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1.
Chem Commun (Camb) ; 55(77): 11583-11586, 2019 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-31495849

RESUMO

The activation of ruthenium-indenylidene complexes containing two unsymmetrical unsaturated N-heterocyclic carbenes (u2-NHCs) by a transmetalation process is reported. The use of copper(i) or gold(i) chlorides promotes the rapid trapping of one NHC ligand, which releases the catalytically active Ru-species. Impressive initiation rates with full-conversions are observed within one minute. This practical protocol demonstrates excellent catalytic performances in various ring-closing metathesis (RCM) and self-metathesis (SM) reactions.

2.
Spectrochim Acta A Mol Biomol Spectrosc ; 205: 146-159, 2018 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-30015020

RESUMO

A novel bis-[1-(2-[(2-hydroxynaphthalen-1-yl) methylidene]amino}ethyl)-1-ethyl-3-phenylthiourea] Schiff base (L) and its binuclear palladium and ruthenium complexes have been prepared and characterized by ESI-MS, elemental analysis, NMR (1H NMR, 13C NMR, COSY, NEOSY and HSQC), FT-IR, ATR, UV-Visible spectra, TGA measurements, conductivity and cyclic voltammetry. The experimental results and the molecular parameters calculated using DFT method revealed a square planar geometry around Pd and octahedral geometry around ruthenium metal. The antibacterial activity of the ligand L and its complexes was evaluated against different human bacteria. In addition, the formation constants of the synthesized Schiff base-metal complexes and the systems formed with these chelates and cholesterol were estimated using spectrophotometric technique. The detection of cholesterol using novel Pd and Ru Schiff base complexes was studied using fluorometric method, and the measurements showed that the sensitive fluorometric response towards cholesterol analysis was determined using palladium complex. The limit of detection (LOD) of cholesterol calculated using this complex (4.6 µM) is lower (better) than LOD found using ruthenium complex (19.1 µM) and different compounds previously published around linear range of 0-5 mM.


Assuntos
Antibacterianos/química , Antioxidantes/química , Paládio/química , Feniltioureia/química , Rutênio/química , Bases de Schiff/química , Antibacterianos/síntese química , Antibacterianos/farmacologia , Antioxidantes/síntese química , Antioxidantes/farmacologia , Colesterol/análise , Estabilidade de Medicamentos , Limite de Detecção , Modelos Lineares , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Modelos Moleculares , Feniltioureia/síntese química , Feniltioureia/farmacologia , Reprodutibilidade dos Testes , Bases de Schiff/síntese química , Bases de Schiff/farmacologia , Análise Espectral
3.
Molecules ; 23(4)2018 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-29642501

RESUMO

A phenylethanoid, two steroids, a flavone glucoside and a chalcone have been isolated for the first time from the stems of Calicotome villosa together with a previously isolated flavone glucoside. Their structures were determined by spectroscopic analyses (NMR, HRMS) as basalethanoïd B (1), ß-sitosterol and stigmasterol (2), chrysine-7-O-ß-d-glucopyranoside (3), chrysine 7-((6''-O-acetyl)-O-ß-d-glucopyranoside) (4) and calythropsin (5). The crude extracts and the isolated compounds (except 4), were evaluated for their antioxidant, antimicrobial (against two Gram-positive bacterial strains: Staphylococcus aureus, Bacillus cereus, four Gram-negative bacterial strains: Staphylococcus epidermidis, Klebsiella pneumonia, Acinetobacter baumanii, and three yeasts: Candida albicans, Candida tropicalis, and Candida glabrata), hemolytic, antidiabetic, anti-inflammatory and cytotoxic activity. The crude extracts showed good ability to scavenge the free radical DPPH. Methanol stem extract followed by the dichloromethane stem extract showed moderate antimicrobial potency; furthermore, at 1 mg/mL the methanol extract showed an inhibition of C. albicans growth comparable to nystatin. Dichloromethane, methanol, and aqueous extracts inhibited 98%, 90%, and 80% of HeLa cell proliferation at 2 mg/mL respectively. Weak hypoglycemic and hemolytic effects were exhibited by the crude extracts. Among all the tested compounds, compound 3 showed remarkable hypoglycemic potential (93% at 0.1 mg/mL) followed by compound 5 (90% at 0.3 mg/mL). Compound 5 was the most effective in the DPPH. scavenging assay (100% at 0.1 mg/mL) and cytotoxic assay on HeLa cells (99% and 90% after 24 and 48 h of treatment at 0.1 mg/mL, respectively). No anti-inflammatory effects were displayed by any of the crude extracts or the isolated compounds at any of the tested concentrations.


