Ferrocenedicarboxylic Acid Research Articles

Defect Engineered Metal–Organic Framework with Accelerated Structural Transformation for Efficient Oxygen Evolution Reaction

AbstractMetal–organic frameworks (MOFs) have been increasingly applied in oxygen evolution reaction (OER), and the surface of MOFs usually undergoes structural transformation to form metal oxyhydroxides to serve as catalytically active sites. However, the controllable regulation of the reconstruction process of MOFs remains as a great challenge. Here we report a defect engineering strategy to facilitate the structural transformation of MOFs to metal oxyhydroxides during OER with enhanced activity. Defective MOFs (denoted as NiFc′xFc1‐x) with abundant unsaturated metal sites are constructed by mixing ligands of 1,1′‐ferrocene dicarboxylic acid (Fc′) and defective ferrocene carboxylic acid (Fc). NiFc′xFc1‐x series are more prone to be transformed to metal oxyhydroxides compared with the non‐defective MOFs (NiFc′). Moreover, the as‐formed metal oxyhydroxides derived from defective MOFs contain more oxygen vacancies. NiFc′Fc grown on nickel foam exhibits excellent OER catalytic activity with an overpotential of 213 mV at the current density of 100 mA cm−2, superior to that of undefective NiFc′. Experimental results and theoretical calculations suggest that the abundant oxygen vacancies in the derived metal oxyhydroxides facilitate the adsorption of oxygen‐containing intermediates on active centers, thus significantly improving the OER activity.

Defect Engineered Metal-Organic Framework with Accelerated Structural Transformation for Efficient Oxygen Evolution Reaction.

Metal-organic frameworks (MOFs) have been increasingly applied in oxygen evolution reaction (OER), and the surface of MOFs usually undergoes structural transformation to form metal oxyhydroxides to serve as catalytically active sites. However, the controllable regulation of the reconstruction process of MOFs remains as a great challenge. Here we report a defect engineering strategy to facilitate the structural transformation of MOFs to metal oxyhydroxides during OER with enhanced activity. Defective MOFs (denoted as NiFc'x Fc1-x ) with abundant unsaturated metal sites are constructed by mixing ligands of 1,1'-ferrocene dicarboxylic acid (Fc') and defective ferrocene carboxylic acid (Fc). NiFc'x Fc1-x series are more prone to be transformed to metal oxyhydroxides compared with the non-defective MOFs (NiFc'). Moreover, the as-formed metal oxyhydroxides derived from defective MOFs contain more oxygen vacancies. NiFc'Fc grown on nickel foam exhibits excellent OER catalytic activity with an overpotential of 213 mV at the current density of 100 mA cm-2 , superior to that of undefective NiFc'. Experimental results and theoretical calculations suggest that the abundant oxygen vacancies in the derived metal oxyhydroxides facilitate the adsorption of oxygen-containing intermediates on active centers, thus significantly improving the OER activity.

Activation of ferrocene-based coordination compounds for oxygen evolution and the application in zinc-air battery

Rational reconstruction of oxygen evolution reaction (OER) pre-catalysts and the performance index is crucial but still challenging. Herein, a coordination compound composed by ferrocenedicarboxylic acid and Co2+ was prepared, which was then treated by NaBH4 solution for the rational reconstruction. The electrochemical activation of the treated product results in the generation of oxyhydroxides with unique microstructure acting as the catalytic active phase, which exhibits excellent electrocatalytic activity with a low overpotential of 256 mV for 10 mA cm−2 towards OER and a half-wave potential of 0.69 V (vs RHE) for oxygen reduction (ORR). Ru species was then loaded on the treated product to further improve the catalytic activity for oxygen reduction. The annealed product (Ru-CoFe/C) presents a core-shell structure with carbon layer on the surface. The product presents an increased half-wave potential of 0.744 V (vs RHE) for ORR with the OER/ORR overpotential gap of 0.776 V for 10 and 1 mA cm−2, respectively, showing the bifunctional catalytic activity. Ru species with small size improves the catalytic activity for ORR; the carbon shell provides the high stability. A Zn-air battery was then fabricated with the Ru-CoFe/C catalyst, which delivers a high power density of 88 mW cm−2 and a large specific capacity of 709 mAh g−1, as well as an excellent cycling stability over 65 h, surpassing commercial Pt/C + RuO2 based counterpart, demonstrating its feasibility in the field of renewable electronic devices. This work affords valuable guidelines for the application of ferrocene-based materials in OER and for the exploring of advanced bifunctional ORR/OER catalysts in rational construction of high-quality Zn-air batteries.

