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1.
Bioorg Med Chem Lett ; 30(18): 127389, 2020 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-32717610

RESUMO

Emergence of antibioresistance is currently a major threat of public health worldwide. Hence there is an urge need of finding new antibacterial material. Herein, we report a simple and eco-friendly method to synthesize homo and heterodicationic ionic liquids based on quaternary phosphonium and ammonium salt. In order to investigate the structure activity relationship (SAR) we measured the MICs of a series of 16 derivatives with structural variations (nature of cations and counter-ions, size of linker and alkyl side chains as well as structural symmetry) over a range of Gram-positive and Gram-negative bacterial strains from the ESKAPE group. Some of the tested structures exhibit high antimicrobial activities (MIC = 0.5 mg/L) and are active over a wide range of bacteria from Gram-positive to Gram-negative. Overall, these results reveal the strong potential of di-cationic derivatives as antibacterial agents and the determination of activities from structural features gives decisive information for future synthesis of such di-cationic structures for biocidal purpose.

2.
ACS Appl Mater Interfaces ; 11(50): 47635-47641, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31769645

RESUMO

An innovative novel interface has been designed and developed to be used as a potential active layer in chemically sensitive field-effect transistor (Chem-FET) sensor devices for the specific sensing of Cs+. In this study, the synthesis of a specific Cs+ probe based on calix[4]arene benzocrown ether, its photophysical properties, and its grafting onto a single lipid monolayer (SLM) recently used as an efficient ultrathin organic dielectric in Chem-FETs are reported simultaneously. On the basis of both optical and NMR titration experiments, the probe has shown high selectivity and specificity for Cs+ compared to interfering cations, even if an admixture is used. Additionally, Attenuated Total Reflectance Fourier Transform Infra Red (ATR-FTIR) spectroscopy was successfully used to characterize and prove the efficient grafting of the probe onto a SLM and the formation of the innovative novel sensing layer.

3.
Bioorg Med Chem Lett ; 28(5): 926-929, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29439903

RESUMO

We report the synthesis of new mono, di and tri phosphonium ionic liquids and the evaluation of their antibacterial activities on both Gram-positive and Gram-negative bacteria from the ESKAPE-group. Among the molecules synthesized some of them reveal a strong bactericidal activity (MIC = 0.5 mg/L) for Gram-positive bacteria (including resistant strains) comparable to that of standard antibiotics. A comparative Gram positive and Gram negative antibacterial activities shows that the nature of counter-ion has no significant effects. Interestingly, the increase of phosphonium lateral chains (from 4 to 8 carbons) results in a decrease of antibacterial activities. However, the increase of the spacer length has a positive influence on the activity on both Gram-positive and Gram-negative bacteria except for E. aerogenes. Finally, the increased charge density has no effect on the Gram-positive antibacterial activities (MIC between 2 and 4 mg/L) but seems to attenuate (except for P. aeruginosa) the discrimination between Gram-positive and Gram-negative. Overall these results suggest a unique mechanism of action of these triphenylamine-phosphonium ionic liquid derivatives.


Assuntos
Aminas/farmacologia , Antibacterianos/farmacologia , Antineoplásicos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Líquidos Iônicos/farmacologia , Compostos Organofosforados/farmacologia , Aminas/química , Antibacterianos/síntese química , Antibacterianos/química , Antineoplásicos/síntese química , Antineoplásicos/química , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Células Hep G2 , Humanos , Líquidos Iônicos/síntese química , Líquidos Iônicos/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Compostos Organofosforados/síntese química , Compostos Organofosforados/química , Relação Estrutura-Atividade
4.
Biofouling ; 34(9): 1055-1063, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30626214

RESUMO

Much current research is focused on preventing and controlling the natural process of colonization by marine organisms of surfaces submerged in seawater. Previously, the authors' laboratory has reported the synthesis and the full physico-chemical characterization of homopolymers obtained from 1-ferrocenylmethyl methacrylate (FMMA), 2-(ferrocenylmethoxy)ethyl methacrylate (FMOEMA), and 3-(ferrocenylmethoxy)propyl methacrylate (FMOPMA). Here, the bacterial anti-adhesion activity of these homopolymers (pFMMA, pFMOEMA and pFMOPMA) is reported when stimulated in 96-well microplates containing a printed electrochemical cell in each well. Polymers were deposited on the printed carbon working electrode of each well in two columns each comprising eight wells. Their electrochemical anti-adhesion properties were evaluated by inoculating a marine biofilm forming bacterial strain, Pseudoalteramonas lipolytica, in each well and then applying recurrent scans for 15 h. The results revealed an intrinsic anti-adhesion activity of all the polymers. This activity was amplified by a factor of 10 when potential recurrent scans were applied.