Assuntos
Anti-Infecciosos/química , Antineoplásicos Fitogênicos/química , Antioxidantes/química , Fabaceae/química , Extratos Vegetais/química , Caules de Planta/química , Anti-Infecciosos/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Antioxidantes/farmacologia , Candida albicans/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Células HeLa , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Extratos Vegetais/farmacologia
4.
Plant Cell Physiol ; 56(9): 1798-807, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26169197

RESUMO

Betaine aldehyde dehydrogenases oxidize betaine aldehyde to glycine betaine in species that accumulate glycine betaine as a compatible solute under stress conditions. In contrast, the physiological function of betaine aldehyde dehydrogenase genes is at present unclear in species that do not accumulate glycine betaine, such as Arabidopsis thaliana. To address this question, we overexpressed the Arabidopsis ALDH10A8 and ALDH10A9 genes, which were identified to code for betaine aldehyde dehydrogenases, in wild-type A. thaliana. We analysed changes in metabolite contents of transgenic plants in comparison with the wild type. Using exogenous or endogenous choline, our results indicated that ALDH10A8 and ALDH10A9 are involved in the synthesis of glycine betaine in Arabidopsis. Choline availability seems to be a factor limiting glycine betaine synthesis. Moreover, the contents of diverse metabolites including sugars (glucose and fructose) and amino acids were altered in fully developed transgenic plants compared with the wild type. The plant metabolic response to salt and the salt stress tolerance were impaired only in young transgenic plants, which exhibited a delayed growth of the seedlings early after germination. Our results suggest that a balanced expression of the betaine aldehyde dehydrogenase genes is important for early growth of A. thaliana seedlings and for salt stress mitigation in young seedlings.


Assuntos
Aldeído Desidrogenase/genética , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Betaína/análogos & derivados , Genes de Plantas , Adaptação Fisiológica/efeitos dos fármacos , Adaptação Fisiológica/genética , Aldeído Desidrogenase/metabolismo , Aminoácidos/metabolismo , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/metabolismo , Betaína/metabolismo , Metabolismo dos Carboidratos/efeitos dos fármacos , Carnitina/metabolismo , Colina/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Germinação/efeitos dos fármacos , Germinação/genética , Plantas Geneticamente Modificadas , Poliaminas/metabolismo , Análise de Componente Principal , Reação em Cadeia da Polimerase em Tempo Real , Cloreto de Sódio/farmacologia , Estresse Fisiológico/efeitos dos fármacos
5.
Inorg Chem ; 54(12): 6043-54, 2015 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-26024151

RESUMO

For the first time, hexanuclear complexes with general chemical formula [Ln6O(OH)8(NO3)6(H2O)n](2+) with n = 12 for Ln = Sm-Lu and Y and n = 14 for Ln = Pr and Nd were stabilized as nanoaggregates in ethylene glycol (EG). These unprecedented nanoaggregates were structurally characterized by (89)Y and (1)H NMR spectroscopy, UV-vis absorption and luminescence spectroscopies, electrospray ionization mass spectrometry, diffusion ordered spectroscopy, transmission electron microscopy, and dynamic light scattering. These nanoaggregates present a 200 nm mean solvodynamic diameter. In these nanoaggregates, hexanuclear complexes are isolated and solvated by EG molecules. The replacement of ethylene glycol by 2-hydroxybenzyl alcohol provides new nanoaggregates that present an antenna effect toward lanthanide ions. This results in a significant enhancement of the luminescence properties of the aggregates and demonstrates the suitability of the strategy for obtaining highly tunable luminescent solutions.

