New Synthesis of Ferrocene Monocarboxylic Acid and Systematic Studies on the Preparation of Related Key‐Intermediates

An improved technique for the preparation of ferrocenecarboxaldehyde and two new methods for the synthesis of ferrocenemonocarboxylic acid from the aldehyde or from acetyl ferrocene are described. Using the aldehyde or the monocarboxylic acid as starting materials, some important ferrocene key intermediates were prepared: monochlorocarbonyl ferrocene, alkali metal and ammonium ferrocenoates, ferrocene carboxyaldehyde diethylacetal, ferrocenecarboxamide, et …, as well as a new ferrocene derivative: piperazinium diferrocenoate.     

Measurement of Ibuprofen Binding to Mixed Monolayers Containing β-Cyclodextrin Active Sites

A molecular imprinting method involving a three-step sequential self-assembly procedure was applied to prepare gold electrodes responsive towards ibuprofen. The electrode modified with the cyclodextrin derivative binds ferrocene to form an electroactive complex with the ferrocene oxidation current decreasing in the presence of ibuprofen in the solution. The competition of ferrocene and ibuprofen for the cyclodextrin cavities in the monolayer provided a means for the determination of the binding constants of ibuprofen with two derivatives of lipoylamide β-cyclodextrin of different hydrophobicity.     

Efficient electronic communication between two identical ferrocene centers in a hydrogen-bonded dimer

A novel ferrocene derivative that contains a donor-donor-acceptor-acceptor (DDAA) hydrogen bonding motif forms highly stable, noncovalent dimers in chloroform and dichloromethane solutions. Its voltammetric behavior and the observation of an intervalence charge-transfer band reveal that the two equivalent ferrocene centers in the hydrogen-bonded dimer exhibit a surprisingly efficient level of electronic communication.     

Synthesis of the first pentaethynylferrocene derivatives

Starting from a bisprotected ferrocene-1,2,3-triscarbaldehyde, Ohira-alkynylation and Pd-catalyzed protection of the free alkyne with 4-iodotoluene leads to a ferrocene in which one Cp-ring is 1,2,3-substituted by two acetal rings (1,2-position) and an internal alkyne. Metalation of the ferrocene nucleus with sec-BuLi, workup with DMF and reduction with LiAlH₄ leads to a 1,2,3,4-tetrasubstituted ferrocene carrying a hydroxymethyl group. The acetal groups are removed by para-toluenesulfonic acid and the aldehyde groups are converted into arylalkynes. A second metalation followed by workup with DMF furnishes a 1,2,3,4,5-pentasubstituted ferrocenecarbaldehyde. The aldehyde is transformed into an alkyne by the Ohira method and converted to an internal alkyne by Pd-catalyzed reaction with 4-iodotoluene. The sequence gives a 1,2,3,4,5-pentasubstituted ferrocene derivative with four alkyne groups and one hydroxymethyl group. Airless Marko oxidation of the alcohol is followed by another Ohira alkynylation. Pd-catalyzed arylation finishes the reaction sequence to give the symmetrical 1,2,3,4,5-pentakis(4′-tolylethynyl)ferrocene, the first pentaethynylferrocene derivative. A second, similar route was explored that furnished 1,2,3,4,5-pentakis(4′-butylphenylethynyl)ferrocene and its butadiyne-bridged dimer.     

Photoinduced charge-transfer between ferrocene derivatives and chloroform molecules confined in poly(methyl methacrylate) thin films

The changes in the electronic absorption spectra (UV-Vis) (after photoexcitations) of poly(methyl methacrylate) (PMMA) thin films doped with a ferrocene derivative and containing chloroform molecules as impurities, have been studied as a function of photoexcitation wavelength (210–750 nm), photoexcitation time (duration), amount of ferrocene derivative in the film and amount of chloroform molecules present in the film. Occurrence of photoinduced charge-transfer between some ferrocene derivatives and chloroform molecules confined in the PMMA thin films has been observed. The effects of the substitution group (attached to the ferrocene unit) on the photoinduced changes are discussed.     

