Crystal Structure of HydG from Carboxydothermus hydrogenoformans: A Trifunctional [FeFe]‐Hydrogenase Maturase

The structure of the radical S‐adenosyl‐L ‐methionine (SAM) [FeFe]‐hydrogenase maturase HydG involved in CN^?/CO synthesis is characterized by two internal tunnels connecting its tyrosine‐binding pocket with the external medium and the C‐terminal Fe₄S₄ cluster‐containing region. A comparison with a tryptophan‐bound NosL structure suggests that substrate binding causes the closing of the first tunnel and, along with mutagenesis studies, that tyrosine binds to HydG with its amino group well positioned for H‐abstraction by SAM. In this orientation the dehydroglycine (DHG) fragment caused by tyrosine Cα?Cβ bond scission can readily migrate through the second tunnel towards the C‐terminal domain where both CN^? and CO are synthesized. Our HydG structure appears to be in a relaxed state with its C‐terminal cluster CysX₂CysX₂₂Cys motif exposed to solvent. A rotation of this domain coupled to Fe₄S₄ cluster assembly would bury its putatively reactive unique Fe ion thereby allowing it to interact with DHG.     

Selective binding of an imprinted polymer resulted from controlling cobalt coordination to nitric oxide

In this article, the binding characteristics of the imprinted polymer P‐1[Co^II(salen)] (salen: bis(2‐hydroxybenzaldehyde)ethylenediimine) to nitric oxide (NO) have been reported. P‐1[Co^II(salen)] was characterized by Fourier transform infrared analysis, thermogravimetric analysis, and differential scanning calorimetry. Batch‐mode adsorption studies were carried out to investigate binding thermodynamics, kinetics, and selective recognition behavior of P‐1[Co^II(salen)] to NO. The kinetics study indicates that binding of the polymer to NO fits the first‐order reaction kinetics with the rate constant k₁ of 0.087 min^?1. Langmuir and Freundlich equations were used to explain the equilibrium character of P‐1[Co^II(salen)] binding to NO. The r² and χ² values suggest that total amount of NO bound by P‐1[Co^II(salen)] can be best fitted by the Langmuir equation. The binding capacity (B_max) of P‐1[Co^II(salen)] was calculated to be 76.28 μmol/g, very close to the experimental value, 75 μmol/g. The thermodynamics and selectivity experiments showed that the affinity of P‐1[Co^II(salen)] to NO was much higher than carbon dioxide (CO₂) and oxygen (O₂), suggesting that P‐1[Co^II(salen)] is a promising functional material for NO storage and NO sensing. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

CuI and H2O2 Inactivate and FeII Inhibits [Fe]‐Hydrogenase at Very Low Concentrations

[Fe]‐Hydrogenase (Hmd) catalyzes reversible hydride transfer from H₂. It harbors an iron‐guanylylpyridinol as a cofactor with an Fe^II that is ligated to one thiolate, two COs, one acyl‐C, one pyridinol‐N, and solvent. Here, we report that Cu^I and H₂O₂ inactivate Hmd (half‐maximal rates at 1 μM Cu^I and 20 μM H₂O₂) and that Fe^II inhibits the enzyme with very high affinity (K_i=40 nM ). Infrared and EPR studies together with competitive inhibition studies with isocyanide indicated that Cu^I exerts its inhibitory effect most probably by binding to the active site iron‐thiolate ligand. Using the same methods, it was found that H₂O₂ binds to the active‐site iron at the solvent‐binding site and oxidizes Fe^II to Fe^III. Also it was shown that Fe^II reversibly binds away from the active site iron, with binding being competitive to the organic hydride acceptor; this inhibition is specific for Fe^II and is reminiscent of that for the [FeFe]‐hydrogenase second iron, which specifically interacts with H₂.     

