Ferrocene Scaffold Research Articles

Revitalizing Dead Zinc with Ferrocene/Ferrocenium Redox Chemistry for Deep-Cycle Zinc Metal Batteries.

Aqueous zinc (Zn) batteries are highly desirable for sustainable and large-scale electrochemical energy storage technologies. However, the ceaseless dendrite growth and the derived dead Zn are principally responsible for the capacity decay and insufficient lifespan. Here, we propose a dissolved oxygen-initiated revitalization strategy to reactivate dead Zn via ferrocene redox chemistry, which can be realized by incorporating a trace amount of poly(ethylene glycol) as a solubilizer to improve the solubility of water-insoluble ferrocene derivatives. Ferrocene scaffold can be spontaneously oxidized to ferricenium cations by dissolved oxygen, which eradicates the dissolved oxygen-involved Zn corrosion and insulating by-product generation. Subsequently, the generated ferricenium cations as the scavenger can rejuvenate electrically isolated dead Zn into electroactive Zn2+ ions to compensate the zinc loss. Through this design, the symmetric cell exhibited improved cycle life of 3700 h at 10 mA cm-2, and 220 h under a high depth of dischargeof 80%. Importantly, the Zn||NaV3O8·1.5H2O full cells demonstrated the impressive cycling stability over 1000 cycles at a low N/P ratio of 3.0. This work presents an innovative solution for the revitalization of dead Zn to extend the lifespan of deep-cycling metal batteries.

Revitalizing Dead Zinc with Ferrocene/Ferrocenium Redox Chemistry for Deep‐Cycle Zinc Metal Batteries

Aqueous zinc (Zn) batteries are highly desirable for sustainable and large‐scale electrochemical energy storage technologies. However, the ceaseless dendrite growth and the derived dead Zn are principally responsible for the capacity decay and insufficient lifespan. Here, we propose a dissolved oxygen‐initiated revitalization strategy to reactivate dead Zn via ferrocene redox chemistry, which can be realized by incorporating a trace amount of poly(ethylene glycol) as a solubilizer to improve the solubility of water‐insoluble ferrocene derivatives. Ferrocene scaffold can be spontaneously oxidized to ferricenium cations by dissolved oxygen, which eradicates the dissolved oxygen‐involved Zn corrosion and insulating by‐product generation. Subsequently, the generated ferricenium cations as the scavenger can rejuvenate electrically isolated dead Zn into electroactive Zn2+ ions to compensate the zinc loss. Through this design, the symmetric cell exhibited improved cycle life of 3700 h at 10 mA cm−2, and 220 h under a high depth of discharge of 80%. Importantly, the Zn||NaV3O8·1.5H2O full cells demonstrated the impressive cycling stability over 1000 cycles at a low N/P ratio of 3.0. This work presents an innovative solution for the revitalization of dead Zn to extend the lifespan of deep‐cycling metal batteries.

Contemporary Developments in Ferrocene Chemistry: Physical, Chemical, Biological and Industrial Aspects.

Ferrocenyl-based compounds have many applications in diverse scientific disciplines, including in polymer chemistry as redox dynamic polymers and dendrimers, in materials science as bioreceptors, and in pharmacology, biochemistry, electrochemistry, and nonlinear optics. Considering the horizon of ferrocene chemistry, we attempted to condense the neoteric advancements in the synthesis and applications of ferrocene derivatives reported in the literature from 2016 to date. This paper presents data on the progression of the synthesis of diverse classes of organic compounds having ferrocene scaffolds and recent developments in applications of ferrocene-based organometallic compounds, with a special focus on their biological, medicinal, bio-sensing, chemosensing, asymmetric catalysis, material, and industrial applications.

A Quantum-Guided Molecular Mechanics Force Field for the Ferrocene Scaffold.

Ferrocene derivatives have a wide range of applications, including as ligands in asymmetric catalysis, due to their chemical stability, rigid backbone, steric bulk, and ability to encode stereochemical information via planar chirality. Unfortunately, few of the available molecular mechanics force fields incorporate parameters for the accurate study of this important building block. Here, we present a MM3* force field for ferrocenyl ligands, which was generated using the quantum-guided molecular mechanics (Q2MM) method. Detailed validation by comparison to DFT calculations and crystal structures demonstrates the accuracy of the parameters and uncovers the physical origin of deviations through excess energy analysis. Combining the ferrocene force field with a force field for Pd-allyl complexes and comparing the crystal structures shows the compatibility with previously developed MM3* force fields. Finally, the ferrocene force field was combined with a previously published transition-state force field to predict the stereochemical outcomes of the aminations of Pd-allyl complexes with different amines and different chiral ferrocenyl ligands, with an R2 of ∼0.91 over 10 examples.