Assuntos
Aderência Bacteriana/fisiologia , Incrustação Biológica/prevenção & controle , Técnicas Eletroquímicas/métodos , Compostos Ferrosos/química , Gammaproteobacteria/crescimento & desenvolvimento , Ácidos Polimetacrílicos/química , Biofilmes/crescimento & desenvolvimento , Carbono , Eletrodos , Metalocenos , Água do Mar/microbiologia
5.
Anal Chem ; 88(7): 3804-9, 2016 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-26974586

RESUMO

We report herein the fabrication of novel microarrays based on air-stable functional lipid monolayers over silicon using a combination of e-beam lithography and lift-off. We demonstrate these microarrays can be use as ultrasensitive platform for Kelvin probe force microscopy in sensing experiments. Specificity of the detection is given by the functional group grafted at the lipid headgroup. The arrays developed for the detection of ferric ions, Fe(3+), using a γ-pyrone derivative chelator, demonstrate subpicomolar limit of detection with high specificity. In addition, the technique takes advantage of the structure of the array with the silicon areas playing the role of reference for the measurement, and we determine critical pattern dimensions below which the probe size/shape impacts the measured results.


Assuntos
Ferro/análise , Membranas Artificiais , Análise em Microsséries/instrumentação , Di-Inos/química , Limite de Detecção , Fosfatidilcolinas/química , Pironas/química , Silício/química
6.
Org Lett ; 16(16): 4074-7, 2014 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-25080102

RESUMO

With the help of mixed ligand catalytic systems, the analogous mechanisms behind the cognate performance by Pd(dba)2 and Pd2(dba)3 in catalyzing C-N and C-S coupling reactions were demonstrated. This information is instrumental in organic synthesis requiring Pd-catalyzed cross-coupling reactions and may also be valuable to other Pd-catalyzed transformations.

7.
Biosens Bioelectron ; 54: 571-7, 2014 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-24333568

RESUMO

Field effect transistors have risen as one of the most promising techniques in the development of biomedical diagnosis and monitoring. In such devices, the sensitivity and specificity of the sensor rely on the properties of the active sensing layer (gate dielectric and probe layer). We propose here a new type of transistor developed for the detection of Fe(3+) ions in which this sensing layer is made of a monolayer of lipids, engineered in such a way that it is not sensitive to pH in the acidic range, therefore making the device perfectly suitable for biomedical diagnosis. Probes are γ-pyrone derivatives that have been grafted to the lipid headgroups. Affinity constants derived for the chelator/Fe(3+) complexation as well as for other ions demonstrate very high sensitivity and specificity towards ferric ions with values as high as 5.10(10) M and a detected concentration as low as 50 fM.


Assuntos
Técnicas Biossensoriais/instrumentação , Compostos Férricos/análise , Ferro/análise , Lipídeos/química , Pironas/química , Transistores Eletrônicos , Cátions/análise , Sensibilidade e Especificidade
9.
Anal Chem ; 85(20): 9968-74, 2013 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-24047448

RESUMO

A novel sulfonamide-conjugated benzo-[2,1-b:3,4-b']bithiophene semiconductor has been designed and synthetized in order to develop a probe for specific detection of anions both in the homogeneous (solution) and heterogeneous phase. Its photophysical and electrochemical data were reported in this study. On the basis of the optical and NMR titrations analysis, the chelator was found to be highly selective for fluoride compared to others anions (Ka = 1.6 × 10(4) M(-1) in dimethyl sulfoxide (DMSO)). In addition, from an intricate sample, the novel chelator shows exceptional specificity toward fluoride and reveals a complete reversibility after addition of trifluoroacetic acid (TFA). Sensing films were obtained by electrochemical polymerization of the probe on an electrode surface, which clearly show effective detection of fluoride.


