Ferrocene

The condensation of 1,1′-ferrocenedimethanol and lipoic acid yields a ferrocene derivative (FcD): 1,1′-ferrocenyl bis(methylene lipoic acid ester), a bipodant linker which was used to aggregate gold nanoparticles (AuNPs). The FcD/AuNP aggregations displayed a very well-resolved signal related to the ferrocene oxidation to ferrocenium. The aggregates were found to form an efficient transducing system for a novel concept of immunosensing based on the shifting of the ferrocene oxidation potential. αHIgG/FcD/AuNP or chicken αGIgG/FcD/AuNP bioconjugates are used along with carbon SPEs as an immunosensing platform for the detection of HIgG or GIgG as model analytes. As shown by CV and DPV, the antigens addition triggers significant anodic potential shifts (up to 75 mV) of the ferrocene oxidation peak as an immunoresponse for the Ag–Ab recognition. The results from selectivity and specificity experiments using bovine serum albumin, ovalbumin and α-lactalbumin as potentially interfering proteins to HIgG Ag showed that these potential shifts would be solely due to the Ag–Ab recognition events with excellent selectivity and specificity in the presence of up to 1000-fold of the competitive proteins.

Ferrocene is an exceptional building block for the development of dyes with reversible redox properties. Dyes absorbing int the near infrared and infrared region are actively researched due to their potential applications ranging from telecommunication to defence systems. In this review, an overview of the different NIR and in-frared dyes reported to date is presented. Parallel to the photophysical characteristics, the synthetic pathways giving access to these structures is presented.

Ferrociphenols have been found to have high antiproliferative activity against estrogen-independent breast cancer cells. The rat and human liver microsome-mediated metabolism of three compounds of the ferrocifen (FC) family, 1,1-bis(4-hydroxyphenyl)-2-ferrocenyl-but-1-ene (FC1), 1-(4-hydroxyphenyl)-1-(phenyl)-2-ferrocenyl-but-1-ene (FC2), and 1-[4-(3-dimethylaminopropoxy)phenyl]-1-(4-hydroxyphenyl)-2-ferrocenyl-but-1-ene (FC3), was studied. Three main metabolite classes were identified: quinone methides (QMs) deriving from two-electron oxidation of FCs, cyclic indene products (CPs) deriving from acid-catalyzed cyclization of QMs, and allylic alcohols (AAs) deriving from hydroxylation of FCs. These metabolites are generated by cytochromes P450 (P450s), as shown by experiments with either N-benzylimidazole as a P450 inhibitor or recombinant human P450s. Such P450-dependent oxidation of the phenol function and hydroxylation of the allylic CH2 group of FCs leads to the formation of QM a...

The synthesis and evaluation of benzetimide derivatives showing potent CXCR3 antagonism are described. Optimization of the screening hits led to the identification of more potent CXCR3 antagonists devoid of anti-cholinergic activity and identification of the key pharmacophore moieties of the series.

In the title compound, [Fe(C18H14NO)(C7H9O)], an N,N-
diphenylcarboxamide moiety and a hydroxyethyl group are
attached to the ferrocene skeleton. The cyclopentadienyl rings
deviate only slightly from an eclipsed conformation. Two C-
H...Pi interactions link the molecules into sheets. According
to the X-ray, IR, and 1H NMR data, the molecule also
possesses an intramolecular O-H...O hydrogen bond.

An unsymmetrical ferrocenyl-substituted azine ligand and its Cu(II) complex have been prepared in this study. The redox active ferrocene-based azine ligand was obtained by condensation of 2-methanehydrazonoylphenol and ferrocenecarboxaldehyde. Structures of the ligand and its Cu(II) complex have been characterized by IR, UV-Vis, NMR, X-ray, magnetic measurements and TG techniques. Redox behaviors of the ligand and its Cu(II) complex have been investigated by cyclic voltammetry. Structural parameters and spectroscopic properties of the azine ligand containing ferrocenyl unit and its Cu(II) complex were calculated by DFT and TD-DFT/CPCM methods and compared with the experimental results.