A new insight into the mechanism of influence of different inorganic salts on optical properties of water‐soluble cationic conjugated polymers

The water‐soluble conjugated polyelectrolyte poly{2,5‐bis[3‐(N,N,N‐triethylammoniumbromide)‐1‐oxapropyl]‐1,4‐phenylenevinylene} (P2) was synthesized and the influences of different inorganic salts on the optical properties of the polyelectrolyte were studied. New absorption and emission peaks at longer wavelength can be observed in the case of P2 with addition of different concentrations of Cl^? or NO₃^?, whereas addition of I^? or ClO₄^? only induces a red shift. Interestingly, addition of SO₄^2? or F^? does not result in considerable changes in optical spectra. Through UV‐visible spectrometry, photoluminescence, ¹H NMR and cyclic voltammetry, we showed that the nature of the inorganic salts brings these different changes. The special structure of the bond of NO₃^? and the large electronegativity of chlorine lead to an electron transfer between the conjugated polymer and the negative ions. The large radius of I^? and the weak electron withdrawing ability of ClO₄^? only bring a red shift of optical spectra. In addition, SO₄^2? and F^? do not affect the spectra significantly, except that the fluorescence intensity falls slightly indicating that P2 is not sensitive to these ions. Copyright © 2011 Society of Chemical Industry     

A glutamic acid-based polymer keeping intact the integrity of all the three original functionalities of the amino acid

Dimethyl glutamate, on treatment with allyl bromide, afforded dimethyl N,N-diallylglutamate which upon alkaline ester hydrolysis followed by acidification with aqueous HCl gave N,N-diallylglutamic acid hydrochloride [(CH₂=CH–CH₂)₂NH⁺CH(CO₂H)(CH₂)₂CO₂H Cl^?] I. Using Butler’s cyclopolymerization protocol, new monomer I underwent ammonium persulfate-initiated polymerization to give pyrrolidine ring-embedded linear cyclopolymer II i.e. ?[?CH₂(C₄H₆)NH⁺{CH(CO₂H)(CH₂)₂CO₂H Cl^?}CH₂?]?_n retaining the integrity of all the three functionalities of glutamic acid. Under the influence of pH, the repeating units of triprotic acid (+) in II were equilibrated to those of water-insoluble diprotic polyzwitterionic acid (±) III, water-soluble monoprotic poly(zwitterion-anion) (±?) IV, and its conjugate base polydianion (=) V. The critical salt concentration required to promote water solubility of (±) III has been determined to be 0.548 M NaCl, 0.271 M NaBr, 0.133 M NaI. The basicity constants of the carboxyl groups and trivalent nitrogen in (=) V have been determined. A 5 ppm and 20 ppm concentrations of III are effective in inhibiting the precipitation of CaSO₄ from its supersaturated solution with a ≈100% scale inhibition efficiency at 40 °C for a duration of over 3 and 16 h, respectively.     

Preparation electroactive film of (n‐pyrrolyl)1,1‐methane dihydroxamic acid and its derivative containing complexing cavities preformed by entwining ligands on metallic centers

The (N‐pyrrolyl)1,1‐methane dihydroxamic acid have been synthesized from its N‐substituted ester group derivative, then chemically polymerized in the presence of oxidants such as ammonium persulphate and Iron(III) perchlorate for hydroxamic acid and ester groups derivatives, respectively. This compound and its ester group derivative was successfully electropolymerized by a cyclic voltammetry method. New functionalized polypyrrole films containing transition metal complexes have been prepared and studied. The strategy is based on the three‐dimensional template effect of a metal center (Cu^II, Ni^II, Cr^III, Fe^III) able to entwine two and three end functionalized chelating ligand before or after polymerization. The used ligand consists of a methyl dihydroxamic acid bearing one pyrrole nuclei. The rigidity of the polymer matrix is sufficient to allow demetalation of the template center (by CN^? or SCN^?) without collapse of the three‐dimensional structure. Such property is related to the expected complex topology of the material prepared. The organic backbone certainly contains interlocking rings and various network substructures. The polymer matrix thus keeps a little memory of the templating metal used for building it. Fe(III) ion turned out to be the most convenient template during the polymer electrosynthesis and seemed to lead to the most structured network. The various complexes obtained using electrochemical synthesis method display electrochemical properties analogous to those of the corresponding catenate in solution. All complexes in low oxidation states are remarkably stabilized by the entwined and entangled system. The conductivity of these polymers and it metal complexes were measured using four‐probe method. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Dyes based on the 2(1H)‐quinolone skeleton as potential colorimetric and fluorescent sensors for cyanide anions

The sensing properties of dyes based on 2(1H) quinolones containing dicyanoethylene groups towards selected anions such as CN^?, F^?, I^?, Cl^?, SCN^?, CH₃COO^?, and were evaluated. The spectroscopic responses of these compounds were investigated in a solution of acetonitrile/water (1:9, v/v) and phosphate buffer at a pH of 7.4. These dyes were found to act as efficient colorimetric and high turn–off fluorescent sensors to cyanide anions. The fluorescence intensity was linearly related to the concentration of CN^? from 1 to 10 µmol/L, and the detection limits reached a micromolar level of 6.7, 11.1, 3.8 and 7.2 µmol/L for 1‐4 , respectively. The cytotoxic effect of the dyes against human neuroblastoma cells (SH‐SY5Y) was also determined by MTT assay. The examined compounds exhibited slight cytotoxicity against cells under experimental conditions.     