Harmicens, Novel Harmine and Ferrocene Hybrids: Design, Synthesis and Biological Activity.

Cancer and malaria are both global health threats. Due to the increase in the resistance to the known drugs, research on new active substances is a priority. Here, we present the design, synthesis, and evaluation of the biological activity of harmicens, hybrids composed of covalently bound harmine/β-carboline and ferrocene scaffolds. Structural diversity was achieved by varying the type and length of the linker between the β-carboline ring and ferrocene, as well as its position on the β-carboline ring. Triazole-type harmicens were prepared using Cu(I)-catalyzed azide-alkyne cycloaddition, while the synthesis of amide-type harmicens was carried out by applying a standard coupling reaction. The results of in vitro biological assays showed that the harmicens exerted moderate antiplasmodial activity against the erythrocytic stage of P. falciparum (IC50 in submicromolar and low micromolar range) and significant and selective antiproliferative activity against the MCF-7 and HCT116 cell lines (IC50 in the single-digit micromolar range, SI > 5.9). Cell localization experiments showed different localizations of nonselective harmicene 36 and HCT116-selective compound 28, which clearly entered the nucleus. A cell cycle analysis revealed that selective harmicene 28 had already induced G1 cell cycle arrest after 24 h, followed by G2/M arrest with a concomitant drastic reduction in the percentage of cells in the S phase, whereas the effect of nonselective compound 36 on the cell cycle was much less pronounced, which agreed with their different localizations within the cell.

Bis[squaramido]ferrocenes as electrochemical sulfate receptors

The bis[squaramido]ferrocene scaffold is introduced and shown to selectively bind and electrochemically report sulfate in competitive water/DMSO mixtures.

Hybrid Compounds Containing a Ferrocene Scaffold as Potential Antimalarials

AbstractMalaria is an infectious disease, and it remains a serious health problem globally. The drugs developed for its treatment suffer from several shortcomings such as low water solubility, poor bioavailability, drug toxicity, and resistance. Molecular hybridization of different bioactive agents is a promising approach for developing hybrid compounds with improved therapeutic effects. Ferrocene, an organometallic, has been hybridized with several pharmacophores resulting in compounds with potent biological activities. In this research, a modified ferrocene scaffold was hybridized with selected pharmacophores. The synthesized compounds were characterized by Fourier‐Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance Spectroscopy (NMR), and Liquid Chromatography‐Mass Spectroscopy. The hybrid compounds were obtained in good yields (53–76 %). In vitro evaluation against NF54 (drug‐sensitive) strain of Plasmodium falciparum parasites revealed the compounds, 16 and 19 (hybrids containing artesunate scaffold), together with 18 and 21 (hybrids containing oleanolic acid scaffold), as promising antimalarial agents. These compounds displayed IC50 values of 116.73±3.18, 56.33±15.20, 78.22±21.05, and 58.22±15.20 nM, respectively. These findings revealed the potency of ferrocene as a precursor for the development of promising antimalarials.

Synthesis and Reactivity of Multinuclear Gold Complexes with (Diphenylphosphanyl)ferrocene and Oxygen Ligands

AbstractAuI complexes combining hard oxygen and soft (diphenylphosphanyl)ferrocene (L) ligands in their molecules were synthesized, viz. the gold hydroxides [Au(OH)(L‐κP)] (5) and [{Au(L‐κP)}2(μ‐OH)][BF4] (4), and the oxonium cluster [{Au(L‐κP)}3(μ3‐O)][BF4] (1). In‐situ auration of 1 produced [{Au(L‐κP)}4(μ4‐O)][BF4]2 (2), which spontaneously converted into a dimeric tetragold complex featuring bridging phosphanylferrocenyl groups geminally diaurated in position 2 of the ferrocene scaffold. The same complex and its isomer incorporating ferrocene‐1,1′‐diyl bridges resulted similarly from 4. Upon crystallization, compound 5 underwent a redox reaction, producing a structurally unique, crown‐like, mixed‐valent Au0/AuI cluster, [Au7(L‐κP)6]OH. Compounds 1 and 5 were used to prepare the analogous, N‐bridged complexes, [{Au(L‐κP)}3(μ3‐NFc)][BF4] (Fc=ferrocenyl) and [{Au(L‐κP)}4(μ4‐N)][BF4]. The compounds were structurally characterized and further studied by DFT calculations.

