Fc Derivatives Research Articles

Ferrocene-functionalized magnetic core-shell nanoparticles based on hydrosilylation reaction for pH-responsive doxorubicin delivery system

This study describes the development of an innovative pH-sensitive drug delivery system (DDS) utilizing ferrocene (Fc) and magnetic nanoparticles (MNPs) for cancer therapy. One potential method for generating a diverse range of functional NPs involves attaching functional substances to MNPs. In this investigation, we display the successful modification of Fe3O4 NPs by an Fc derivative (4-Ferrocenylbutyl)dimethylsilane through a hydrosilylation reaction toward the synthesis of the Fe3O4@SiO2@VTES@Fc nanocarrier (NC). The doxorubicin (DOX) drug was loaded onto Fe3O4@SiO2@VTES@Fc NC with a drug loading capacity of about 80 % via π-π stacking interactions. Also, the prepared materials were thoroughly characterized using FT-IR, XRD, FE-SEM, EDX-MAP, VSM, DAPI, MTT, antioxidants, and CV techniques. In vitro studies on the release of DOX from Fe3O4@SiO2@VTES@Fc NC indicated a pH-responsive behavior with a lower release rate (< 10 %) at pH 7.4 compared to pH 5 (approximately 70 %) over a period of 96 h. Moreover, cytotoxicity assessments demonstrated notable cytotoxic effects of DOX-loaded Fe3O4@SiO2@VTES@Fc on MCF-7 cells (IC50 value: ∼8 µg/mL). The study findings suggest that the fabricated magnetic core-shell NC (Fe3O4@SiO2@VTES@Fc/DOX) exhibits stimulus-responsive behavior and holds promise as a sophisticated approach to specifically transport therapeutic agents into tumor sites while minimizing exposure to healthy tissues.

Ferrocene Derivatives for Photothermal Applications.

Ferrocene (Fc) and Fc derivatives have gained popularity in recent years due to their unique structure and characteristics. Among Fc's diverse performances, photothermal conversion, as a primary source of energy conversion, has sparked substantial study attention. This Review summaries Fc and Fc derivatives with photothermal characteristics, as well as their applications developed recently. First, methods for the synthesis of Fc-based materials are systematically discussed. Then, the photothermal conversion mechanism based on nonradiative relaxation is summarized. Furthermore, the most recent advances in Fc-based materials in photothermal applications are described, including photothermal degradation, photothermal antibacterial, photothermal therapies, photothermal catalysis, solar-driven water production, and photothermal CO2 separation. Finally, a summary and insights on the photothermal application of Fc-based materials are provided. This paper seeks to provide researchers with a better knowledge of photothermal behavior while also highlighting the potential of Fc and its derivatives in photothermal fields.

Density Functional Theory-Based Predictions and Experimental Evaluations of Ferrocene Derivatives Considered as Mediator for Anodic Catalysts of Glucose and Oxygen Enzymatic Biofuel Cells

The redox potential (ERedox) of a ferrocene (Fc) derivative differs, depending on its functional group. In this study, the various Fc derivatives are considered as mediators of anodic catalysts to promote glucose oxidation reaction (GOR) in glucose/oxygen enzymatic biofuel cells (EBFCs). Initially, their lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energies are calculated using density functional theory to predict their ERedox pattern. According to the calculations, the LUMO and HOMO energies of Fc derivatives combined with electron-donating groups (EDGs) are higher than those of Fc derivatives combined with electron-withdrawing groups (EWGs), including the results that Fc(NH2) has the highest molecular orbital (MO), while Fc(CHO) has the lowest. To verify the prediction for ERedox pattern, electrochemical evaluations are conducted. When glucose is provided, the onset potential (EOnset) of GOR is measured, while the ERedox of Fc derivatives and EOnset of GOR are linearly proportional to each other ( R 2 = 0.98 ) and DFT calculations. As the energies increase, the above two potentials are shifted more negatively. More specifically, the ERedox of Fc(NH2) and EOnset of GOR show the most negative values at (−0.112 and −0.17) V, respectively, while the ERedox of Fc(CHO) and EOnset of GOR show the most positive values at (0.496 and 0.40) V, respectively. Then, when this correlation is adopted for EBFCs, EBFCs using Fc(NH2) combined with EDG show 3.7 times higher maximum power density than those using Fc(COOH), as representatives combined with EWG. Based on that, it is well established how DFT and electrochemical evaluations should be used to design anodic catalysts including Fc derivatives as mediators for GOR.

