RESUMEN
In this brief review mainly based on our own work, we summarised the electrochemical investigations into those iron carbonyl complexes relevant to the iron centres of [FeFe]-and [Fe]-hydrogenases in the following aspects: (i) electron transfer (E) coupled with a chemical reaction (C), EC process, (ii) two-electron process with potential inversion (ECisoE), and (iii) proton-coupled electron transfer (PCET) and the role of an internal base group in the non-coordination sphere. Through individual examples, these processes involved in the electrochemistry of the iron carbonyl complexes are discussed. In probing the complexes involving a two-electron process with potential inversion, the co-existence of one- and two-electron for a complex is demonstrated by incorporating intramolecularly a ferrocenyl group(s) into the complex. Our studies on proton reduction catalysed by three diiron complexes involving the PCET mechanism are also summarised. Finally, perspectives of the electrochemical study in iron carbonyl complexes inspired by the iron-containing enzymes are mentioned in the sense of developing mimics of low overpotentials for hydrogen evolution through exploiting the PCET effect.
Asunto(s)
Hidrogenasas/metabolismo , Compuestos de Hierro Carbonilo/metabolismo , Proteínas Hierro-Azufre/metabolismo , Hidrogenasas/química , Compuestos de Hierro Carbonilo/química , Proteínas Hierro-Azufre/química , Modelos Moleculares , Estructura MolecularRESUMEN
The flexible maneuvering of microliter liquid droplets is significant in both fundamental science and practical applications. However, most current strategies are limited to the rigid locomotion on confined geographies platforms, which greatly hinder their practical uses. Here, we propose a magnetism-actuated superhydrophobic flexible microclaw (MSFM) with hierarchical structures for water droplet manipulation. By virtue of precise femtosecond laser patterning on magnetism-responsive poly(dimethylsiloxane) (PDMS) films doped with carbonyl iron powder, this MSFM without chemical contamination exhibits powerful spatial droplet maneuvering advantages with fast response (<100 ms) and lossless water transport (â¼50 cycles) in air. We further performed quantitative analysis of diverse experimental parameters including petal number, length, width, and iron element proportion in MSFM impacting the applicable maneuvering volumes. By coupling the advantages of spatial maneuverability and fast response into this versatile platform, typical unique applications are demonstrated such as programmable coalescence of droplets, collecting debris via droplets, tiny solid manipulation in aqueous severe environments, and harmless living creature control. We envision that this versatile MSFM should provide great potential for applications in microfluidics and cross-species robotics.
Asunto(s)
Dimetilpolisiloxanos/química , Compuestos de Hierro Carbonilo/química , Transportes/instrumentación , Animales , Diseño de Equipo , Interacciones Hidrofóbicas e Hidrofílicas , Isópodos , Fenómenos Magnéticos , Fenómenos Mecánicos , Transportes/métodos , Agua , HumectabilidadRESUMEN
In the present research, the effectiveness of developed methodology based on solvent cast 3D printing technique was investigated by printing the different geometries of the stents. The carbonyl iron powder (CIP) reinforced polycaprolactone (CIPC) was used to print three pre-existing stent designs such as ABBOTT BVS1.1, PALMAZ-SCHATZ, and ART18Z. The physicochemical behavior was analyzed by X-ray diffraction and scanning electron microscopy. The radial compression test, three-point bending test and stent deployment test were carried out to analyze the mechanical behavior. The degradation behavior of the stents was investigated in static as well as dynamic environment. To investigate the hemocompatible and cytocompatible behaviors of the stents, platelet adhesion test, hemolysis test, protein adsorption, in vitro cell viability test, and live/dead cell viability assay were performed. The results revealed that stents had the adequate mechanical properties to perform the necessary functions in the human coronary. The degradation studies showed slower degradation rate in the dynamic environment in comparison to static environment. in vitro biological analysis indicated that the stents represented excellent resistance to thrombosis, hemocompatible functions as well as cytocompatible nature. The results concluded that PALMAZ-SCHATZ stent represented better mechanical properties, cell viability, blood compatibility, and degradation behavior.
