Ferrocene Groups Research Articles

Enhanced Electrochemical Detection of Nonelectroactive Compounds Based on Surface Supramolecular Interactions on Chevron-like Graphene Nanoribbons Modified through Click Chemistry.

In this study, we have developed a nanostructured electrochemical sensor based on modified graphene nanoribbons tailored for the analysis of nonelectroactive compounds via a surface competitive assay. Stigmasterol, a nonelectroactive phytosterol, was selected as a representative case. Chevron-like graphene nanoribbons, chemically synthesized, were immobilized onto glassy carbon electrodes and covalently functionalized to allow the on-surface formation of a supramolecular complex. To this end, the nanoribbons were first modified through a diazotization process by electrochemical reduction of a 4-azidoaniline diazonium salt, leaving the electrode surface with azide groups exposed to solution. Next, the incorporation of a ferrocene group, as a redox probe, was carried out by a click chemistry reaction between ethynylferrocene and these azide groups. Finally, the recognition event leads to the formation of a supramolecular complex between ferrocene and a macrocyclic receptor on the electrode surface. To this end, the receptors cucurbit[7]uril, cucurbit[8]uril, and β-cyclodextrin were evaluated, with the better results obtained with β-cyclodextrin. Atomic force microscopy and scanning electron microscopy measurements were performed for the morphological characterization of the resulting electrochemical platform surface. The ability of β-cyclodextrin to form an inclusion complex with ferrocene or with stigmasterol allows to perform a competitive assay, which translates into the decrease and recovery of the ferrocene electrochemical signal. For stigmasterol determination, a linear concentration range between 200 and 750 μM and a detection limit of 60 μM were obtained, with relative errors and relative standard deviations less than 7.1 and 9.8%, respectively.

CO2/N2 and redox dual-responsive organogels based on ferrocenemethanol and octadecylamine

Herein, we report a CO2/N2 and redox dual-responsive organogel using low molecular mass gelators (LMWGs) of octadecylamine (NC18) and ferrocenemethanol (FcOH). The organogels of NC18-FcOH in cyclohexane have a layered stacking structure and the critical gelling concentration (CGC) is 55 mmol/L. The organogel can be reversibly switched between gel and solution states by CO2 trigger, resulting from the reversible protonation of NC18. Moreover, the organogel can be destroyed by a redox reaction after adding Ce(NH4)2(NO3)6, originating from the oxidization of the ferrocene group in FcOH. Compared with other redox-responsive gelators, complex organic synthesis could be avoided since FcOH is a commercially available compound. The dual responsiveness of the organogel allows for the smart control of the “sol-gel” transition, which has potential applications in functional materials and sensors.

Stimuli‐Responsive Nanoplatforms: ZIF‐8‐Decorated Ferrocenyl Surfactant‐Based Vesicles for Synergistic Therapeutic Applications

AbstractOne of the most important issues in the design and preparation of drug delivery systems in the recent years is versatility which includes providing synergistic therapeutic effects and sustainability. This study uses a redox‐active ferrocenyl surfactant (FcN+(CH2CH3)3(CH2)10CH3, Fc(C11) where Fc is ferrocene) and pH responsive Zeolitic Imidazolate Framework‐8 (ZIF‐8) structures to form multifunctional assemblies (Fc(C11)‐AOT/Rhb@ZIF‐8/PDA) that can be used in several application including the drug delivery. The vesicles prepared using AOT‐FC(C11) constitute the core of the structure. Since the location of the ferrocene group in the molecule structure, which is next to head group, the surface of the vesicles is decorated with the ferrocene group which can act as a Fenton reaction catalyst. The polydopamine (PDA) covered ZIF‐8 are used to decorate the surface of the vesicles, creating a truly remarkable structure. The porous structure of ZIF‐8 as well as the core of the vesicles can accommodate drug molecules. With the added NIR‐responsive character upon PDA coating, this assembled structure can be used for phototermal therapy applications. The properties of this designed multifunctional and multi‐responsive system are studied at different pH and under NIR‐laser irradiation and show that it has potential to display a triple chemodynamic/ photothermal/ chemotherapeutic effect.

