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1.
J Phys Chem Lett ; 10(15): 4164-4169, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31265312

RESUMO

Various architectures have been generated and observed by STM at a solid/liquid interface resulting from an in situ chemical reaction between the bipyridine terminal groups of a ditopic ligand and Co(II) ions. Large monodomains of one-dimensional (1D) double wires are formed by Co(II)/ligand coordination, with polymer lengths as long as 150 nm. The polymers are organized as parallel wires 8 nm apart, and the voids between wires are occupied by solvent molecules. Two-dimensional (2D) grids, showing high surface mobility, coexist with the wires. The wires are formed from linear chain motifs where each cobalt center is bonded to two bipyridines. 2D grids are generated from a bifurcation node where one cobalt bonds to three bipyridines. Surface reconstruction of the grids and of the 1D wires was observed under the STM tip. As an exciting result, analysis of these movements strongly indicates surface reactions at the solid/liquid interface.

2.
Org Lett ; 21(7): 1999-2003, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30855968

RESUMO

The polytopic hemicryptophane cage HC1 combining a cyclotriveratrylene (CTV) unit and a tris(2-aminoethyl)amine (tren) moiety connected by three 2-hydroxyisophthalamide linkers was synthesized in 12 steps. The resulting highly functionalized covalent host is soluble in aqueous medium and has been used to complex Gd(III) ion. The Gd(III)@HC1 complex presents promising relaxivity properties when compared to the clinically used Dotarem MRI agent.

3.
ChemMedChem ; 13(20): 2229-2239, 2018 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-30157309

RESUMO

As a growing public health concern, the worldwide spread of antimicrobial resistance urges the development of new therapies. Antibacterial photodynamic therapy (a-PDT) may be an alternative to conventional antibiotic therapy. Herein we report the synthesis and characterization of seven original reactive oxygen species (ROS)-producing ruthenium(II) polypyridyl complexes. These are part of a collection of 17 derivatives varying in terms of the nature of the substituent(s), molecular symmetry, electrical charge, and counterions. They were characterized by considering 1) their physical properties (absorption coefficient at irradiation wavelength, 1 O2 generation quantum yield, luminescence) and 2) their antibacterial activity in a series of photodynamic assays using Gram-positive and Gram-negative bacteria of clinical relevance. The results unveiled some structure-activity relationships: one derivative that combines multiple beneficial features for a-PDT was effective against all the bacteria considered, regardless of their Gram status, species, or antibiotic resistance profile. This systematic study could guide the design of next-generation ruthenium-based complexes for enhanced antibacterial photodynamic strategies.


Assuntos
Antibacterianos/farmacologia , Complexos de Coordenação/farmacologia , Fenantrolinas/farmacologia , Fármacos Fotossensibilizantes/farmacologia , Rutênio/química , Antibacterianos/síntese química , Antibacterianos/efeitos da radiação , Antibacterianos/toxicidade , Complexos de Coordenação/síntese química , Complexos de Coordenação/efeitos da radiação , Complexos de Coordenação/toxicidade , Escherichia coli/efeitos dos fármacos , Ligantes , Luz , Luminescência , Medições Luminescentes , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Estrutura Molecular , Fenantrolinas/síntese química , Fenantrolinas/efeitos da radiação , Fenantrolinas/toxicidade , Fármacos Fotossensibilizantes/síntese química , Fármacos Fotossensibilizantes/efeitos da radiação , Fármacos Fotossensibilizantes/toxicidade , Pseudomonas aeruginosa/efeitos dos fármacos , Oxigênio Singlete/metabolismo , Relação Estrutura-Atividade
4.
J Am Chem Soc ; 138(30): 9381-4, 2016 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-27430366

RESUMO

A new heteroleptic polypyridyle Ru(II) complex was synthesized and deposited on surface by the diazonium electroreduction process. It yields to the covalent grafting of a monolayer. The functionalized surface was characterized by XPS, electrochemistry, AFM, and STM. A precise organization of the molecules within the monolayer is observed with parallel linear stripes separated by a distance of 3.8 nm corresponding to the lateral size of the molecule. Such organization suggests a strong cooperative process in the deposition process. This strategy is an original way to obtain well-controlled and stable functionalized surfaces for potential applications related to the photophysical properties of the grafted chromophore. As an exciting result, it is the first example of a self-organized monolayer (SOM) obtained using diazonium electroreduction.