Asunto(s)
Materiales Biocompatibles Revestidos/química , Compuestos de Hierro Carbonilo/química , Poliésteres/química , Polvos/química , Stents , Adsorción , Plaquetas/metabolismo , Adhesión Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Humanos , Cinética , Ensayo de Materiales , Fenómenos Mecánicos , Impresión Tridimensional , Proteínas/metabolismoRESUMEN
BACKGROUND: To improve the outcome of cancer treatment, the combination of multiple therapy models has proved to be effective and promising. Gas therapy (GT) and chemodynamic therapy (CDT), mainly targeting the mitochondrion and nucleus, respectively, are two emerging strategy for anti-cancer. The development of novel nanomedicine for integrating these new therapy models is greatly significant and highly desired. METHODS: A new nanomedicine is programmed by successive encapsulation of MnO2 nanoparticles and iron carbonyl (FeCO) into mesoporous silica nanoparticle. By decoding the nanomedicine, acidity in the lysosome drives MnO2 to generate ROS, ·OH among which further triggers the decomposition of FeCO into CO, realizing the effective combination of chemodynamic therapy with gas therapy for the first time. RESULTS: Acidity in the TEM drives MnO2 to generate ROS, âOH among which further triggers the decomposition of FeCO into CO, realizing the effective combination of CDT and CDGT. The co-released ROS and CO do damage to DNA and mitochondria of various cancer cells, respectively. The mitochondrial damage can effectively cut off the ATP source required for DNA repair, causing a synergetic anti-cancer effect in vitro and in vivo. CONCLUSIONS: The combination of CDT and CDGT causing a synergetic anti-cancer effect in vitro and in vivo. The proposed therapy concept and nanomedicine designing strategy might open a new window for engineering high-performance anti-cancer nanomedicine.
Asunto(s)
Monóxido de Carbono/química , Compuestos de Hierro Carbonilo/química , Compuestos de Manganeso/química , Nanopartículas/química , Óxidos/química , Especies Reactivas de Oxígeno/química , Dióxido de Silicio/química , Animales , Monóxido de Carbono/administración & dosificación , Línea Celular Tumoral , Supervivencia Celular , Humanos , Ratones Endogámicos BALB C , Nanomedicina , Oxidación-Reducción , Porosidad , Especies Reactivas de Oxígeno/administración & dosificaciónRESUMEN
We report a spectroscopic investigation of the ultrafast dynamics of the second-generation poly(aryl ether) dendritic hydrogenase model using two-dimensional infrared (2D-IR) spectroscopy to probe the metal carbonyl vibrations of the dendrimer and a reference small molecule, [Fe(µ-S)(CO)3]2. We find that the structural dynamics of the dendrimer are reflected in a slow phase of the spectral diffusion, which is absent from [Fe(µ-S)(CO)3]2, and we relate the slow phase to the quality of the solvent for poly(aryl ether) dendrimers. We observe a solvent-dependent modulation of the initial phase of vibrational relaxation of the carbonyl groups, which we attribute to an inhibition of solvent assistance in the intramolecular vibrational redistribution process for the dendrimer. There is also a clear solvent dependence of the vibrational frequencies of both the dendrimer and [Fe(µ-S)(CO)3]2. Our data represent the first 2D-IR study of a dendritic complex and provide insight into the solvent dependence of molecular conformation in solution and the ultrafast dynamics of moderately sized, conformationally mobile compounds.
Asunto(s)
Dendrímeros/metabolismo , Hidrogenasas/metabolismo , Compuestos de Hierro Carbonilo/metabolismo , Sustancias Macromoleculares/metabolismo , Dendrímeros/química , Difusión , Hidrogenasas/química , Compuestos de Hierro Carbonilo/química , Sustancias Macromoleculares/química , Modelos Moleculares , Conformación Molecular , Estructura Molecular , Control de Calidad , Solventes/química , Espectroscopía Infrarroja por Transformada de Fourier , Azufre/química , Azufre/metabolismo , VibraciónRESUMEN
Autoimmune diseases are characterized by dendritic cell (DC)-driven activation of pro-inflammatory Tâ cell responses. Therapeutic options for these severe diseases comprise small molecules such as dimethyl fumarate, or "gasotransmitters" such as CO. Herein we describe the synthesis of bifunctional enzyme-triggered CO-releasing molecules (ET-CORMs) that allow the simultaneous intracellular release of both CO and methyl fumarate. Using bone-marrow-derived DCs the impressive therapeutic potential of these methyl fumarate-derived compounds (FumET-CORMs) is demonstrated by strong inhibition of lipopolysaccharide-induced pro-inflammatory signaling pathways and blockade of downstream interleukin-12 or -23 production. The data also show that FumET-CORMs are able to transform DCs into an anti-inflammatory phenotype. Thus, these novel compounds have great clinical potential, for example, for the treatment of psoriasis or other inflammatory conditions of the skin.