A new azine-based ferrocenophane for azo dyes degradation in dark–ambient conditions

In a novel approach, 1,1′-bis(2,3-diazabuta-l,3‑dien)ferrocenophane (Fc-azine) synthesized by self-condensation of 1,1′-Ferrocenedicarboxaldehyde hydrazone (FcDH) with the aid of Zn(OAc)2·2H2O or acetic acid at 120 °C under high pressure. Fc-azine as an insoluble compound was fully characterized by Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance spectroscopy (DRS), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller analyses (BET), powder x-ray diffraction (XRD) and single crystal x-ray diffraction. The narrow band gap (Eg = 1.93 eV) and the presence of ferrocene and azine functional groups encouraged us to use Fc-azine as an advanced oxidation process (AOP) catalyst. Interestingly, the addition of Fc-azine (1 g L-1) to aqueous solutions of 50 ppm of Congo red (CR) and 10 ppm of methyl orange (MO) led to the fast degradation of CR (over 80 % in 5 min) and the slow degradation of MO (98 % in 48 h) in the dark, without additional energy sources or chemical reagents. It was found that Fc-azine can degrade CR in six cycles with high efficiency (over 80 %). CR degradation by Fc-azine can be performed in acid and basic environments (pH= 3–9), and effective MO degradation happens in slightly acidic and natural environments (pH= 5–7). Possible adsorption, reactive oxygen species production (·OH, O2·−), and the mechanism of CR and MO degradation were also studied.

Well designed iridium-phosphinite complexes: Biological assays, electrochemical behavior and density functional theory calculations

Mononuclear phosphinite Iridium complexes based on ferrocene group have been prepared and characterized by various spectroscopic techniques. The complexes were subjected to cyclic voltammetry studies in order to determine the energies of HOMO and LUMO levels and to estimate their electrochemical and some electronic properties. Organic complex-based memory substrates were immobilized using TiO2-modified ITO electrodes, and the memory functions of phosphinite-based organic complexes were verified by chronoamperometry (CA) and open-circuit potential amperometry (OCPA). Extensive theoretical and experimental investigations were directed to gain a more profound understanding of the chemical descriptors and the diverse electronic transitions taking place within the iridium complexes, as well as their electrochemical characteristics. The quantum chemical calculations were carried out for the iridium complexes at the DFT/CAM-B3LYP level of theory in the gas phase. Furthermore, the antioxidant, antimicrobial, DNA binding, and DNA cleavage activities of the complexes were tested. Complex 2 exhibited the highest radical scavenging activity (67.5 ± 2.24 %) at 200.0 mg/L concentration. It was observed that the complexes formed an inhibition zone in the range of 8–15 mm against Gram + bacteria and in the range of 0–13 mm against Gram – bacteria. The agarose gel electrophoresis method was used to determine the DNA binding and DNA cleavage activities of the complexes. All of the tested complexes had DNA binding activity; however, complexes 1, 2, and 8 showed better binding activity than the others.

Tailored Porous Ferrocene-Based Metal-Organic Frameworks as High-Performance Proton Conductors.

Although crystalline metal-organic frameworks (MOFs) have gained a great deal of interest in the field of proton conduction in recent years, the low stability and poor proton conductivity (σ) of some MOFs have hindered their future applications. As a result, resolving the issues listed above must be prioritized. Due to their exceptional structural stability, MOFs with ferrocene groups that exhibit particular physical and chemical properties have drawn a lot of attention. This study describes the effective preparation of a set of three-dimensional ferrocene-based MOFs, MIL-53-FcDC-Al/Ga and CAU-43, containing both main group metals and 1,1'-ferrocene dicarboxylic acid (H2FcDC). Multiple measurements, including powder X-ray diffraction (PXRD), infrared (IR), and scanning electron microscopy (SEM), confirmed that the addition of ferrocene groups enhanced the thermal, water, and acid-base stabilities of the three MOFs. Consequently, their proton-conductive behaviors were meticulously measured utilizing the AC impedance approach, and their best proton conductivities are 5.20 × 10-3, 2.31 × 10-3, and 1.72 × 10-4 S/cm at 100 °C/98% relative humidity (RH), respectively. Excitingly, MIL-53-FcDC-Al/Ga demonstrated an extraordinarily ultrahigh σ of above 10-4 S·cm-1 under 30 °C/98% RH. Using data from structural analysis, PXRD, SEM, thermogravimetry (TG), and activation energy, their proton transport mechanisms were thoroughly examined. The fact that these MOFs are notably easy to assemble, inexpensive, toxin-free, and stable will increase the range of practical uses for them.