The long-distance charge transfer process in ferrocene-based MOFs with FeO6 clusters boosts photocatalytic CO2 chemical fixation

Metal nodes and organic ligands are important structural units of MOFs, and their properties can profoundly affect the photocatalytic activity. Herein, two ferrocene-based MOFs with FeO6 or AlO6 clusters as the metal nodes and 1,1′-ferrocenedicarboxylic acid (H2FcDC) as the ligands were successfully synthesized. Comparing with normal organic ligands, ferrocene ligands have longer-lived photogenerated charges due to metal-to-ligand charge transfer (MLCT) process, leading to a better photocatalytic activity of the corresponding ferrocene-based MOFs. In addition, the FeO6 clusters are able to further accept the photogenerated electrons from ferrocene ligands compared to the inert AlO6 clusters, allowing a long-distance charge transfer process, namely the proposed metal-to-ligand-to-metal charge transfer (MLMCT) process, which results in a better performance towards photocatalytic CO2 cycloaddition reaction. This work sheds a light on designing MOFs using ferrocene ligands with high photocatalytic activity.

Multiple stimuli-switchable electrocatalysis and logic gates of l-cysteine based on P(DEA–co-VPBA) hydrogel films

In this work, poly(N',N-diethylacrylamide-co-4-vinylphenylboronic acid) (P(DEA-co-VPBA)) hydrogel films were successfully assembled on the pyrolytic graphite (PG) electrode by a simple radical polymerization. Reversible thermal, glucose and pH-triggered electrochemical reactions were obtained in the presence of 1,1′-ferrocene dicarboxylic acid (FDA) with electro-redox properties. The thermal response performances of the thin-film electrode were attributed to the PDEA component, the sensitive behaviors of glucose were ascribed to the VPBA component, and the sensitive behaviors of pH were affected by PDEA and VPBA. The electrocatalytic oxidation of l-cysteine by FDA on the hydrogel film electrodes significantly enhanced the difference between the on and off states of the multi-response cyclic voltammetry (CV) signals. This smart polymer hydrogel film electrode with amplified signals could be further used to realize a 4-input/9-output binary logic circuit, which was constructed with temperature, glucose, pH, and cysteine as inputs and different levels of Ipa and Ipc responses as outputs. Furthermore, a 2-to-4 decoder, a 4-to-2 encoder, and a 4-input keypad lock were built on the same platform. This polymer electrocatalysis system provides a novel idea for constructing complex biological computing systems.

A Facile Sensor for Detection of Lysozyme in Egg White Based on AuNPs and Ferrocene Dicarboxylic Acid

Lysozyme (Lyz) is found in animal and human bodily fluids, and is frequently utilized as a biomarker for various diseases. Even trace amounts of Lyz in food can potentially trigger adverse immune system reactions in sensitive individuals. Therefore, it is very important to monitor Lyz concentration in foods for safety. In this study, a simple and convenient electrochemical sensor for Lyz detection was prepared by modifying gold nanoparticles (AuNPs) and ferrocene dicarboxylic acid (Fc(COOH)2) on a glass carbon electrode (GCE), which was characterized fully by various electrochemical methods and field emission scanning electron microscope (FESEM). The proposed method utilized Fc(COOH)2 as a probe and AuNPs as an electron transfer medium to improve the sensor’s current response performance. Under optimal conditions, the sensor was used to detect Lyz with a linear range from 0.10~0.70 mmol·L−1 with a sensitivity of 50.55 μA·mM−1·cm−2, and a limit of detection (LOD) of 0.07 mmol·L−1. In the standard addition experiment of food samples (egg white), a total R.S.D. of less than 6.75% and an average recovery between 95.45% and 102.62% were obtained.

