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1.
Pharmacol Rep ; 75(6): 1597-1609, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37837521

RESUMO

BACKGROUND: Glioblastoma is a severe brain tumor that requires aggressive treatment involving surgery, radiotherapy, and chemotherapy, offering a survival rate of only 15 months. Fortunately, recent nanotechnology progress has enabled novel approaches and, alongside ferrocenes' unique properties of cytotoxicity, sensitization, and interaction with reactive oxygen species, have brought new possibilities to complement chemotherapy in nanocarrier systems, enhancing treatment results. METHODS: In this work, we developed and characterized a temozolomide-loaded nanoemulsion and evaluated its cytotoxic potential in combination with ferrocene in the temozolomide-resistant T98G and temozolomide-sensitive U87 cell lines. The effects of the treatments were assessed through acute assays of cell viability, cell death, mitochondrial alterations, and a treatment protocol simulation based on different two-cycle regimens. RESULTS: Temozolomide nanoemulsion showed a z-average diameter of 173.37 ± 0.86 nm and a zeta potential of - 6.53 ± 1.13 mV. Physicochemical characterization revealed that temozolomide is probably associated with nanoemulsion droplets instead of being entrapped within the nanostructure, allowing a rapid drug release. In combination with ferrocene, temozolomide nanoemulsion reduced glioblastoma cell viability in both acute and two-cycle regimen assays. The combined treatment approach also reversed T98G's temozolomide-resistant profile by altering the mitochondrial membrane potential of the cells, thus increasing reactive oxygen species generation, and ultimately inducing cell death. CONCLUSIONS: Altogether, our results indicate that using nanoemulsion containing temozolomide in combination with ferrocene is an effective approach to improve glioblastoma therapy outcomes.


Assuntos
Neoplasias Encefálicas , Glioblastoma , Humanos , Temozolomida/farmacologia , Temozolomida/uso terapêutico , Glioblastoma/patologia , Metalocenos/uso terapêutico , Espécies Reativas de Oxigênio/metabolismo , Linhagem Celular Tumoral , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/patologia
2.
J Biol Inorg Chem ; 28(6): 549-558, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37462740

RESUMO

A series of new ferrocenyl nitroheterocyclic sulfonylhydrazones (1a-4a and 1b-2b) were prepared by the reaction between formyl (R = H) or acetyl (R = CH3) nitroheterocyclic precursors [4/5-NO2(C5H2XCOR), where X = O, S)] and ferrocenyl tosyl hydrazine [(η5-C5H5)Fe(η5-C5H4SO2-NH-NH2)]. All compounds were characterized by conventional spectroscopic techniques. In the solid state, the molecular structures of compounds 1a, 2b, and 3a were determined by single-crystal X-ray diffraction. The compounds showed an E-configuration around the C=N moiety. Evaluation of trypanocidal activity, measured in vitro against the Trypanosoma cruzi and Trypanosoma brucei strains, indicated that all organometallic tosyl hydrazones displayed activity against both parasite species with a higher level of potency toward T. brucei than T. cruzi. Moreover, the biological evaluation showed that the 5-nitroheterocyclic derivatives were more efficient trypanocidal agents than their 4-nitroheterocyclic counterparts.


Assuntos
Doença de Chagas , Tripanossomicidas , Trypanosoma cruzi , Humanos , Metalocenos , Doença de Chagas/tratamento farmacológico , Doença de Chagas/parasitologia
3.
Molecules ; 27(23)2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-36500436