A new all-atom force field, for the molecular modeling of metallocenes was constructed. Quantum chemical calculations were performed to obtain several force field terms not yet defined in the literature. The remainder were transferred from the OPLS-AA/AMBER framework. The parametrization work included the obtention of geometrical parameters, torsion energy profiles, and distributions of atomic charges that blend smoothly with the OPLS-AA specification for a variety of organic molecular fragments. Validation was carried out by comparing simulated and experimental data for five different ferrocene derivatives in the crystalline phase. The present model can be regarded as a step toward a general force field for metallocenes, built in a systematic way, easily integrated with OPLS-AA, and transferable between different metal−ligand combinations.

A novel, easy, quick, and inexpensive integrated electrochemical methodology composed of cyclic
voltammetry and amperometry has been developed for the determination of the kinetic stability of
higher oxidation states for inorganic complexes. In this study, ferrocene and its derivatives have been
used as model systems and the corresponding ferrocenium cations were generated in situ during the
electrochemical experiments to determine their kinetic stabilities. The study found that the ferrocenium
cations decompose following the first-order kinetics at 27
3 C in the presence of ambient oxygen
and water. The half-lives of the ferrocenium, carboxylate ferrocenium, and decamethyl ferrocenium
cations were found to be 1.27  103, 1.52  103, and[11.0  103 s, respectively, in acetonitrile solvent
having a 0.5 M tetrabutylammonium hexafluorophosphate electrolyte. These results are in agreement
with the previous reports, i.e. the ferrocenium cation is unstable whereas the decamethyl ferrocenium
cation has superior stability. The new methodology has been established by performing various
experiments using different concentrations of ferrocene, variable scan rates in cyclic voltammetry,
different time periods for amperometry, and in situ spectroelectrochemical experiments.

The aim of this work was to investigate the mechanism of action of 2-ferrocenyl-1,1-diphenylbut-1-ene (1) on HL-60 human leukemia cells. While inactive against noncancerous cells, 1 provoked a concentration-dependent decrease in viable tumor cells, primarily via apoptosis, as evidenced by analysis of cell morphology, activation of caspases 3 and 7, increased DNA fragmentation, and externalization of phosphatidylserine. Necrosis was observed only at the highest tested concentration (4 μM). Compound 1 interfered with the cell cycle, causing an accumulation of cells in the G1 /G0 phase. Interaction of 1 with dsDNA and ssDNA was observed by differential pulse voltammetry and confirmed by hyperchromicity in the UV/Vis spectra of dsDNA, with an interaction constant of 2×10(4) M(-1). Both the organic analogue 1,1,2-triphenylbut-1-ene (2) and ferrocene were inactive against cancer and noncancer cell lines and did not react with DNA. These results reinforce the idea that the hybrid strategy of conjugating ferrocene to the structure of tamoxifen derivatives is advantageous in finding new substances with antineoplastic activity.

The influence of model biological medium on the properties and structure of epoxy-polyurethane (EPU) ferrocene compositions has been investigated by physical-mechanical IR-spectroscopic and X-ray methods. It has been established that the EPU compositions biodegrade most intensively after 1 month of incubation, accompanied by a decline in strength at 80–92 % break. According to the IR-spectroscopic studies biodegradation occurs by ester and to a greater extent ether linkages with simultaneous redistribution of hydrogen bonds system, which is associated with structuring of polymer compositions in model biological medium 199 (BM 199). The relaxing nature of structure formation processes in the volume of polymer composites under the influence of BM 199 has been confirmed. According to small-angle X-ray diffraction upon exposure of sample EPU (10.0F) during 6 months in BM 199 the rise of similar microareas of heterogeneity is observed, which may be the result of specific interaction of molecules of enzymes that are presented in BM 199 with urethane and amide EPU groups.