Ferrocene-Based Antioxidant Self-Healing Hydrogel via the Biginelli Reaction for Wound Healing.

The development of antioxidant wound dressings to remove excessive free radicals around wounds is essential for wound healing. In this study, we developed an efficient strategy to prepare antioxidant self-healing hydrogels as wound dressings by combining multicomponent reactions (MCRs) and postpolymerization modification. A polymer containing ferrocene and phenylboronic acid groups was developed via the Biginelli reaction, followed by efficient modification. This polymer is antioxidant due to its ferrocene moieties and can rapidly cross-link poly(vinyl alcohol) to realize an antioxidant self-healing hydrogel through dynamic borate ester linkages. This hydrogel has low cytotoxicity and is biocompatible. In in vivo experiments, this hydrogel is superior to existing clinical dressings in promoting wound healing. This study demonstrates the value of the Biginelli reaction in exploring biomaterials, potentially offering insights into the design of other multifunctional polymers and related materials using different MCRs.

Photooxidation driven formation of Fe-Au linked ferrocene-based single-molecule junctions

Metal-metal contacts, though not yet widely realized, may provide exciting opportunities to serve as tunable and functional interfaces in single-molecule devices. One of the simplest components which might facilitate such binding interactions is the ferrocene group. Notably, direct bonds between the ferrocene iron center and metals such as Pd or Co have been demonstrated in molecular complexes comprising coordinating ligands attached to the cyclopentadienyl rings. Here, we demonstrate that ferrocene-based single-molecule devices with Fe-Au interfacial contact geometries form at room temperature in the absence of supporting coordinating ligands. Applying a photoredox reaction, we propose that ferrocene only functions effectively as a contact group when oxidized, binding to gold through a formal Fe3+ center. This observation is further supported by a series of control measurements and density functional theory calculations. Our findings extend the scope of junction contact chemistries beyond those involving main group elements, lay the foundation for light switchable ferrocene-based single-molecule devices, and highlight new potential mechanistic function(s) of unsubstituted ferrocenium groups in synthetic processes.

Regio- and Stereoselective Iodoamination of Ferrocene-Containing Allenylphosphonates: Synthesis of Multifunctional Tetrasubstituted Allylic Amines and Allylic Azides.

A general and practical methodology for the regio- and stereoselective synthesis of multifunctional tetrasubstituted allylic amines and azides based on iodoamination of ferrocene-containing allenylphosphonates with anilines and sodium azide is described. A tetrasubstituted olefin moiety, as well as an iodine atom, a phosphonate, and a ferrocene group, are installed to the allylic amine motif simultaneously in moderate to good yields.

A ferrocene-based hydrogel as flexible electrochemical biosensor for oxidative stress detection and antioxidation treatment

Real-time sensing of reactive oxygen species (ROS) and timely scavenging of excessive ROS in physiological environments are critically important in the diagnosis and prevention of ROS-related diseases. To solve the mismatch problem between conventional rigid ROS biosensors and biological tissues in terms of both modulus and composition, here, we present a flexible ferrocene-based hydrogel biosensor designed for oxidative stress detection and antioxidation treatment. The hydrogel was fabricated through a supramolecular assembly of ferrocene-grafted polyethylenimine (PEI-Fc), sodium alginate (SA), and polyvinyl alcohol (PVA). Multiple non-covalent interactions, including electrostatic interactions between PEI-Fc and SA, hydrophobic interactions and π–π stacking among ferrocene groups, and the PVA crystalline domain, synergistically improve the mechanical properties of the PVA/SA/PEI-Fc hydrogel. The flexible PVA/SA/PEI-Fc hydrogel biosensor exhibited a broad detection range for hydrogen peroxide (H2O2), from 0 to 120 μM, using the differential pulse voltammetry method. Furthermore, the hydrogel demonstrated effective ROS scavenging and oxygen generation performance, desirable biocompatibility, and satisfactory antibacterial activity, making it suitable for biological interfaces. In vitro studies revealed that the PVA/SA/PEI-Fc hydrogel could monitor H2O2 concentration in the proximity of inflammatory cells, and effectively scavenge ROS to protect cells from oxidative stress damage. This all-in-one multifunctional hydrogel, integrating both sensing and treatment functions, holds great promise for clinical applications in the diagnosis and management of ROS-related diseases.