Реакции пентафенил- и пента(пара-толил)сурьмы с ферроцендикарбоновой кислотой

In reactions of pentaphenyl- and penta(para-tolyl)antimony with ferrocene dicarboxylic acid (molar ratios 1:1 and 2:1) in toluene (20 С, 24 h), hydrogen in one or two carboxylate groups is replaced with formation of tetraarylantimony ferrocene carboxylates HOOС5H4FeС5H4C(O)OSbPh4 (1), HOOС5H4FeС5H4C(O)OSbTol4 (2), Ph4SbC(O)OC5H4FeС5H4C(O)OSbPh4 (3) and p-Tol4SbC(O)OC5H4FeС5H4C(O)OSbTol4 (4), yielding up to 83 %. Compounds 1–4 have been identified by elemental analysis, IR spectroscopy, and X-ray diffraction analysis for 4. X-ray diffraction analysis of complex 4 has been performed on a D8 Quest Bruker automatic four-circle diffractometer (Mo Kα radiation, λ = 0.71073 Å, graphite monochromator ) at 293 K. Crystallographic characteristics of compound 4: monoclinic system, space group P21/c, a = 17.227(17), b = 11.064(9), c = 30.59(3) Å, β = 100.00(4) deg., V = 5742(9) Å3, Z = 4, calc = 1.440 g/cm3, 2 6.02-49.08 deg., total reflections 124343, independent reflections 9436, number of refined parameters 684, Rint = 0.1051, GOOF 1.094, R1 = 0.0536, wR2 = 0.1309, residual electron density (max/min) 0.88/1.21 e/Å3. According to the X-ray diffraction analysis data, in crystal 4 coordination of the antimony atoms is distorted octahedral due to the fact that the carboxylate ligand is a bidentate chelating ligand. The diagonal angles in the two octahedra are 146.4(2), 154.0(3), 171.0(2) and 147.4(2), 154.8(2), 166.9(2). The SbO distances are 2.296(5), 2.502(5) Å and 2.289(5), 2.453(5) Å, the SbC bonds are significantly different (2.146(7)2.166(7) and 2.123(6)2.165(7) Å). The structural organization of the crystal is mainly due to the interactions of the СН•••-type.

A fluorescent turn on/off probe for glucose detection based on a boronic acid-capped 1,1′-ferrocenedicarboxylic acid functional graphene oxide

The accurate determination of glucose in the human body is highly desired because excessive ingestion of glucose may lead to obesity, diabetes and other diseases. This work demonstrates a fluorescent probe for sugar detection using the unique affinity of boronates for cis -diols. The fluorescent sensing system is composed of two components: 1) Aminated graphene oxide (GON) decorated with phenylboronic acid (BPA) and 1,1'-ferrocenedicarboxylic acid (FCA) as a fluorescence quencher (FCA–GON–BPA); and 2) fluorophores of a cis -diol modified tetraphenylethylene derivative (TPBD) with aggregation-induced emission (AIE) characteristics as the luminescence. FCA–GON–BPA can selectively bind cis -diol-containing fluorogens, such as TPBD, resulting in fluorescence quenching of the probe system. Upon addition of glucose, a new cyclic boronate ester is formed, resulting in the cis -diol-containing fluorogen dissociating from the quenched system, and TPBD fluorescence is recovered. The probe has an obvious response to the presence of glucose and a low limit of detection (LOD, 4.36 mg/mL). • The fluorophore has the characteristics of aggregation-induced emission. • The reaction platform is graphene oxide with high adsorption surface area. • Glucose preempts binding of fluorophore and quencher to release fluorescence.

New Ferrocene-Based Metalloligand with Two Triazole Carboxamide Pendant Arms and Its Iron(II) Complex: Synthesis, Crystal Structure, 57Fe Mössbauer Spectroscopy, Magnetic Properties and Theoretical Calculations

The new ferrocene-based metalloligand bis (N-4-[3,5-di-(2-pyridyl)-1,2,4-triazoyl])ferrocene carboxamide (L) was prepared through derivatization of 1,1′-ferrocenedicarboxylic acid with 4-amino-3,5-di(pyridyl)-4H-1,2,4-triazole. The composition and purity of L in the solid state was determined with elemental analysis, FT-IR spectroscopy, and its crystal structure with single-crystal X-ray analysis, which revealed that the substituted cyclopentadienyl rings adopt the antiperiplanar conformation and the crystal structure of L is stabilized by O–H···N and N–H···O hydrogen bonds. The molecular properties of L in solution were investigated with NMR and UV-VIS spectroscopies, and cyclic voltammetry disclosed irreversible redox behavior providing one oxidation peak at E1/2 = 1.133 V vs. SHE. Furthermore, the polymeric FeII complex {Fe(L)(C(CN)3)2}n (1) was prepared and characterized with elemental analysis, FT-IR spectroscopy, 57Fe Mössbauer spectroscopy, and magnetic measurements. The last two methods confirmed that a mixture of low- and high-spin species is present in 1; however, the spin crossover properties were absent. The presented study was also supported by theoretical calculations at the DFT/TD-DFT level of theory using TPSS and TPSSh functionals.