Sandwich-type electrochemical immunosensing of hypopharyngeal carcinoma biomarker carcinoembryonic antigen based on N-doped hollow mesoporous nanocarbon spheres/gold hybrids as sensing platform and gold/ferrocene as signal amplifier

In the present work, a highly sensitive sandwich-type electrochemical immunosensor of carcinoembryonic antigen (CEA) was developed by preparing N-doped hollow mesoporous nanocarbon spheres/gold hybrids (NHMN/Au) hybridsas sensing platformand Au/ferrocene (Au/Fc) as signal amplifiers. The large surface area and high conductivity as well as good biocompatibility of NHMN/Au can increase the loading of primary antibody (Ab1) and accelerate the electron transport rate of the electrode surface, while Au can carry immobilized secondary antibodies (Ab2) and Fc derivative (Fc-SH).By using Fc-SH as response probe, the experiments show that the peak current of probe could increase after occurring the specific recognition of Ab1-CEA-Ab2, thus a novel sandwich-type immunosensor of CEA was developed. Finally, the proposed method for CEA detection was applied in human serum and the obtained results are satisfactory, indicating the developed method has important clinical applications for CEA determination.

Structure-activity-relationship study of semi-synthetically modified fusicoccins on their stabilization effect for 14-3-3-phospholigand interactions

The diterpene glucoside fusicoccin-A (FC-A) is a fungal phytotoxin that stabilizes the interaction of plant 14-3-3 protein and plasma membrane H+-ATPase by forming a stable ternary complex. Previous studies demonstrated that structurally modified FC-A derivatives exhibit significant antitumor activities but their synthesis involves an explosive reagent, limiting their utility and opportunities for further structure–activity-relationship studies. In this study, we synthesized a series of FC derivatives by introducing various substituents on the fusicoccan scaffold and on the glucoside moiety, and evaluated their stabilization effects on the binding of 14-3-3 to fluorescently labeled mode-1 and mode-3 phosphopeptides. The results showed that introducing an amino group at the 6′-position of the glucoside moiety improves stabilization. Furthermore, cell-based evaluation demonstrated that 6′-amino benzyl 21b exhibits higher antiproliferative activity than previously developed FC agents.

Redox Reactions of Isolated Ferrocene Derivatives Observed By Electrochemical Scanning Tunneling Microscope