Synthesis and Characterization of Novel Ferrocenyl-Substituted Pyrroles

The syntheses of new ferrocene substituted pyrroles has been carried out by the reaction of TosMIC with an α, β-unsaturated ferrocene derivative.     

Click chemistry inspired synthesis of ferrocene amino acids and other derivatives

This work reports the synthesis of a wide range of ferrocenyl-amino acids and other derivatives in excellent yield. Diverse amino acid containing azides were synthesized and ligated to ferrocene employing click reaction to access ferrocenyl amino acids. Chiral alcohols, esters, diols, amines containing azido group were tagged to ferrocene via click reaction to generate ferrocene derived chiral derivatives. A novel strategy for direct incorporation of ferrocene into a peptide and a new route to 1, 1′disubstituted ferrocene amino acid derivative are reported.     

Electrodeposition of metal nanostructures by galvanic displacement powered with insoluble crystals of a ferrocene derivative.

The deposition of metal nanostructures (wires and particles) on a graphite surface from an aqueous electrolyte solution was induced by galvanic displacement, via the oxidation of insoluble crystals of a ferrocene derivative (either n-butyl ferrocene or decamethyl ferrocene) present on the same substrate. Micron-to-millimetre-scale crystallites of decamethyl ferrocene were deposited on the graphite surface by evaporation from a solution of a nonpolar solvent (1,2-dichloroethane). Immersion of this modified surface into a dilute solution of a metal ion (e.g., CuII, AgI, PdII, PtII and others) caused the deposition of metal nanoparticles at step edges present on the graphite surface. The reducing equivalents required for the metal deposition process are provided by oxidation of the ferrocene derivative on the surface, as directly evidenced by elemental analysis and chronoamperometric experimental data presented here.     

Chiral ferrocene amines derived from amino acids and peptides: synthesis, solution and X-ray crystal structures and electrochemical investigations

For the recognition of all but the simplest naturally occurring molecules, electrochemical sensors based on ferrocene will certainly require chiral centers. To advance the necessary chemistry, this work describes the synthesis and properties of ferrocene derivatives of enantiomerically pure amino acids, peptides, and other chiral amines. Ferrocene aldehyde is condensed with amino acid esters to yield the corresponding Schiff bases 2, which are reduced by NaBH4 in methanol to the ferrocene methyl amino acids 3. An X-ray single-crystal analysis was carried out on the phenylalanine derivative 3a (monoclinic space group P2(1), a = 10.301(1) A, b = 9.647(1) A, c = 18.479(2) A, beta = 102.98(2) degrees, Z = 4). Further peptide chemistry at the C terminus proceeds smoothly as demonstrated by the synthesis of the ferrocene labeled dipeptide Fc-CH2-Phe-Gly-OCH3 5 (Fc = ferrocenyl ((eta-C5H4)Fe(eta-C5H5))). We also report the synthesis of the C,N-bis-ferrocene labeled tripeptide Phe-Ala-Leu and its electrochemical characterization. Starting from the enantiomerically pure ferrocene derivative 9, which was synthesized from ferrocene aldehyde and L-1-amino-ethylbenzene, two diastereomers 10 were obtained by peptide coupling with N-Boc protected D- and L-alanine. There was, however, only very little diastereomeric induction if 0.5 equiv of a racemic mixture of alanine were used. This suggests that amino acid activation rather than coupling is the rate-determining step. A combination of NOESY (nuclear Overhauser effect spectroscopy) spectra and molecular modeling furnished detailed insights into the solution structures of 3, 9, and 10 and was used to rationalize their different reactivity.     