Ferrocene‐Terminated Perylene Diimide‐Based Small Molecular Electrolyte as Electron‐Transport Layer for Efficient Organic Solar Cells

The electron‐transport layer (ETL) is essential for achieving high performance and stability of organic solar cells (OSCs). However, most organic ETLs suffer from low conductivity, low electron mobility, and difficult modification, resulting in mitigation of charge collection and transport. Metal–organic complex, such as ferrocene, is a promising candidate to improve organic ETL due to their excellent film‐forming property, easy preparation, and high electrical properties. Herein, a small molecule, PDIN‐Fc, based on PDIN modified by ferrocene is designed, which can be synthesized by environmentally friendly esterification and quaternization reactions. PDIN‐Fc displays outstanding alcohol solubility and tunable work function. Interestingly, introducing the ferrocene group can lead to increased self‐doping of PDIN‐Fc. As a result, PDIN‐Fc shows significantly improved charge transport performance and conductivity compared to PDIN. When using PM6:L8‐BO as the photoactive layer, the OSCs with PDIN‐Fc as ETL achieve a remarkable power conversion efficiency of 18.45% and exhibit notable high light stability. This study demonstrates an effective strategy to design efficient ETLs by incorporating metal complexes, which enable thickness insensitivity, good stability, and high‐performance photovoltaic devices.

Electrochemically Controlled Release from a Thin Hydrogel Layer.

In this study, we present a thermoresponsive thin hydrogel layer based on poly(N-isopropylacrylamide), functionalized with β-cyclodextrin groups (p(NIPA-βCD)), as a novel electrochemically controlled release system. This thin hydrogel layer was synthesized and simultaneously attached to the surface of a Au quartz crystal microbalance (QCM) electrode using electrochemically induced free radical polymerization. The process was induced and monitored using cyclic voltammetry and a quartz crystal microbalance with dissipation monitoring (QCM-D), respectively. The properties of the thin layer were investigated by using QCM-D and scanning electron microscopy (SEM). The incorporation of β-cyclodextrin moieties within the polymer network allowed rhodamine B dye modified with ferrocene (RdFc), serving as a model metallodrug, to accumulate in the p(NIPA-βCD) layer through host-guest inclusion complex formation. The redox properties of the electroactive p(NIPA-βCD/RdFc) layer and the dissociation of the host-guest complex triggered by changes in the oxidation state of the ferrocene groups were investigated. It was found that oxidation of the ferrocene moieties led to the release of RdFc. It was crucial to achieve precise control over the release of RdFc by applying the appropriate electrochemical signal, specifically, by applying the appropriate potential to the electrode. Importantly, the electrochemically controlled RdFc release process was performed at a temperature similar to that of the human body and monitored using a spectrofluorimetric technique. The presented system appears to be particularly suitable for transdermal delivery and delivery from intrabody implants.

Metallodendrimers Unveiled: Investigating the Formation and Features of Double-Decker Silsesquioxane-Based Silylferrocene Dendrimers.

Dendrimers exhibiting reversible redox properties have attracted extensive attention for their potential as electron transfer mediators, catalysts, and molecular sensors. In this study, we introduce intriguing G1 and G2 dendrimers featuring double-decker silsesquioxane cores and silylferrocene moieties. Through a carefully orchestrated sequence of condensation, reduction, and hydrosilylation reactions, these compounds were synthesized and comprehensively characterized spectroscopically and spectrometrically. Our investigation also encompassed the examination of their properties, including thermal stability, solubility in common organic solvents, and electrochemical behavior. We determined that these dendrimers possess the capability to form monolayers on platinum electrodes, which we conclusively demonstrated through the probing of cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy imaging. Notably, this study marks the first-ever example of modifying double-decker silsesquioxane cores with ferrocene groups while simultaneously representing one of the scarce instances of dendrimers exhibiting an open double-decker silsesquioxane core.