RESUMO

Immunomodulatory agents are widely used for the treatment of immune-mediated diseases, but the range of side effects of the available drugs makes necessary the search for new immunomodulatory drugs. Here, we investigated the immunomodulatory activity of new ferrocenyl-N-acyl hydrazones derivatives (SintMed(141−156). The evaluated N-acyl hydrazones did not show cytotoxicity at the tested concentrations, presenting CC50 values greater than 50 µM. In addition, all ferrocenyl-N-acyl hydrazones modulated nitrite production in immortalized macrophages, showing inhibition values between 14.4% and 74.2%. By presenting a better activity profile, the ferrocenyl-N-acyl hydrazones SintMed149 and SintMed150 also had their cytotoxicity and anti-inflammatory effect evaluated in cultures of peritoneal macrophages. The molecules were not cytotoxic at any of the concentrations tested in peritoneal macrophages and were able to significantly reduce (p < 0.05) the production of nitrite, TNF-α, and IL-1ß. Interestingly, both molecules significantly reduced the production of IL-2 and IFN-γ in cultured splenocytes activated with concanavalin A. Moreover, SintMed150 did not show signs of acute toxicity in animals treated with 50 or 100 mg/kg. Finally, we observed that ferrocenyl-N-acyl hydrazone SintMed150 at 100 mg/kg reduced the migration of neutrophils (44.6%) in an acute peritonitis model and increased animal survival by 20% in an LPS-induced endotoxic shock model. These findings suggest that such compounds have therapeutic potential to be used to treat diseases of inflammatory origin.


Assuntos
Hidrazonas , Agentes de Imunomodulação , Animais , Hidrazonas/química , Metalocenos , Compostos Ferrosos/farmacologia , Compostos Ferrosos/química , Lipopolissacarídeos
4.
IUCrdata ; 7(Pt 10): x221011, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36405852

RESUMO

The structure of 4,5-diferrocenyl-1,2-di-thiole-3-thione, [Fe2(C5H5)2(C13H8S3)] or C23H18Fe2S3, at 130 K has monoclinic (P21/c) symmetry. The molecule has two ferrocenyl units attached to a 1,2-di-thiole-3-thione moiety. It is of inter-est with respect to the question if the introduction of ferrocenyl substituents into biologically active mol-ecules offers the potential to obtain more efficacious therapeutic drugs. The crystal structure displays inter-molecular contacts of the C-H⋯S and S-π(C-C) types.

5.
Protein Pept Lett ; 29(12): 1088-1098, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36177620

RESUMO

BACKGROUND: Fungal and parasitic diseases are global health problems, and the available treatments are becoming ineffective, mainly due to the emergence of resistant strains of pathogens. Furthermore, the drugs currently in use exhibit high toxicity and side effects. The scarcity of efficient treatments for fungal and parasitic diseases has motivated the search for new drug candidates, including antimicrobial peptides. The chemokine class RP1 peptide shows inhibitory activity against bacteria, viruses, cancer cells and parasites. In addition, the organometallic compound ferrocene showed antiparasitic activity. OBJECTIVE: Study aimed to assess the effect of conjugation of the RP1 peptide with ferrocene in terms of its structure, biological activity against fungi and parasites and toxicity. METHODS: Peptides and conjugates were synthesized using solid phase peptide synthesis (SPPS). The Fc-RP1 peptide showed antifungal and antimalarial activities with low toxicity in the U87 and HepG2 cell lines. RESULTS: The mechanism of action of these peptides, analyzed by flow cytometry in the fungus Cryptococcus neoformans, was through membrane permeabilization, with an emphasis on the Fc-RP1 peptide that presented the highest rate of PI-positive cell marking. CONCLUSION: In conclusion, ferrocene conjugated to antimicrobial peptide RP1 is an attractive biomolecule for drug discovery against fungal and parasitic diseases.


Assuntos
Antimaláricos , Metalocenos/farmacologia , Antifúngicos/farmacologia , Peptídeos Antimicrobianos
6.
Acta Crystallogr E Crystallogr Commun ; 78(Pt 8): 818-820, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35974822

RESUMO

The title compound, [Fe(C5H5)(C8H7N2S)], was synthesized by the direct reaction of acetyl-ferrocene, thio-urea and resublimed iodine. The structure shows one mol-ecule in the asymmetric unit. The amino-thia-zole ring makes an angle of 14.53 (13)° with the ferrocenyl ring to which it is attached. In the crystal, pairs of complex mol-ecules inter-act via inter-molecular N-H⋯N hydrogen bonds, forming a cyclic dimer which then inter-acts with other dimers through C-H⋯π inter-actions.

