Ferrocenyl Group Research Articles

New ferrocenyl-containing organic hole-transporting materials for perovskite solar cells in regular (n-i-p) and inverted (p-i-n) architectures.

Three triphenylamine derivatives containing ferrocenyl groups (JW6, JW7 and JW8) were synthesized by facile syntheses. Their HOMO levels match the valence band energy of CH3NH3PbI3. The introduction of ferrocenyl was aimed to obtain hole transporting materials with high mobility for perovskite solar cells. JW7 shows higher hole mobility (4.2 × 10−4 cm2 V−1 s−1) than JW6 (1.3 × 10−4 cm2 V−1 s−1) and JW8 (1.5 × 10−4 cm2 V−1 s−1). Their film-forming properties are affected by their molecule structures. The methoxyl and N,N-dimethyl terminal substituents of JW7 and JW8 are beneficial for having better solubility than JW6. The regular mesoporous TiO2-based perovskite solar cells (n-i-p) and the inverted planar heterojunction perovskite solar cells (p-i-n) fabricated using JW7 show the highest power conversion efficiency of 9.36% and 11.43% under 100 mW cm−2 AM1.5G solar illumination. For p-i-n cells, the standard HTM PEDOT-based cell reaches an efficiency of 12.86% under the same conditions.

Cellulose-Supported Ionic Liquid Phase Catalyst-Mediated Mannich Reaction

Cellulose-supported ionic liquid phase (SILP) catalyst containing a camphor sulfonate anion with a pendant ferrocenyl group was prepared and characterised with different analytical techniques such as Fourier-transform infrared, Fourier-transform Raman, and cross polarization–magic angle spinning (CP-MAS) 13C NMR spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The SILP catalyst displayed excellent catalytic activity in the synthesis of β-amino carbonyl compounds by Mannich reaction. Recycling studies revealed that SILP catalyst could be reused six times without significant decrease in catalytic activity.

Synthesis and Antioxidant Activities of Ferrocenyl-containing Curcumin Analogues

Background: Metal organic compounds have attracted considerable attention since the advent of Salvarsan, a metal organic compound for the treatment of syphilis. Ferrocene as an effective phenyl bioisostere is becoming a viable platform for drug design by virtue of its redox properties, high lipophilicity and three-dimensional metallocene unit, which may lead to some changes in selectivity toward biological targets compared with phenyl or alkyl groups. Therefore, ferrocene seems to an appropriate candidate for improving the antioxidant activity of drugs. Methods: We synthesized four ferrocenyl-containing curcumin analogues by introducing ferrocenyl groups into the active methylene groups to obtain higher antioxidant activity than the parent ferrocene- substituted curcumin analogues, and their antioxidant activities were evaluated in 2, 2′- azobis (2-amidinopropane hydrochloride) (AAPH) and Cu2+/glutathione(GSH) -induced oxidation of DNA, and in trapping 2, 2′-diphenyl-1-picrylhydrazyl (DPPH), 2, 2′-azinobis(3-ethylbenzothiazoline- 6-sulfonate) cationic radicals (ABTS+•) and galvinoxyl radicals. Results: These ferrocenyl-containing curcumin analogues can protect DNA against Cu2+/GSHinduced oxidation, and scavenge 5.7, 6.9, 5.5 and 5.3 radicals in protecting DNA against AAPHinduced oxidation. Compounds (3)~(5) can trap more DPPH, ABTS+• and galvinoxyl radicals than compound (6). The substituents and iron atoms play an antioxidant role in ferrocenyl-containing curcumin analogues. Conclusion: The introduction of ferrocenyl group results in a higher antioxidant activity than the traditional hydroxyl-involved curcumin analogues. The ferrocenyl group is a powerful antioxidative group that could be used to modify natural antioxidants. The electron-accepting group attaching to the phenyl-group could further increase the antioxidant activity. Ferrocene-containing curcumin analogues show higher activities in quenching radicals and protecting DNA against radical-induced oxidation. Therefore, the introduction of ferrocenyl group into the natural antioxidant may contribute to increase the antioxidant activity.

