Ferrocenyl Compound Research Articles

Organometallic N‐acylhydrazones of 5‐nitrofuran and 5‐nitrothiophene based: Synthesis, electrochemical, antiparasitic evaluation, and computational study

In searching for new therapeutic agents for treating American trypanosomiasis and Human African trypanosomiasis, four nitroheterocyclic acylhydrazones of general formulae [R1‐CH=N‐NH‐C(O)‐(5‐C4H2X)] (where R1 = ferrocenyl or cyrhetrenyl, and X = O or S) have been synthesized and characterized by spectroscopic techniques. Comparative studies of their stability by 1H‐NMR and UV–Vis experiments were reported. Single‐crystal X‐ray diffraction confirmed the molecular structures of NF‐1 and NT‐2. Their X‐ray crystal structures reveal that both adopt an E‐configuration on the C=N moiety. Regarding the ‐NH‐C(O)‐ bond, the structure of NF‐1 confirmed a trans conformation, while NT‐2 exhibited a cis‐amide conformation. The cyclic voltammetry and electron spin resonance (ESR) experiments were conducted to study the electrochemical behavior of N‐acylhydrazones. The antiparasitic activities of compounds against Trypanosoma cruzi (epimastigotes) and Trypanosoma brucei (trypomastigotes) revealed that cyrhetrenyl complexes were more effective than their ferrocenyl analogs. The cyrhetrenyl derivative NT‐2 (EC50 = 2.25 μM) showed activity against T. brucei comparable to the standard drug nifurtimox (Nfx, EC50 = 3.56 μM). The ferrocenyl compound NT‐1 (>200 μM) was at least two times less cytotoxic than the Nfx (88.7 μM) against the L6 rat skeletal myoblast cell line and exhibited a selectivity like Nfx toward T. brucei. Density functional theory (DFT) calculations were utilized as an approximation to explain the impact of organometallic and heterocyclic rings on antiparasitic activities. This study supported the experimental results, confirming that the cyrhetrenyl fragment in N‐acylhydrazone derivatives plays a significant role in the antitrypanosomal activity, which can be attributed to an increase in positive charge on the metal.

Mass Transport Properties and Influence of Natural Convection for Voltammetry at the Agarose Hydrogel Interface

Agarose hydrogel, a solid electrolyte, was investigated voltammetrically in terms of transport properties and natural convection effects using a ferrocenyl compound as a redox probe. To confirm the diffusion properties of solute on the agarose interface, the diffusion coefficients (D) of ferrocenemethanol in agarose hydrogel were determined by cyclic voltammetry (CV) according to the concentration of agarose hydrogel. While the value of D on the agarose interface is smaller than that in the bulk solution, the square root of the scan rate-dependent peak current reveals that the mass transport behavior of the solute on the agarose surface shows negligible convection or migration effects. In order to confirm the reduced natural convection on the gel interface, scan rate-dependent CV was performed in the solution phase and on the agarose surface, respectively. Slow scan voltammetry at the gel interface can determine a conventional and reproducible diffusion-controlled current down to a scan rate of 0.3 mV/s without any complicated equipment.

Synthesis and Spectroscopic Properties of Ferrocenyl Derivative Containing Donor and Acceptor Groups

Much interest has been devoted to organometallic NLO materials. We have become interested in exploring the utility of ferrocenyl group as the conjugating bridge. Thus, we synthesized 1-{{[1,3-(5-methylbenzo)dithiol]-2-yli- dene}methyl}-1’-[2-(p-nitrophenyl)-(E)-ethenyl]ferrocene (1). This new ferrocenyl compound has a donor and an acceptor group in 1,1’-positions. Investigations of the solvatochromic property of the compound revealed that it has polarized structure in a polar solvent, such as DMF. SHG efficiency of the compound was estimated by an SHEW (second-harmonic generation with the evanescent wave) method.

Synthesis of new binuclear ferrocenyl compounds by hydrosilylation reactions

Ferrocenyl silanes are prepared by treatment of Grignard reagents produced from 4-chlorobutylferrocene derivatives and chlorodimethylsilane in THF. Butenylferrocenes are prepared by the elimination reaction of 4-chlorobutylalkylferrocenes by sodium tert-butoxide in DMSO. A hydrosilylation reaction between a butenyl compound and ferrocenylsilane occurred in dry toluene at room temperature in the presence of the Karstedt catalyst to produce the desired binuclear ferrocenyl compound in good to high yields. The electrochemical behavior of new ferrocenyl compounds were studied by cyclic voltammetry in CH3CN/0.1 M LiClO4, and the relation between the peak currents and the square root of the scan rate, showed that the redox process is diffusion-limited.

ChemInform Abstract: Peptide‐Catalyzed Desymmetrization of an Achiral Ferrocenyl Compound to Induce Planar Chirality.