Assuntos
Técnicas de Química Analítica/instrumentação , Fluoretos/análise , Semicondutores , Sulfonamidas/química , Tiofenos/química , Dimetil Sulfóxido/química , Eletroquímica , Fluoretos/química , Modelos Moleculares , Conformação Molecular
10.
Phys Chem Chem Phys ; 14(5): 1635-41, 2012 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-22193370

RESUMO

The electron transport through molecules in molecular devices is typically influenced by the nature of the interfaces with the contacting electrodes and by the interactions between neighbouring molecules. It is a major goal of molecular electronics to adjust the electronic function of a molecular device by tailoring the intrinsic molecular properties and the interfacial and intermolecular interactions. Here, we report on the tunability of the electronic properties of coronene derivatives, namely dodecakis(arylthio)coronenes (DATCs), which are found to exhibit a three-dimensional aromatic system. Scanning tunnelling microscopy (STM), spectroscopy (STS) and simulations based on the density functional theory (DFT) are employed to characterize the structural and electronic properties of these molecules deposited on Au(111) surfaces. It is shown that modifications of the peripheral aryl-groups allow us to specifically affect the self-assembly and the charge transport characteristics of the molecules. Molecular assemblies like supramolecular wires with highly delocalized orbitals and single molecules with molecular "quantum dot" characteristics are obtained in this way.

11.
Chem Commun (Camb) ; 47(37): 10410-2, 2011 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-21837349

RESUMO

Fine control of the N/S ratio and/or the position of the bridged heteroatoms in mixed heterocalix[4]arenes leads to a new approach to generate inherent chiral scaffolds and represents a new challenge to fine-tune cooperative properties.

12.
Org Lett ; 12(12): 2722-5, 2010 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-20481643

RESUMO

Novel nitrogen-bridged aza[1(4)]cyclophanes with fine-tuned cavities have been synthesized by nucleophilic aromatic substitution of 1,5-difluoro-2,4-dinitrobenzene with diaminobenzene derivatives.

13.
Org Lett ; 11(17): 3846-9, 2009 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-19670852

RESUMO

One of the shortest and most efficient routes toward a series of functionalized pentahelicenes is reported. Benzylic (dibromo)methine coupling is an important entry into functional helicene chemistry. It allowed a mono- or a double functionalization by some metal-catalyzed Ar-C, Ar-S, Ar-CN, and Ar-I bond formations. Those functions offer new avenues for further applications. For instance, helicene (4) can be supported on a Ag(001) surface, which was characterized by high-resolution NC-AFM imaging.

14.
Chem Commun (Camb) ; (48): 6507-9, 2008 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-19057761

RESUMO

A new class of sulfurated, semi-rigid, radial and low-valent glycosylated asterisk ligands with potential dual function as ligand and probe has some of the highest inhibition potencies of Con A-induced hemagglutination, by using a cross-linking mechanism of Con A which amplifies the enhancement to near nanomolar concentrations with the alpha-d-mannose asterisk.


Assuntos
Concanavalina A/química , Testes de Hemaglutinação , Animais , Glicosilação , Coelhos
15.
Chemistry ; 14(33): 10357-63, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18846601

RESUMO

We have synthesized a novel class of dendrimers, consisting of a polysulfurated pyrene core with appended poly(thiophenylene) dendrons (PyG0, PyG1, and PyG2, see Scheme 1), which exhibit remarkable photophysical and redox properties. In dichloromethane or cyclohexane solution they show a strong, dendron-localized absorption band with a maximum at around 260 nm and a band in the visible region with a maximum at 435 nm, which can be assigned to the pyrene core strongly perturbed by the four sulfur substituents. The dendrimers exhibit a strong (Phi=0.6), short-lived (tau=2.5 ns) core-localized fluorescence band with maximum at approximately 460 nm in cyclohexane solution at 293 K. A strong fluorescence is also observed in dichloromethane solution at 293 K, in dichloromethane/chloroform rigid matrix at 77 K, and in the solid state (powder) at room temperature. The dendrimers undergo reversible chemical and electrochemical one-electron oxidation with formation of a strongly colored deep blue radical cation. A second, reversible one-electron oxidation is observed at more positive potential values. The photophysical and redox properties of the three dendrimers are finely tuned by the length of their branches. The strong blue fluorescence and the yellow to deep blue color change upon reversible one-electron oxidation can be exploited for optoelectronic devices.