Impact of the α‐Ferrocenyl Group on the Solvolytic Reactivity – Electrofugality – of Ferrocenylphenylmethyl Cations

The electron‐donating effect of the ferrocenyl group in α‐position to the reaction center on SN1 solvolytic reactivity has been quantified by determining the electrofugalities (Ef) of a series of ferrocenyl‐X‐phenylmethyl cations according to the LFER equation: log k = sf(Ef + Nf). Due to highly stabilized transition state, the Ef values are about eight units higher than those of the corresponding benzhydryl cations. Impact of the phenyl group in ferrocenylphenylmethyl derivatives on stabilization of the positive charge is somewhat leveled by the ferrocenyl group, so the rate effect of the substituents on the phenyl ring is suppressed, causing narrow range of Ef parameters and small absolute values of the ρ+ constant. Calculations at B2PLYP‐D3/may‐cc‐pVTZ level of theory showed that the positive charge in ferrocenylphenylmethyl cation is largely shifted from the phenyl to ferrocenyl moiety, and that the substituents on the phenyl ring have small impact on its stability.

Hetero‐Diels‐Alder Reactions of α‐Nitrosoalkenes with Ferrocenyl, Hetaryl and Cycloaliphatic Thioketones

AbstractThe in situ generated α‐nitrosoalkenes react with ferrocenyl, hetaryl and cycloaliphatic thioketones yielding 4H‐1,5,2‐oxathiazines as products of the hetero‐Diels‐Alder reaction. These products are formed in a perfect regioselective manner. A similar reactivity is displayed by a thiochalcone (1,3‐diphenylprop‐2‐ene‐1‐thione), and in that case, the [4+2]‐cycloaddition occurs also chemoselectively and regioselectively along the C=S bond acting as a heterodienophile. The stability of the 4H‐1,5,2‐oxathiazines depends on the type of substituents, and in the case of ferrocenylthioketones, the diferrocenyl representative is the reagent of choice. The replacement of one ferrocenyl group by an ethyl group leads to a dramatic decrease of the product stability. Sterically crowded cycloaliphatic thioketones derived from 2,2,4,4‐tetramethylcyclobutane‐1,3‐dione are exceptional dienophiles in reactions with trifluoromethyl‐substituted nitrosoalkenes, and in these cases, a remarkably stable 3‐trifluoromethyl‐4H‐1,5,2‐oxathiazine derivative was obtained. For the first time, perfectly stable and non‐odorous 2,2,4,4‐tetramethylcyclobutane‐1,3‐dithione was explored as an active heterodienophile for a two‐fold hetero‐Diels‐Alder reaction.

Revisiting reactions of alkynes with Ru3(CO)12: Effects of alkyne substituents and solvents on the structures of ruthenium cluster products

The reactions of Ru3(CO)12 with alkynes R1CCR2 (R1 = pyridyl, R2 = Ph (1); R1 = pyridyl, R2 = ferrocenyl (2); R1 = R2 = Ph (3)) in toluene afforded a linear triruthenium cluster (1a/1b), a triangular triruthenium cluster (2a) and two biruthenium clusters (3a and 3b). All clusters were characterized by FT-IR, NMR, ESI-MS spectrometry and single-crystal X-ray diffraction. The structures of 1a/1b (two polymorphs) contain each a Ru3 linear skeleton, which arises from the coupling and coordination of two ligands 1 with the ruthenium centers and formation of two six-membered rings with a common edge. The structure of 2a contains a metallacyclopentadienyl framework formed by two coupled ligands 2 bonding with a triangular-arranged ruthenium skeleton via a μ4-η1:η2:η1:η1 bonding mode, and a four-membered ring formed by the third ligand 2 bonding with ruthenium atom in a μ3-η1:η1 bonding mode and linking of its pyridyl N atom with another ruthenium atom. The reaction of 3 and Ru3(CO)12 in toluene gave unexpected ruthenole 3a and a reported cluster 3b. A detailed investigation on the reaction processes suggested that the nitrogen atoms of the pyridyl groups in the alkyne ligand 1–2 directs the formation of the triruthenium clusters 1a/1b and 2a. The electronic and steric effects of a ferrocenyl group are distinctly different from those of a phenyl group and lead to the diverse structures of the products 1a/1b and 2a in the reactions of Ru3(CO)12 with alkynes 1–2, respectively. Moreover, the solvent properties exert great effects on the product distribution.