Redox reactions on electrode surfaces have been widely applied to fundamental technologies such as energy conversion and storage, metal refining, and electronics. Recently, it has become clear that local structures at the single-atom and single-molecule level affect the efficiency and selectivity of redox reactions [1]. EC-STM, a combination of scanning tunneling microscopy (STM) and electrochemical (EC) measurements, allows direct observation of electrochemical interfaces with high spatial resolution [2], and we aimed to observe the redox reactions of single molecules using this technique. As a target molecule, ferrocene (Fc) was coupled to a tripodal base molecule [3], which was known to form an ordered self-assembled monolayer (SAM) on a gold electrode. By preparing mixed SAM with the molecules with and without Fc moieties, we could stably deposit Fc species on the Au (111) electrode in an isolated and dispersed state, which enables us to observe clear changes in the EC-STM images upon the redox reaction of the single Fc derivative. A mixture of 8,13-trimercaptotriptycene (Trip) and its Fc derivative (Fc-Trip) was deposited on an Au(111) electrode (the molecules were provided by the Fukushima Lab., Chemical Biology Laboratory, Tokyo Institute of Technology, and the Suzuki Lab., Graduate School of Science, Hokkaido University). Cyclic voltammetry (CV) was performed with a potentiostat (HZ-7000, Hokuto Denko) at a sweep rate of 100 mV/s in 0.1 M HClO4 solution. STM measurements were performed using an MS-10 STM (Bruker), controlled by a NanoScope V (Bruker). A Pt/Ir wire coated with Apiezon wax was used as a probe in the home-made electrochemical cell. The sample potential (Esample) was varied from 0.2 V (vs Ag/AgCl) to 0.4 V while the potential difference between the tip and the sample was kept at 0.3 V.The CV results are shown in Fig. 1 (a), where the peak originating from the redox reactions of Fc-Trip is observed (dotted line is only for Trip), indicating that the redox potential of Fc-Trip is ~0.3 V. Since the full width at half maximum of the peak is about 0.1 V, Fc-Trip do not interact with each other and are considered to be isolated and dispersed on the Au(111) electrode [4]. Corresponding EC-STM images are shown in Fig. 1 (c)-(e). While the bright spots derived from Fc-Trip are observed at Esample = 0.2 V (the tip potential Etip is 0.5 V), as indicated by white circles, the bright spots almost disappeared at Esample = 0.4 V (Etip = 0.7 V). We confirmed that the change of the height is reversible with respect to the applied potentials, as shown in Fig. 1(c) and 1(e). The height of the bright spot in the EC-STM image reflects the electron transfer rate through the redox molecule between the tip and the sample. When the sample potential is set to 0.2 V, Fc-Trip is formally in the reduced state, but the electrons are readily transferred to the tip regulated at 0.5 V. On the other hand, when the sample potential is set to settle the oxidized state (0.4 V), the molecule cannot pass electrons to the high potential tip. Therefore, in the case of Fig. 1(d), the current between the tip and the sample is not increased with the presence of the Fc moiety, leading to the apparent disappearance of spots. We noticed that some bright spots did not disappear at Esample = 0.4 V (an arrow in Fig. 1(d)), which suggests that there is heterogeneity in the redox reactivity. In the future, we plan to investigate the heterogeneity by combining spectroscopic techniques with the EC-STM measurement.[1] J. H. K. Pfisterer et al., Nature , 74, 549 (2017)[2] Y. Yokota et al., J. Phys. Chem. C, 111, 7561 (2007)[3] F. Ishiwari et al., J. Am. Chem. Soc., 141, 5995 (2019)[4] C. E. D. Chidsey et al., J. Am. Chem. Soc., 112, 4301 (1990) Figure 1

Competitive Self-Assembly Interaction between Ferrocenyl Units and Amino Acids for Entry into the Cavity of β-Cyclodextrin for Chiral Electroanalysis.

At present, chiral electroanalysis of nonelectroactive chiral compounds still remains a challenge because they cannot provide an electrochemical signal by themselves. Here, a strategy based on a competitive self-assembly interaction of a ferrocene (Fc) unit and the testing isomers entering into the cavity of β-cyclodextrin (β-CD) was carried out for chiral electroanalysis. First of all, the Fc derivative was directly bridged to silica microspheres, followed by inclusion into the cavity of β-CD. As expected, once it was modified onto the surface of a carbon working electrode as an electrochemical sensor, SiO2@Fc-CD-WE, its differential pulse voltammetry signal would markedly decrease compared with the uncovered Fc. Next, when l- and d-isomers of amino acids that included histidine, threonine, phenylalanine, and glutamic acid were examined using SiO2@Fc-CD-WE, it showed an enantioselective entry of amino acids into the cavity of β-cyclodextrin instead of Fc, resulting in the release of Fc with signal enhancement. For histidine, glutamic acid, and threonine, l-isomers showed a higher peak current response compared with d-isomers. The peak current ratios between l- and d-isomers were 2.88, 1.21, and 1.40, respectively. At the same time, the opposite phenomenon occurred for phenylalanine with a peak current ratio of 3.19 between d- and l-isomers. In summary, we are assured that the recognition strategy based on the supramolecular interaction can enlarge the detection range of chiral compounds by electrochemical analysis.