Structural changes and crystallization kinetics of polylactide under CO2 investigated using high‐pressure Fourier transform infrared spectroscopy

The structural changes and crystallization kinetics of polylactide (PLA) during cold crystallization under CO₂ at 80 °C were studied using in situ high‐pressure Fourier transform infrared (FTIR) spectroscopy. The FTIR spectra show that PLA can crystallize under air and CO₂, and some differences are observed. In the second‐derivative spectra, the 1220 cm^?1 band is only found for PLA crystallized under CO₂, and the tt conformer of PLA crystallized under CO₂ is located at 1749 cm^?1, while that of PLA crystallized under air is located at 1751 cm^?1. From wide‐angle X‐ray diffraction, only the α′‐crystal is observed when PLA is crystallized under air, whereas the α‐crystal appears when crystallized under CO₂. The crystalline‐sensitive bands at 921 and 1458 cm^?1 were used to analyze the crystallization kinetics of PLA. When PLA crystallizes under air, the 1458 cm^?1 band changes faster than the 921 cm^?1 one; when it crystallizes under CO₂, the result reverses. This suggests that CO₂ hinders interchain interactions while promoting the helix conformation. © 2015 Society of Chemical Industry     

Copper(II)‐bis‐Histidine Coordination Structure in a Fibrillar Amyloid β‐Peptide Fragment and Model Complexes Revealed by Electron Spin Echo Envelope Modulation Spectroscopy

Truncated and mutated amyloid‐β (Aβ) peptides are models for systematic study—in homogeneous preparations—of the molecular origins of metal ion effects on Aβ aggregation rates, types of aggregate structures formed, and cytotoxicity. The 3D geometry of bis‐histidine imidazole coordination of Cu^II in fibrils of the nonapetide acetyl‐Aβ(13–21)H14A has been determined by powder ¹⁴N electron spin echo envelope modulation (ESEEM) spectroscopy. The method of simulation of the anisotropic combination modulation is described and benchmarked for a Cu^II‐bis‐cis‐imidazole complex of known structure. The revealed bis‐cis coordination mode, and the mutual orientation of the imidazole rings, for Cu^II in Ac‐Aβ(13–21)H14A fibrils are consistent with the proposed β‐sheet structural model and pairwise peptide interaction with Cu^II, with an alternating [‐metal‐vacancy‐]_n pattern, along the N‐terminal edge. Metal coordination does not significantly distort the intra‐β‐strand peptide interactions, which provides a possible explanation for the acceleration of Ac‐Aβ(13–21)H14A fibrillization by Cu^II, through stabilization of the associated state and low‐reorganization integration of β‐strand peptide pair precursors.     

Ion flotation and solvent sublation of cobalt cyanide complexes

An experimental investigation into the batch ion flotation of cobalt complex anions with the cationic surfactant, cetylpyridinium chloride is described. The concentration ratio of cetyl-pyridinium: cobalt in the foam was determined and found to be 2.0–2.7 for CoCl₂ plus KCN solution and 3.0–3.3 for K₃[Co(CN)₆] solution. Spectroscopic measurements of the former anion show that mainly [Co(CN)₅H₂O]²- anions were floated. The [Co(CN)₆]^3- flotation was established in the presence of Cl^?, Br^?, I^?, CN^?, NO₃^? and SO₄^2- anions. The accelerating influence of the ion flotation produced by the presence of Cl^?, Br^?, I^?, CN^?, NO₃^? and SO₄^2- increased as their partial molal volume increased. The solvent sublation of [Co(CN)₆]^3- anions was established in the presence of these anions.     