Stimuli-Responsive Supramolecular Gels Constructed by Hierarchical Self-Assembly Based on Metal-Ligand Coordination and Host-Guest Recognition.

Metal-ligand coordination and host-guest recognition are introduced into the hybrid system in order to prepare supramolecular gels, which can be responsive to multiple external stimuli such as metal ions, competitive guest/host molecules, and oxidants. To this end, the triangular terpyridine-based metallocycles functionalized with 1-adamantyl and ferrocenyl groups are constructed through self-assembly, and further used as supramolecular cross-linkers for gelation of β-CD-containing copolymers. Their gelation and stimuli-response tests are discussed, and an application of the metallotriangles for serving as supramolecular glue is demonstrated through a series of adhesion experiments. This approach enables facile access to construction of multifunctional metallosupramolecules as well as functional hybrid materials.

Magnetic Nanoparticle Decorated N-Heterocyclic Carbene–Nickel Complex with Pendant Ferrocenyl Group for C–H Arylation of Benzoxazole

Magnetic nanoparticle decorated N-heterocyclic carbene–nickel complex with pendant ferrocenyl group has been prepared by multi-step procedure. The formation of complex was confirmed on the basis of analytical techniques such as Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman) and X-ray photoelectron spectroscopy (XPS) as well as by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) analysis. The complex proved to be an efficient heterogeneous catalyst for C–H arylation of benzoxazole with aryl boronic acids. The recycling studies revealed that complex could be reused for six times without significant decrease in catalytic activity.

Microwave-Assisted Synthesis, In Vivo Anti-Inflammatory and In Vitro Anti-Oxidant Activities, and Molecular Docking Study of New Substituted Schiff Base Derivatives

In view of considerable interest in the design and synthesis of new heterocyclic compounds with promising biological activities for medical and biological applications, a series of eight imine derivatives have been synthesized through microwave-assisted Schiff base formation by reacting 2-(4-methoxyphenyl)acetohydrazide (3) and 4-amino-3-(4-methoxybenzyl)-1H-1,2,4-triazole-5(4H)-thione (6) with various substituted aldehydes. Structures of the newly synthesized compounds were characterized by FT-IR, 1H NMR and 13C NMR spectral analysis. All the synthesized derivatives were screened for their in vivo anti-inflammatory and in vitro anti-oxidant activities using carrageenan induced rat paw edema test and DPPH free radical scavenging assay, respectively. In addition, molecular docking experiment was also performed to check the actual binding affinity of ligand against target protein. Compounds 4a, 4c, 7a, and 7c screened as potent anti-inflammatory drugs significantly lowered the volume of rat paw edema (P < 0.05). In case of anti-oxidant assay, compound 7a with ferrocenyl group as substituent R and 3,4-disubstitued 1,2,4-triazole as side coupled group exhibited IC50 value of 7.2 ± 2.7 μg/mL comparable with that of the reference ascorbic acid (2.61 ± 0.29 μg/mL) and was the most active compound among the series. However, no prominent results were obtained in case of aralkanoic acid hydrazide substituted Schiff base derivatives 4a – 4d. It is believed that the synthesized Schiff base derivatives can be used for the development of potent anti-inflammatory and anti-oxidant drugs with considerable advantages of convenient synthetic strategy possessing high product yield, short reaction time, and convenient handling. The molecular docking results were found in good correlation with experimental IC50 values.