5.
Phys Chem Chem Phys ; 18(6): 4924-41, 2016 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-26808207

RESUMO

One- and two-photon absorption cross-sections and spectra and the photophysical properties of eight perylenetetracarboxy-3,4:9,10-diimide (PDI) derivatives are reported and analyzed. The investigated compounds are characterized by direct binding of the phenyl rings of the substituents to the bay positions of the perylene core. They have been designed to test the effects of differences in the electronic nature - electron donating (anisole) or accepting (cyanobenzene) - and binding topology (cis or trans, meta or para disubstitution or tetrasubstitution) of the bay substituents on the above optical and photophysical observables. (TD)DFT and Hückel MO calculations have provided theoretical information on the ground-state geometries, the MOs and the electronic spectra of several model compounds. For tetrasubstituted and cis disubstituted derivatives, strong steric interactions in the bay area determined the preferred conformations, with perylene cores distorted near the substituted bay(s) and a 42-44° twisting of the substituent rings relative to the core, quite irrespective of the electronic nature of the substituents. On the other hand, in trans-disubstituted PDI steric hindrance in the bay areas was much weaker and similar in the cyanobenzene and the anisole derivatives. So, the large differences found in the conformational preferences were completely attributable to electronic effects. With electron-accepting cyanobenzene, the substituent rings were found normal to the central planar perylene core, thus enabling the assignment of the moderate spectroscopic effects to inductive interactions. The DFT analysis of the PDI trans-disubstituted with electron-donating anisoles gave quite strongly distorted perylene-core geometries and less twisted (59°) substituent rings. The corresponding increased substituent/core conjugative interactions resulted in new CT allowed electronic transitions and an extremely pronounced solvent-polarity dependence of the emission spectra and intensities. All anisole substituted PDI feature a very fast radiationless decay path in polar solvents, likely related to a relaxation to a charge-separated configuration in the lowest excited-state.

6.
Chimia (Aarau) ; 69(11): 666-9, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26671050

RESUMO

This study deals with the fine tuning of the photophysical characteristics, and especially two-photon absorption (2PA) properties, of several homo- and heteroleptic ruthenium(II) complexes involving 5-substituted-1,10-phenanthroline ligands. The 2PA spectra of the complexes were determined in the 700-930 nm range by investigating their two-photon excited luminescence (2PEL). Structure - linear and nonlinear optical properties correlations are discussed, and potential applications (therapy and optical power limiting in the near infrared) can be anticipated.


Assuntos
Fluorenos/química , Fenantrolinas/química , Fótons , Compostos de Rutênio/química , Estrutura Molecular , Análise Espectral
9.
Dalton Trans ; 44(36): 16127-35, 2015 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-26289593

RESUMO

A new Ir(iii) cyclometallated complex bearing a fluorenyl 5-substituted-1,10-phenanthroline ligand ([Ir(ppy)2()][PF6], ppy = 2-phenylpyridine) is presented which exhibits enhanced triplet oxygen sensing properties. The efficacy of this complex to act as a photosensitiser for altering the morphology of C6 Glioma cells that represent malignant nervous tumours has been evaluated. The increased heavy metal effect and related spin-orbit coupling parameters on the photophysical properties of this complex are evidenced by comparison with Ru(ii) analogues. The complex [Ir(ppy)2()][PF6] is shown to exhibit relatively high two-photon absorption efficiencies for the lowest energy MLCT electronic transitions with two-photon absorption cross sections that range from 50 to 80 Goeppert-Mayer units between 750 to 800 nm. Quantum yields for the complex were measured up to 23% and the Stern-Volmer quenching constant, KSV was determined to be 40 bar(-1) in acetonitrile solution, confirming the high efficiency of the complex as a triplet oxygen sensitiser. Preliminary in vitro experiments with C6 Glioma cells treated with [Ir(ppy)2()][PF6], show that the complex is an efficient sensitizer for triplet oxygen, producing cytotoxic singlet oxygen ((1)O2) by two-photon excitation at 740 nm resulting in photodynamic effects that lead to localised cell damage and death.