7.
Bioelectrochemistry ; 146: 108147, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35504230

RESUMO

Ferrocene-based polymers as redox mediators are considered versatile and important in the study of glucose biosensors. Poly-L-lysine (PLL), as a cationic polymer, possesses good properties including biocompatibility, biodegradation and water solubility. In this work, PLL was modified with ferrocene carboxylate in a very simple way by activating the carboxyl group of Fc, which reacted with the amino groups of the polymer. The resulting product was analysed by FTIR. Performance as a redox mediator (Fc-PLL) with the enzyme glucose oxidase was tested by cyclic voltammetry and showed an increase in the oxidation current in the presence of glucose in PBS pH 7.4. Additionally, performance as a biosensor was evaluated by amperometry and gave a linear range of 0-10 mM, a limit of detection of 23 µM, a sensitivity of 6.55 µA/cm2 mM and high selectivity. To evaluate the charged regions of Fc-PLL/GOx on the electrode surface, analysis by scanning electrochemical microscopy showed remarkable activity. The Fc-PLL redox polymer as a glucose biosensor has been well accepted as this kind of material, and the results showed remarkable activity as an electron transfer mediator between the redox polymer and the GOx enzyme.


Assuntos
Técnicas Biossensoriais , Glucose , Técnicas Biossensoriais/métodos , Eletrodos , Enzimas Imobilizadas/química , Glucose/análise , Glucose Oxidase/química , Metalocenos , Oxirredução , Polilisina/metabolismo , Polímeros/química
8.
J Biol Inorg Chem ; 26(5): 599-615, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34292404

RESUMO

A series of novel water-soluble short peptide-bioconjugates containing a ferrocenoyl (Fc) or ruthenocenoyl (Rc) unit was synthesized and characterized to combine the unique activity of ferrocene and the isoelectronic ruthenocene with precisely designed peptide structures. We aim at evaluating these bioconjugates as a new class of OrganoMetallic Short AntiMicrobial Peptides (OM-SAMPs). The series of OM-SAMPs was designed with a set of linear and "head-to-tail" cyclic metallocene-based hexapeptides derived from the homo-sequence H-KKKKKK-NH2 by substitution of lysine (K) by tryptophan (W) and by orthogonal derivatization of the ε-N-amine group of lysine by a metallocene moiety. Peptide conjugates were characterized by RP-HPLC, mass spectrometry (ESI and MALDI-TOF) and circular dichroism (CD) spectroscopy. Gram-positive and Gram-negative antibacterial activity testings were carried out to explore the role of insertion of the metallocene fragment into the peptide, and the effect of the modification of the cationic charge and aromatic residues on the physiochemical properties of these OM-SAMPs. These results show that the insertion of two tryptophan residues and ferrocenoyl/ruthenocenoyl moieties into a linear homo-sequence peptides increase significantly their antibacterial activity with minimum inhibitory concentration values as low as 5 µM for the most active compounds. However, "head-to-tail" cyclic metallocene-based hexapeptides were not active against Gram-negative bacteria up to concentrations of 50 µM. These studies provide a better understanding of the role of structural modifications to enhance antibacterial peptide activity, which is promising for their therapeutic application.


Assuntos
Antibacterianos/farmacologia , Compostos Ferrosos/farmacologia , Metalocenos/farmacologia , Oligopeptídeos/farmacologia , Compostos Organometálicos/farmacologia , Técnicas de Síntese em Fase Sólida , Antibacterianos/síntese química , Antibacterianos/química , Compostos Ferrosos/química , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Metalocenos/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Oligopeptídeos/síntese química , Oligopeptídeos/química , Compostos Organometálicos/química , Solubilidade , Água/química
9.
Bioorg Med Chem Lett ; 48: 128240, 2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34217828

RESUMO

A simple and fast methodology under microwave irradiation for the synthesis of 2-aminopyrimidine and pyrazole derivatives using Atwal reaction is reported. After the optimization of the reaction conditions, eight 2-aminolpyrimidines containing ferrocene and heterocycles and three ferrocene pyrazoles were synthesized from the respective chalcones in good yields. Eight compounds had their structure determined by X-ray diffraction. The molecular hybrid 6a-h and 9a-c were tested on four cancer cell lines - HCT116, PC3, HL60 and SNB19 - where four pyrimidine 6a, 6f-h and one pyrazole 9c derivatives show promising antiproliferative activity. In addition, docking simulation and machine learning methods were carried out to explain the biological activity achieved by the synthetized compounds.