Ferrocenyl Janus mixed-dendron stars and their stabilization of Au and Ag nanoparticles

Janus molecular architectures have recently attracted attention due to their structures and properties that differ from those of traditional symmetric structures. Herein, two new small redox-reversible mixed-dendron star-shape molecules containing three ferrocenyl groups have been synthesized by linking two distinct dendrons using an esterification reaction. These organometallic nano structures were characterized by 1H and 13C NMR, MS, IR and UV–vis. spectroscopies and cyclic voltammetry confirming the number of ferrocenyl groups and AFM and DLS showing micellar assemblies. Au and Ag nanoparticles were stabilized in the presence of a mixed-dendron structure having amidoferrocene termini upon reaction of the nanoparticle metal precursor with NaBH4. Compared reactions of the two star-molecules with HAuCl4 showed a slow redox reaction leading to Au nanoparticles only with the star-molecule terminated with triazolyferrocene termini, which is taken into account by the difference of their redox potentials.

Development of a Novel Ferrocenyl Histone Deacetylase Inhibitor for Triple-Negative Breast Cancer Therapy

Owing to the lack of target-directed therapies, triple-negative breast cancer (TNBC) is difficult to effectively treat. In this article, a novel organometallic histone deacetylase (HDAC) inhibitor, Fc-SelSA, based on the selenocyanide (SelSA) zinc-binding motif, was synthesized using a ferrocenyl group as the cap to confer activity against TNBC. The synthesized Fc-SelSA was evaluated for bioactivity in vitro and in vivo. An enzymatic assay showed that Fc-SelSA was a potent HDAC inhibitor with a half-maximum inhibitory concentration (IC50) of 14.8 nM. Molecular docking studies of Fc-SelSA with HDAC suggested that the ferrocenyl unit overlaps with the phenyl group of suberoylanilide hydroxamic acid (SAHA) and the amido group of Fc-SelSA can form hydrogen bonds with the D98 and G151 residues of HDAC, but SAHA and SelSA do not show similar interactions. Moreover, Fc-SelSA reactivated the estrogen receptor alpha (ERα) expression, sensitized TNBC cells to the antagonist tamoxifen, and exerted more potent antitu...

Synthesis of Ferrocenyl-Substituted Organochalcogenyldichlorogermanes

Reaction of the isolable ferrocenyldichlorogermyl anion, Fc*GeCl2− (Fc* = 2,5-bis(3,5-di-t-butylphenyl)-1-ferrocenyl), with the isolable chalcogenenyl halides resulted in the formation of the corresponding organochalcogenyldichlorogermanes that were structurally characterized. Thus, it was demonstrated the use of sterically demanding ferrocenyl groups allowed isolating stable crystalline organochalcogenyldichlorogermanes.

Theoretical understanding of the inversion of rectification direction in ferrocenyl-embedded tridecanethiolate single-molecule rectifiers

The rectifying properties of single-molecule diodes, which consist of one ferrocenyl-embedded tridecanethiolate (SCnFc13−n, n = 0–13) sandwiched between two symmetric Ag(111) electrodes, have been theoretically studied by first-principles calculations. The numerical results show that rectification direction as well as the rectification ratio of the single-molecule rectifiers can be well controlled by judiciously designing the site of ferrocenyl (Fc) group within the tridecanethiolate backbone. Further analysis reveals that frontier molecular orbitals (FMOs) of the molecules are spatially localized on the Fc group. Asymmetrically positioning of the Fc group within the tridecanethiolate backbone causes asymmetric evolutions of the FMOs under forward and backward bias voltages, which is the underlying rectification mechanism for the single-molecule diodes. Furthermore, varying the location of Fc group within the tridecanethiolate backbone modifies the evolving feature of the FMOs under bias voltages and hence changes the rectification performance and rectification direction of the molecular diodes. In addition, a simple model is proposed here to understand the asymmetric evolutions of the spatially localized FMOs, which are ascribed to the electric potential energy effect of electronic wavefunctions in external electric field. Our first-principles and modeling results give a deeper insight into the recent experimental observation [Nat. Commun.6, 6324 (2015)] and are of great help to future rational design of molecular rectifiers.