6.
Org Biomol Chem ; 13(17): 4940-52, 2015 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-25812481

RESUMO

The simple octyl ß-D-galactofuranoside was previously described as a good bacteriostatic agent against Mycobacterium smegmatis, a non-pathogenic model of M. tuberculosis. In order to decipher its mechanism of action, STD NMR on whole M. smegmatis cells was implemented. It outlined the crucial role of the alkyl chain and the possibility of modulation on the furanosyl entity. Then, 16 new alkyl furanosides were synthesized in order to optimize the mycobacteriostatic activity. They all present the pending alkyl chain in a 1,2-trans configuration relative to the sugar ring. Three families were studied that differ by a substituent on the primary position of the galactofuranose ring, the series or the pending alkyl chain. Four of these neofuranosides showed growth inhibition inferior to the parent octyl ß-D-galactofuranoside. Double alkyl chains at C-1 and a polar substituent on the primary position of the furanoside significantly favored the activity. Finally, a mixed biantennary alkyl/aryl ß-D-galactofuranoside exhibited the best growth inhibition concentration at 90 µM.


Assuntos
Antibacterianos/farmacologia , Galactosídeos/farmacologia , Mycobacterium smegmatis/efeitos dos fármacos , Antibacterianos/química , Relação Dose-Resposta a Droga , Galactosídeos/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Mycobacterium smegmatis/crescimento & desenvolvimento , Estereoisomerismo , Relação Estrutura-Atividade
7.
Inorg Chem ; 52(1): 346-54, 2013 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-23249389

RESUMO

Trimethylaluminum (TMA) complexes of methyl-, n-propyl-, cyclopropyl-, allyl-, and propargylamine were synthesized and their experimental properties and theoretical characteristics were compared with the respective amine-borane analogues. The amine ligand of an amine-TMA Lewis acid-base complex can be easily changed by another amine through a 2:1 amine-TMA intermediate in pentane at room temperature. The exchange of the same ligands in the case of amine-boranes requires remarkably more time in line with the calculated relative energy of the respective transition state. The (1)H and (13)C NMR experiments examining the addition of one or more equivalent of amine to the respective Lewis acid-base complex conclude in the fast exchange of the amine ligand in the NMR time scale only in the cases of amine-TMA complexes, which could also be caused by similar 2:1 complexes. However, in gas phase, only 1:1 amine-TMA complexes are present as evidenced by ultraviolet photoelectron spectroscopy (UPS). The observed UP spectra, which are the first recorded photoelectron spectra of primary amine-TMA compounds, indicate that the stabilization effect of the lone electron pair of nitrogen atom in amines during the borane complexation is stronger than that of the TMA complexation. In line with this observation, the destabilization of the σ(Al-C) orbitals is lower than that of σ(B-H) orbitals during the formation of amine-TMA and amine-borane complexes, respectively. As showed by theoretical calculations, the CH(4) elimination of the studied amine-TMA complexes is exothermic, indicating the possibility of using these compounds in metal organic chemical vapor deposition techniques (MOCVD). On the other hand, our experimental conditions avoid this methane elimination and constitutes the first procedure employing distillation to isolate primary amine-TMA complexes.


Assuntos
Alumínio/química , Aminas/química , Boranos/química , Compostos Organometálicos/química , Compostos Organometálicos/síntese química , Teoria Quântica
8.
Chemistry ; 18(20): 6289-301, 2012 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-22492467