Synthesis and properties of acyldiphenylphosphine oxides photoinitiators carrying ferrocene group for free radical photopolymerization

Thick film curing has become a research hotspot in photocuring systems, among which designing and synthesizing visible light initiators is particularly important. Herein, two new visible light initiators of (diphenylphosphoryl)(ferrocene-1-yl)methanone (FEPO) and ferrocene-1,1′-diylbis((diphenylphosphoryl)methanone) (FSPO) were designed and synthesized from diphenylphosphine oxide reacting with ferrocenecarboxaldehyde and 1,1′-ferrocenedicarboxaldehyde, respectively. FEPO and FSPO possess good solubility in different solvents and acrylic monomers. The UV-Vis spectrums of FEPO and FSPO showed that they exhibit a wide absorption range of 300–670 nm, and the maximum absorption wavelengths are about 494 nm and 505 nm, with a molar extinction coefficient of around 1226 M⁻¹cm⁻¹ and 299 M⁻¹cm⁻¹, suggesting that they are likely to be visible light photoinitiator (PI). The addition of N-phenylglycine (NPG) significantly improved the curing efficiency of FEPO and FSPO, the degree of double bond conversion (DC) of FSPO increased from 27 % to 48 % under the irradiation of LED@480 nm, while, under the irradiation of LED@405 nm, the DC of FEPO/NPG is about 52 %. Moreover, the curing depth of FEPO/NPG/trimethylolpropane triacrylate (TMPTA) (1.75 cm) was about 1.8 times that of diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO)/TMPTA (0.98 cm) after irradiating for 5 min. In addition, FEPO can be used in laser cladding deposition (LCD) 3D printers with light-emitting diode (LED)@405 nm. Using steady-state photolysis and electron spin resonance spin-trapping studies, the photocuring mechanism was examined. Additionally, photoinitiators (PIs) also exhibit superior biocompatibility performance demonstrated by cytotoxicity assays, suggesting they might be utilized in 3D printing in biological materials and coatings for food packaging.

Faradaic Rhenium Recovery with Polyvinyl Ferrocene (PVF) Electrodeposited Carbon Electrodes