10.
Phys Chem Chem Phys ; 16(28): 14826-33, 2014 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-24921680

RESUMO

The synthesis and photophysical properties of small gold nanoparticles (NPs, AuNP-[Ru-PFF]) surface functionalized by 5-substituted-1,10-phenanthroline-ligand based Ru(II) complexes are described. Luminescence of the grafted and confined Ru(II) complexes is totally quenched on the gold surface. Nonlinear optical properties were determined via Z-scan measurements in the range 600-1300 nm for both the free Ru(II) complex and the related NPs. In the short wavelength range (around 600 nm) the behaviour switches from that of two-photon absorption (2PA) for the complex to saturable absorption for the NPs. 2PA applications such as optical power limiting or two-photon dioxygen sensitization can be anticipated for these nanoplatforms.


Assuntos
Ouro/química , Nanopartículas Metálicas/química , Compostos Organometálicos/química , Fenantrolinas/química , Rutênio/química , Estrutura Molecular , Compostos Organometálicos/síntese química , Tamanho da Partícula , Propriedades de Superfície
11.
Dalton Trans ; 42(34): 12157-64, 2013 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-23839769

RESUMO

A new cyclen derivative L, bearing a methyl-chromeno-pyridinylidene hydrazone moiety, was synthesized and studied in MeOH, as potential fluorescent "OFF-on-ON" sensors for Zn(ii). Photophysical properties of this ligand being PET regulated, L was only weakly emissive in the absence of metal ions (OFF). L fluorescence was increased modestly upon addition of one equivalent of Zn(II), and further increased upon addition of a second equivalent. Therefore, Zn : L behaved as a highly sensitive ON sensor for zinc. This efficiency was correlated to Zn(II) coordination via the hydrazone moiety of the fluorophore, producing an efficient CHelation-Enhanced Fluorescence (CHEF) effect. A complementary theoretical study carried out with DFT calculations further elucidated the optical properties.


Assuntos
Corantes Fluorescentes/química , Compostos Heterocíclicos/química , Espectrometria de Fluorescência , Zinco/análise , Íons/química , Ligantes , Teoria Quântica
12.
Dalton Trans ; 42(34): 12410-20, 2013 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-23860731

RESUMO

The synthesis, optical properties and efficiency of new multifunctional nanoparticles as theranostic (fluorescence/MRI/PDT) agents are described. They are based on a polysiloxane network and surrounded by gadolinium(III) chelates and ruthenium(II) complexes. The size of the nanoparticles is maintained under 5 nm in order to permit their efficient elimination from the body. Their potential use as a theranostic agent (PDT/MRI) is described. The magnetic properties of the nanoparticles are studied by relaxometry (r1 = 9.21 mM(-1) s(-1) at 40 MHz; r2/r1 = 1.14) and the signal enhancement is validated by the acquisition of phantoms on a 3 T MRI imager. The therapeutic potential for photodynamic therapy of the nanoparticles has been studied in vitro on HEK293 cells and an effective quantum yield of 0.33 for (1)O2 production has been determined in deuterated water.