Asunto(s)
Antiinflamatorios no Esteroideos/farmacología , Monóxido de Carbono/metabolismo , Esterasas/metabolismo , Ácido Fusárico/análogos & derivados , Inflamación/tratamiento farmacológico , Compuestos de Hierro Carbonilo/farmacología , Animales , Antiinflamatorios no Esteroideos/química , Antiinflamatorios no Esteroideos/metabolismo , Monóxido de Carbono/química , Cristalografía por Rayos X , Células Dendríticas/efectos de los fármacos , Células Dendríticas/metabolismo , Esterasas/química , Ácido Fusárico/química , Ácido Fusárico/metabolismo , Ácido Fusárico/farmacología , Inflamación/metabolismo , Interleucina-12/antagonistas & inhibidores , Interleucina-12/biosíntesis , Interleucina-23/antagonistas & inhibidores , Interleucina-23/biosíntesis , Compuestos de Hierro Carbonilo/química , Compuestos de Hierro Carbonilo/metabolismo , Ratones , Modelos Moleculares , Estructura Molecular , Polisacáridos/antagonistas & inhibidores , Polisacáridos/farmacologíaRESUMEN
A mononuclear hexa-coordinated iron carbonyl complex [Fe(µ-bdt)(CO)2(PTA)2] 1 (bdt = 1,2-benzenedithiolate; PTA = 1,3,5-triaza-7-phosphaadamantane) with two bulky phosphine ligands in the trans position was synthesized and characterized by X-ray structural analysis coulometry data, FTIR, electrochemistry and electronic structure calculations. The complex undergoes a facilitated two-electron reduction 1/12- and shows an inverted one-electron reduction for 1/1- at higher potentials. Electrochemical investigations of 1 are compared to the closely related [Fe(bdt)(CO)2(PMe3)2] compound. A mechanistic suggestion for the hydrogen evolution reaction upon proton reduction from acid media is derived. The stability of 1 in both weak and strong acids is monitored by cyclic voltammetry.
Asunto(s)
Dominio Catalítico , Complejos de Coordinación/química , Compuestos Ferrosos/química , Hidrogenasas/química , Compuestos de Hierro Carbonilo/química , Fosfinas/química , Adamantano/análogos & derivados , Adamantano/química , Derivados del Benceno/química , Complejos de Coordinación/síntesis química , Técnicas Electroquímicas , Hidrógeno/química , Concentración de Iones de Hidrógeno , Compuestos de Hierro Carbonilo/síntesis química , Ligandos , Modelos Químicos , Conformación Molecular , Compuestos Organofosforados/química , Oxidación-Reducción , ProtonesRESUMEN
The validated method based on the use of headspace solid phase microextraction (HS-SPME) coupled with the comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection (GC×GC/TOFMS) proved to be appropriate for this first simultaneous quantitative determination of six toxic compounds (formaldehyde, acetaldehyde, ethyl carbamate, furan, furfural and acrolein) found in wines. Acetaldehyde and acrolein coeluted with other wine compounds, which indicated that difficulties could arise if only one-dimensional gas chromatography was used for the determination of these compounds. The advancement of the ripeness degree and increasing the grape maceration time seems to result in higher concentrations of toxic compounds. The exposure to furan, acrolein and ethyl carbamate through wine consumption may pose risks to consumer health, since calculated MOE values were lower than 10,000.