Rhenium, a valuable rare element used in catalysts and superalloys, is difficult to recover in micromolar concentrations (Schulz, 2017). Electrodes coated with the redox active polymer poly vinyl ferrocene (PVF) have shown the ability to selectively adsorb several transition metal oxyanions, but limited adsorption capacity and longevity remain a challenge for these selective electrosorption technologies(Chen et al., 2021; Kim et al., 2020). In this study, we elucidate the impact of electrochemical deposition conditions on PVF coating as measured by capacitance, rhenium uptake, and longevity. PVF films were electrodeposited onto carbon substrate electrode at three different potentials across the oxidation window of the ferrocene-based metallopolymer to understand how the rate of charge transfer influences the resulting electrodeposited polymer coating. It was observed that PVF films electrodeposited at the peak oxidation current potential of 0.45 V (vs. Ag/AgCl) showed both the highest adsorption of Rhenium (458 ± 61 mg Re/g adsorbent) and capacitance (217 F/g). In comparison, the electrodeposition at 0.35 V and 0.6 V leads to a lower average capacitance 355.36 mg Re/g adsorbent and 342.03 mg Re/g adsorbent respectively. The enhanced performance for 0.45 V electro-deposited electrode can likely be attributed to a more stable deposition structure of the polymer (Pater et al., 1998), which enhances adhesion substrate and charge transfer between the substrate and the PVF. The 0.45 V electro-deposited PVF-carbon paper (PVF-CP) electrode illustrates high capacity and stability, indicating the benefits of polymer coating on selective adsorption of rhenium and prevention of electrode corrosive degradation in capacitive deionization systems. The excellent rhenium uptake and longevity demonstrates potential and will be the platform towards a full techno-economic analysis of the hybrid adsorption system in the future.Method Materials: Polyvinyl ferrocene (34801-99-5, produced by Polysciences, U.S.) and tetrabutylammonium perchlorate (1923-70-2, for electrochemical analysis, ≥99%, produced by Sigmar Aldrich Chemistry, U.S.) were used for electrodeposition. Carbon nanotubes (multiwalled, outer diameter of 7−12 nm, length of 0.5 - 10 μm, >99% carbon) were used as conductivity additives in dip coating electrode fabrication. Toray paper (carbon fiber composite carbon paper, produced by FuelCellStore) was used as the substrate for ferrocene polymer deposition under all conditions. Electrodeposition Electrodeposition performed on 2 cm x 1 cm rectangles of carbon paper substrate attached to copper wire with copper tape in a three-electrode cell configuration with a quasi-Ag/organic solution reference and CP counter electrode. 0.35 V, 0.45 V and 0.6 V were applied respectively to the working electrode in 2 mg/mL PVF solution until 0.12 C of charge had passed. Dip the electrodes into chloroform twice to rinse and stored the electrodes in the Milli-Q water. Cyclic Voltammetry (CV) CV test was performed in a three-electrode cell configuration with PVF deposited carbon paper as working electrode, platinum wire as counter electrode and Ag/AgCl reference. The voltage was swept between 0 V and 0.7 V in 0.5 M sodium perchlorate solution to capture characterize redox peak around 0.35 V. Rhenium Uptake The adsorption and desorption experiments were performed in the same three electrode cell but with a solution containing 1 mM NaReO4 or 10 mM NaCl, respectively. The voltage on working electrode maintained 0.8 V for adsorption and -0.8 V for desorption with stirring bar on the bottom stirring at 300 rpm for an hour.ResultsThe deposition happens when the positive charges transferred to the PVF that diffuse to the CP surface. The positive charged ferrocene groups combine with perchlorate, which decreases the solubility of PVF and leads to the deposition. According to the gravimetric mass measurement, the deposition mass range for 0.6 V, 0.45 V and 0.35 V are 0.1 – 0.25 mg, 0.2 – 0.35 mg and 0.4 – 0.55 mg, respectively. Comparing with theoretical deposition mass (0.26 mg, calculated from the total charge transfer), higher transition current and shorter deposition time promote a more sufficient charge transfer and a more localized deposition on the electrode interface. The CV plot (Figure 1(a)) elucidates the prominent specific capacitance for 0.45 V deposited electrode (216.50 F/g on average) and an obvious oxidize peak positive movement for 0.35 V deposition, which is corresponding to a higher deposited mass (0.4-0.55 mg) that may lead to a higher resistance. The mass normalized Re uptake reaches 457.87 mg Re/g polymer with a regeneration rate of 64.47%. For next step, the longevity test will be performed to obtain a further understanding to the depletion of regeneration rate along the increase of cycle number.

A highly sensitive and robust electrochemical biosensor for microRNA detection based on PNA-DNA hetero-three-way junction formation and target-recycling catalytic hairpin assembly amplification

Robust and sensitive methods for the detection of microRNAs (miRNAs) are crucial in the clinical diagnosis of cancers. In this study, a novel electrochemical biosensor with high sensitivity for miRNA-21 detection is developed, which relies on the formation of a peptide nucleic acid (PNA)-DNA hetero-three-way junction (H3WJ) and target-recycling catalytic hairpin assembly (CHA) amplification. The electroneutral PNA probes are initially immobilized onto a gold electrode to construct the sensor. Upon introduction of miRNA-21, target-recycling CHA is initiated, resulting in abundant double-stranded CHA products. Subsequently, association between the PNA probes and these products leads to the formation of PNA-DNA H3WJs. Consequently, the electrode surface is densely populated with numerous electroactive Ferrocene (Fc) groups, resulting in a significantly amplified current response for highly sensitive detection of miRNA-21 at concentrations as low as 0.15 fM. This approach demonstrates remarkable specificity towards target miRNAs and can be utilized for quantitative monitoring of miRNA-21 expression in human cancer cells. More importantly, the sensor exhibits exceptional stability and shows a significant reduction in background noise during miRNA detection, making this method a highly promising sensing platform for monitoring various miRNA biomarkers to facilitate the diagnosis of diverse cancers.