Redox-controlled reversible micelles transition and lyotropic liquid-crystalline behavior of novel polymerizable ferrocenyl surfactants

A novel photopolymerizable surfactant with ferrocenyl group, (11-ferrocenylundecyl) (ethyl methacrylate) dimethylammonium bromide (I+), was synthesized through the reaction of 11-bromoundecyl ferrocene and N,N-(dimethylamino) ethyl methacrylate. Based on the results of voltammetric cycle, the small potential difference ΔE was 72 mV, which indicates that the I+ has good redox reversibility. The critical micellar concentration (CMC) values were about 0.5 and 22.7 mM for I+ in the reduction (CMCred) and oxidation state (CMCox) and it could aggregate and disaggregate by using redox reaction and photopolymerization when its concentrations was between their CMCred and CMCox values. The lyotropic liquid-crystalline properties of I+ in water were investigated by X-ray diffraction (XRD) and plarized optical microscope (POM). The results indicate when the concentration of the I+ solution over 40 wt %, an ordered lamellar liquid crystal structure was formed. With increasing concentration, the nanoscopic long-range order improved. Moreover, the lyotropic liquid-crystalline properties of I+ could also be controlled by using redox reaction and photopolymerization. In a word, the novel polymerizable ferrocenyl surfactants are good environmental responsive materials and can potentially act as the drug carrier and the scavenger for removing dissolved organic impurities in water.

N-ferrocenylphthalimide; A single redox couple formed by attaching a ferrocene moiety to phthalimide for non-aqueous flow batteries

N-ferrocenylphthalimide (FcPI) is prepared by replacing the hydrogen atom at the N-site of phthalimide with a ferrocene moiety. Phthalimide shows irreversible redox reaction due to H atom at the N-site of phthalimide. By replacing H atom of phthalimide with non-detachable functional group, such as alkyl group, redox reaction becomes reversible. Reversibility of redox reaction is requirement for redox couple due to cycling performance in battery system. In this work, electroactive group, not the simple functional group, is introduced to substitute H atom of phthalimide. As an electroactive group, ferrocenyl group has two main benefits. First, the redox reaction of the initial phthalimide with H atom at the N-site becomes reversible at E1/2 = −1.87 V (vs. Fc/Fc+) with an excellent stability. Second, FcPI is a single redox couple with Ecell = 1.94 V in a non-aqueous electrolyte because the ferrocene moiety in the molecule is also redox-active at E1/2 = 0.07 V (vs. Fc/Fc+) with stability. A non-flowing coin-type cell employing FcPI as a single redox couple exhibits an excellent Coulombic efficiency of 97.3% and stable cycle performance during the 50th cycle. Furthermore, rate test realizes fast charge transfer kinetics as voltage efficiency of 96.5–90.1% at 1.0–3.0 C.

Redox-responsive diphenylalanine aggregate mediated by cyclodextrin

The molecular assembling properties can be dramatically improved using redox-responsive nanoplatforms, which can bring quite different aggregation modes and binding behaviors in the redox states. In this work, we fabricated a redox-responsive system based on the host–guest complexation of β-cyclodextrin (β-CD) with ferrocene-modified diphenylalanine (Fc-FF). The morphological conversion of Fc-FF can be easily achieved from nanofibers to nanospheres in the presence of β-CD, and the supramolecular nanospheres can be reversibly assembled and disassembled by the chemical redox of ferrocenyl groups in the Fc-FF⊂β-CD nanoassemblies. These results demonstrate that the incorporation of stimuli-switchable components with macrocyclic receptors may become a promising approach to the construction of smart peptide-involved supramolecular assemblies.

