FeIII Ions Research Articles

New bidimensional honeycomb CoII–FeIII and brick wall FeII–CoIII cyanido-bridged coordination polymers: Synthesis, crystal structures and magnetic properties

New bidimensional cyanido-bridged heterometallic coordination polymers, [{Co(L1)}3{Fe(CN)6}2]·6CH3OH·6H2O (1) and [{Fe(L2)}3{Co(CN)6}2]·2CH3OH·13H2O (2), have been assembled following a building-block approach (L1 and L2 are macrocyclic ligands obtained by the template condensation between 2,6-diacetylpyridine and 3,4-dioxaoctane-1,8-diamine, and triethylenetetramine, respectively). The crystal structure of 1 consists of honeycomb layers, each [FeIII(CN)6]3− unit connecting three [Co(L1)]2+ nodes through three facial cyanido groups. On the other hand, the self-assembly process between [CoIII(CN)6]3− and [Fe(L2)]2+ ions affords 2-D layers with a brick wall topology. Each [CoIII(CN)6]3− metalloligand is surrounded by three [Fe(L2)]2+ units, which adopt a meridional configuration around the cobalt metalloligand for compound 2. The magnetic properties of the two compounds have been investigated. Compound 1 shows a ferromagnetic order below 3K. The magnetic properties of 2 are characteristic of non-interacting high spin FeII ions, which exhibit a moderate uniaxial magnetic anisotropy (D/kB=−5.5K).

Oxidative treatment of biomass using catalysts based on iron(iii) oxides

The catalyst based on iron(iii) oxides was prepared by hydrolising FeIII salt in water and adding surfactants. The catalyst is active in decomposing H2O2 and accelerates the oxidative destruction of ligno-containing biomass at atmospheric pressure and moderate temperatures of 60–70 °C under the action of H2O2 and O2. The particle size in the initial catalyst is several nanometers. The catalyst activity in decomposition of H2O2 changes nonlinearly and non-monotonically with increasing initial brutto-concentration of the FeIII ions. The catalyst obtained under the optimal conditions decomposes H2O2 as fast as the most active relevant systems do. As the result of thermal-oxidative destruction the biomass (sawdust, peat, olive pulp, straw) is transformed to the low-molecular products of oxidation of lignine, cellulose, lipoproteides, and sugars; the solid residue is represented by cellulose and its derivatives. The yield of solid residue depends on the biomass nature, concentration ratios of the reagents (biomass, catalyst, hydrogen peroxide), and the duration of destruction. On the basis of the data on the rate of peroxide consumption, evolution and transformation of catalyst, and concentration dependences the conclusion was made, that the nanocatalyst based on iron(iii) oxides combined with H2O2 and O2 forms the catalytic system for oxidative destruction of ligno-containing biomass, activity of which depends on the type of organic raw materials and oxidizer.

Magnetite/Bi‐Doped Carboxylate‐Rich Carbon Spheres – A Highly Efficient Magnetic Photocatalyst Based on Dimetallic FeII/FeIII and BiIII/BiIV Photoredox Cycles

AbstractA new magnetically separable visible‐light photocatalyst, magnetite/Bi‐doped carboxylate‐rich carbon spheres (Bi‐MCRCSs), was synthesized under ultrasonic irradiation by using magnetite/carboxylate‐rich carbon spheres (MCRCSs) as a precursor. The Bi‐MCRCSs showed much better photocatalytic activity than MCRCSs in the degradation of methylene blue (MB) under visible‐light irradiation (λ > 420 nm). Compared with MCRCSs, the Bi‐MCRCSs show more intensive photoabsorption in the whole UV and visible region. In particular, Bi‐MCRCSs display a broad absorption band centered at 550 nm, which give Bi‐MCRCSs advantages over MCRCSs in the utilization of visible light for the degradation of organic pollutants. Owing to the Bi3+ doping, the BiIII/BiIV redox cycle can be established in the FeII/FeIII redox cycle system, which result in the establishment of dimetallic FeII/FeIII and BiIII/BiIV photoredox cycles for Bi‐MCRCSs. This dimetallic FeII/FeIII and BiIII/BiIV photoredox cycle possesses a significantly enhanced photocatalytic degradation rate compared to that of the monometallic photocycles of FeII/FeIII for MCRCS. The synergistic effects between the FeII/FeIII cycle and the BiIII/BiIV cycle promote the regeneration of FeII ions in FeII/FeIII cycle and, hence, accelerate the degradation of organic pollutants. In addition, the magnetic saturation (Ms) value is about 20 emu/g. After completion of the reaction, the Bi‐MCRCSs could be rapidly separated under an applied magnetic field.