Selective monohydrogenation of an achiral ferrocenebis(enal) was achieved with a resin-supported peptide catalyst to afford an enantioenriched planar-chiral product. It was also demonstrated that the reaction was followed by a kinetic resolution through cyclization of the product.

Peptide‐Catalyzed Desymmetrization of an Achiral Ferrocenyl Compound To Induce Planar Chirality

AbstractSelective monohydrogenation of an achiral ferrocenebis(enal) was achieved with a resin‐supported peptide catalyst to afford an enantioenriched planar‐chiral product. It was also demonstrated that the reaction was followed by a kinetic resolution through cyclization of the product.

Ionic Ferrocenyl Compounds Containing Polycyano Anions. Synthesis, Structures, and Effects on Thermal Decomposition of Core Components of Solid Propellants

AbstractFor lowering high migration tendency of alkyl‐substituted ferrocenes as burning‐rate catalysts in composite solid propellants, eight new ionic ferrocenyl compounds, [FcCH2N(CH3)2(CnH2n+1]+X– (Fc = ferrocenyl; X– = 1,1,3,3‐tetracyanopropenide; n = 3–10; consequently numbered as 1–8), were synthesized and characterized by 1H NMR, 13C NMR, FT‐IR and UV/Vis spectroscopy as well as elementary analysis. In addition, the structures of 1, 3, and 5 were confirmed by single‐crystal X‐ray diffraction analysis and their cations were studied by density functional theory calculations (DFT). 1, 3, and 5 crystallize in the triclinic space group P$\bar{1}$. 1–6 show highly thermal stability (>166 °C), whereas compounds 7 and 8 exhibit volatility to a certain degree. Cyclic voltammetry studies suggested that each salt exhibits a quasi‐reversible redox wave of the ferrocenyl group. The effects of the new compounds on thermal decomposition of ammonium perchlorate (AP), 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), and 1,2,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) were investigated by DSC technique. The results show that all the new compounds can catalyze thermal degradation of AP and RDX effectively and are higher in catalytic activity than the corresponding nitrates and picrates, verifying the prospect that relatively high nitrogen content in an ionic ferrocenyl compound is able to enhance its combustion catalytic efficiency.

Diffusion coefficients in viscous sodium alginate solutions

Sodium alginate solution, being viscous hydrocolloid, was examined voltammetrically in the context of viscous effects by use of a ferrocenyl compound as a redox probe. Voltammograms were almost independent of concentrations of sodium alginate even in a solid-like state. Diffusion coefficients of the ferrocenyl compound did not vary with viscosity evaluated by a viscometer. Ionic conductivity of sodium alginate was also independent of the viscosity. In contrast, diffusion coefficients of the latex particle 0.84μm in diameter decreased with an increase in the viscosity. The intrinsic viscosity was evaluated. The value is equivalent to the volume as large as 3m3 of water in which one mole of the unit of sodium alginate polymer generates the viscosity. Consequently, redox species diffuse through water portions circumventing the alginate network. As an application, sodium alginate solutions were used for long-time chronoamperometry. The current was decayed with the time even of 1500s without any effect of natural convection, whereas that in the aqueous solution was irreproducible for times longer than 20s. The other application was electroplating of silver. The silver surface deposited in sodium alginate had no morphology by the SEM image, while the surface plated without sodium alginate showed morphology even on an optical microscopy scale.

Synthesis, Cytotoxicity, and COMPARE Analysis of Ferrocene and [3]Ferrocenophane Tetrasubstituted Olefin Derivatives against Human Cancer Cells

Herein we report the antiproliferative effects of a series of 28 compounds against the MDA-MB-231 breast cancer cell line, including the synthesis of seven new [3]ferrocenophanyl and four new ferrocenyl compounds. For each p-R-phenyl substitution pattern investigated, the [3]ferrocenophanyl derivatives were more cytotoxic than the corresponding ferrocenyl derivative, with the highest activity found for compounds with protic substituents. Theoretical calculations of the HOMO-LUMO gap for the molecules in the Fe³(+) oxidation state suggest a higher reactivity for the [3]ferrocenophanyl derivatives. A lead compound from each series, a [3]ferrocenophanyl and a ferrocenyl compound, possessing two phenol groups, were screened against the NCI/DTP 60-cell-line panel. The mean activity over all cell lines was better than cisplatin for both compounds, and both compounds showed subpanel selectivity for leukemia, CNS cancer, and renal cancer. Low systemic toxicity and lack of interaction with DNA (when in the reduced form), suggest that the compounds may act as prodrugs.