Assuntos
Complexos de Coordenação/química , Gadolínio/química , Nanopartículas Metálicas/química , Fármacos Fotossensibilizantes/química , Rutênio/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Complexos de Coordenação/síntese química , Células HEK293 , Humanos , Luz , Imagem por Ressonância Magnética , Nanopartículas Metálicas/toxicidade , Fotoquimioterapia , Fármacos Fotossensibilizantes/síntese química , Fármacos Fotossensibilizantes/toxicidade , Siloxanas/química , Oxigênio Singlete/química
13.
Chemistry ; 19(19): 6122-36, 2013 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-23512788

RESUMO

New, ultrasmall nanoparticles with sizes below 5 nm have been obtained. These small rigid platforms (SRP) are composed of a polysiloxane matrix with DOTAGA (1,4,7,10-tetraazacyclododecane-1-glutaric anhydride-4,7,10-triacetic acid)-Gd(3+) chelates on their surface. They have been synthesised by an original top-down process: 1) formation of a gadolinium oxide Gd2O3 core, 2) encapsulation in a polysiloxane shell grafted with DOTAGA ligands, 3) dissolution of the gadolinium oxide core due to chelation of Gd(3+) by DOTAGA ligands and 4) polysiloxane fragmentation. These nanoparticles have been fully characterised using photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), a superconducting quantum interference device (SQUID) and electron paramagnetic resonance (EPR) to demonstrate the dissolution of the oxide core and by inductively coupled plasma mass spectrometry (ICP-MS), mass spectrometry, fluorescence spectroscopy, (29)Si solid-state NMR, (1)H NMR and diffusion ordered spectroscopy (DOSY) to determine the nanoparticle composition. Relaxivity measurements gave a longitudinal relaxivity r1 of 11.9 s(-1) mM(-1) per Gd at 60 MHz. Finally, potentiometric titrations showed that Gd(3+) is strongly chelated to DOTAGA (complexation constant logß110 =24.78) and cellular tests confirmed the that nanoconstructs had a very low toxicity. Moreover, SRPs are excreted from the body by renal clearance. Their efficiency as contrast agents for MRI has been proved and they are promising candidates as sensitising agents for image-guided radiotherapy.


Assuntos
Gadolínio/química , Compostos Heterocíclicos com 1 Anel/química , Dióxido de Silício/química , Siloxanas/química , Substância P/análogos & derivados , Meios de Contraste/química , Imagem por Ressonância Magnética/métodos , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Transmissão , Nanopartículas/química , Radioterapia Guiada por Imagem , Espectrometria de Fluorescência , Substância P/química
14.
Phys Chem Chem Phys ; 13(38): 17304-12, 2011 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-21879060

RESUMO

In this article, the synthesis of a novel high-conjugated ligand and its corresponding Ru(II) complex PTFTF:Ru is reported, along with the linear and nonlinear optical characterizations. Two-photon absorption based optical power limiting properties (OPL), especially in the near infrared, are described and compared to those of the analogous complexes previously published. Combined with a preliminary theoretical approach, this allows us to highlight several key parameters for OPL optimization in such molecular systems and more particularly the spectral overlap between TPA and excited-state absorption.

15.
Nanotechnology ; 20(35): 355603, 2009 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-19671982

RESUMO

The tremendous development of materials with fine tuning of their composition, shape, size and chemical functionalities at the nanometer scale has opened a wide range of applications, particularly in medicine. Metallic nanoparticles are extremely interesting for such developments. The fundamental study of surface plasmon resonance (SPR) versus the shape/size of a particle is an important challenge. In this field, we propose a synthetic strategy using an original biphasic emulsion process linked to chemo-reduction of gold salt HAuCl(4). This method allows the preparation of new functional nanocapsules. These nanomaterials are fully characterized.

16.
Chem Commun (Camb) ; (30): 4590-2, 2009 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-19617993

RESUMO

A novel water-soluble Ru(ii) complex has been prepared, which represents a promising new class of selective two-photon sensitizers for use in photodynamic therapy within a confined space.