Assuntos
Antineoplásicos/farmacologia , Compostos Ferrosos/farmacologia , Aprendizado de Máquina , Metalocenos/farmacologia , Micro-Ondas , Simulação de Acoplamento Molecular , Pirazóis/farmacologia , Pirimidinas/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Compostos Ferrosos/síntese química , Compostos Ferrosos/química , Humanos , Metalocenos/síntese química , Metalocenos/química , Estrutura Molecular , Pirazóis/síntese química , Pirazóis/química , Pirimidinas/síntese química , Pirimidinas/química , Relação Estrutura-Atividade
10.
Bioelectrochemistry ; 138: 107692, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33291002

RESUMO

Peptides with an active redox molecule are incorporated into nanostructured films for electrochemical biosensors with stable and controllable physicochemical properties. In this study, we synthesized three ferrocene (Fc)-containing peptides with the sequence Fc-Glu-(Ala)n-Cys-NH2, which could form self-assembled monolayers on gold and be attached to antibodies. The peptide with two alanines (n = 2) yielded the immunosensor with the highest performance in detecting C-reactive protein (CRP), a biomarker of inflammation. Using electrochemical impedance-derived capacitive spectroscopy, the limit of detection was 240 pM with a dynamic range that included clinically relevant CRP concentrations. With a combination of electrochemical methods and polarization-modulated infrared reflection-absorption spectroscopy, we identified the chemical groups involved in the antibody-CRP interaction, and were able to relate the highest performance for the peptide with n = 2 to chain length and efficient packing in the organized films. These strategies to design peptides and methods to fabricate the immunosensors are generic, and can be applied to other types of biosensors, including in low cost platforms for point-of-care diagnostics.


Assuntos
Técnicas Biossensoriais/métodos , Proteína C-Reativa/análise , Imunoensaio/métodos , Nanoestruturas/química , Peptídeos/química , Proteína C-Reativa/química , Impedância Elétrica , Eletroquímica , Compostos Ferrosos/química , Ouro/química , Limite de Detecção , Metalocenos/química
11.
Acta Crystallogr E Crystallogr Commun ; 76(Pt 8): 1403-1406, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32844037

RESUMO

The title ferrocene derivative, [Fe(C5H5)2(C8NO2)], including an alkyne bonded to a para-nitro-phenyl substituent, which was synthesized from a copper-free Sonogashira cross-coupling reaction between ethynylferrocene and 4-bromo-1-nitro-benzene, crystallizes in the P21/n space group. In the ferrocene unit, the penta-dienyl (Cps) rings are in an eclipsed conformation. The angle of rotation between the substituted cyclo-penta-dienyl ring and the p-nitro-phenyl group is 6.19 (10)°, yielding a quasi-linear extension of the ferrocenyl substitution. Important inter-molecular inter-actions arise from π-π stacking between the Cp rings and the p-nitro-phenyl, from corners of the Cp rings that are perpendicularly aligned, and between the O atoms from the nitro substituent and carbons at the corners of the Cp rings, propagating along all three crystallographic axes.

12.
Biosens Bioelectron ; 138: 111311, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31103930

RESUMO

A novel electrochemical sensor with inherent redox activity mediated by ferrocene for Cystatin C (CysC), an early kidney failure biomarker, is described. The current response was mediated by graphene oxide-ferrocene nanofilm with redox-activity coming from electroactive species surface-confined. Anti-CysC antibodies were immobilized by their Fc portions on the drop-casting polyethyleneimine (PEI) film for improving the sensitivity and reproducibility. Stepwise modifications of the nanostructured surface were characterized by electrochemical techniques, FT-IR and AFM. FT-IR confirmed the formation of the Fc-GO nanocomposite and PEI deposition on the electrode surface. The AFM micrographs confirmed a nanometric film of Fc-GO and PEI. The sensor platform showed a response from 0.1 to 1000 ng/mL and lower limit of detection (LOD) of 0.03 ng/mL of CysC, with good accuracy, specificity and it was successfully applied for CysC detection. Advantages of this immunosensor include rapid testing with minimal steps by the simple use of an intrinsic redox probe, working in a reduction potential, which avoids potential interferences. This proposal attempts to circumvent amperometric detection limitations and provides a promising candidate for future point-of-care diagnostics without redox probe additional solutions for measurements.