Self‐nucleation behaviors of olefinic blocky copolymer/montmorillonite nanocomposites with collapsed and intercalated clay layers

The self‐nucleation behavior of olefinic blocky copolymer (OBC) / organically modified montmorillonite (OMMT) nanocomposites with a novel collapsed clay structure (c‐OMMT) was studied and compared with that of the nanocomposites with an intercalated clay structure (OBC/i‐OMMT). Their behaviors appear different in three temperature domains, Domain I (D_I) in which the polymer is completely melted and only the heterogeneous nuclei are present, Domain II (D_II) in which only self‐nucleation occurs and Domain III (D_III) where both self‐nucleation and annealing take place. As the OMMT loading increases, the boundary temperature of D_I and D_II (T_I→II) shifts to lower temperature and D_II becomes narrower. For the OBC/c‐OMMT nanocomposites, the T_I→II or T_I→III (the boundary temperature of D_I and D_III) can be lower than the end melting temperature ( ) and leads to appearance of a subdomain of D_I, D_I′, in which the self‐nuclei of un‐melted fragmental crystals exist but the following crystallization is still initiated by c‐OMMT. D_II may even disappear at high c‐OMMT loadings. By contrast, the T_I→II of the OBC/i‐OMMT nanocomposites is always approximate to or higher than the . D_II does not disappear and no D_I′ is observed for the OBC/i‐OMMT nanocomposites. The nucleation efficiency of c‐OMMT is also evidently higher than that of i‐OMMT. These results verify that the c‐OMMT has stronger nucleation ability than i‐OMMT at the same OMMT loading. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41771.     

High‐Impact Polyamide Composites with Linear Ethylene–Norbornene Anhydride Copolymers from Insertion Polymerization

Toughening of polyamide 66 with novel linear norbornene anhydride functionalized polyethylenes leads to an impact performance in the Charpy‐notch impact testing at 23 °C and ?30 °C as high as a_CN = 18.0 ± 1.0 and 13.7 ± 0.8 kJ m^?2, respectively, which compares favorably to a state of the art functional low density polyethylene (LDPE) from high‐pressure copolymerization with a Charpy‐notch impact strength of a_CN = 16.8 ± 0.0 and 13.8 ± 2.1 kJ m^?2 at 23 and ?30 °C, respectively. The linear copolymers are obtained by insertion polymerization at mild ethylene pressures of 5 to 15 bars with phosphinesulfonato Pd (II) catalysts, to yield linear copolymers with norbornene anhydride incorporations as high as 4.8 mol% along with a polymer molecular weight of >10⁵ g mol^?1. Furthermore, the norbornene anhydride functionality serves as a reaction site for postpolymerization functionalization with alcohols to obtain the respective half‐ and diesters of the anhydride functionality. Notably, the impact performance is improved with the increase of the alkyl chain length and degree of branching of the ester functionality in the order methanol < n‐butanol < 2‐ethyl hexanol from 10.0 to 13.8 kJ m^?2.     

Synthesis and chemical properties of electrochromic π‐conjugated polyphenylenes with pendant viologen‐TCNQ salts

Polyphenylene (PP) with NH₂ side groups, namely, PFluNH ₂ , was synthesized by the Pd‐catalyzed reaction of 2,5‐dibromoaniline with 9,9‐dihexylfluorene‐2,7‐diboronic acid bis(1,3‐propanediol) ester. The reaction of PFluNH ₂ with 1‐hexyl‐1′‐(2,4‐dinitrophenyl)‐4,4′‐bipyridinium diiodide ( SaltBPy(I^?) ) eliminated 2,4‐dinitroaniline to yield PPs with viologen (1,1′‐disubstituted 4,4′‐bipyridinium dications), PFluBPy(I^?) . The reaction of PFluBPy(I^?) with Li⁺TCNQ ^? resulted in anion exchange between Cl ^? and TCNQ ^? , and yielded PFluBPy(TCNQ^?) . The reaction of PFluBPy(TCNQ^?) with the neutral TCNQ⁰ resulted in an interaction between TCNQ ^? and TCNQ⁰, and yielded PFluBPy(TCNQ^?‐TCNQ⁰) . Cyclic voltammetry measurements suggested that an electrochemical reduction of the viologen moiety and oxidation of the polymer backbone within PFluBPy(TCNQ^?) and PFluBPy(TCNQ^?‐TCNQ⁰) . Furthermore, this reaction was accompanied by electrochromism. The electric conductivities (σ) of the pellets molded from PFluBPy(TCNQ^?) to PFluBPy(TCNQ^?‐TCNQ⁰) were 2.7 × 10 ^{? 4} and 4.2 × 10 ^{? 4} Scm ^{? 1}, respectively; these σ values were higher than that observed for PFluNH ₂ (σ < 10 ^{? 8} Scm ^{? 1}) due to the self‐doping in the polymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Long Residence Times Revealed by Aurora A Kinase‐Targeting Fluorescent Probes Derived from Inhibitors MLN8237 and VX‐689