Synthesis and Reactivity of Multinuclear Gold Complexes with (Diphenylphosphanyl)ferrocene and Oxygen Ligands

AuI complexes combining hard oxygen and soft (diphenylphosphanyl)ferrocene (L) ligands in their molecules were synthesized, viz. the gold hydroxides [Au(OH)(L-κP)] (5) and [{Au(L-κP)}2 (μ-OH)][BF4 ] (4), and the oxonium cluster [{Au(L-κP)}3 (μ3 -O)][BF4 ] (1). In-situ auration of 1 produced [{Au(L-κP)}4 (μ4 -O)][BF4 ]2 (2), which spontaneously converted into a dimeric tetragold complex featuring bridging phosphanylferrocenyl groups geminally diaurated in position 2 of the ferrocene scaffold. The same complex and its isomer incorporating ferrocene-1,1'-diyl bridges resulted similarly from 4. Upon crystallization, compound 5 underwent a redox reaction, producing a structurally unique, crown-like, mixed-valent Au0 /AuI cluster, [Au7 (L-κP)6 ]OH. Compounds 1 and 5 were used to prepare the analogous, N-bridged complexes, [{Au(L-κP)}3 (μ3 -NFc)][BF4 ] (Fc=ferrocenyl) and [{Au(L-κP)}4 (μ4 -N)][BF4 ]. The compounds were structurally characterized and further studied by DFT calculations.

Enantioselective C-H Alkenylation of Ferrocenes with Alkynes by Half-Sandwich Scandium Catalyst.

The enantioselective C-H alkenylation of ferrocenes with alkynes is, in principle, a straightforward and atom-efficient route for the construction of planar-chiral ferrocene scaffolds bearing alkene functionality but has remained scarcely explored to date. Here we report for the first time the highly enantioselective C-H alkenylation of quinoline- and pyridine-substituted ferrocenes with alkynes by a half-sandwich scandium catalyst. This protocol features broad substrate scope, high enantioselectivity, and 100% atom efficiency, selectively affording a new family of planar-chiral ferrocenes bearing N/alkene functionalities. The mechanistic details have been clarified by DFT analyses. The use of a quinoline/alkene-functionalized ferrocene product as a chiral ligand for asymmetric catalysis is also demonstrated.

A New Class of C2 -Symmetric Chiral Cyclopentadienyl Ligand Derived from Ferrocene Scaffold: Design, Synthesis and Application.

A new class of C2 -symmetric, chiral cyclopentadienyl ligand based on planar chiral ferrocene backbone was developed. A series of its corresponding rhodium(I), iridium(I), and ruthenium(II) complexes were prepared as well. In addition, the rhodium(I) complexes were evaluated in the asymmetric catalytic intramolecular amidoarylation of olefin-tethered benzamides via C-H activation.

Renewable forest bioresources for pest management: Semisynthesis of esters containing ferrocene scaffolds of podophyllotoxin from Juniperus sabina L. as botanical pesticides

To investigate potentially pesticidal candidates for pests management, podophyllotoxin esters containing ferrocene scaffolds were prepared as botanical agrochemicals. Against Mythimna separata Walker, compounds 11c and 11d exhibited the most potential insecticidal activity; against Tetranychus cinnabarinus Boisduval, the acaricidal activity of compounds 10c and 10d was ≥ 13-fold of that of podophyllotoxin. This indicated that 6,7-methylenedioxy was necessary for the insecticidal activity, and 6,7-dimethoxy was important for the acaricidal activity; furthermore, halogenation of E-ring of podophyllotoxin could give pronounced compounds as well as introduction of ferrocenylmethanoyl or 2-ferrocenylacetyloxy at their C-4 position.