Glucose oxidase as a blocking agent-based signal amplification strategy for the fabrication of label-free amperometric immunosensors

An effective electrochemical signal amplification strategy based on enzyme membrane modification and redox probe immobilization was proposed to construct an amperometric immunosensor. L-cysteine@ferrocene functionalized chitosan, which possessed not only efficient redox-activity but also excellent film-forming ability, was coated on the bare glass carbon electrode. Moreover, the thiol groups (-SH) in the ferrocenyl compound were used for gold nanoparticles immobilization via the strong bonding interaction, which could further be utilized for the immobilization of antibody biomolecules with well-retained bioactivities. Finally, glucose oxidase (GOD) as the enzyme membrane was employed to block the possible remaining active sites and avoid the nonspecific adsorption. With the excellent electrocatalytic properties of GOD towards glucose, the amplification of antigen-antibody interaction and the enhanced sensitivity could be achieved. Under the optimal conditions, the linear range of the proposed immunosensor for the determination of carcinoembryonic antigen (CEA) was from 0.05 to 100 ng/mL with a detection limit of 0.02 ng/mL (S/N = 3). Moreover, the immunosensor exhibited good selectivity, stability and reproducibility, which provided a promising potential for clinical immunoassay.

Study on Anion Electrochemical Recognition Based on a Novel Ferrocenyl Compound with Multiple Binding Sites

A novel ferrocenyl anion receptor N, N, N, N-(dimethyl, ethyl, ferrocenecarboxylic amidodimethylene) ammonium fluoborate 2 with multiple binding sites was synthesized. Its anion recognition behaviors were investigated by CV, 1H NMR and UV-vis spectrum. It was found that the combination of two interactions enforced the anion binding ability and the binding selectivity of 2 to phosphate anion. The effects of scan rate on the CV curves of 2 with phosphate were also investigated. In different scan rate, the CV curves kept stable which indicated the strong binding between 2 and phosphate. According to relationships of peak potential, peak currents and scan rate of 2 binding with phosphate, the kinetic parameters of electrode process such as diffusion coefficient Dapp, surface transfer coefficient alphan alpha, and standard rate constant k0 were calculated.

Ferrocene Catalyzed Carbon Nanotube Formation in Carbonaceous Solid

Carbon nanotubes are formed in a carbonaceous solid from thermal decomposition of various amounts of 1,4-diferrocenylbutadiyne in the presence of an excess amount of a multi(ethynyl)aromatic compound. Only a small amount of the ferrocenyl compound is needed to achieve the formation of carbon nanotubes in high yield. The method described here permits the large-scale production of carbon nanotubes in a shaped, solid configuration. The carbon nanotubes form under atmospheric pressure during the carbonization process above 500 °C in the carbonaceous solid. The Fe atoms, nanoclusters, and/or nanoparticles formed from the decomposition of the 1,4-diferrocenylbutadiyne are the key to the formation of the carbon nanotubes in the developing carbonaceous solid by reacting with the developing polycondensed aromatic ring system. The carbonaceous solids were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy studies.

The influence of phenolic hydroxy substitution on the electron transfer and anti-cancer properties of compounds based on the 2-ferrocenyl-1-phenyl-but-1-ene motif

The ferrocenyl compound 2-ferrocenyl-1,1-bis(4-hydroxyphenyl)-but-1-ene (), is very cytotoxic against breast cancer cells (IC(50) = 0.44 microM against MDA-MB-231). We now report the synthesis of a new series of para- and meta- substituted mono- and di- ferrocenyl phenols [2-ferrocenyl-1-(3-hydroxyphenyl)-1-phenyl-but-1-ene (), 2-ferrocenyl-1-(3-hydroxyphenyl)-1-(4-hydroxyphenyl)-but-1-ene (), 1,2-di-ferrocenyl-1-(4-hydroxyphenyl)-but-1-ene (), and 1,2-di-ferrocenyl-1-(3-hydroxyphenyl)-but-1-ene ()] and their electrochemical and biochemical properties, especially in comparison to the previously reported "standard" compounds [2-ferrocenyl-1-(4-hydroxyphenyl)-1-phenyl-but-1-ene () and ()]. We also report the synthesis and characterization of the diphenyl analogue, 2-ferrocenyl-1,1-diphenyl-but-1-ene (). This structure-activity relationship study was motivated by our hypothesis that the cytotoxicity of is related to its ability to form a quinone methide structure after two in situ 1-electron oxidations, a process which requires the presence of at least one p-phenol. The mono-ferrocenyl compounds (including those previously reported) are reasonably well recognized by the oestrogen receptors alpha (RBAs = 0.9-9.6%) and beta (RBAs = 0.28-16.3%), although the bulkier di-ferrocenyl compounds show very little affinity. In vitro, the cytotoxic effects of the phenolic complexes are related to the positioning of the hydroxyl group (para- superior to meta-), and to the number of ferrocenyl groups (one superior to two), with IC(50) values against the MDA-MB-231 cell line ranging from 0.44-3.5 microM. On the hormone-dependent breast cancer cell line MCF-7, the observed effect seems to be the result of two components, one cytotoxic (antiproliferative) and one estrogenic (proliferative). Electrochemical studies show that only the compounds with a p-phenol engage in proton-coupled intramolecular electron transfer.