We report the development of three fluorescent probes for protein kinase Aurora A that are derived from the well‐known inhibitors MLN8237 and VX‐689 (MK‐5108). Two of these probes target the ATP site of Aurora A, and one targets simultaneously the ATP and substrate sites of the kinase. The probes were tested in an assay with fluorescence polarisation/anisotropy readout, and we demonstrated slow association kinetics and long residence time of the probes (k_on 10⁵–10⁷ M ^?1 s^?1, k_off 10^?3–10^?4 s^?1; residence time 500–3000 s). The presence of the Aurora A activator TPX2 caused a significant reduction in the on‐rate and increase in the off‐rate of fluorescent probes targeting ATP site. These observations were supported by Aurora A inhibition assays with MLN8237 and VX‐689. Overall, our results emphasise the importance of rational design of experiments with these compounds and correct interpretation of the obtained data.     

Theoretical investigation of a water‐gas‐shift catalytic membrane for diesel reformate purification

The novel application of a catalytic water‐gas‐shift membrane reactor for selective removal of CO from H₂‐rich reformate mixtures for achieving gas purification solely via manipulation of reaction and diffusion phenomena, assuming Knudsen diffusion regime and the absence of hydrogen permselective materials, is described. An isothermal, two‐dimensional model is developed to describe a tube‐and‐shell membrane reactor supplied with a typical reformate mixture (9% CO, 3% CO₂, 28% H₂, and 15% H₂O) to the retentate volume and steam supplied to the permeate volume such that the overall H₂O:CO ratio within the system is 9:1. Simulations indicate that apparent CO:H₂ selectivities of 90:1 to >200:1 at H₂ recoveries of 20% to upwards of 40% may be achieved through appropriate design of the catalytic membrane and selection of operating conditions. Under these conditions, simulations predict an apparent hydrogen permeability of 2.3 × 10^?10 mol m^?1 Pa, which compares favorably against that of competing hydrogen‐permselective membranes. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4334–4345, 2013     

Synthesis and Crystal Structure Characterization of Oxysilicate Apatites for Stabilization of Sr and Rare‐Earth Elements

Strontium (Sr) containing rare‐earth oxysilicate apatite A^I₄A^II₆(SiO₄)₆O₂ is considered a good matrix to accommodate radionuclide as its cation sites can incorporate lanthanide elements other than Sr. Here, we report a study on the synthesis of Nd₈Sr₂(SiO₄)₆O₂ and Yb₈Sr₂(SiO₄)₆O₂, which adopt P6₃/m apatite symmetry, as well as the characterization of crystallographic structures using X‐ray diffraction and electron microscopy. It is found that A^I position is shared by Nd, Yb and Sr, and A^IO₆ polyhedra are face‐connected, forming column structures, which are linked to SiO₄ tetrahedra, creating continuous channels. The Rietveld refinement shows that Nd and Yb prefer the A^II position in the channel. The twisted angle of adjacent triangle faces in an A^I‐O polyhedron along [001] is a critical parameter to identify the channel volume and its value varies when different cations are incorporated. The twisted angles for Nd‐apatite and Yb are 24.2° and 22.7° The findings provide a new insight into nuclear waste stabilization by apatite‐type structure.     

Metal‐organic framework membrane process for high purity CO2 production

Gas separation by metal‐organic framework (MOF) membranes is an emerging research field. Their commercial application potential is, however, still rarely explored due in part to unsatisfied separation characteristics and difficulty in finding suitable applications. Herein, we report “sharp molecular sieving” properties of high quality isoreticular MOF‐1 (IRMOF‐1) membrane for CO₂ separation from dry, CO₂ enriched CO₂/CH₄, and CO₂/N₂ mixtures. The IRMOF‐1 membranes exhibit CO₂/CH₄ and CO₂/N₂ separation factors of 328 and 410 with CO₂ permeance of 2.55 × 10^?7 and 2.06 × 10^?7 mol m^?2 s^?1 Pa^?1 at feed pressure of 505 kPa and 298 K, respectively. High grade CO₂ is efficiently produced from the industrial or lower grade CO₂ feed gas by this MOF membrane separation process. The demonstrated “sharp molecular sieving” properties of the MOF membranes and their potential application in production of value‐added high purity CO₂ should bring new research and development interest in this field. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3836–3841, 2016     

