containing analogs of TAC-101, which is a bioactive synthetic retinoid with selective affinity for retinoic acid receptor α (RAR-α) binding. We also report further transformations of the silylated products into useful derivatives.


Assuntos
Fluoretos/química , Hidrocarbonetos Fluorados/química , Silanos/síntese química , Compostos de Trimetilsilil/química , Estrutura Molecular , Prótons , Silanos/química
13.
Molecules ; 22(5)2017 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-28524100

RESUMO

It was found that 1,2-trifluoromethylation reactions of ketones, enones, and aldehydes were easily accomplished using the Prakash reagent in the presence of catalytic amounts of cesium carbonate, which represents an experimentally convenient, atom-economic process for this anionic trifluoromethylation of non-enolisable aldehydes and ketones.


Assuntos
Carbonatos/química , Césio/química , Chalconas/química , Éteres/síntese química , Cetonas/química , Silanos/síntese química , Aldeídos/química , Catálise , Técnicas de Química Sintética , Halogenação , Metilação , Estrutura Molecular , Estereoisomerismo
14.
Eur J Med Chem ; 135: 70-76, 2017 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-28433777

RESUMO

The efficacy of current influenza vaccines and small molecule antiviral drugs is curtailed by the emerging of multidrug-resistant influenza viruses. As resistance to the only FDA-approved oral influenza antiviral, oseltamivir (Tamiflu), continues to rise, there is a clear need to develop the next-generation of antiviral drugs. Since more than 95% of current circulating influenza A viruses carry the S31N mutation in their M2 genes, the AM2-S31N mutant proton channel represents an attractive target for the development of broad-spectrum antivirals. In this study we report the design and synthesis of the first class of organosilanes that have potent antiviral activity against a panel of human clinical isolates of influenza A viruses, including viruses that are resistant to amantadine, oseltamivir, or both.


Assuntos
Antivirais/farmacologia , Desenho de Drogas , Farmacorresistência Viral Múltipla/efeitos dos fármacos , Vírus da Influenza A/efeitos dos fármacos , Silanos/farmacologia , Antivirais/síntese química , Antivirais/química , Relação Dose-Resposta a Droga , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Silanos/síntese química , Silanos/química , Relação Estrutura-Atividade , Proteínas da Matriz Viral/genética
15.
Molecules ; 22(4)2017 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-28333113

RESUMO

Diopside (DIOP) was introduced into polyetheretherketone/polyglycolicacid (PEEK/PGA) scaffolds fabricated via selective laser sintering to improve bioactivity. The DIOP surface was then modified using a silane coupling agent, 3-glycidoxypropyltrimethoxysilane (KH570), to reinforce interfacial adhesion. The results showed that the tensile properties and thermal stability of the scaffolds were significantly enhanced. It could be explained that, on the one hand, the hydrophilic group of KH570 formed an organic covalent bond with the hydroxy group on DIOP surface. On the other hand, there existed relatively high compatibility between its hydrophobic group and the biopolymer matrix. Thus, the ameliorated interface interaction led to a homogeneous state of DIOP dispersion in the matrix. More importantly, an in vitro bioactivity study demonstrated that the scaffolds with KH570-modified DIOP (KDIOP) exhibited the capability of forming a layer of apatite. In addition, cell culture experiments revealed that they had good biocompatibility compared to the scaffolds without KDIOP. It indicated that the scaffolds with KDIOP possess potential application in tissue engineering.


Assuntos
Silanos/síntese química , Ácido Silícico/química , Linhagem Celular , Humanos , Silanos/química , Propriedades de Superfície
16.
J Am Chem Soc ; 139(6): 2192-2195, 2017 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-28117996

RESUMO

We report a highly enantioselective CuH-catalyzed Markovnikov hydrosilylation of vinylarenes and vinyl heterocycles. This method has a broad scope and enables both the synthesis of isolable silanes and the conversion of crude products to chiral alcohols. Density functional theory calculations support a mechanism proceeding by hydrocupration followed by σ-bond metathesis with a hydrosilane.