RESUMO

The factors governing the stability and the reactivity towards cyclic esters of heteroleptic complexes of the large alkaline earth metals (Ae) have been probed. The synthesis and stability of a family of heteroleptic silylamido and alkoxide complexes of calcium [{LO(i)}Ca-Nu(thf)(n)] supported by mono-anionic amino ether phenolate ligands (i = 1, {LO(1)}(-) = 4-(tert-butyl)-2,6-bis(morpholinomethyl)phenolate, Nu(-) = N(SiMe(2)H)(2)(-), n = 0, 4; i = 2, {LO(2)}(-) = 2,4-di-tert-butyl-6-{[2-(methoxymethyl)pyrrolidin-1-yl]methyl}phenolate, Nu(-) = N(SiMe(2)H)(2)(-), n = 0, 5; i = 4, {LO(4)}(-) = 2-{[bis(2-methoxyethyl)amino]methyl}-4,6-di-tert-butylphenolate, Nu(-) = N(SiMe(2)H)(2)(-), n = 1, 6; Nu(-) = HC≡CCH(2)O(-), n = 0, 7) and those of the related [{LO(3)}Ae-N(SiMe(2)H)(2)] ({LO(3)}(-) = 2-[(1,4,7,10-tetraoxa-13-azacyclopentadecan-13-yl)methyl]-4,6-di-tert-butylphenolate Ae = Ca, 1; Sr, 2; Ba, 3) have been investigated. The molecular structures of 1, 2, [(4)(2)], 6, and [(7)(2)] have been determined by X-ray diffraction. These highlight Ae⋅⋅⋅H-Si internal ß-agostic interactions, which play a key role in the stabilization of [{LO(i)}Ae-N(SiMe(2)H)(2)] complexes against ligand redistribution reactions, in contrast to regular [{LO(i)}Ae-N(SiMe(3))(2)]. Pulse-gradient spin-echo (PGSE) NMR measurements showed that 1, 4, 6, and 7 are monomeric in solution. Complexes 1-7 mediate the ring-opening polymerization (ROP) of L-lactide highly efficiently, converting up to 5000 equivalents of monomer at 25 °C in a controlled fashion. In the immortal ROP performed with up to 100 equivalents of exogenous 9-anthracenylmethanol or benzyl or propargyl alcohols as a transfer agent, the activity of the catalyst increased with the size of the metal (1<2<3). For Ca-based complexes, the enhanced electron-donating ability of the ancillary ligand favored catalyst activity (1>6>4≈5). The nature of the alcohol had little effect over the activity of the binary catalyst system 1/ROH; in all cases, both the control and end-group fidelity were excellent. In the living ROP of L-LA, the HC≡CCH(2)O(-) initiating group (as in 7) proved superior to N(SiMe(2)H)(2)(-) or N(SiMe(3))(2)(-) (as in 6 or [{LO(4)}Ca-N(SiMe(3))(2)] (B), respectively).

9.
Carbohydr Res ; 346(12): 1490-4, 2011 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-21546004
10.
Plant J ; 64(2): 215-29, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21070405

RESUMO

Thellungiella salsuginea, a Brassicaceae species closely related to Arabidopsis thaliana, is tolerant to high salinity. The two species were compared under conditions of osmotic stress to assess the relationships between stress tolerance, the metabolome, water homeostasis and growth performance. A broad range of metabolites were analysed by metabolic fingerprinting and profiling, and the results showed that, despite a few notable differences in raffinose and secondary metabolites, the same metabolic pathways were regulated by salt stress in both species. The main difference was quantitative: Thellungiella had much higher levels of most metabolites than Arabidopsis whatever the treatment. Comprehensive quantification of organic and mineral solutes showed a relative stability of the total solute content regardless of the species or treatment, meaning that little or no osmotic adjustment occurred under stress. The reduction in osmotic potential observed in plants under stress was found to result from a passive loss of water. Thellungiella shoots contain less water than Arabidopsis shoots, and have the ability to lose more water, which could contribute to maintain a water potential gradient between soil and plant. Significant differences between Thellungiella and Arabidopsis were also observed in terms of the physicochemical properties of their metabolomes, such as water solubility and polarity. On the whole, the Thellungiella metabolome appears to be more compatible with dehydration. Osmotic stress was also found to impact the metabolome properties in both species, increasing the overall polarity. Together, the results suggest that Thellungiella copes with osmotic stress by tolerating dehydration, with its metabolic configuration lending itself to osmoprotective strategies rather than osmo-adjustment.