Asunto(s)
Cromatografía de Gases/métodos , Furanos/química , Compuestos de Hierro Carbonilo/química , Vitis/química , Vino/análisisRESUMEN
We have developed a new class of bistable Pickering foams, which can remain intact for weeks at room temperature but can be destroyed rapidly and on-demand with the use of a magnetic field. Such responsive foam systems can find application in various industrial and environmental processes that require controlled defoaming. These foams are stabilized by particles of hypromellose phthalate (HP-55) and contain oleic acid-coated carbonyl iron particles embedded in the HP-55 matrix. The complex behavior of these foams arises from several factors: a robust anisotropic particle matrix, the capacity to retain a high amount of water, as well as an age-dependent response to an external field. We report how the structure and viscoelastic properties of the foams change with time and affect their collapse characteristics. The evolution of foam properties is quantified by measuring the rate of liquid drainage from the foam as well as the rate of bubble growth in the foam with respect to time elapsed (in the absence of a magnetic field). We also evaluate the time necessary for foam collapse in magnetic fields as a function of magnetic particle content. A decreasing liquid volume fraction in the foam during aging leads to an increase in the elasticity and rigidity of the foam structure. These data allow us to identify a transition time separating two distinct stages of foam development in the absence of field. We propose different mechanisms which control foam collapse for each stage in a magnetic field. The stiffening of foam films between air bubbles with age plays a key role in distinguishing between the two destabilization regimes.
Asunto(s)
Compuestos de Hierro Carbonilo/química , Metilcelulosa/análogos & derivados , Ácidos Oléicos/química , Campos Magnéticos , Metilcelulosa/química , Tamaño de la Partícula , Propiedades de Superficie , ViscosidadRESUMEN
Cyclic complex 2 with bridging carbonyl ligands was synthesized from a facile and reversible intermolecular carbonyl-borylene ligand coupling reaction at room temperature. Complex 2 exhibits an unprecedented coordination mode for boron-metal complexes, which is also reflected in its remarkable (11)B NMR chemical shift of -57.2 ppm. Findings from spectroscopic, X-ray, and computational studies are presented, along with a proposed mechanism.
Asunto(s)
Complejos de Coordinación/química , Compuestos de Hierro Carbonilo/química , Manganeso/química , Compuestos de Boro/química , Ligandos , Modelos MolecularesRESUMEN
Triiron dodecacarbonyl allows for the selective reduction of esters into the corresponding ethers. This protocol has a wide substrate scope. In addition, cholesteryl pelarogonate has been reduced under the reaction conditions with an excellent yield.
Asunto(s)
Ésteres/química , Éteres/síntesis química , Compuestos de Hierro Carbonilo/química , Compuestos de Organosilicio/química , Catálisis , Éteres/química , Estructura MolecularRESUMEN
A new class of magnetoelastic gel that demonstrates drastic and reversible changes in storage modulus without using strong magnetic fields was obtained. The magnetic gel consists of carrageenan and carbonyl iron particles. The magnetic gel with a volume fraction of magnetic particles of 0.30 exhibited a reversible increase by a factor of 1400 of the storage modulus upon a magnetic field of 500 mT, which is the highest value in the past for magnetorheological soft materials. It is considered that the giant magnetoelastic behavior is caused by both high dispersibility and high mobility of magnetic particles in the carrageenan gel. The off-field storage modulus of the magnetic gel at volume fractions below 0.30 obeyed the Krieger-Dougherty equation, indicating random dispersion of magnetic particles. At 500 mT, the storage modulus was higher than 4.0 MPa, which is equal to that of magnetic fluids, indicating that the magnetic particles move and form a chain structure by magnetic fields. Morphological study revealed the evidence that the magnetic particles embedded in the gel were aligned in the direction of magnetic fields, accompanied by stretching of the gel network. We conclude that the giant magnetoelastic phenomenon originates from the chain structure consisting of magnetic particles similar to magnetic fluids.
Asunto(s)
Carragenina/química , Hidrogeles/química , Compuestos de Hierro Carbonilo/química , Campos Magnéticos , Elasticidad , Tamaño de la Partícula , Propiedades de SuperficieRESUMEN
Reaction of Fe(3)(CO)(12) with pyridinyl thioester ligand PyCH(2)SCOCH(3) (L(1), Py = pyridin-2-yl) produced complex, [Fe(2)(κ-COCH(3))(µ-SCH(2)Py)(CO)(5)] (1) (PyCH(2)S = pyridin-2-ylmethanethiolate). When complex 1 reacted with PPh(3), a monosubstituted complex, [Fe(2)(κ-COCH(3))(µ-SCH(2)Py)(CO)(4)PPh(3)] (2), was derived. Reaction of the same precursor with analogous thioester ligand PyCH(2)SCOPy (L(2)) generated three novel diiron complexes, [Fe(2)(κ-Py)(µ-SCH(2)Py)(CO)(5)] (3), [Fe(2)(κ-Py)'(µ-SCH(2)Py)(CO)(5)] (4), and [Fe(2)(κ-Py)(µ-SCH(2)Py)(CO)(6)] (5). Complexes 3 and 4 are structural isomers. Complex 5 could be converted into complex 4 but the conversion from complex 5 to the isomer 3 was not observed. All the five complexes were fully characterised using FTIR, NMR, and other techniques. Their structures were determined using X-ray single crystal diffraction analysis. The oxidative formation of complexes 1, 3, 4, and 5 involved C-S and/or C-C bonds cleavages. To probe possible mechanisms for these cleavages, DFT calculations were performed. From the calculations, viable reaction pathways leading to the formation of all the isolated products were delineated. The results of the theoretic calculations also allowed rationalisation of the experimental observations.