Assuntos
Alcenos/química , Cobre/química , Compostos Heterocíclicos/química , Hidrogênio/química , Silanos/síntese química , Compostos de Vinila/química , Catálise , Estrutura Molecular , Silanos/química
17.
Angew Chem Int Ed Engl ; 56(4): 1092-1096, 2017 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-27976482

RESUMO

Iridium catalysts containing dative nitrogen ligands are highly active for the borylation and silylation of C-H bonds, but chiral analogs of these catalysts for enantioselective silylation reactions have not been developed. We report a new chiral pyridinyloxazoline ligand for enantioselective, intramolecular silylation of symmetrical diarylmethoxy diethylsilanes. Regioselective and enantioselective silylation of unsymmetrical substrates was also achieved in the presence of this newly developed system. Preliminary mechanistic studies imply that C-H bond cleavage is irreversible, but not the rate-determining step.


Assuntos
Irídio/química , Nitrogênio/química , Oxazóis/química , Silanos/síntese química , Catálise , Ligantes , Estrutura Molecular , Silanos/química , Estereoisomerismo
18.
Org Biomol Chem ; 15(1): 132-143, 2016 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-27824204

RESUMO

Procedures for selective installation of acyl, silyl ether and para-methoxybenzyl (PMB) ether groups to glycoside substrates have been developed, employing phenylboronic esters as protected intermediates. The sequence of boronic ester formation, functionalization and deprotection can be accomplished with only a single purification step, and the boronic acid component can be recovered and reused after deprotection. Key advances include the identification of reaction conditions for installation of PMB groups in the presence of boronic esters, and the use of the 'phase switching' protocol developed by Hall and co-workers as an efficient method for boronic ester cleavage. The relatively mild conditions for boronate deprotection are tolerant of several functional groups, including esters, silyl ethers, ketals and thioglycosides.


Assuntos
Ácidos Borônicos/síntese química , Glicosídeos/química , Acilação , Alquilação , Ácidos Borônicos/química , Ésteres/síntese química , Ésteres/química , Glicosídeos/síntese química , Silanos/síntese química , Silanos/química
19.
Angew Chem Int Ed Engl ; 55(50): 15559-15563, 2016 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-27862732

RESUMO

A method for the palladium-catalyzed fluorination of cyclic vinyl triflates has been developed. As with several previous palladium-catalyzed fluorination reactions using fluoride salts, controlling the regioselectivity presented a challenge in developing a practical synthetic procedure. The addition of triethyl(trifluoromethyl)silane (TESCF3 ) was found to effectively address this problem and resulted in drastically improved regioselectivities in this palladium-catalyzed fluorination reaction. This discovery, along with the use of a new biarylphosphine ligand, allowed for the development of an efficient and highly regioselective protocol for the fluorination of vinyl triflates. This method is compatible with a range of sensitive functional groups and provides access to five-, six-, and seven-membered cyclic vinyl fluorides.


Assuntos
Mesilatos/química , Paládio/química , Silanos/química , Compostos de Vinila/química , Catálise , Ciclização , Halogenação , Mesilatos/síntese química , Silanos/síntese química , Estereoisomerismo , Compostos de Vinila/síntese química
20.
Macromol Rapid Commun ; 37(23): 1939-1944, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27775202

RESUMO

Highly swellable, dual-responsive hydrogels, consisting of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) and redox-responsive poly(ferrocenylsilane) (PFS) based poly(ionic liquid)s (PILs) are formed by photo-polymerization. PFS chains bearing cross-linkable vinylimidazolium (VIm) side groups are copolymerized with NIPAM in aqueous solutions under ultraviolet light (λ = 365 nm) in the presence of a photoinitiator. The PFS-PILs serve as a macro-cross-linker and also provide redox responsiveness. The swelling ratio, morphology, and lower critical solution temperature (LCST) of the hydrogels are studied as a function of the PNIPAM/PFS ratio. The value of the LCST is dependent on the choice of the counterion of the PIL and the PNIPAM/PFS ratio. The hydrogel is employed as a reducing environment for the in situ fabrication of gold nanoparticles (AuNPs), forming AuNP-hydrogel composites. The localized surface plasmon resonance peak of the as-synthesized Au nanoparticles inside the hydrogel could be tuned by altering the temperature.


Assuntos
Resinas Acrílicas/química , Compostos Ferrosos/química , Hidrogéis/química , Líquidos Iônicos/química , Silanos/química , Resinas Acrílicas/síntese química , Compostos Ferrosos/síntese química , Ouro/química , Líquidos Iônicos/síntese química , Nanopartículas Metálicas/química , Estrutura Molecular , Oxirredução , Silanos/síntese química , Ressonância de Plasmônio de Superfície , Temperatura Ambiente
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