ESR spectroscopy of FeIII ions in sodium silicate glasses

The state of FeIII ions doped in sodium silicate glasses of the composition (100 − x)Na2O-xSiO2−yFe2O3 (x = 75, 81 mol.%; y = 0.05−13 wt.%) was studied by electron spin resonance (ESR). X-band ESR spectra exhibited three resonance signals at g ≈ 2.0, 4.3, and 6. The computer simulation of ESR spectra was performed on the basis of spin-Hamiltonian of rhombic symmetry. The nature of observed signals was interpreted as a combination of five types of FeIII complexes. Three of them were clustered iron ions and two other were isolated paramagnetic ones. The ratio of observed forms was found for different glass compositions and various total amounts of FeIII ions in a matrix containing 0.55, 2.5, 4, 7, and 13 wt.% of Fe2O3.

Photophysical Properties of a Novel Metalloporphyrin FeBr [TCPP-(CH3)4]·0.5(CH3OH) (TCPP = meso-tetra (4-Carboxyphenyl) Porphyrin)

A new porphyrin FeBr [TCPP-(CH3)4]·0.5(CH3OH) (1), (TCPP = meso-tetra (4-carboxyphenyl) porphyrin), has been synthesized via a solvothermal reaction and characterized by X-ray diffraction. Compound 1 is characterized as an isolated structure with a distorted nonplanar porphyrin macrocycle and an embedded FeIII ion coordinating to four pyrrole nitrogen atoms and one bromine atom. The TCPP is esterified with methanol. The reaction mechanism and photophysical properties were explored.

The Interstellar Sight-Line Towards the M33 Galaxy

We present medium resolution ultraviolet absorption measurements recorded with the HST-COS and FUSE spectrographs towards the Wolf-Rayet star UIT-236 belonging to the BCLMP 99 HII region in the M33 galaxy. We have detected at least 5 major absorption systems along the 840 kpc sight-line to UIT-236 with average gas cloud LSR velocities of -205, -170, -135, -32, and +3 km s-1. The three most negative velocity cloud components, which we associate with gas in the M33 galaxy, have been detected in the line profiles of CII, CII∗,CIII, NI, NII, OI, OVI, SiII, SiII∗, SiIII, SiIV, PII, SII, ArI, FeII, and FeIII ions. These profiles have been fit with absorption models to determine ion column densities for each cloud component. For the case of highly ionized gas components, the observed column density ratios of OVI/SiIV are most compatible with the predictions of ionization by turbulent mixing layers or in a shock driven medium. A possible formation scenario is that the SiIV is formed within a photo-ionized stellar wind bubble that is being driven into surrounding gas that collisionally produces the observed OVI ions. Using the column density ratios of the CII/CII∗ lines, we have determined electron density values in the range 1.8–6.0 cm-3 for the ionized M33 gas clouds. Such values are similar to those found for other ionized interstellar bubbles such as N51D (in the Large Magellanic Cloud), γ2 Vel, and NGC 2244 (the Rosette Nebula). We have carried out a gas phase element abundance analysis of the three cloud components, indicating that C, N, O, Si, P, Ar, Fe, and Ni are all depleted relative to their solar abundance values. This pattern is confirmed by the observed N(OI)/N(HI) column density ratios which suggest a low metallicity for all three of the neutral gas components. The presence of interstellar shocks and expanding supershells of gas driven by stellar wind outflows from stars like UIT-236 may well account for the element depletion values observed along the M33 sight-line.