Ferrocene-modified dendrimers as support of copper nanoparticles: evaluation of the catalytic activity for the decomposition of ammonium perchlorate

Ferrocene (Fc)-based systems are frequently used as burning rate catalysts in the decomposition of ammonium perchlorate (AP)-based propellants. However, small Fc derivatives migrate to the surface of the propellant resulting in undesirable changes in the designed burning parameters and unstable combustion. To retard the migration and to increase the combustion rate of AP, fourth-generation polyamidoamine (PAMAM) dendrimers modified with Fc (PAMAM generation 4 [G4]-Fc) were synthetized and used as support for the obtention of copper nanoparticles (CuNPs). PAMAM G4 produced smaller nanoparticles (1–2 nm) with lower aggregation than PAMAM G4-Fc (12–14 nm). X-ray photoelectron spectroscopy (XPS) characterization confirmed the superior stabilizing and protecting effect against oxidation of CuNPs by PAMAM G4 in comparison to PAMAM G4-Fc, whereas molecular dynamics simulations have shown less flexibility and lower presence of stabilizing sites for nanoparticles in PAMAM G4-Fc. Antimigration tests confirmed the negligible migration of PAMAM G4-Fc compared with Fc, whereas PAMAM G4-Fc|CuNP affected the high-temperature decomposition of AP positively, decreasing the decomposition temperature in 87 °C owing to a synergistic effect between CuNPs and Fc. PAMAM G4-Fc can act both as an effective antimigration system of Fc and as a stabilizing framework of metal nanoparticles with application as catalysts of AP.

Highly Sensitive Electrochemical Immunosensing for Listeria Monocytogenes Based on 3,4,9,10-Perylene Tetracarboxylic Acid/Graphene Ribbons as a Sensing Platform and Ferrocene/Gold Nanoparticles as an Amplifier.

As a gram-positive foodborne pathogen, Listeria monocytogenes (LM) can cause many serious diseases to the human health coupled with high mortality rates; thus, constructing an effective method to detect LM is of great significance. Herein, a novel sandwich-type electrochemical immunosensor is proposed for LM by introducing 3,4,9,10-perylene tetracarboxylic acid/graphene ribbons (PTCA/GNR) nanohybrids as a sensing platform and ferrocene/gold nanoparticles (Fc/Au NPs) as a signal amplifier. The high conductivity and large surface area of GNR can increase the immobilizing amount of the primary antibody (PAb) and enhance the electron transport rate, while Au NPs can carry secondary antibodies (SAb) and Fc derivative (Fc-SH) to form a SAb-Au NPs-Fc signal amplifier. Through using Fc molecules as a signal probe, its peak current can appear and increase varied from the LM concentrations; hence, a highly sensitive sandwich-type immunosensor was constructed wide linear range from 10 to 2 × 104-CFU mL-1 and low limit of detection of low to 6 CFU mL-1. Furthermore, the specificity of the immunosensor was also studied and a satisfactory result was obtained.

Functioning Water-Insoluble Ferrocenes for Aqueous Organic Flow Battery via Host-Guest Inclusion.

Ferrocene (Fc) is one of the very limited organic catholyte options for aqueous organic flow batteries (AOFBs), a potential electrochemical energy storage solution to the intermittency of renewable electricity. Commercially available Fc derivatives are barely soluble in water, while existing methods for making water-soluble Fc derivatives by appending hydrophilic or charged moieties are tedious and time-consuming, with low yields. Here, a strategy was developed based on host-guest inclusion to acquire water-soluble Fc-based catholytes by simply mixing Fc derivatives with β-cyclodextrins (β-CDs) in water. Factors determining the stability and the electrochemical behavior of the inclusion complexes were identified. When adopted in a neutral pH AOFB, the origin of capacity loss was identified to be a chemical degradation caused by the nucleophilic attack on the center FeIII atom of the oxidized Fc derivatives. By limiting the state of charge, a low capacity fade rate of 0.0073 % h-1 (or 0.0020 % per cycle) was achieved. The proposed strategy may be extended to other families of electrochemically active water-insoluble organic compounds, bringing more electrolyte options for practical AOFB applications.

User-Customized, Multicolor, Transparent Electrochemical Displays Based on Oxidatively Tuned Electrochromic Ion Gels.