Syntheses and properties of 2-[(dimethylamino)methyl]-1-hydroxyferrocene and its derivatives

A 1,2-disubstituted ferrocene derivative, 2-[(dimethylamino)methyl]-1-hydroxyferrocene (I), was prepared from 2-[(dimethylamino)methyl]-1-iodoferrocene via 2-[(dimethylamino)methyl]-1-acetoxyferrocene. On complexation, compound I served as a stable monovalent chelate ligand of a 1,2-disubstituted ferrocene derivative. In addition, a dihydroxy derivative, 2-(hydroxymethyl)-1-hydroxyferrocene, was obtained from hydrolysis of the methiodide formed from I.     

Electronic control of stereoselectivity. 20. Crystal and molecular structure of the ferrocene derived from tricyclo[5.2.1.02,6]Deca-2,5,8-triene

Reaction of the isodicyclopentadienide anion and its dehydro congener with Fe(II) leads to a stereochemically homogeneous ferrocene derivative in each instance. Through chemical correlation and X-ray analysis, above-plane complexation is established for both halves within the two sandwich compounds.     

Synthesis of ferrocene/hydrofullerene hybrid and functionalized bucky ferrocenes

Hydroferration reaction of [60]fullerene or its derivative with [Fe(C5H5)(CO)2]2 gives regioselectively a ferrocene/hydrofullerene hybrid, which upon treatment with Bu4NOH and an alkyl halide affords the corresponding alkylated bucky ferrocene, again regioselectivity via an anion of the ferrocene.     

Highly sensitive and selective dopamine biosensor based on a phenylethynyl ferrocene/graphene nanocomposite modified electrode

A new ferrocene derivative (1-[(4-amino) phenylethynyl]ferrocene, Fc-NH(2)) was synthesized for the first time. The ferrocene derivative molecule contained the phenylethynyl skeleton, ferrocene and amino groups with excellent electrochemical properties. The graphene/Fc-NH(2) nanocomposite was prepared by mixing graphene solution and Fc-NH(2) solution in one pot and the nanocomposite was utilized to construct a Nafion/graphene/Fc-NH(2) modified glassy carbon electrode (GCE). The ferrocene derivative immobilized on the graphene can enhance the charge-transport ability of the nanocomposite, stabilize the graphene and prevent the leakage of ferrocene. The detection signal of dopamine (DA) was significantly amplified on the Nafion/graphene/Fc-NH(2)/GCE. It was experimentally demonstrated that the signal enhancement results from the synergy amplification effect of graphene and the Fc-NH(2). The oxidation peak currents of DA were linearly related to the concentrations in the range of 5 × 10(-8) to 2 × 10(-4) M with the detection limit of 20 nM in the absence of uric acid (UA) and ascorbic acid (AA). In the presence of 10(-3) M AA and 10(-4) M UA, the linear response range was 1 × 10(-7) to 4 × 10(-4) M, and the detection limit was 50 nM at S/N = 3. Using the proposed Nafion/Fc-NH(2)/graphene/GCE, DA was successfully determined in real samples with the standard addition method.     

新型含二茂铁基螺苝嗪类光致变色化合物的合成及其光谱研究

合成了一种新的含二茂铁基螺 嗪类光致变色化合物 ,并研究了其吸收光谱和荧光光谱。发现在分子内引入二茂铁基团提高了热不可逆性 ,发生光致变色反应前后化合物结构的不同对其荧光特性影响很大     

A first one-pot synthesis, isomerization and synthetic utility of mono- and bis Morita-Baylis-Hillman adducts of 1,1′-ferrocenedialdehyde

A one-pot synthesis of mono- and bis-Morita-Baylis-Hillman adducts of 1,1′-ferrocenedialdehyde has been achieved. These adducts undergo a facile and efficient stereoselective isomerization with a number of saturated, unsaturated, aromatic alcohols, phenols and thiophenol with a montmorillonite K10 clay catalyst to afford highly functionalized trisubstituted alkene derivatives of ferrocene. The synthetic utility of isomerized derivatives has been demonstrated by a ferrocene appended novel macrocycle synthesis, a ferrocenyl bis-triazole synthesis and an evaluation of the liquid crystalline property of a cholesterol derivative of ferrocene.     