Investigation on pH and redox-trigged emulsions stabilized by ferrocenyl surfactants in combination with Al2O3 nanoparticles and their application for enhanced oil recovery

Pickering emulsions are regarded as promising chemical flooding agents to control profile in enhanced oil recovery (EOR). Stimuli responsive Pickering emulsions are introduced to simplify the process of subsequent demulsification. In the present work, we construct pH and redox-triggered emulsions stabilized by oxidized 1,1′-ferrocenedicarboxylic acid-(N,N-dimethyldodecylamine)2 (FDA-(DMDA)2-Ox) and Al2O3 nanoparticles. Stable emulsions with low water separation rate (18.5 %) after 12-day storage can be obtained by combining a low concentration of FDA-(DMDA)2-Ox (< 0.07 wt%) and Al2O3 nanoparticles. The emulsions can undergo the conversion of emulsion type (from oil-in-dispersion emulsions to oil-in-water Pickering emulsions) triggered by pH (surface charge switchability of Al2O3 nanoparticles) and emulsification/demulsification switchable behaviors triggered by redox reaction (redox response of FDA-(DMDA)2-Ox). The switch mechanism is revealed via the measurements of optical micrographs, zeta potential, cyclic voltammetry curves, and interfacial tension. Micromodel tests display that both oil-in-dispersion emulsions and oil-in-water Pickering emulsions can improve the displacement efficiency and enhance the sweep efficiency respectively to greatly enhance oil recovery. The pH and redox responsive flooding fluid display promising adaptability to complicated reservoir conditions and convenient implement for subsequent demulsification, transportation and refining

Sheet-like units of ferrocene-based coordination compounds for oxygen evolution

Metal-organic frameworks represent an emerging class of effective pre-electrocatalysts with low cost and high activity for oxygen evolution, which is a critical process involved in water splitting and metal-air batteries. In this study, a new electrode with ferrocene-based coordination compounds supported by nickel foam was designed and prepared, in which the coordination compounds are assembled by cobalt chloride and 1, 1'-ferrocenedicarboxylic acid. The as-obtained pre-catalytic electrode shows remarkable electrocatalytic activity and stability towards oxygen evolution. In 1 M KOH, the electrode can provide a current density of 50 mA cm−2 at an overpotential of 268 mV with Tafel slope of 109 mV dec−1. During the catalytic process, the metal-organic framework surface shows an obvious phase evolution behavior. The synergetic effect between Co and Fe sites, and the unique microstructure of the in situ derived active species are believed to be responsible for the excellent electrocatalytic performance. The catalytic electrode was also investigated as a cathode in a Zn-air battery, which presents an energy density of 572 mW h gZn−1, a peak power density of 60 mW cm−2, and an excellent cyclability of over 50 h. This work presents a new type pre-catalytic electrode for oxygen evolution and would provide some hints for the development of advanced catalytic electrodes.

Investigation on novel redox-responsive ferrocenyl surfactants with reversible interfacial behavior and their recycling application for enhanced oil recovery

Stimuli responsive surfactants with reversible properties may effectively solve the problems of traditional surfactants (the switching of interfacial activity and the demulsification difficulty of emulsions) in enhanced oil recovery (EOR). In the present study, we fabricate brand-new redox-responsive double-tailed ferrocenyl surfactants 1,1′-ferrocenedicarboxylic acid-(N,N-dimethyldodecylamine)2 (FDA-(DMDA)2) via the dynamic supramolecular assembly. The reversible redox-responsive interfacial behaviors of ferrocenyl surfactants are estimated by measuring the interfacial tension reduction capacity, emulsifying performance, and wettability reversal ability. Compared with oxidized single-tailed ferrocenyl surfactant (FA-DMDA-Ox), oxidized double-tailed ferrocenyl surfactant (FDA-(DMDA)2-Ox) displays higher interfacial activity, which can be accurately switched by redox trigger. Cyclic micromodel flooding tests show that the FDA-(DMDA)2-Ox can in-situ emulsify the kerosene in pore media, and the addition of Na2SO3 to the produced fluid can achieve the recycle of the surfactants. Oil displacement tests demonstrate that the developed double-tailed ferrocenyl surfactants possess the potential in EOR and recycling.