Transparent displays have emerged as a class of cutting-edge electronics. Here, we propose user-customized, design-it-yourself (DIY) transparent displays based on electrochromic (EC) ion gels including viologens. To achieve multiple colors and enhance the functionality of EC displays (ECDs), the incorporation of several EC chromophores is inevitable. However, the issue related to the discrepancy of coloration voltages is inherent due to the different electrochemical characteristics of each material, causing unbalance of the color contrast. To overcome this problem without significantly affecting the performance of ECDs, we suggest a simple but effective strategy by adjusting the oxidation activity of electrolyte-soluble anodic species (i.e., ferrocene (Fc) derivatives) by modifying pendant groups. We systematically investigated the effects of the employed Fc derivatives on the EC behaviors of ECDs in terms of the coloration voltage, maximum transmittance contrast, device dynamics, coloration efficiency, and operational stability. We determine the conditions for implementing red-green-blue (RGB) colors with comparable intensities at similar voltages. Last, we draw images using RGB EC inks for conceptual demonstration of the DIY transparent displays. The fabricated ECDs exhibit transparent bleached states and user-customized images in the colored states. Overall, this result implies that the extremely simple DIY ECDs, which do not require conventional lithography or printing, have great potential as future transparent displays that can be easily customized.

Redox-Guest-Induced Multimode Photoluminescence Switch for Sequential Logic Gates in a Photoactive Coordination Cage.

Molecular or supramolecular level photoluminescence (PL) modulation combining chemical and photonic input/output signals together in an integrated system can provide potential high-density data memorizing and process functions intended for miniaturized devices and machines. Herein, a PL-responsive supramolecular coordination cage has been demonstrated for complex interactions with redox-active guests. PL signals of the cage can be switched and modulated by adding or retracting Fc derivatives or converting TTF into different oxidation states through chemical or photochemical pathways. As a result, reversible or stepwise PL responses are displayed by these host-guest systems because of the occurrence of photoinduced electron-transfer (PET) or fluorescence resonance energy transfer (FREnT) processes, providing unique nanodevice models bearing off/on logic gates or memristor-like sequential memory and Boolean operation functions.

The observation of ion-pairing effect based on substituent effect of ferrocene derivatives

Abstract The ion-pairing effect was investigated based on the substituent effect of ferrocene (Fc) derivatives using cyclic voltammetry. It was shown that the presence of ion-pairing strongly affected the electrochemical redox behavior in the organic solvent. The formal redox potential ( E 0′ , the average of anodic and cathodic peak potential) shifted negatively with the increasing ion-pairing effect. That was because the formation of ion pair (Fc + ·ClO 4 − ) was beneficial to equilibrium shift from Fc to Fc + in thermodynamics. In this work, electron-donating and electron-withdrawing substituents of ferrocene derivatives were employed for a deep study of ion-pairing effect, respectively. It is confirmed that both ion-pairing effect and electron-donating substituent effect facilitated the negative shift of E 0′ for ferrocene derivatives, showing the positive cooperativity. While the electron-withdrawing substituent effect resulted in the positive shift of E 0′ for ferrocene derivatives and was unfavorable for the oxidation of Fc derivatives, reflecting the negative cooperativity with ion-pairing effect. In addition, the reversal phenomenon of weak electron-withdrawing substituent was revealed when the ion-pairing effect was stronger than the electron-withdrawing substituent effect, indicating that the ion-pairing function has a significant effect on electrochemical behavior of ferrocene derivatives.

Micropatterned ferrocenyl monolayers covalently bound to hydrogen-terminated silicon surfaces: effects of pattern size on the cyclic voltammetry and capacitance characteristics.

The effect of the size of patterns of micropatterned ferrocene (Fc)-functionalized, oxide-free n-type Si(111) surfaces was systematically investigated by electrochemical methods. Microcontact printing with amine-functionalized Fc derivatives was performed on a homogeneous acid fluoride-terminated alkenyl monolayer covalently bound to n-type H-terminated Si surfaces to give Fc patterns of different sizes (5 × 5, 10 × 10, and 20 × 20 μm(2)), followed by backfilling with n-butylamine. These Fc-micropatterned surfaces were characterized by static water contact angle measurements, ellipsometry, X-ray photoelectron spectroscopy (XPS), infrared reflection-absorption spectroscopy (IRRAS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The charge-transfer process between the Fc-micropatterned and underlying Si interface was subsequently studied by cyclic voltammetry and capacitance. By electrochemical studies, it is evident that the smallest electroactive ferrocenyl patterns (i.e., 5 × 5 μm(2) squares) show ideal surface electrochemistry, which is characterized by narrow, perfectly symmetric, and intense cyclic voltammetry and capacitance peaks. In this respect, strategies are briefly discussed to further improve the development of photoswitchable charge storage microcells using the produced redox-active monolayers.