Synthesis, computational studies and biological activity of oxamohydrazide derivatives bearing isatin and ferrocene scaffolds

Abstract Ferrocene-based anti-inflammatory drug discovery has become an important area in medicinal chemistry. Utilizing the condensation of isatin or ferrocene carbaldehyde with nucleophile, such as oxamic acid hydrazide, the desired isatin 1, and ferrocene 2 oxamohydrazide derivatives were smoothly synthesized in high purity and yield. The structures of the isatin, and ferrocene oxamohydrazides were elucidated using single crystal X-ray diffraction technique, and DFT calculations. Hirshfeld analysis sheds the light on the importance of the O⋯H hydrogen bonds in the molecular packing in both compounds. The oxamohydrazides were examined for anti-inflammatory, and anti-leishmanial activities. The ferrocene oxamohydrazide analogue 2, (IC50 = 5.7 ± 0.3 μM) exhibited a potent anti-inflammatory effect, and was two times more active than the tested ibuprofen as control (IC50 = 11.2 ± 1.9 μM).

Combined experimental and theoretical study of the novel ferrocene derivatives and examining the effect of E-Z stereoisomerism on their optical properties

Herein, we present the primary results on two valuable E-Z stereoisomers containing ferrocene scaffold [(E)-5,5-dimethyl-3-oxo-2-(2-phenyl-2-ferrocenyl-vinyl)cyclohex-1-en-1-yl acetate (E-FerCycAc) and its Z-stereoisomer (Z-FerCycAc)]. These compounds were both prepared from 1-phenylvinyl-ferrocene and 5,5-dimethyl-1,3-cyclohexanedione under catalysis of manganese(III) acetate according to the radical addition mechanism. The prominent spectroscopic data of the target stereoisomers were provided by FT-IR, LC-MS, 1H NMR, 13C NMR techniques, and their stereochemical identification was made primarily by NOESY analysis. The corresponding data (absorbance, transmittance and optical and transport energy gap) were collected from UV–vis studies. The optical properties of the glass slides coated with E-FerCycAc and Z-FerCycAc films were examined and consequently, the optical and transport energy band gap values of the E-FerCycAc were found significantly lower than Z-FerCycAc. The physicochemical and spectroscopic findings (HOMO-LUMO energies, bandgap values, UV–vis, FT-IR, 1H, and 13C NMR spectra) were also compared and supported with the acquired DFT calculations.

Triorganostannyl(IV) benzoates with pendulous framework appended with ferrocene scaffold

A series of four new long chain triorganotin(IV) esters containing a diazenyl- and an imino-groups appended with ferrocene scaffold were designed and synthesized. Ferrocene based metallo pro-ligands H'HFcL1 and H'HFcL2 were obtained by reacting isomeric 3-/4-ferrocenylanilines with 2-[(E)-2-(3-formyl-4-hydroxyphenyl)-1-diazenyl]benzoic acid, which upon reactions with appropriate triorganotin(IV) precursors yielded compounds namely, [nBu3Sn(HFcL1)] 1, [Ph3Sn(HFcL1) 2, [nBu3Sn(HFcL2)] 3 and [Ph3Sn(HFcL2) 4. Compounds 1–4 have been characterized by elemental analysis and their spectroscopic properties were investigated using IR, UV-Vis and NMR spectroscopic techniques. The molecular structures of H'HFcL1 and two representative heterobimetallic compounds 3 and 4 have been determined by X-ray crystallography. Compound 3 is a 1D polymer and 4 is a discrete molecule; their structural differences relative to those of H'HFcL1 clearly indicate the influence of the binding of the tin cluster. The redox properties of the metallo pro-ligands and their compounds were also investigated by cyclic voltammetry.

Syntheses, Structural Snapshots, Solution Redox Properties, and Cytotoxic Performances of Designated Ferrocene Scaffolds Appended with Organostannyl(IV) benzoates en Route for Human Hepatic Carcinoma

Although several strategies have been established to circumvent the limitations of platinum-based chemotherapy, the basic problems still persist. For this purpose, the new series of heterobimetallic formulations [FcLnSnPh3] (1, 3, and 9)], [FcLnSnBu3]n (2, 4 and 8), [FcL3SnCy3] (10), and [FcL3SnR3(MeOH)] (R = Me (5), Et (6), or Pr (7)), where FcLn (n = 1–3) refers to the isomeric 2-/3-/4-ferrocenylbenzoates, was synthesized which can target cancer cells and successively support functional iron deficiencies during chemotherapy. Compounds 1–10 have been characterized by elemental analysis, and their spectroscopic properties were investigated using IR, NMR, electronic, and fluorescence techniques. The molecular structures of metallo proligands FcL1H and FcL3H and the six heterobimetallic compounds 2, 3, 5–7, and 10 have been determined by X-ray crystallography. The redox properties of FcLnH and their compounds 1–10 were also investigated by cyclic voltammetry. In vitro cytotoxic activities of compounds 1–4, ...