Many plant pathogenic bacteria and fungi are known to infect olive trees, causing considerable crop losses. The present work deals with targeting some olive tree pathogens by ferrocene derivatives [1,1-bis-(4-hydroxyphenyl)- 2-ferrocenyl-but-1-ene] (P1); (Z+E)-1-(p-aminophenyl)- 1-phenyl-2-ferrocenyl-but-1-ene (P2); 2-ferrocenyl- 1-(4-N-acetylaminophenyl)-1-phenyl-but-1-ene (P3); tamoxifen analogous hydroxyferrocifen (P4); 1,1- bis[4-(3-dimethylaminopropoxy)phenyl]-2-ferrocenyl- but-1-ene (P5); 1-[4-(3-dimethylamoniumpropoxy) phenyl]-1-(4-hydroxyphenyl)-2-ferrocenyl-but-1-ene citrate (P7) and 1,1-bis[4-(3-dimethylaminiumpropoxy) phenyl]-2-ferrocenyl-but-1-ene citrate (P8)] and an organic compound 1-[4-(3-dimethylamoniumpropoxy) phenyl]-1-(4-hydroxyphenyl)-2-phenyl-but-1-ene (P6), whose antimicrobial activity was tested in vitro against Pseudomonas savastanoi pv. savatanoi (the agent of olive knot), Agrobacterium tumefaciens (responsible for crown gall) and the fungus Fusarium solani...

Abstract Ferrocenes with up to four formyl functionalities have been synthesized by selective one- or two-fold ortho-lithiation of 1,1′-di(1,3-dioxan-2-yl)ferrocene followed by the reaction with dimethylformamide. Subsequent deprotection afforded tri- and tetraformyl-ferrocene in good yields. Wittig reactions convert the aldehydes to tri- and tetravinyl-ferrocene. The structures of three formyl-ferrocenes in the solid-state have been determined by single crystal X-ray diffraction. In two of the structures the ferrocene moieties form 1D chains by parallel displaced π-interactions with Cp⋯Cp distances as short as 3.21 A. Electrochemical measurements (CV) demonstrated an irreversible behavior of the electron-poor multi-formyl ferrocenes. Reducing the measurement temperature down to −40 °C and the usage of [NnBu4][B(C6F5)4] prevents side reactions and hence reversible redox-processes could be obtained. It was found that the number of formyl functionalities correlates with the ferrocenyl's redox potential in a strictly linear fashion.

A novel, easy, quick, and inexpensive integrated electrochemical methodology composed of cyclic voltammetry and amperometry has been developed for the determination of the kinetic stability of higher oxidation states for inorganic complexes. In this study, ferrocene and its derivatives have been used as model systems and the corresponding ferrocenium cations were generated in situ during the electrochemical experiments to determine their kinetic stabilities. The study found that the ferrocenium cations decompose following the first-order kinetics at 27 ± 3 °C in the presence of ambient oxygen and water. The half-lives of the ferrocenium, carboxylate ferrocenium, and decamethyl ferrocenium cations were found to be 1.27 × 10(3), 1.52 × 10(3), and ≫11.0 × 10(3) s, respectively, in acetonitrile solvent having a 0.5 M tetrabutylammonium hexafluorophosphate electrolyte. These results are in agreement with the previous reports, i.e. the ferrocenium cation is unstable whereas the decamethyl...