Structural, Magnetic, and Vibrational Investigations of FeIII Spin‐Crossover Compounds [Fe(4‐MeO–SalEen)2]X with X = NO3– and PF6–

AbstractThe spin‐crossover properties of two spin‐crossover materials [FeIII(4‐MeO–SalEen)2]X (X = NO3–, PF6–, and H–4‐MeO–SalEen = condensation product of 4‐methoxy‐substituted salicylaldehyde and N‐ethylethylenediamine) in the crystalline form were investigated by magnetic and―for the first time at SOLEIL Synchrotron―combined single‐crystal Raman and X‐ray diffraction measurements. The NO3– salt exhibits a spin transition at approximately 78 K with a thermal hysteresis (ΔT = 7.5 K), whereas the PF6– salt shows a progressive spin crossover centered at approximately 225 K. For this latter compound, the reversible curve extracted from the single‐crystal Raman measurements is fully comparable with the magnetic and structural data. The crystal structures were determined at 293, 100, and 50 K (for X = NO3–) and 293 and 106 K (for X = PF6–). It appears from this analysis that the hysteretic behavior of the NO3– salt results from a first‐order isostructural phase transition. The strongly cooperative and bistable behavior of this compound is favored at such a temperature by a 2D network of complexes that communicate through moderate intermolecular interactions. The presence of direct van der Waals contacts that involve the phenolato groups linked to the FeIII ions might influence the ligand‐field strength and the transition temperature. The thermal trapping of the metastable HS phase was magnetically detected, and its relaxation to the LS ground state was observed at approximately 34.5 K. The spin crossover of the PF6– compound was analyzed as the combination of progressive processes that characterize quite similar cations that occupy two crystallographic sites.

Mössbauer spectroscopy monitoring the spin transition of a FeII 1D chain with a fluorinated 4-R-1,2,4-triazole

The spin transition properties of [Fe(fletrz)3](BF4)2•2H2O are described. Fletrz (4-(2’-fluoroethyl)-4H-1,2,4-triazole) is a novel fluorine substituted 1,2,4-triazole ligand which forms 1D chain upon self-assembly with FeII ions. This coordination polymer exhibits reversible abrupt thermochromic spin transition that has been probed by SQUID magnetometry, variable temperature 57Fe Mossbauer spectroscopy (77–300 K) and differential scanning calorimetry (100–300 K).

Iron(II) Complexes Based on π‐Conjugated Terpyridine Ligands with Tetrathiafulvalene or Its Radical Analogue

Two tetrathiafulvalene (TTF) functionalized 2,2′:6′,2″-terpyridine derivatives, 4′-tetrathiafulvalene-2,2′:6′,2″-terpyridine (L1) and 6,6″-dimethyl-4′-tetrathiafulvalene-2,2′:6′,2″-terpyridine (L2), were synthesized and characterized. Based on L1 and L2, four electrochemically active TTF-containing iron(II) complexes, [FeII(L1)2][ClO4]2 (1), [FeII(L1·+)2][ClO4]4 (2), [FeII(L1)2][CF3SO3]2 (3) and [FeII(L2)2][ClO4]2 (4), were successfully obtained. The preparation, spectroscopic and electrochemical properties of these new compounds as well as the crystal structures of complexes 1, 3 and 4 are described. Magnetic studies on 4 (with the ligand L2) suggest that the FeII ion is in the high-spin state. Complex 2 was isolated as an interesting and stable open-shell substance, and the free spin is mainly associated with the TTF radicals, as indicated by EPR, UV/Vis spectra, electrochemical analysis, spectroelectrochemical measurements and XPS spectra. After the oxidation and the formation of the radical cation, the electrical conductivity of 2 is almost 3 orders of magnitude higher than that of 1. DFT and TDDFT calculations provided insight into interpreting the electronic properties of complex 1 and its oxidized states.

Chemical transformation of ferrihydrite coating into green rust followed by Raman and X-ray photoelectron spectroscopies

This study describes the mineralogical transformation of ferrihydrite (Fh) coated on grains of pozzolana into mixed FeII–FeIII sulphated green rust {GR(SO42-)}. The formed GR(SO42-) coating is intended to be used for the reduction of nitrate in batch and column experiments. Raman and X-ray photoelectron spectroscopies (XPS) are used to characterize the pozzolana substrate and the coatings and proved that in the presence of sulphated anions and FeII cations, Fh is transformed into chemically stable sulphated green rust. The Raman spectra exhibit the presence of characteristic bands of sulphated green rust, spectra on which we rely on to interpret the O 1s XPS high resolution spectra which are characterized by a major contribution located around 531.5 eV, in good agreement with the formation of OH− coordinated to FeII and FeIII ions in brucite-like layers of GR. The reduction of nitrate by GR(SO42-) coatings is then investigated from combined solution and solid phases analyses. In agreement with previous studies carried out on bulk mineral, GR(SO42-) coating reduces nitrate into ammonium and is mainly transformed into magnetite.