Asunto(s)
Ésteres/química , Compuestos de Hierro Carbonilo/química , Compuestos de Azufre/química , Espectroscopía de Resonancia Magnética , Estructura Molecular , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos XRESUMEN
The atomic alignment effect has been studied for the dissociative energy transfer reaction of metal carbonyls (Fe(CO)(5), Ni(CO)(4)) with the oriented Ar ((3)P(2), M(J) = 2). The emission intensity from the excited metal products (Fe*, Ni*) has been measured as a function of the atomic alignment in the collision frame. The selectivity of the atomic orbital alignment of Ar ((3)P(2), M(J) = 2) (rank 2 moment, a(2)) is found to be opposite for the two reaction systems; the Fe(CO)(5) reaction is favorable at the Π configuration (positive a(2)), while the Ni(CO)(4) reaction is favorable at the Σ configuration (negative a(2)). Moreover, a significant spin alignment effect (rank 4 moment, a(4)) is recognized only in the Ni(CO)(4) reaction. The atomic alignment effect turns out to be essentially different between the two reaction systems; the Fe(CO)(5) reaction is controlled by the configuration of the half-filled 3p atomic orbital of Ar ((3)P(2)) in the collision frame (L dependence), whereas the Ni(CO)(4) reaction is controlled by the configuration of the total angular moment J (including spin) of Ar ((3)P(2)) in the collision frame (J dependence). As the origin of J dependence observed only in the Ni(CO)(4) reaction, the correlation (and/or the interference) between two electron exchange processes via the electron rearrangements is proposed.
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Argón/química , Compuestos de Hierro Carbonilo/química , Níquel/química , Transferencia de EnergíaRESUMEN
The dispersion stability of soft magnetic carbonyl iron (CI)-based magnetorheological (MR) fluids was improved by applying a unique functional coating composed of a conducting polyaniline layer and a multiwalled carbon nanotube nest to the surfaces of the CI particles via conventional dispersion polymerization, followed by facile solvent casting. The coating morphology and thickness were analyzed by SEM and TEM imaging. Chemical composition of the polyaniline layer was detected by Raman spectroscope, which also confirmed the coating performance successfully. The influence of the functional coating on the magnetic properties was investigated by measuring the MR performance and sedimentation properties using a vibrating sample magnetometer, rotational rheometer, and Turbiscan apparatus. Improved dispersion characteristics of the MR fluid were observed.
Asunto(s)
Compuestos de Hierro Carbonilo/química , Magnetismo , Compuestos de Anilina/química , Nanotubos de Carbono/química , Espectrometría RamanRESUMEN
We introduce a new class of Pickering foams which can be manipulated using a magnetic field. These foams are stabilized by a mixture of magnetic and nonmagnetic particles. They exhibit excellent stability in the absence of a magnetic field, but can be rapidly destroyed on demand with the application of a threshold field. We characterize their stability in the absence of a magnetic field by measuring the rate of water drainage from the foam as a function of time. We also correlate their collapse behavior under a magnetic field to the foam liquid fraction, as well as the concentration of magnetic particles in the foam. This novel system can be used to study the properties of Pickering foams, and has potential applications in noncontact defoaming processes.