Ferrocene is one of the most widely established compounds in the chemical literature, and it is frequently used as a starting material in both organometallic and organic chemistry transformations. 1 This sandwich-type compound consists of an iron(II) atom bonded in an   fashion to two cyclopentadienide rings (Cp). Redox cycling between the Fe 2+ /Fe 3+ states is both chemically and electrochemically reversible. 2 Certainly this final point is one main reason why ferrocene has been so popular as a redox reporter in supramolecular structures. 3 The Cp rings are aromatic and hence it is possible to perform typical electrophilic substitution reactions on one or both of the rings. 4 Selective reactions on a single Cp ring to introduce two disparate functional groups (e.g. PPh 2 , dihydrooxazole) is also possible. 5 For this latter case the ferrocene subunit is used as a planar chiral ligand for asymmetric catalysis applications. 6 For each ring to incorporate a different functional group can be complex, often requiring selective BuLi reactions at low temperatures. 7 A long reaction time and a convoluted purification method is possible starting from 1,1′-ferrocenedicarboxaldehyde. 8 A very mild and fast method to achieve a similar outcome would appear to be appealing, provided the two functional groups are useful for further reactions. 9 It turned out that, as part of our research effort into producing ferrocene-based porphyrin and borondipyrromethene (Bodipy) compounds, we discovered such a simple procedure. The oxidation of ferrocenecarboxaldehyde using aqueous KMnO 4 in acetone is well documented to produce the corresponding carboxylic acid. 10 Repeating the literature method afforded ferrocenecarboxylic acid in reasonable yield. However, we found that the same procedure applied to 1,1′-ferrocenedicarboxyaldehyde in acetone or acetonitrile did not produce the corresponding dicarboxylic acid (Scheme 1). The 1 H NMR spectrum for the major product isolated from the acetonitrile reaction showed different resonances for the two Cp rings, confirming the product to be unsymmetrical. Furthermore, two downfield resonances at  193.21 and 170.77 for the 13 C{ 1 H} NMR spectrum were consistent with the presence of aldehyde and carboxylic acid groups. The mass spectrum showed a peak at m/z 259, and a broad peak at ca. 2939 cm 1 in the FT-IR spectrum confirmed production of a carboxylic acid group. The combined evidence verified the product to be compound 1, in which one aldehyde was oxidized but the other remained untouched. Hence, under these conditions the ferrocene is desymmetrized since it contains two different functional groups. The overall yield for 1 is 49% after a fast and chromatography-free work up, providing material pure enough for further synthetic reactions. A similar reaction performed using an acetone/H 2 O mixture (ca. 1:1) did not afford a product with a 1 H NMR spectrum consistent with compound 1. Instead, additional resonances were observed in the olefinic region ( = 7.35 and 6.30, J = 16.2 Hz), a methyl resonance ( = 2.25) and a downfield resonance ( = 197.51) in the 13 C NMR spectrum, which is consistent with the existence of a CH 3 CO group (see Supporting Information). 11 The mass spectrum showed a peak at m/z 299, and once again the FT-IR spectrum corroborated the presence of a carboxylic acid (2934 cm 1). 12 The spectroscopic data are fully consistent with compound 2 with a trans double bond. We speculate that oxidation of one aldehyde to the carboxylic acid activates the other carbonyl in 1 to a condensation reaction with the acetone present in solution. Presumably for ferrocenecarboxaldehyde the reaction of the aldehyde with acetone is too slow to compete with oxidation. Rather surprisingly, compounds 1 and 2 could not be found in the literature using popular search tools (i.e., Scifinder, Reaxys). The closest analogue to 2 is the structural isomer (C 15 H 14 FeO 3) in which one ring has a formyl and the other the (E)--(methoxycarbonyl)ethenyl subunit. 8 This material was produced by a controlled Wittig reaction with 1,1′-ferrocenedicarboxaldehyde, yielding a mixture of compounds which had to be separated by chromatography. Again for compound 1 the structural analogue (C 12 H 10 FeO 3) has both the formyl and carboxylic acid substituted on the same Cp ring. 13 Scheme 1. Reagents and Conditions: (i) KMnO 4 , CH 3 CN/H 2 O, 0 °C; (ii) KMnO 4 , acetone/H 2 O, 0 °C. Scheme 2. Reagents and Conditions: (i) 2-acetylpyridine, aq. NaOH/NH 4 OH, dark; (ii) (a) diethyl malonate, NaOEt, EtOH; (b) H 2 O, H + .