16.
Chem Commun (Camb) ; (40): 4167-9, 2007 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-17925964

RESUMO

Gold nanoparticles with average diameter of 1.0 nm and narrow size distribution can be easily obtained by disproportionation of Au(+) ions, in the presence of a persulfurated coronene dendrimer that favors encounters between Au(+) ions and protects the resulting small nanoparticles from further aggregation.

17.
Angew Chem Int Ed Engl ; 46(7): 1010-7, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17195264
18.
Angew Chem Int Ed Engl ; 45(11): 1686-712, 2006 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-16511821

RESUMO

Persulfurated arenes have been known for about 50 years but they were underexploited in chemistry in spite of facile, mild, and high-yielding syntheses. Their properties (redox potentials, UV/Vis absorption, conductivity, nonlinear optical properties, etc.) are mainly due to the aromaticity of the ring with sp2-hybridized carbon atoms and to the electronic contribution from numerous divalent sulfur ligands, which also stabilize negative or positive charges. The characteristic conformational patterns of the sulfur ligands often facilitate preorganization in supramolecular assemblies, with or without thiophilic metal cations, for designing redox sensors, ion-selective membranes, clathrates, organic conductors, nonlinear optical materials, liquid crystals, coordination polymers, and bioinorganic systems. A new class of supramolecules with various molecular shapes such as asterisks, chains, wheels, and windmills were reported.

19.
Chemistry ; 12(11): 2960-6, 2006 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-16440391

RESUMO

The dimer and trimer of 3,4-phenylenedioxythiophene (PheDOT) have been synthesized. Unlike the parent systems based on 3,4-ethylenedioxythiophene (EDOT), these compounds are quite stable under atmospheric conditions. The electronic absorption spectra of di- and tri-PheDOT exhibit a well-resolved vibronic fine structure indicative of self-rigidification of the conjugated structure by noncovalent intramolecular sulfur-oxygen interactions. Comparison of UV-visible data for the PheDOT oligomers with those of the corresponding EDOT oligomers reveals a faster decrease of the HOMO-LUMO gap with chain length for the former. Cyclic voltammetric data show that whereas PheDOT oxidizes at a lower potential than EDOT, the PheDOT dimer and trimer exhibit much higher oxidation potentials than their EDOT-based analogues. A comparative analysis of the electropolymerization of the three PheDOT-based systems shows that although PheDOT is very difficult to polymerize, its dimer and trimer can be readily electropolymerized. This unexpected increase of reactivity with chain extension is discussed with the aid of theoretical calculations.

20.
J Phys Chem B ; 109(35): 16616-27, 2005 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-16853114

RESUMO

We report here the synthesis of three novel pi-conjugated heterocyclic mixed trimers that contain two electron-donating 3,4-ethylenedioxy-2-thienyl (EDOT) units covalently attached to a central proquinoid electron-accepting thienopyrazine moiety (two of these narrow-HOMO-LUMO gap D-A-D compounds also bear hexyl side chains attached either to the outermost alpha positions of the EDOT end rings or to the beta positions of the pyrazine fused ring). The modification of the terthiophene structure upon EDO, pyrazine, and hexyl substitutions has been treated in detail with spectroscopic and theoretical arguments. Solid-state properties reveal the occurrence of short intramolecular contacts between heteroatoms of adjacent rings. The analysis of the structure of the pi-conjugated backbone of each molecule is consistent with a partial quinoid-like pattern which partially reverts to be subtly more aromatic depending on the topology of the positive inductive effect of the hexyl chains. This quinoidization is a consequence of the appearance of a D(EDOT)-->A(PyT)<--D(EDOT) intramolecular charge transfer which further polarizes the structure. The same chemical concepts have been applied to address their electrochemical behavior. The three mixed trimers exhibit amphoteric properties due to the combination of electron acceptor and donor groups. Given their relative low HOMO-LUMO energy gap, these trimers promise to be good candidates for obtaining polymers with significant low energy gap combining electroactivity.

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