Magnetically retrievable N-heterocyclic carbene-silver complex with wingtip ferrocenyl group for Sonogashira coupling

A new magnetically retrievable N-heterocyclic carbene-silver complex with wingtip ferrocenyl group has been prepared by multi-step procedure. The formation of complex was confirmed on the basis of analytical techniques such as FT-IR, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-Ray diffraction (XRD), transmission electron microscopy (TEM) and VSM (vibrating sample magnetometer) analysis. The complex was successfully employed as an efficient heterogeneous catalyst for Sonogashira coupling reaction of aryl halides with terminal alkynes. The complex could be separated easily by applying external magnet. The reusability studies revealed that complex can be reused up to eight times without significant decrease in catalytic activity.

Macrocycles Bearing Ferrocenyl Pendants and their Electrochemical Properties upon Binding to Divalent Transition Metal Cations.

Metal complexes of Cu2+ , Co2+ , Cd2+ , Zn2+ , and Ni2+ formed with the ligands [Fc(cyclen)] (1) and [Fc(cyclen)2 ] (2) (Fc=ferrocene, cyclen=1,4,7,10-tetraazacyclododecane) are synthesised and characterised. The X-ray structure of the Cu2+ complex of 2, Fc([Cu(cyclen)(CH3 CN)]2 (ClO4 )4 , is reported, and shows that the two positively charged Cu2+ -cyclen units have a coordination number of five, adopting a distorted trigonal-bipyramidal configuration. The Cu2+ -cyclen units are arranged in a trans-like configuration with respect to the Fc group, presumably to minimise electrostatic repulsion. The voltammetric oxidation of the free ligands 1 and 2 in a CH2 Cl2 /CH3 CN (1:4) solvent mixture yields two closely spaced oxidation processes. Both electron-transfer steps are associated with the ferrocenyl moiety, implying strong communication between the cyclen nitrogen atoms and the ferrocenyl group. In contrast, cyclic voltammograms display only a simple reversible one-electron process if 1 and 2 are complexed with Cd2+ , Cu2+ , Zn2+ , Ni2+ , or Co2+ . Binding of these metal ions produces a significant shift in the reversible midpoint potential (Em ). Except for Ni2+ , Em is linearly proportional to the charge density of the transition metal ion, demonstrating that 1 and 2 may undergo redox switching. The diffusion coefficients of Fc, DmFc, 1 and 2, and their metal ion complexes correlate well with their molecular weights.

(Ar-CO-C[triple bond, length as m-dash]C)(PEt3)Au and (Ar-C[triple bond, length as m-dash]C)(PEt3)Au complexes bearing pyrenyl and ferrocenyl groups: synthesis, structure, and luminescence properties.

Two types of (acetylide)(triethylphosphine)gold(i) complexes ArCOC[triple bond, length as m-dash]CAuPEt3 (1a and 1b) and ArC[triple bond, length as m-dash]CAuPEt3 (2a and 2b) bearing Ar = pyren-1-yl or ferrocenyl group were synthesized and the effect of a carbonyl moiety on the structure, propensity to ligand scrambling in solution and luminescence properties were investigated. We found that the complexes bearing acetylenic ketone-derived ligands underwent ligand scrambling in solution to afford mixtures of ArCOC[triple bond, length as m-dash]CAuPEt3 and [(ArCOC[triple bond, length as m-dash]C)2Au]-[Au(PEt3)2]+. The latter complexes were isolated and their structures were confirmed by single crystal X-ray diffraction studies. The aurophilic interaction of AuAu in these complexes resulted in the formation of wire-like structures.

Synthesis of novel ferrocenyl Mannich bases and their antibacterial activities

In this work, a series of Mannich bases bearing ferrocenyl groups were synthesized via Mannich reactions. The effects of different conditions on the reaction were explored, and the newly synthesized compounds were well characterized by NMR and FT-IR. All compounds have been screened for in vitro antibacterial and antifungal, and the compounds 1-ferrocenyl-3-phenyl-3-(m-nitrophenylamino)-1-acetone (2f) and 1-ferrocenyl-3-phenyl-3-(p-nitrophenylamino)-1-acetone (2g) were shown to be significant activity against all the tested bacterial strains, such as Staphylococcus aureus, Streptococcus, Actinomycete, Escherichia coli, Saccharomyces cerevisiae.