Redox-Active Ferrocene as a Tuning Functionality for Magnetic Superexchange Interactions of Bis(oxamato) Type Complexes

The reaction of 1,1′-diaminoferrocene with two equivalents of ethyloxalyl chloride in THF afforded the diethyl ester of N,N′-ferrocenylenebis(oxamic acid) (1,1′-fcbaH2Et2, 1). 1 was converted readily to its saponificated form only, namely [nBu4N]2[(1,1′-fcbaH2)] (2), when treated with 4 equiv of [nBu4N]OH followed by the subsequent addition of [Ni(H2O)6]Cl2, whereas [nBu4N]2[Cu(1,1′-fcba)] (3) was obtained in ca. 70% yield by using CuCl2·2H2O. Oxidation of 3 with I2 led to the formation of [nBu4N][Cu(1,1′-fcba)] (4). A combined study of 4 by ESR and 57Fe Mössbauer spectroscopy, supported by DFT calculations, revealed the iron atom of 4 to possess the oxidation state +3. Treatment of 1 with MeNH2 resulted in the exclusive formation of the methyl ester of ferrocenylene-1-(N-methyloxamide)-1′-(oxamic acid) (1,1′-fcooH3Me2, 5). Successive treatment of 5 with [Cu2(OAc)4(H2O)2] and [nBu4N]OH gave rise to the formation of [nBu4N]2[Cu(fcooMe)]·2H2O (6A·2H2O and 6B·2H2O), for which single crystals of the compositions [nBu4N]2[Cu(1,1′-fcooMe)]·1/2MeOH·1/2H2O (6A·1/2MeOH·1/2H2O) and [nBu4N]2[Cu(1,1′-fcooMe)]·2.25H2O (6B·2.25H2O) were grown. Single-crystal X-ray diffraction studies revealed 6A·1/2MeOH·1/2H2O and 6B·2.25H2O to contain [Cu(fcooMe)]2– fragments in the form of two different conformers, having a significant difference in their total energy, as found by DFT calculations. Treatment of 3 and 4, respectively, with [Cu(pmdta)(NO3)2] afforded the tetranuclear complexes [Cu3(1,1′-fcba)(pmdta)2](NO3)n (n = 2 (7), 3 (8)). The solid-state structures of 1–3, 7, and 8 were determined by single-crystal X-ray diffraction studies. The magnetic properties of 3, 4, 7, and 8 were studied by susceptibility measurements versus temperature. For 4 a weak antiferromagnetic coupling between the CuII and FeIII ions has been obtained with J = −2 cm–1, whereas 3 can be understood as a purely paramagnetic, CuII/FeII-containing complex only. For 7 a J parameter of −58 cm–1 has been obtained due to an antiferromagnetic interaction between its CuII ions. This magnetic exchange interaction modifies in 8 to −64 cm–1, and an additional ferromagnetic coupling of 4 cm–1 between the FeIII ion and the central CuII ion is obtained.

High-pressure synthesis and crystal structure of the mixed valent iron borate Fe8B15O28(OH)8

The new mixed valent iron borate Fe8B15O28(OH)8 was synthesized under high-pressure/high-temperature conditions of 12 GPa and 850 °C in a multianvil device (Walker-type module). It crystallizes with four formula units in the tetragonal space group I41/a with the structural parameters a = 1142.3(2) and c = 1537.4(2) pm (V = 2.006(1) nm3, R1 = 0.0586, wR2 = 0.0721 (all data)). Fe8B15O28(OH)8 is composed exclusively from corner-sharing BO4 tetrahedra and can be described as two identical interpenetrating three-dimensional networks that are built up from B11O28 building blocks and interconnecting BO2O(OH) units. The FeII and FeIII ions in FeII5FeIII3B15O28(OH)8 are located in the interspaces between the two networks. 57Fe Mössbauer, Raman, and infrared spectroscopic data are reported.