Novel anticancer and antibacterial organometallic polymer based on ferrocene as a building block and xanthone bioactive scaffolds: Synthesis, characterization, and biological study

Poly(azine ferrocene‐triazole‐xanthone amide) (PAFTXA) was successfully synthesized from azine ferrocene bisacetylene (AFcB) and 2,7‐(N‐2‐azidoacetamide) xanthone (NAzX) by using click chemistry protocol. In this paper, innovative AFcB moiety incorporated in this procedure as a monomer. This monomer was prepared in three steps from ferrocene scaffold, and the synthetic processes were discussed in details. Characterization of the synthesized novel intermediate materials, monomer, and the resulting polymer was performed by nuclear magnetic resonance, Fourier transform infrared, thermal gravimetric analysis, differential scanning calorimetry, and ultraviolet‐visible spectrophotometer. In addition, the in vitro antibacterial activity of the polymer was appraised against Gram‐positive and Gram‐negative bacteria by using minimum inhibitory concentration method. Moreover; antitumoral effects of synthesized polymer were evaluated on Hela, MCF‐7, and Saos cancer cell lines and compared with normal fibroblast cell line by means of 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. Promising antiproliferative effects were detected on both epitheloid and mesenchymal cancer cell lines depending on PAFTXA concentration and time. Survey on its characteristic features revealed the proficiencies of our prepared biomaterial such as its high thermal stability as well as valuable antitumoral and antibacterial capabilities that make it an appreciable candidate for further bioapplications.

Phosphine–Borane Frustrated Lewis Pairs Derived from a 1,1′-Disubstituted Ferrocene Scaffold: Synthesis and Hydrogenation Catalysis

(Dimesitylphosphino)ferrocene (FcPMes2) (1) reacted with HB(C6F5)2 (2 equiv) by disproportionation to give adduct FcPMes2·H2B(C6F5) (4) plus B(C6F5)3, whereas 1-(dimesitylphosphino)-1′-vinylferrocene (2) was cleanly hydroborated with HB(C6F5)2 to afford [Fe(η5-C5H4PMes2)(η5-C5H4CH2CH2B(C6F5)2)] (7). Compound 7 adopted an open non-interacting P/B frustrated Lewis pair (FLP) structure in the crystal state as well as in a solution. This frustrated Lewis pair heterolytically cleaved dihydrogen under mild conditions to give the respective zwitterionic [P]H+/[B]H– phosphonium/hydroborate product, [Fe(η5-C5H4PHMes2){η5-C5H4CH2CH2BH(C6F5)2}] (8), which served as a catalyst for the hydrogenation of the electron-rich π-systems (imine, enamine) as well as the electron-deficient carbon–carbon double and triple bonds in some enones and an ynone under more forcing conditions (50 bar H2 pressure, 50 °C).

Recent advances in the synthesis, biological activities and various applications of ferrocene derivatives

Ferrocene derivatives constitute an important class of organometallic compounds with not only an extensive range of biological activities but also diverse industrial as well as material science applications. These stimulating features of ferrocene derivatives spurred us to review the recent advances in synthesis methods and biological and other applications reported in the latest literature. An effort has been made to summarize the recent developments in synthetic methods providing access to ferrocene scaffolds and the useful medicinal and material applications, including agricultural, catalytic, polymer, conducting, redox mediating, ferrocenyl stationary phase, rocket propellant and ion sensing applications. Ferrocene‐based bulky metallocenes are also discussed.

ChemInform Abstract: First Synthesis of Ferrocenyl‐Substituted 1,2‐Dihydro‐2‐oxopyridine‐3‐carbonitriles.

In the present investigation, the first incorporation of both ferrocene scaffold and 1,2-dihydro-2-oxopyridine-3-carbonitrile pharmacophore leading to a series of structurally novel ferrocene-based hybrids has been achieved, involving the condensation reaction of ferrocenyl substituted chalcones with 2-cyanoacetamide in a freshly prepared EtONa solution at 70°. The molecular structures of these newly synthesized products were confirmed by IR, and 1H- and 13C-NMR analyses.