PH-responsive Mannose-modified ferrocene Metal-Organic frameworks with rare earth for Tumor-targeted synchronous Chemo/Chemodynamic therapy

The combination of chemodynamic therapy (CDT) and chemotherapy is a promising strategy to achieve enhanced anticancer effects. Metal-organic frameworks (MOFs), as multifunctional drug delivery vehicles, have received extensive attention in the biomedical field. Carbohydrate has excellent biocompatibility and targeting ability, which can be used as a targeting ligand due to a specific recognition with glycoprotein receptors that overexpress on cancer cell membranes. Herein, the pH-responsive mannose-modified ferrocene MOFs with rare earth metal were synthesized via coordination-driven self-assembly of 1,1′-Ferrocenedicarboxylic acid and ytterbium chloride. Subsequently, DOX@Fc-MOFs-Mann nanoparticles (NPs) were obtained by loading doxorubicin (DOX) and modifying mannose (Mann), where DOX@Fc-MOFs-Mann NPs were able to precisely target HepG2 cells via mannose receptor and slowly decompose in the acidic environment of tumor to release ferrocene, DOX, and Yb3+. Fe2+ in ferrocene effectively activated Fenton reaction to produce high levels of reactive oxygen species (ROS) for irreversible induction of cell apoptosis or necroptosis. Combined with the chemotherapy (CT) ability of DOX, Yb3+ further induced cell death through its own toxicity to successfully achieved the rare earth metal synergistic CDT and CT combination therapy. This synergistic CDT and CT strategy not only opens up new horizons for rare earth metals in biomedical applications but also provides new inspiration into the construction of glycosyl-modified MOFs.

Glucose Oxidase Integrated Porphyrinic Covalent Organic Polymers for Combined Photodynamic/Chemodynamic/Starvation Therapy in Cancer Treatment.

The anticancer effect of photodynamic therapy (PDT) is usually impeded by the hypoxia microenvironment in solid tumors; thus, it requires integration with other treatment tactics to achieve an optimal anticancer efficacy. Porphyrin-containing nanotherapeutic agents are broadly used for PDT in tumor treatment. However, chemodynamic therapy (CDT) of porphyrin-based namomaterials has been rarely reported. Here, a novel nanoscale porphyrin-containing covalent organic polymer (PCOP) was designed by the cross-linking of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin with 1,1'-ferrocenedicarboxylic acid at room temperature. After glucose oxidase (GOx) was loaded, the obtained nanotherapeutic agent of PCOPs@GOx presented an augmented synergy of PDT, CDT, and energy starvation to suppress tumor growth upon near-infrared light irradiation. In vitro and in vivo outcomes demonstrated that this multifunctional nanoplatform not only realized excellent tumor inhibition but also provided a new tactic for designing chemodynamic/photodynamic/starvation combined therapy in one material.

-Ferrocenedicarboxylic Acid Salts as Burning Rate Modifiers of Double-Base Propellant

To expand the possibilities of using solid propellants in gas generators or civil- purpose rockets, the properties of new compounds proposed as burning rate modifiers were considered. -ferrocenedicarboxylic acid and its insolubility in water copper, iron, and lead salts were synthesized. The effect of the salts on the burning rate of a double-base propellant was studied. It was shown that individually 3% of copper salt (CFDA) has the most considerable effect on the burning rate, increasing by times at the pressure interval of 1–10 MPa. It is possible to lower the n value in the burning law from 0.71 to 0.21 in a pressure range of 6–15 MPa with use of lead salt. Carbon nanotubes significantly increase the efficiency of FDA salts. An interesting phenomenon was discovered: Iron salt (IFDA) affects the burning rate only at pressure up to 2 MPa, and at higher pressures, but only in combination with a carbon nanotube. IFDA also reduces the efficiency of CFDA. An explanation of that fact was suggested.

Facile Synthesis of Ferrocene-Based Polyamides and Their Organic Analogues Terpolyamides: Influence of Aliphatic and Aromatic Sequences on Physico-Chemical Characteristics

Efforts have been devoted to synthesize and characterize processable polymers with desired properties. Herein, four different series of aromatic and aliphatic terpolyamides were prepared via solution phase polycondensation of 4,4′-oxydianiline and hexamethylenediamine (HMDA) with various diacids chlorides (isophthalyol dichloride, terepthalyol dichloride, 1, 1′-ferrocene dicarboxylic acid chloride and trans-azobenzene-4, 4′-dicarbonyl chloride). The structural, morphological and physico-chemical nature of as prepared polymers was explored by Fourier-transform infrared spectroscopy, scanning electron microscopy, thermal analysis (TGA and DSC), and wide-angle x-ray diffraction. Moreover, an aliphatic diamine was incorporated in varying concentration as a flexible methylene spacer and the effect of its concentration on the properties of polyamides was also studied. Changes in various physico-chemical properties such as solubility, inherent viscosity, surface morphology and flame retarding behaviour were investigated. Marked difference in morphology and solubility was observed with the change in the ratio of segments in the chain. Inherent viscosities of polymers ranged from 1.8052–1.6274 dl/g indicating reasonably moderate molecular weights. Interestingly, ferrocene based aromatic polymers were more thermally stable (Tg 260 °C, Ti 310 °C, Th 525 °C, Tf 720 °C, for PF0), and also found to exhibit best flame retarding behavior (limiting oxygen index value for PF0is LOI 33.15%).