Preparation of zwitterionic electron acceptors and donors

The reactions of 4, 4'-bipyridine and nicotinamide with 1, 3-propane sultone yields zwitterionic electron acceptors. Reaction of dimethylaminoethyl ferrocene with 1, 3-propane sultone yields a zwitterionic ferrocene electron donor. The electron acceptors and donor are reduced and oxidized to the respective radical anions and ferrocenyl cation. Dipropyl-4, 4'-bipyridinium disulfonate and the ferrocene derivative quench the excited Ru(bipy)₃²⁺.     

Single-component and mixed ferrocene-terminated alkyl monolayers covalently bound to Si(111) surfaces

Self-assembled ferrocene monolayers covalently bound to monocrystalline Si(111) surfaces have been prepared from the attachment of an amine-substituted ferrocene derivative to a pre-assembled acid-terminated alkyl monolayer using carbodiimide coupling. This derivatization strategy yielded nanometer-scale clean, densely packed monolayers, with the ferrocene units being more than 20 A from the semiconductor surface. The amount of immobilized electroactive units could be varied in the range 2 x 10(-11) to approximately 3.5 x 10(-10) mol cm(-2) by diluting the ferrocene-terminated chains by inert n-decyl chains. The highest coverage obtained for the single-component monolayer corresponded to 0.25-0.27 bound ferrocene per surface silicon atom. The electrochemical characteristics of the mixed n-decyl/ferrocene-terminated monolayers were found to not depend significantly on the surface coverage of ferrocene units. The reversible one-electron wave of the ferrocene/ferrocenium couple was observed at E degrees ' = 0.50 +/- 0.01 V vs SCE, and the rate constant of electron transfer kapp was about 50 s(-1).     

One-electron oxidations of ferrocenes: A pulse radiolysis study

Using the pulse radiolysis technique we have studied the oxidation by various inorganic radicals of four water soluble ferrocene derivatives, hydroxyethyl, dimethylaminomethyl, monocarboxylic acid and dicarboxylic acid. We report the second order rate constants for these reactions, the stabilities and spectral properties of the ferrocinium products, and the electrochemically determined ferrocinium/ferrocene redox potentials. We also present preliminary estimates of tyrosine and tryptophan radical redox potentials obtained with the dicarboxylic acid ferrocene derivative as reference, and we discuss the relationship between redox potential differences and the reactivities of the ferrocenes with the inorganic radicals.     

Stereoselective synthesis of a chiral ferrosalen ligand using an aromatization strategy

A new chiral salen ligand based on two ferrocenyl groups is designed. Unlike known salen ligands, of which chirality originates from central and axial chiral centers, the chirality of this ligand comes from the planar chiral ferrocenyl groups. The ligand is synthesized stereoselectively using a novel aromatization strategy starting from a ferrocene derivative, which was readily prepared using a known chiral auxiliary approach.     

In situ Ellipsometric Study of Redox Induced Orientation of a Short Chained Ferrocenylalkylthiol Monolayer Self-Assembled on Gold

The structural modifications accompanying the redox switching of a short ferrocene derivative [(C₅H₅)Fe(C₅H₄)CO(CH₂)₅SH] monolayer self-assembled on gold are investigated using ellipsometry. Average values for the complex refractive index and thickness of the monolayer are estimated from ex situ and in situ experiments. The changes in the optical parameters are monitored during potential cycling and between two potential values, where the ferrocene is in its either reduced or oxidized form. The optical changes point to an increase of 1 to 2 Å in the monolayer thickness as the ferrocene is oxidized to the ferricinium cation. The thickness variation is in very good agreement with the rotation of the ferrocene rings towards a more perpendicular position relative to the electrode surface. The changes in orientation are reversible when the potential is cycled. However, instability of the monolayer is observed when the modified electrode is polarized for a few minutes at potentials where the monolayer is oxidized and then returned to the reduced form. This instability is associated with the ferrocene moiety, since a loss of electroactivity is simultaneously detected by cyclic voltammetry.