Electroreduction of hexavalent chromium by polyaniline

BACKGROUND: A plate‐gap model interpretation of enzymatic reaction kinetics and rotating disc voltammetry were applied for evaluation of the nature of the reaction of the electroreduction of Cr(VI) (as dichromate ions) on a polyaniline (PANI)‐modified glassy carbon (GC) electrode. RESULTS: The kinetic parameters (the maximal current (V_max) and Michaelis constant (K_M)) for electroreduction of Cr(VI) on the PANI‐modified GC electrode were determined as V_max = 0.34 × 10^?7 mol cm^?3 s^?1 and K_M = 0.47 × 10^?6 mol cm^?3. The reduction of dichromate is intensified by PANI film growth. CONCLUSION: To characterise the electroreduction of Cr(VI) on a PANI‐modified GC electrode, the kinetic parameters of the reaction were determined using a plate–gap model interpretation of enzymatic reaction kinetics and rotating disc voltammetry. The catalytic nature of Cr(VI) electroreduction on the PANI‐modified electrode has been shown. Copyright © 2009 Society of Chemical Industry     

Non‐dispersive absorption of CO2 in parallel and cross‐flow membrane modules using EMISE

BACKGROUND: This paper reports an analysis of the mass transfer behaviour of CO₂ absorption in hollow fibre membrane modules in parallel and cross‐flow dispositions. The ionic liquid EMISE, 1‐ethyl‐3‐methylimidazolium ethylsulfate, is used to achieve a zero solvent emission process and the experimental results are compared with CO₂ permeation through the membrane, without solvent in the lumenside. RESULTS: Overall mass transfer coefficients K_{overall, CF} = (0.74 ± 0.02) × 10^?6 m s^?1 and K_{overall, PF} = (0.37 ± 0.018) × 10^?6 m s^?1 were obtained for cross‐flow and parallel flow, respectively. These values are one order of magnitude lower than the coefficient obtained in permeability experiments, K_{overall, PERM} = (6.16 ± 0.1) × 10^?6 m s^?1, indicating the influence of the absorption in the process. Including the specific surface and gas volume of each contactor in the analysis, a similar value of a first‐order kinetic rate constant, K_R = 2.7 × 10^?3 s^?1 is obtained, showing that the interfacial chemical reaction CO₂‐ionic liquid is the slow step in the absorption process. CONCLUSION: An interfacial chemical reaction rate constant K_R = 2.7 × 10^?3 s^?1, describes the behaviour of the CO₂ absorption in the ionic liquid EMISE using membrane contactors in parallel and cross‐flow dispositions. Copyright © 2012 Society of Chemical Industry     

Magnetic behavior of polycarbosilazane ?FeII, ?FeIII and mixed‐valence ?FeII–III chloride metallopolymers

Fe^II, Fe^III and mixed‐valence Fe^II–III chlorides were reacted with poly[N,N′‐bis(dimethylsilyl)ethylenedi‐ amine], [? Si(CH₃)₂NHCH₂CH₂NH? ]_n, to form the corresponding Fe‐polycarbosilazane macromolecular complexes. The average chain–chain spacing in these materials was estimated from X‐ray diffraction data and found to be 6.94, 7.29, 7.30 and 7.45 Å in metal‐free and Fe^II? , Fe^III? and Fe^II–III‐containing polycarbosilazanes, respectively. This demonstrates that Fe^II, Fe^III and Fe^II–III chlorides are encapsulated between the polycarbosilazane chains. The chain–chain expansions in the divalent Fe^II and trivalent Fe^III chloride macromolecular complexes are comparable, but less than that in the Fe^II–III chloride analog, which suggests that different chain–chain packings exist in the mixed‐valence macromolecular complex. The magnetic properties of the resulting complexes were investigated by measuring the magnetization in magnetic fields up to 8 kOe and in the temperature range from liquid nitrogen temperature to room temperature. Copyright © 2007 Society of Chemical Industry