Novel powder catalysts of ferrocene-based metal-organic framework and their catalytic performance for thermal decomposition of ammonium perchlorate

It is of great significance to develop a novel and efficient combustion catalyst for thermal decomposition of ammonium perchlorates (AP) to regulate combustion performance of solid propellants. In this work, a series of ferrocene-based transition metals organic frameworks(MOFs) with 1,1′-ferrocenedicarboxylic acid (FcDA) as ligand, namely M-FcDA-MOFs (M = Co(II)、Mn(II)、Cu(II)、Fe(III) and Zn(II)), were successfully fabricated via simple solvothermal method. The samples were characterized by Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The specific surface area and thermal stability of the samples were analyzed by N2 absorption/desorption isotherms and thermogravimetry (TG). Catalytic performance of the M-FcDA-MOFs towards the thermal decomposition of AP was investigated with differential scanning calorimetry-thermogravimetry (DSC-TG) techniques. The results show that the ferrocene-based MOFs have large specific surface area and high thermal stability, and can remarkably decrease the high temperature decomposition peak temperature (HTD) and apparent activation energy, enhance the apparent heat release of AP, and their catalytic performance is better than that of commercial combustion catalyst catocene. Among the samples investigated here, the Co-FcDA-MOF exhibited the best catalytic activity, which can decrease the HTD peak temperature and activation energy of AP by 90 °C and 20.4%, respectively, and increase the apparent heat release by 1082 J·g−1.

Simulation-based evaluation of homogeneous electrocatalytic reaction within a thin layer modified electrode

Electroactive species modified electrodes are extensively studied as the mediator donor in homogeneous electrocatalytic reaction for electrochemical sensing purpose. In this paper, homogeneous electrocatalytic reaction within a thin layer modified electrode is investigated theoretically and experimentally to illustrate the electroactive species distribution on ferrocenedicarboxylic acid modified carbon black paste electrodes (FDACBPE). The voltammetric analysis of the fabricated FDACBPE reveals that the electrode is in diffusional control at the scan rate lower than 50 mV s−1 while a surface control electrode reaction is observed at a higher scan rate. Based on the experimental results, three finite element models including thin layer model, fixed mediator model and combined model are established to evaluate the homogeneous electrocatalytic reaction with FDACBPE. The numerical results show that the anodic peak gap order of 3 models is as follows: fixed mediator model > combined model > thin layer model. As validation of the proposed model, the comparison between experimental results and numerical data on both polished and unpolished FDACBPE indicates that the combined model data are more suitable for the description of experimental voltammograms compared with the other two models. Also, the comparison between these models suggests that both surface confined and diffusional FDA exist when FDACBPE is employed.

Synthesis and Cytotoxicity of the Dihydroartemisinin Ester of 1,1′-Ferrocenedicarboxylic Acid

Synthesis and Cytotoxicity of the Dihydroartemisinin Ester of 1,1′-Ferrocenedicarboxylic Acid

Ferrocene-Based Metal-Organic Framework Nanosheets as a Robust Oxygen Evolution Catalyst.

We report the synthesis of two-dimensional metal-organic frameworks (MOFs) on nickel foam (NF) by assembling nickel chloride hexahydrate and 1,1'-ferrocenedicarboxylic acid (NiFc-MOF/NF). The NiFc-MOF/NF exhibits superior oxygen evolution reaction (OER) performance with an overpotential of 195 mV and 241 mV at 10 and 100 mA cm-2 , respectively under alkaline conditions. Electrochemical results demonstrate that the superb OER performance originates from the ferrocene units that serve as efficient electron transfer intermediates. Density functional theory calculations reveal that the ferrocene units within the MOF crystalline structure enhance the overall electron transfer capacity, thereby leading to a theoretical overpotential of 0.52 eV, which is lower than that (0.81 eV) of the state-of-the-art NiFe double hydroxides.