Assuntos
Arabidopsis/metabolismo , Plantas Tolerantes a Sal/metabolismo , Estresse Fisiológico , Água/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/crescimento & desenvolvimento , Metaboloma , Metabolômica , Salinidade , Plantas Tolerantes a Sal/efeitos dos fármacos , Plantas Tolerantes a Sal/crescimento & desenvolvimento , Cloreto de Sódio/administração & dosagem , Equilíbrio Hidroeletrolítico
11.
Dalton Trans ; (36): 7356-8, 2009 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-19727454

RESUMO

A trihydroxyammonium chloride has proved to be an efficient protective agent for Rh(0) nanoparticles and the hydrogenation of arene compounds has been investigated. Significant formation of cyclohexanone in the reduction of anisole has been demonstrated.

12.
Biomacromolecules ; 10(7): 1757-67, 2009 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-19459672

RESUMO

Enzymatic degradation of standard κ-carrageenan and the low-gelling hybrid κ-/µ-carrageenan were conducted using recombinant Pseudoalteromonas carrageenovora κ-carrageenase. The initial velocity of the enzyme was determined as a function of varying Tris or NaI concentrations and at constant 200 mM cosolutes concentration, adjusting NaI and Tris concentrations accordingly. In both cases, we observed strong inhibition of the enzyme with increasing amounts of iodide. The characterization of the κ- and κ-/µ-carrageenan ordering by optical rotation and the visualization of iodide binding on carrageenan by (127)I NMR revealed that inhibition was not caused by the disordered-ordered transition of carrageenan in NaI, but by iodide binding. These results were confirmed by analysis of the degradation products by gel permeation chromatography. Degradation of carrageenan in the disordered state led to a rapid decrease in molecular mass and the production of all possible neo-κ-carrabiose oligomers. In the ordered conformation, the degradation kinetics, the decrease of average molecular weight, and the chain population distribution of degradation products varied with iodide concentration. These observations were interpreted to be the result of increasing amounts of bound iodide on carrageenan helices that, in turn, impede enzyme catalysis. Based on these results, we propose a single-helix ordered conformation state for κ-carrageenan and reject the previously advocated double-helix model.


Assuntos
Proteínas de Bactérias/metabolismo , Carragenina/química , Glicosídeo Hidrolases/metabolismo , Proteínas de Bactérias/antagonistas & inibidores , Carragenina/metabolismo , Inibidores Enzimáticos/química , Glicosídeo Hidrolases/antagonistas & inibidores , Iodetos/metabolismo , Cinética , Conformação Proteica , Pseudoalteromonas/enzimologia , Soluções , Trometamina/metabolismo , Água
13.
J Org Chem ; 72(15): 5743-7, 2007 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-17602592

RESUMO

The preparation of O-hexofuranosides was accomplished from unprotected 1-thioimidoyl furanosides as donors. The present methodology was first used for the synthesis of octyl galactofuranoside and further extended to D-galactofuranose-containing disaccharides. Within this study, we emphasized the need for additional complexing cations to maintain the furanose ring in its initial size. After experimentation, calcium ion was first used concomitantly with trimethylsilyl trifluoromethanesulfonate, the latter being able to activate the thioimidate and the former being likely to inhibit ring expansion. Moreover, an improvement was performed by using copper(II) trifluoromethanesulfonate which could then meet the requirements as both promoter and complexing agent.


Assuntos
Imidas/química , Cátions Bivalentes , Glicosilação , Espectroscopia de Ressonância Magnética , Espectrometria de Massas
14.
J Am Chem Soc ; 128(37): 12243-55, 2006 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-16967976

RESUMO

The synthesis and structural, photophysical, and second-order nonlinear optical (NLO) properties of a novel lanthanide terpyridyl-like complex family LLn(NO(3))(3) (Ln = La, Gd, Dy, Yb, and Y) are reported. The isostructural character of this series in solution and in the solid state has been established on the basis of X-ray diffraction analysis in the cases of yttrium and gadolinium complexes, theoretical optimization of geometry (DFT), and NMR spectroscopy. The absorption, emission, and solvatochromic properties of the free terpyridyl-like ligand L were thoroughly investigated, and the twist intramolecular charge transfer (TICT) character of the lowest energy transition was confirmed by theoretical calculation (TDDFT and CIS). The similar ionochromic effect of the different lanthanide ions was evidenced by the similar UV-visible spectra of the complete family of complexes. On the other hand, the quadratic hyperpolarizability coefficient beta, measured by the harmonic light scattering (HLS) technique, is clearly dependent on the nature of the metal, and a careful examination of the particular case of yttrium unambiguously confirms the contribution of metal f electrons to the NLO activity.