A Comprehensive Study on Triplesalen‐Based [MnIII6FeIII]3+ and [MnIII6FeII]2+ Complexes: Redox‐Induced Variation of Molecular Magnetic Properties

AbstractThe synthesis and structural, mass spectrometric, FT‐IR, Mössbauer, and UV/Vis spectroscopic, electrochemical, and DC and AC magnetic properties of three [MnIII6FeIII]3+ (short for [{(talen)MnIII3}2{FeIII(CN)6}]3+) compounds {[MnIII6FeIII(MeOH)6]Cl3·11MeOH·H2O (1a), [MnIII6FeIII(MeOH)6]Cl3·3MeOH·H2O (1b), and [MnIII6FeIII(MeOH)6](PF6)2(OAc)·11MeOH (3)} and the one‐electron reduced congener [MnIII6FeII(MeOH)4](BPh4)2·3MeOH·toluene (2) are presented. The half‐wave potential of the FeIII/FeII couple in [MnIII6FeIII/II]3+/2+ is E1/2 = –0.06 V versus Fc/Fc+. The overall molecular structures of the complexes resemble those of the already published [MnIII6Mc]3+ compounds (Mc = CrIII, CoIII, MnIII, FeIII). The [MnIII6FeII]2+ dication, however, exhibits shorter Mn–NC≡N bonds than the tricationic [MnIII6Mc]3+ complexes, as well as a higher degree of aromaticity of the central benzene ring of the triplesalen ligand. The electronic absorption spectrum of [MnIII6FeII]2+ differs considerably from the superimposable spectra of tricationic [MnIII6Mc]3+ complexes in exhibiting lower‐energy ligand field transitions due to stronger π‐donation of the surrounding ligands and weaker absorption features in the 27000–35000 cm–1 region, due to a weaker keto‐enamine character of the central phloroglucinol unit. AC susceptibility measurements indicate single‐molecule magnet (SMM) behavior for 1a and 3. Analysis of the DC magnetic data (μeff vs. T, VTVH) of these compounds by a full‐matrix diagonalization of the spin‐Hamiltonian including isotropic exchange, zero‐field splitting with full consideration of the relative orientation of the D‐tensors, and Zeeman interaction reveals JMn,Mn = –1.00 to –1.15 cm–1 (Ĥex = –2JijŜi·Ŝj), JFe,Mn = +0.50 to +0.80 cm–1, and DMn = –3.5 cm–1. These values are similar to those previously found for [MnIII6FeIII][FeIII(CN)6]. For 2, the simulations indicate very weak antiferromagnetic MnIII–MnIII interactions within the trinuclear triplesalen subunits (JMn,Mn(1) = –0.20 cm–1) as well as across the central diamagnetic FeII ion (JMn,Mn(2,cis) = –0.06 cm–1, JMn,Mn(2,trans) = –0.18 cm–1), whereas DMn = –3.5 cm–1. The JMn,Mn(1) coupling in 2 is much less antiferromagnetic than in the tricationic [MnIII6Mc]3+ compounds; this is interpreted in terms of a stronger ferromagnetic contribution to the exchange interaction due to more efficient spin‐polarization through the central benzene ring, the aromatic nature of which is more pronounced.

A Conserved Tyrosine in Ferritin Is a Molecular Capacitor

A highly conserved tyrosine residue of unknown function is present in the vicinity of the di-iron catalytic center of the ubiquitous iron-storage protein ferritin. The di-iron center with a gateway FeII/FeIII-binding site nearby provides the vital iron-storage mechanism of the protein. It is believed that, in eukaryotic ferritin, this center catalyzes simultaneous oxidation of two FeII ions, whereas in microbial ferritin it catalyzes simultaneous oxidation of three FeII ions. To understand the role of the conserved tyrosine, we studied the intermediates and products that are formed during catalysis of FeII oxidation in the di-iron catalytic centers of the hyperthermophilic archaeal Pyrococcus furiosus ferritin and of eukaryotic human H ferritin. Based on our spectroscopic studies and modeling, we propose a merger of the models for eukaryotic and bacterial ferritin into a common mechanism of FeII oxidation in which the conserved tyrosine acts as a single-electron molecular capacitor to facilitate oxidation of FeII.

Magnetic properties of a family of quinternary oxalates

We report on the magnetic properties of four isomorphous compounds of a family of quinternary oxalates down to 60 mK. In all these materials, the magnetic FeII ions with a strong magneto-crystalline anisotropy form a distorted kagome lattice, topologically equivalent to a perfect kagome one if nearest-neighbor interactions only are considered. All the compounds order at low temperature in an antiferromagnetic arrangement with magnetic moments at 120{\deg}. A remarkable magnetic behavior emerges below the N\'eel temperature in three compounds (with inter-kagome-layer Zr, Sn, Fe but not with Al): the spin anisotropy combined with a low exchange path network connectivity lead to domain walls intersecting the kagome planes through strings of free spins. These produce an unfamiliar slow spin dynamics in the ordered phase observed by AC susceptibility, evolving from exchange-released spin-flips towards a cooperative behavior on decreasing the temperature.