Assuntos
Etilenoglicol/química , Compostos Organometálicos/química , Fármacos Fotossensibilizantes/química , Rutênio/química , Humanos , Estrutura Molecular , Fotoquimioterapia , Fótons , Solubilidade , Água
17.
Chemistry ; 15(20): 5047-55, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19338035

RESUMO

The synthesis and optical properties of 4,5-disubstituted (tert-butyldimethylsilyloxy)-protected catechol derivatives are reported. One or two carbon-carbon triple bond functions were introduced through the Sonogashira cross-coupling reaction. The effects on the optical properties of monosubstitution at the 4-position or disubstitution at the 4- and 5-positions of these catechol derivatives with electron-withdrawing or -donating substituents have been investigated. The experimental chemical-structure-polarisability relationship has been studied by using the Lippert-Mataga correlation and compared with the results of a theoretical study carried out with DFT calculations. These compounds are promising candidates for the fine-tuning of internal charge transfer, but also as potential non-linear chromophores and ligands within multifunctional coordination complexes.

19.
Langmuir ; 22(26): 10874-6, 2006 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-17154554

RESUMO

The self-assembly of long-alkyl-chain substituted phenanthroline derivatives on highly oriented pyrolitic graphite (HOPG) and gold(111) is compared. Whereas the adsorption on HOPG is controlled by the affinity of alkyl chains for the substrate, which leads to flat-lying adsorbed molecules, alignments of upright-oriented molecules are formed on gold(111). This situation is explained by the bonding of chelating species with gold(111) surfaces and by the pi-stacking interaction between conjugated moieties. This intermediate situation between strong thiol-like chemical bonding and the weak n-alkane-like physical adsorption opens the route toward laterally organized functional molecular assemblies.

20.
Chemistry ; 12(28): 7421-32, 2006 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-16874821

RESUMO

The synthesis and characterization of [FeII(trim)2]Cl2 (2), [FeII(trim)2]Br2MeOH (3), and [FeII(trim)2]I2MeOH (4), including the X-ray crystal structure determinations of 2 (50 and 293 K) and 4 (293 K), have been performed and their properties have been examined. In agreement with the magnetic susceptibility results, the Mössbauer data show the presence of high-spin (HS) to low-spin (LS) crossover with a range of T1/2 larger than 300 K (from approximately 20 K for [FeII(trim)2]F2 (1) to approximately 380 K for 4). All complexes in this series include the same [Fe(trim)2]2+ complex cation: the ligand field comprises a constant contribution from the trim ligands and a variable one originating from the out-of-sphere anions, which is transmitted to the metal center by the connecting imidazole rings and hydrogen bonds. The impressive variation in the intrinsic characteristics of the spin-crossover (SCO) phenomenon in this series is then interpreted as an inductive effect of the anions transmitted to the nitrogen donors through the hydrogen bonds. Based on this qualitative analysis, an increased inductive effect of the out-of-sphere anion corresponds to a decreased SCO temperature T1/2, in agreement with the experimental results. Electronic structure calculations with periodic boundary conditions have been performed that show the importance of intermolecular effects in tuning the ligand field, and thus in determining the transition temperature. Starting with the geometries obtained from the X-ray studies, the [FeII(trim)2]X2 complex molecules 1-4 have been investigated both for the single molecules and the crystal lattices with the local density approximation of density functional theory. The bulk geometries of the complex cations deduced from the X-ray studies and those calculated are in fair agreement for both approaches. However, the trend observed for the transition temperatures of 1-4 disagrees with the trend for the spin-state splittings ES (difference EHS-ELS between the energy of the HS and LS isomers) calculated for the isolated molecules, whereas it agrees with the trend for ES calculated with periodic boundary conditions. The latter calculations predict the strongest stabilization of the HS state for the fluoride complex, which actually is essentially HS above T=50 K, while the most pronounced stabilization of the LS state is predicted for 4, in line with the experimental results.

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