Recent Progress in Ferrocene-Modified Thin Films and Nanoparticles for Biosensors.

This article reviews recent progress in the development of ferrocene (Fc)-modified thin films and nanoparticles in relation to their biosensor applications. Redox-active materials in enzyme biosensors commonly use Fc derivatives, which mediate electron transfer between the electrode and enzyme active site. Either voltammetric or amperometric signals originating from redox reactions of Fc are detected or modulated by the binding of analytes on the electrode. Fc-modified thin films have been prepared by a variety of protocols, including in situ polymerization, layer-by-layer (LbL) deposition, host-guest complexation and molecular recognitions. In situ polymerization provides a facile way to form Fc thin films, because the Fc polymers are directly deposited onto the electrode surface. LbL deposition, which can modulate the film thickness and Fc content, is suitable for preparing well-organized thin films. Other techniques, such as host-guest complexation and protein-based molecular recognition, are useful for preparing Fc thin films. Fc-modified Au nanoparticles have been widely used as redox-active materials to fabricate electrochemical biosensors. Fc derivatives are often attached to Au nanoparticles through a thiol-Au linkage. Nanoparticles consisting of inorganic porous materials, such as zeolites and iron oxide, and nanoparticle-based composite materials have also been used to prepare Fc-modified nanoparticles. To construct biosensors, Fc-modified nanoparticles are immobilized on the electrode surface together with enzymes.

A Simple Road for the Transformation of Few-Layer Graphene into MWNTs

We report the direct formation of multiwalled carbon nanotubes (MWNT) by ultrasonication of graphite in dimethylformamide (DMF) upon addition of ferrocene aldehyde (Fc-CHO). The tubular structures appear exclusively at the edges of graphene layers and contain Fe clusters. Fc in conjunction with benzyl aldehyde, or other Fc derivatives, does not induce formation of NT. Higher amounts of Fc-CHO added to the dispersion do not increase significantly MWNT formation. Increasing the temperature reduces the amount of formation of MWNTs and shows the key role of ultrasound-induced cavitation energy. It is concluded that Fc-CHO first reduces the concentration of radical reactive species that slice graphene into small moieties, localizes itself at the edges of graphene, templates the rolling up of a sheet to form a nanoscroll, where it remains trapped, and finally accepts and donates unpaired electron to the graphene edges and converts the less stable scroll into a MWNT. This new methodology matches the long held notion that CNTs are rolled up graphene layers. The proposed mechanism is general and will lead to control the production of carbon nanostructures by simple ultrasonication treatments.

Electron- and Hydride-Transfer Reactivity of an Isolable Manganese(V)−Oxo Complex