Asunto(s)
Imanes/química , Metilcelulosa/análogos & derivados , Compuestos de Hierro Carbonilo/química , Campos Magnéticos , Metilcelulosa/química , Ácido Oléico/química , Tamaño de la Partícula , Soluciones/químicaRESUMEN
Interaction of the copper, {[3,5-(CF(3))(2)Pz]Cu}(3), and silver, {[3,5-(CF(3))(2)Pz]Ag}(3), macrocycles [3,5-(CF(3))(2)Pz = 3,5-bis(trifluoromethyl)pyrazolate] with cyclooctatetraeneiron tricarbonyl, (cot)Fe(CO)(3), was investigated by IR and NMR spectroscopy for the first time. The formation of 1:1 complexes was observed at low temperatures in hexane. The composition of the complexes (1:1) and their thermodynamic characteristics in hexane and dichloromethane were determined. The π-electron system of (cot)Fe(CO)(3) was proven to be the sole site of coordination in solution and in the solid state. However, according to the single-crystal X-ray data, the complex has a different (2:1) composition featuring the sandwich structure. The complexes of ferrocene with copper and silver macrocycles have a columnar structure (X-ray data).
Asunto(s)
Cobre/química , Compuestos Ferrosos/química , Compuestos de Hierro Carbonilo/química , Compuestos Organometálicos/síntesis química , Pirazoles/química , Plata/química , Ligandos , Metalocenos , Modelos Moleculares , Compuestos Organometálicos/químicaRESUMEN
Infrared, Raman, and nuclear resonant vibrational (NRVS) spectroscopies have been used to address the Fe-H bonding in trans-HFe(CO) iron hydride compound, HFe(CO)(dppe)2, dppe = 1,2-bis(diphenylphosphino)ethane. H and D isotopomers of the compound, with selective substitution at the metal-coordinated hydrogen, have been considered in order to address the Fe-H/D stretching and bending modes. Experimental results are compared to the normal mode analysis by density functional theory (DFT). The results are that (i) the IR spectrum does not clearly show Fe-H stretching or bending modes; (ii) Fe-H stretching modes are clear but weak in the Raman spectrum, and Fe-H bending modes are weak; (iii) NRVS 57Fe spectroscopy resolves Fe-H bending clearly, but Fe-H or Fe-D stretching is above its experimentally resolved frequency range. DFT calculations (with no scaling of frequencies) show intensities and peak locations that allow unambiguous correlations between observed and calculated features, with frequency errors generally less than 15 cm(-1). Prospects for using these techniques to unravel vibrational modes of protein active sites are discussed.
Asunto(s)
Compuestos de Hierro Carbonilo/química , Espectrofotometría Infrarroja/métodos , Espectrometría Raman/métodos , Análisis Espectral/métodos , Hidrógeno/química , Hierro/química , VibraciónRESUMEN
Ultrafast X-ray absorption near edge spectroscopy has been carried out for photo excited iron pentacarbonyl in ethanol with 2 picosecond resolution. A temporal resolution limited dissociation process was observed, followed by the formation of the mono-substituted complex Fe(CO)(4)EtOH within a few tens of picoseconds. The measurements have been carried out with a newly developed X-ray absorption instrument at station 7 ID-C of the Advanced Photon Source. The results show that single picosecond temporal resolution can be achieved at a synchrotron beam line.
Asunto(s)
Etanol/química , Compuestos de Hierro Carbonilo/química , Ligandos , Espectroscopía de Absorción de Rayos XRESUMEN
By using "click" chemistry between a diazide and a diiron model complex armed with two alkynyl groups, two polymeric diiron complexes (Poly-Py and Poly-Ph) were prepared. The two polymeric complexes were investigated using infrared spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), Mössbauer spectroscopy, and cyclic voltammetry (Poly-Py only, due to the insolubility of Poly-Ph). To probe the coordinating mode of the diiron units in the two polymeric complexes, two control complexes (3 and 4) were also synthesised using a monoazide. Complexes 3 and 4 were well characterised and the latter was further crystallographically analysed. It turns out that in both complexes (3 and 4) and the two polymeric diiron complexes, one of the two iron atoms in the diiron unit coordinates with one of the triazole N atoms. Our results revealed that both morphologies and properties of Poly-Py and Poly-Ph are significantly affected by the organic moiety of the diazide. Compared to the protonating behaviour of the complexes 3 and 4, Poly-Py exhibited proton resistance. In electrochemical reduction, potentials for the reduction of the diiron units in Poly-Py and hence its catalytic reduction of proton in acetic acid-DMF shifted by over 400 mV compared to those for complexes 3 and 4. It is likely that the polymeric nature of Poly-Py offers the diiron units a "protective" environment in an acidic medium and more positive reduction potential.