A selective and efficient catalytic method was developed for the synthesis of new styryl-conjugated silyl-ferrocene materials. The use of an effective palladium catalytic system [Pd(h 2-dba)(P(o-tolyl) 3) 2 ] (3) with a K 3 PO 4 base solution allowed us to obtain new, reactive ferrocene olefins which can be used in various applications. In addition, using the stereo-control silylative coupling reaction we received unique new organosilicon trans-vinylene products with a built-in metallocene.

In this study, ruthenocene-containing -diketones, ruthenocene-, cobalticeniumand/or ferrocenecontaining enaminones and ruthenocenyl and/or ferrocenyl containing titanium(IV) complexes were synthesised. Forty seven of these compounds were previously unknown. The keto-enol isomerization kinetics of the -diketones RcCOCH2COR with R = C10F21, CF3, C6F5, C10H21, CH3, Rc and Fc have been studied by H NMR spectroscopy in CD3CN. The influence of the solvent on this equilibrium has also been investigated utilising CD2Cl2 and CDCl3 as different solvents. The substitution reactions of the monodentate ferrocene-containing alkoxy groups of [Ti(O(CH2)nFc)2(RcCOCHCOCH3)2] {n = 1, 2, 3} with HO(CH2)nFc {n = 2, 3, 4} and the substitution of the bi-dentate -diketonato ligand of [Ti(O(CH2)4Fc)2(RcCOCHCOR)2] {R = CH3, CF3} with RcCOCH2COR {R = CH3, CF3} is reported. Both revealed large positive entropy values, which suggest a dissociative substitution mechanism. Electrochemical studies were conducte...

1 July 2011 A sensitive and selective electrochemical method for the determination of isoproterenol (ISPT) was developed by using a ferrocene multi wall carbon nanotubes paste electrode (FCMWCNTPE). The fabrication of FCMWCNTPE and its electrocatalytic effect for electrochemical oxidation of ISPT were investigated by electrochemical impedance spectroscopy (EIS) and voltammetric methods. The cyclic voltammetric results indicate that multi wall carbon nanotubes (MCNTs) remarkably enhance the oxidation of ISPT in wide

Abstract: The contemporary organometallic chemistry stems from the discovery of ferrocene Fe(C5H5)2, i.e., di-cyclopentadienyle iron (FeCp2 or Fc) half a century ago [1,2]. Since its discovery, the heated debate whether the eclipsed or the staggered is the most stable structure of Fc continues. The fact that electronic structures and many properties of the Fc conformers are strikingly similar has been a key hurdle to differentiate or separate the configurations from one another [3]. We recently discovered theoretically using DFT calculations that the 400-500 cm-1 region of the infrared (IR) spectra of Fc [4] exhibits the fingerprint conformers. Such the discovery was later confirmed by IR experimental measurements in a number of solutions, in polar and non-polar solvents [5]. Understanding of the structure and dynamics of the sandwich complex is important as Fc derivatives may inherit particular properties which only exist in one conformer such as catalysis. It is further discovered...

Ferrocene was used as a catalyst in a hydrocarbon solution to carry out injection chemical vapour deposition (CVD) growth of carbon nanomaterials in a horizontal tube furnace. The presence and quality of various carbon materials was determined using Raman spectroscopy, thermogravimetric analysis, and electron microscopy. Products ranged from amorphous carbon (a-C), multi walled carbon nanotubes (MWNTs) and vapour grown fibers (VGFs). Catalyst concentration, growth temperature, injection rate, carrier gas flow rate, and the choice of hydrocarbon were found to influence the product outcome. Slower injection rates gave higher isolated yield. High catalyst concentrations were found to produce less pure carbon materials with iron oxides impurities. Higher temperatures were favourable to nanotube formation. The use of benzene was found to increase yield compared with the other hydrocarbons. In this work we developed a process map to chart the various carbon nanomaterial allotropes that were created according to reaction parameters.