Assuntos
Cistatina C/análise , Compostos Ferrosos/química , Grafite/química , Metalocenos/química , Nanocompostos/química , Biomarcadores/análise , Técnicas Biossensoriais , Técnicas Eletroquímicas , Imunoensaio , Limite de Detecção , Oxirredução , Polietilenoimina/química , Sensibilidade e Especificidade
13.
Molecules ; 22(11)2017 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-29135944

RESUMO

In order to obtain gold electrode surfaces modified with Human Papillomavirus L1 protein (HPV L1)-derived peptides, two sequences, SPINNTKPHEAR and YIK, were chosen. Both have been recognized by means of sera from patients infected with HPV. The molecules, Fc-Ahx-SPINNTKPHEAR, Ac-C-Ahx-(Fc)KSPINNTKPHEAR, Ac-C-Ahx-SPINNTKPHEAR(Fc)K, C-Ahx-SPINNTKPHEAR, and (YIK)2-Ahx-C, were designed, synthesized, and characterized. Our results suggest that peptides derived from the SPINNTKPHEAR sequence, containing ferrocene and cysteine residues, are not stable and not adequate for electrode surface modification. The surface of polycrystalline gold electrodes was modified with the peptides C-Ahx-SPINNTKPHEAR or (YIK)2-Ahx-C through self-assembly. The modified polycrystalline gold electrodes were characterized via infrared spectroscopy and electrochemical measurements. The thermodynamic parameters, surface coverage factor, and medium pH effect were determined for these surfaces. The results indicate that surface modification depends on the peptide sequence (length, amino acid composition, polyvalence, etc.). The influence of antipeptide antibodies on the voltammetric response of the modified electrode was evaluated by comparing results obtained with pre-immune and post-immune serum samples.


Assuntos
Proteínas do Capsídeo/química , Desenho de Fármacos , Eletrodos , Ouro , Proteínas Oncogênicas Virais/química , Peptídeos/química , Sequência de Aminoácidos , Animais , Ouro/química , Estrutura Molecular , Peptídeos/síntese química , Estabilidade Proteica , Coelhos , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica
14.
J Inorg Biochem ; 166: 141-149, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27863300

RESUMO

The reaction of E-2-ferrocenylmethylidenetetralones and E,E-2,6-bis-(ferrocenylmethylidene)-cyclohexanone with 2-aminothiophenol proceed with high diastereoselectivity, forming the ~4.5:1 mixture of trans- and cis-isomers of polycyclic ferrocenylthiazepines, respectively. The reactions of E,E-2,5-bis-(ferrocenylmethylidene)cyclopentanone and E,E-3,5-bis-(ferrocenylmethylidene)-1-methyl-4-piperidone with 2-aminothiophenol take place stereo specifically to form the diastereomeric tricyclic thiazepines of cis- and trans-configuration, respectively. The structures of the obtained compounds were established by IR, 1H and 13C NMR spectroscopy and mass-spectrometry. The structures of the trans-tetralino[1,2a]-, trans-5,7-dimethyltetralino[1,2a]-2-ferrocenyl [1,5]benzo-2,3-dihydrothiazepines and cis-5-ferrocenyl-methylidenecyclopentano[1,2a]-2-ferrocenyl- [1,5]benzo-2,3-dihydrothiazepine were confirmed by X-ray diffraction analysis. An electrochemical study reveals that the diferrocenyl derivatives belong to a Class I compounds of the Robin-Day classification. This behavior is explained by the analysis of frontier orbitals as calculated by density functional theory, showing that only one ferrocenyl unit participates in the generation of HOMO and LUMO orbitals. Compounds 4a and 4c showed similar capacity to inhibit the proliferation of HM1: IMSS trophozoite cultures than the first choice drug for human amoebiasis treatment, metronidazole. Morphological changes induced in the trophozoites after drug exposure suggest a redox in balance as the probable mechanism of the parasite death.