The electron-transfer and hydride-transfer properties of an isolated manganese(V)−oxo complex, (TBP8Cz)Mn(V)(O) (1) (TBP8Cz = octa-tert-butylphenylcorrolazinato) were determined by spectroscopic and kinetic methods. The manganese(V)−oxo complex 1 reacts rapidly with a series of ferrocene derivatives ([Fe(C5H4Me)2], [Fe(C5HMe4)2], and ([Fe(C5Me5)2] = Fc*) to give the direct formation of [(TBP8Cz)Mn(III)(OH)]− ([2-OH]−), a two-electron-reduced product. The stoichiometry of these electron-transfer reactions was found to be (Fc derivative)/1 = 2:1 by spectral titration. The rate constants of electron transfer from ferrocene derivatives to 1 at room temperature in benzonitrile were obtained, and the successful application of Marcus theory allowed for the determination of the reorganization energies (λ) of electron transfer. The λ values of electron transfer from the ferrocene derivatives to 1 are lower than those reported for a manganese(IV)−oxo porphyrin. The presumed one-electron-reduced intermediate, a Mn(IV) complex, was not observed during the reduction of 1. However, a Mn(IV) complex was successfully generated via one-electron oxidation of the Mn(III) precursor complex 2 to give [(TBP8Cz)Mn(IV)]+ (3). Complex 3 exhibits a characteristic absorption band at λ(max) = 722 nm and an EPR spectrum at 15 K with g(max)′ = 4.68, g(mid)′ = 3.28, and g(min)′ = 1.94, with well-resolved 55Mn hyperfine coupling, indicative of a d3 Mn(IV)S = 3/2 ground state. Although electron transfer from [Fe(C5H4Me)2] to 1 is endergonic (uphill), two-electron reduction of 1 is made possible in the presence of proton donors (e.g., CH3CO2H, CF3CH2OH, and CH3OH). In the case of CH3CO2H, saturation behavior for the rate constants of electron transfer (k(et)) versus acid concentration was observed, providing insight into the critical involvement of H+ in the mechanism of electron transfer. Complex 1 was also shown to be competent to oxidize a series of dihydronicotinamide adenine dinucleotide (NADH) analogues via formal hydride transfer to produce the corresponding NAD+ analogues and [2-OH]−. The logarithms of the observed second-order rate constants of hydride transfer (k(H)) from NADH analogues to 1 are linearly correlated with those of hydride transfer from the same series of NADH analogues to p-chloranil.

A General Synthetic Method for 1,1′-Bis(diacetylene-group)-Connected Ferrocene and π-Electronic System

Abstract In contrast to the facile synthon ethynylferrocene for diacetylene ferrocene (Fc) derivatives, 1,1′-diethynylferrocene for the corresponding 1,1′-bis(diacetylene-group)-connected Fc derivatives is extremely difficult to handle under ordinary conditions, giving rise to spontaneous self-polymerization. Under modified Eglinton oxidative coupling conditions, it has been possible to generate 1,1′-diethynylferrocene in situ readily from a trimethylsilyl-protected precursor and to react it with other terminal acetylenes. The present tandem reactions could provide a general synthetic method for an extended π-electronic conjugation system of 1,1′-bis(diacetylene-group)-connected Fc derivatives, of which the chemistry has been scarcely developed.

Oligo(FcDC-co-CholDEA) with Ferrocene in the Main Chain and Cholesterol as a Pendant Group—Preparation and Unusual Properties

With ever-increasing need for thin, flexible, and functional materials in electrochemical systems, various techniques have been explored for creating materials used in fuel cells, batteries, electrochromic devices, solar cells, and sensors. In the present study, a novel ferrocene (Fc) and cholesterol (Chol)-containing oligomer, oligo(FcDC-co-CholDEA), was specially designed and prepared by putting Fc in the main chain and Chol as a side group. MALDI-TOF MS and freezing point depression measurements revealed that in average each oligomer contains three Fc units and three Chol units. Cyclic voltammetric measurements revealed that the oligomer displays superior electrochemical stability if compared with other Fc derivatives containing only one Fc unit and one or two Chol unit and with poly(ferrocenylsilane) with Fc in the main chain. In particular, the Fc-containing oligomer possesses an unusual oxidation center, of which the oxidation potential could be as high as 1.81 V. The oligomer is also superior in self-assembly, as demonstrated by forming an LB film of layered structures. Furthermore, supramolecular films with high mechanical strength in the wet state can be prepared by employing a simple solution casting method. This finding demonstrates that self-assembly is a simple but effective way to create films of potential uses in real-life applications provided proper building blocks are designed and employed.

Recent Progress in the Synthesis and Applications of Some Ferrocene Derivatives and Ferrocene-Based Polymers

In the past decades, a lot of ferrocene (Fc) derivatives have been synthesized and used in many different applications. In addition, Fc-containing polymers have emerged, as an important class of the metal-containing polymers, with unique electrical, magnetic and optical properties and thus much considerable attention has been paid for the application of these polymer systems. These Fc-containing polymers have many different applications such as amperometric biosensors, immunosensors for proteins, DNA and hepatitis B surface antigen (HBsAg) and carbon monoxide sensors and also they can be used for the fabrication of optical logic gates. This paper reviews the recent progress in the synthetic methodologies, functionalization and the applications of Fc-based polymers as well as some Fc derivatives.