15.
Glycobiology ; 15(4): 393-407, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15590774

RESUMO

Small reducing and linear oligo-beta-(1,3)-glucans, which are able to act as phytoallexin elicitors or as immunostimulating agents in anticancer therapy, were synthesized according to an iterative strategy that involved a unique key monosaccharidic donor. To avoid anomeric mixtures, the reducing entity of the target oligomers was first locked with benzyl alcohol and further selective deprotection of the 3-OH with DDQ afforded the desired building block as an acceptor. The latter was then used in a second cycle of glycosylation/deprotection to afford the desired disaccharide, and successive reiterations of this process provided the desired oligomers. Unusual conformational behaviors were observed by standard NMR sequences and supported by NOESY studies. Finally, removal of protecting groups afforded free tri-, tetra-, and pentaglucosides in good overall yields. Two oligosaccharides representing linear laminaritetraose and laminaripentaose were compared to the recently described beta-(1,3)-glucan phycarine. Following an intraperitoneal injection, the influx of monocytes and granulocytes into the blood and macrophages into the peritoneal cavity was comparable to that caused by phycarine. Similarly, both oligosaccharides stimulated phagocytic activity of granulocytes and macrophages. Using ELISA, we also demonstrated a significant stimulation of secretion of IL-1beta. Together these results suggest that the synthetic oligosaccharides have similar stimulatory effects as natural beta-(1,3)-glucans.


Assuntos
Oligossacarídeos/imunologia , beta-Glucanas/imunologia , Animais , Configuração de Carboidratos , Sequência de Carboidratos , Linhagem Celular Tumoral , Granulócitos/imunologia , Interleucina-1/metabolismo , Macrófagos Peritoneais/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Oligossacarídeos/síntese química , Oligossacarídeos/farmacologia , Fagocitose/efeitos dos fármacos , Fagocitose/imunologia , beta-Glucanas/síntese química , beta-Glucanas/farmacologia
16.
Chemistry ; 10(18): 4454-66, 2004 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-15378623

RESUMO

A series of D3 (Fe(II), Ru(II), Zn(II), Hg(II)) and D2d (Cu(I), Ag(I), Zn(II)) octupolar metal complexes featuring different functionalized bipyridyl ligands has been synthesized, and their thermal, linear (absorption and emission), and nonlinear optical (NLO) properties were determined. Their quadratic NLO susceptibilities were determined by harmonic light scattering at 1.91 microm, and the molecular hyperpolarizability (beta0) values are in the range of 200-657 x 10(-30) esu for octahedral complexes and 70-157 x 10(-30) esu for tetrahedral complexes. The octahedral zinc(II) complex 1 e, which contains a 4,4'-oligophenylenevinylene-functionalized 2,2'-bipyridine, exhibits the highest quadratic hyperpolarizability ever reported for an octupolar derivative (lambdamax=482 nm, beta1.91(1 e)=870 x 10(-30) esu, beta0(1 e)=657 x 10(-30) esu). Herein, we demonstrate that the optical and nonlinear optical (NLO) properties are strongly influenced by the symmetry of the complexes, the nature of the ligands (donor endgroups and pi linkers), and the nature of the metallic centers. For example, the length of the pi-conjugated backbone, the Lewis acidity of the metal ion, and the increase of ligand-to-metal ratio result in a substantial enhancement of beta. The contribution of the metal-to-ligand (MLCT) transition to the molecular hyperpolarizability is also discussed with respect to octahedral d6 complexes (M=Fe, Ru).


Assuntos
2,2'-Dipiridil/química , Metais Pesados/química , Compostos Organometálicos , Estrutura Molecular , Compostos Organometálicos/síntese química , Compostos Organometálicos/química
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