Signal-on electrogenerated chemiluminescence detection of gonyautoxin 1/4 based on proximity ligation-induced an electrode-bound pseudoknot DNA

A “signal on” electrogenerated chemiluminescence (electrochemiluminescence, ECL) aptasensor based on proximity ligation-induced an electrode-bound pseudoknot DNA for sensitive detection of gonyautoxin 1/4 (GTX1/4) was developed on basis of the competitive type reaction mode. Aptamer was adopted as recognition element. Ru(bpy)32+ as ECL signal, was attached on the glassy carbon electrode (GCE) surface modified with nafion and gold nanoparticles (AuNPs) by electrostatic attraction to obtain the ECL platform. The pseudoknot DNA as capture probe, was immobilized onto the ECL platform via Au–S bond to obtain the ECL aptasensor. In the absence of GTX1/4, Y-shape proximate cooperative complex among aptamer, pseudoknot DNA and DNA1 was formed, drawing the ferrocene groups Fc, as ECL quencher) of both pseudoknot DNA and DNA1 near the electrode surface and resulting in low ECL signal. In the presence of GTX1/4, GTX1/4 competed with pseudoknot DNA and DNA1 for aptamer in homogeneous solution, preventing the formation of proximate cooperative complex and keeping the capture DNA in the pseudoknot conformation with Fc groups far away from the electrode surface, generating a high ECL signal. The recovery of ECL intensity increased with the GTX1/4 concentration and allowed the detection of GTX1/4 in the range of 0.01 ng/mL to 10 ng/mL with a detection of limit as low as 6.56 pg/mL. Additionally, the accuracy of this method was validated for analysis of spiked sea water samples with good recoveries, which indicates great potential in commercial application.

Oxidized dextran-crosslinked ferrocene-chitosan-PEI composite porous material integrating adsorption and degradation to malachite green

Treating wastewater containing malachite green (MG) using porous materials with both adsorption and degradation functions have become a major challenge in achieving the carbon neutrality goal. Herein by incorporating the ferrocene (Fc) group as a Fenton active center, a novel composite porous material (DFc-CS-PEI) was prepared using chitosan (CS) and polyethyleneimine (PEI) as skeletons and oxidized dextran as a crosslinker. DFc-CS-PEI not only possesses satisfactory adsorption performance to MG but also excellent degradability in the presence of a minor amount of H2O2 (3.5 mmol/L) without any additional assistance, due to high specific surface area and active Fc group. The maximum adsorption capacity is ca. 177.73 ± 3.11 mg/g, outperforming most CS-based adsorbents. The removal efficiency of MG is significantly enhanced from 20 % to 90 % as DFc-CS-PEI and H2O2 coexist, due to ·OH-dominated Fenton reaction, and remained in a wide pH range (2.0–7.0). Cl− exhibits notable suppression on the degradation of MG because of quenching effects. Note that DFc-CS-PEI has a very small iron leaching (0.2 ± 0.015 mg/L), and can be rapidly recycled by simple water-washing, without any harmful chemicals and potential second pollution. Such versatility, high stability, and green recyclability make the as-prepared DFc-CS-PEI a promising porous material for the treatment of organic wastewater.

Linear and macrocyclic oligo(p-phenylene iminoboranes) with ferrocenyl side groups - observation of selective, non-templated macrocyclization.

A series of linear oligo(p-phenylene iminoboranes), which are BN-modified congeners of oligo(p-phenylene vinylenes), featuring pendent ferrocene groups have been prepared. Stoichiometric reaction of a bis-silylamine with a bisborane led to selective formation of an unprecedented macrocycle, without the use of a template.

Charge Density Overcomes Steric Hindrance of Ferrocene Surfactant in Switchable Oil-in-Dispersion Emulsions.

A ferrocene surfactant can be switched between single and double head form (FcN+ C12 /Fc+ N+ C12 ) triggered by redox reaction. FcN+ C12 can neither stabilize an O/W emulsion alone nor an oil-in-dispersion emulsion in combination with alumina nanoparticles due to the steric hindrance of the ferrocene group. However, such steric hindrance can be overcome by increasing the charge density in Fc+ N+ C12 , so that oil-in-dispersion emulsions can be co-stabilized by Fc+ N+ C12 and alumina nanoparticles at very low concentrations (1×10-7 M (≈50 ppb) and 0.001 wt %, respectively). Not only can reversible formation/destabilization of oil-in-dispersion emulsions be achieved by redox reaction, but also reversible transformation between oil-in-dispersion emulsions and Pickering emulsions can be obtained through reversing the charge of alumina particles by adjusting the pH. The results provide a new protocol for the design of surfactants for stabilization of smart oil-in-dispersion emulsions.