Assuntos
Amebíase/tratamento farmacológico , Amebicidas , Entamoeba histolytica/metabolismo , Compostos Ferrosos , Compostos Policíclicos , Tiazepinas , Amebicidas/síntese química , Amebicidas/química , Amebicidas/farmacologia , Compostos Ferrosos/síntese química , Compostos Ferrosos/química , Compostos Ferrosos/farmacologia , Humanos , Compostos Policíclicos/síntese química , Compostos Policíclicos/química , Compostos Policíclicos/farmacologia , Tiazepinas/síntese química , Tiazepinas/química , Tiazepinas/farmacologia , Trofozoítos/metabolismo
15.
Acta Crystallogr E Crystallogr Commun ; 72(Pt 6): 868-71, 2016 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-27308062

RESUMO

A new ferrocene complex, 16-ferrocenylmethyl-3ß-hy-droxy-estra-1,3,5(10)-trien-17-one dimethyl sulfoxide monosolvate, [Fe(C5H5)(C24H27O2)]·C2H6OS, has been synthesized and structurally characterized by single-crystal X-ray diffraction techniques. The mol-ecule crystallizes in the space group P21 with one mol-ecule of dimethyl sulfoxide. A hydrogen bond links the phenol group and the dimethyl sulfoxide O atom, with an O⋯O distance of 2.655 (5) Å. The ferrocene group is positioned in the ß face of the estrone moiety, with an O-C-C-C torsion angle of 44.1 (5)°, and the carbonyl bond length of the hormone moiety is 1.216 (5) Å, typical of a C=O double bond. The average Fe-C bond length of the substituted Cp ring [Fe-C(Cp*)] is similar to that of the unsubstituted one [Fe-C(Cp)], i.e. 2.048 (3) versus 2.040 (12) Å. The structure of the complex is compared with those of estrone and eth-oxy-methyl-estrone.

16.
Materials (Basel) ; 9(3)2016 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-28773289

RESUMO

The synthesis of four amphiphilic organometallic complexes with the general formula RC = M(CO)5NH(CH2)15CH3, where R is a ferrocenyl 2(a-b) or a phenyl 4(a-b) group as a donor moiety and a Fischer carbene of chromium (0) or tungsten (0) as an acceptor group, are reported. These four push-pull systems formed Langmuir (L) monolayers at the air-water interface, which were characterized by isotherms of surface pressure versus molecular area and compression/expansion cycles (hysteresis curves); Brewster angle microscopic images were also obtained. By using the Langmuir-Blodgett (LB) method, molecular monolayers were transferred onto glass substrates forming Z-type multilayers. LB films were characterized through ultraviolet-visible spectroscopy, atomic force microscopy and X-ray diffraction techniques. Results indicated that films obtained from 2b complex [(Ferrocenyl)(hexadecylamine)methylidene] pentacarbonyl tungsten (0) are the most stable and homogeneous; due to their properties, these materials may be incorporated into organic electronic devices.

17.
Rev. colomb. ciencias quim. farm ; 43(1): 39-54, Jan.-June 2014. ilus, tab
Artigo em Português | LILACS | ID: lil-729560

RESUMO

O comportamento de elétrodos modificados por camada de ferroceno nos processos da eletrooxidação de certos compostos orgânicos em meios neutro e ácido foi descrito matematicamente, sendo os modelos correspondentes analisados por meio da teoria de estabilidade linear e da análise de bifurcações. Através da comparação dos modelos foi avaliada a influência do pH ao comportamento dos elétrodos, modificados por ferroceno.


The behavior of the electrodes modified by ferrocene layer in the electrooxidation of certain organic compounds in neutral and acid media was mathematically described and the mathematical models were analyzed by linear stability theory and bifurcation analysis. Comparing the models, the influence of pH on the electrodes´ behavior was evaluated.