Ferrocenyl Compound as a Multiresponsive Calcium Chemosensor with Remarkable Fluorescence Properties in CH3CN

We have synthesized a novel disubstituted ferrocenyl compound [Fe(C5H4CO(CH=CH)2C6H4NEt2)2] (3) that displays a remarkable fluorescence quantum yield (1.1 x 10(-1)) in acetonitrile, and we have studied its capacity for calcium detection in depth using both electrochemical and optical techniques in this medium. The results of our NMR analysis reveal that the ligand-calcium interaction is CO-centered and that an uncommon equilibrium occurs between 3 and calcium triflate, involving five species of different stoichiometries. In contrast, our analysis of the UV-vis absorption data indicates that only three species of different stoichiometries are formed when calcium perchlorate is used with 3. Mass spectrometry measurements provide strong support for the formation of all these different species in solution. In addition, the electrochemical detection of calcium triflate by 3 leads to an irreversible Fe(II)/Fe(III) oxidation process with an unusual negative shift (-60 mV) caused by the (n)Bu4NBF4 salt effect on the Ca2+-3 interaction process. Compound 3 can also be an original optical probe to detect calcium perchlorate over a wide range of salt concentration by UV-vis absorption spectroscopy. The most original and intriguing property of compound 3 is that it exhibits an unprecedented "multistep" fluorescence behavior upon addition of this salt.

Aryl (ferrocenyl)-capped ethenylazaferrocenes: synthesis, structure and electrochemistry

The Horner–Wadsworth–Emmons reaction of 2,5-dimethylazaferrocene-1′-carbaldehyde with diethyl benzylphosphonate, diethyl p-methoxybenzylphosphonate and diethyl (ferrocenylmethyl)phosphonate afforded (E)-1-(2,5-dimethylazaferrocen-1′-yl)-2-phenylethene (2a), (E)-1-(2,5-dimethylazaferrocen-1′-yl)-2-(p-methoxyphenyl)ethene (2b) and (E)-1-(2,5-dimethylazaferrocen-1′-yl)-2-ferrocenylethene (2c), respectively. Cyclic voltammetry showed significant difference in the electrochemical behaviour of these compounds in comparison to their ferrocenyl counterparts. The styryl group, which is an electron-withdrawing group in the ferrocenyl compound, displays a reverse effect in the azaferrocenyl complex 2a. Introduction of the p-methoxystyryl group to 2,5-dimethylazaferrocene brings about a cathodic shift of the redox potential of 370 mV, whereas for the ferrocenyl analog the shift is only 60 mV. Compound 2c shows two redox waves due to two non-equivalent metallocenyl moieties, but there is only weak electronic coupling between redox centres. The W(CO)5-complex of 2c (4) was synthesised and its structure determined by X-ray diffraction.

First fluorescent ferrocenyl compound as multiresponsive calcium-sensing device. NMR, electrochemical, and photophysical preliminary investigations in CH(3)CN.

A new ferrocene receptor binds a calcium guest via complex processes involving the whole unsaturated core of the ligand. Complexation induces significant changes in the ligand properties, as evidenced by the unprecedented cation sensing observed both by electrochemistry and fluorescence spectroscopy.

DSC and TG study of the stability in vacuum of ferrocenyl compounds and their compatibility with ammonium perchlorate

Ferrocenyl compounds are used as burning rate modifiers for propellants containing ammonium perchlorate. An admixture of a ferrocenyl compound and ammonium perchlorate is highly sensitive to an electrostatic discharge. When ammonium perchlorate is added to a propellant mix, a cloud of ammonium perchlorate dust is formed above the mix, and if the ferrocenyl compound is volatile at the mixing temperature of 150°F and at 5 mm vacuum then a potentially hazardous operation may exist. A simple, fast, isothermal and dynamic thermogravimetry method was developed to determine the stability and half-life of the ferrocenyl compound under processing conditions. The half-lives of nine ferrocenyl compounds were found to range from one hour to over one year in vacuo at 150°F. Dynamic DSC showed interactions between the components in the mixture. In a vacuum, individual ferrocenyl compounds and ammonium perchlorate showed endothermic peaks due to decomposition and sublimation, respectively. In the mixture exothermic decomposition peaks were observed for the moieties at lower temperatures than those for the neat components. The activation energies for the thermal decomposition of the ferrocenyl compounds were decreased by 20% in the mixtures.