18.
Sensors (Basel) ; 11(2): 1361-74, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22319356

RESUMO

The present paper describes the characterization of a carbon ceramic electrode modified with ferrocenecarboxylic acid (designated as CCE/Fc) by electrochemical techniques and its detection ability for dopamine. From cyclic voltammetric experiments, it was observed that the CCE/Fc presented a redox pair at E(pa) = 405 mV and E(pc) = 335 mV (ΔE = 70 mV), related to the ferrocene/ferrocenium process. Studies showed a considerably increase in the redox currents at the same oxidation potential of ferrocene (E(pa) = 414 mV vs. Ag/AgCl) in the presence of dopamine (DA), differently from those observed when using only the unmodified CCE, in which the anodic peak increase was considerably lower. From SWV experiments, it was observed that the AA (ascorbic acid) oxidation at CCE/Fc occurred in a different potential than the DA oxidation (with a peak separation of approximately 200 mV). Moreover, CCE/Fc did not respond to different AA concentrations, indicating that it is possible to determine DA without the AA interference with this electrode.


Assuntos
Carbono/química , Cerâmica/química , Técnicas Eletroquímicas/métodos , Compostos Ferrosos/química , Ácido Ascórbico/química , Dopamina/química , Eletrodos , Eletrólitos , Concentração de Íons de Hidrogênio , Metalocenos , Microscopia Eletrônica de Varredura , Espectrometria por Raios X
19.
Rev. colomb. quím. (Bogotá) ; 36(2): 199-211, sep.-dic. 2007. ilus, tab
Artigo em Espanhol | LILACS | ID: lil-636609

RESUMO

En esta comunicación se reporta la síntesis y caracterización de nuevos compuestos de rutenio(II) con ligantes ferrocenílicos y/o fosfínicos de fórmula general: [RuCl2(PP)(NN)], donde PP = 1,1'-bis (difenilfosfina)ferroceno (dppf) ó 1,2-bis (difenilfosfina)etano (dppe); NN = 3,3'- dicarboxi-2,2'-bipiridina (3,3'-dcbpy) ó 2,2'-bipiridina (bpy). El estudio teórico DFT de estos compuestos permitió racionalizar algunos resultados experimentales y a la vez dio indicios teóricos de que compuestos de Ru(II) con ligantes ferrocenílicos tienen ciertas propiedades para utilizarlos como fotosensibilizadores en celdas solares sensibilizadas mediante colorantes (CSSC). La caracterización de los ligantes y de los complejos de rutenio( II) se realizó por 1 H-RMN y 31P - RMN, UV-Vis, IR, voltametría cíclica y diferencial de pulso.


Novel ruthenium(II) complexes with ferrocenylic and/or phosphinic ligands of the type [RuCl2(PP)(NN)], with PP = 1,1'- bis(diphenylphosphino)ferrocene (dppf) or 1,2-dipheylphospinoethane (dppe) and NN = 3,3'-dicarboxyl- 2,2'-bipyridine (3,3'- dcbpy) or 2,2'-bipyridine (bpy) were synthesized and characterized. DFT studies of these compounds allowed to explain some experimental aspects, leading to a theoretical design of modified Ru(II) ferrocenylic complexes in order to be used as a dye for Photosensitized Solar Cells. The ligands and the complexes were characterized by 1H y 31P - NMR, UV-Vis, IR and Cyclic and differential pulse voltammetries.


Nesta comunicação reporta-se a síntese e caracterização de novos compostos de rutênio(II) com ligantes ferrocenílicos e/ou fosfínicos de fórmula geral: [RuCl2 (PP)(NN)], onde PP = 1,1'-bis (difenilfosfina) ferroceno (dppf) ou 1,2-bis(difenilfosfina) etano (dppe); NN = 3,3'-dicarboxi- 2,2'-bipiridina (3,3'-dcbpy) ou 2,2'-bipiridina (bpy). O estudo teórico DFT destes compostos permitia racionalizar alguns resultados experimentais e, ao mesmo tempo, deu indicações teóricas de que compostos de Ru(II) com ligantes ferrocenílicos têm umas propriedades para utilizar-se como fotosensivilizadores em Células Solares Sensibilizadas diante Colorantes (CSSC). A caracterização dos ligantes e dos complexos de rutênio(II) foi por 1H-RMN e 31P-RMN, UV-Vis, voltametria cíclica e diferencial de pulso.

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