Optimized Synthesis of Fe/N/C Cathode Catalysts for PEM Fuel Cells: A Matter of Iron–Ligand Coordination Strength

It's all in the detail: Highly active Fe/N/C catalysts for the oxygen-reduction reaction in polymer-electrolyte-membrane (PEM) fuel cells can be obtained from a precursor constructed from the zeolitic imidazolate framework ZIF-8 and an iron–ligand complex if, and only if, the displacement of ZnII ions from ZIF-8 by FeII ions is restricted (see picture; TPTZ=2,4,6-tris(2-pyridyl)-s-triazine).

Synthesis, magnetic and spectroscopic characterization of a new Fe7 cluster with a six-pointed star topology

A heptanuclear FeIII7 cluster is reported, prepared from the reaction of [Fe3O(O2CPh)6(H2O)3]+ and a combination of aliphatic aminoalcohol ligands, namely apH (3-amino-1-propanol) and hmpipH (2-hydroxymethyl piperidine). The (apH2)[Fe7O3(OH)3(hmpip)6(O2CPh)7] complex possesses a metal core resembling a metal-centered non-planar six-pointed star. Thermogravimetric analysis was used to monitor the thermal stability of 1, and shows stepwise loss of mass for this complex upon heating, while Mössbauer spectroscopy was used to evaluate the chemical environment of the Fe ions. The latter confirmed the existence of only high-spin FeIII ions in the cluster, as also suggested by X-ray crystallography. Dc and ac magnetic susceptibilities were measured on microcrystalline samples of 1, and the ground state for this cluster was found to be S=21/2, with low lying excited states. Attempts to rationalize the observed spin using two different magnetostructural correlation relationships, previously derived for oxide-bridged FeIII dimers, suggested the presence of spin frustrated pathways along the peripheral hexagon, which in turn produce a high-spin ground state. The observed S=21/2 was finally rationalized using the results of this magnetostructural analysis, and assuming a combination of Si=5/2 and intermediate Si=3/2 spin projections. This Fe7 cluster is the third reported example of a heptanuclear Fe cluster with this topology, featuring a tetrahedral Fe ion at the center, and joins a small family of Fe clusters based on the aliphatic ligands apH and hmpipH.

One new dicoumarol-based fluorescent compound: Synthesis, crystal structure and metal ions recognition

A new dicoumarol-based compound (C6H4)[CH2NHCO(C9O2H4)N(C2H5)2]21 was synthesized and characterized by IR, UV spectroscopy and single-crystal X-ray diffraction analysis. The structure of 1 exhibits a transoid formation with the two coumarin-containing arms sited on the two sides of the center benzene ring. In the crystal packing the molecule further interact with each other and form a three-dimensional framework through π–π stacking interactions and multiform hydrogen bonds. The compound 1 shows the main emission peak at 540nm corresponding to the green hue in the solid state. The fluorescence recognition behaviors for various metal ions were investigated and 1 exhibits a highly fluorescence-quenching selectivity for FeIII ion in the mixed CH3CNH2O solvent.

The activity of acrylic-silicon/nano-TiO2 films for the visible-light degradation of formaldehyde and NO2

Through a novel green and low-cost emulsion blend method, acrylic-silicon/nano-TiO2 films (ASTF) were prepared showing a broad absorption band in the visible light region and could be used for the photodegradation of indoor gaseous pollutants under visible light irradiation. Compared with acrylic-silicon films, the photodegradation rate of ASTF with TiO2 content of 1% (w/v) increased by almost twice for both gaseous formaldehyde (from 28% to 76.7% at the initial concentration of 0.8 mg/m3) and NO2 (from 20% to 68% at the initial concentration of 3.7 mg/m3) under visible light irradiation for 24 h and 50 h, respectively. The binary gas degradation confirmed the higher affinity of NO2 for ASTF. In addition, ASTF with FeⅢ ion doping (<100 mg/L) showed even higher photocatalytic activity with maximum degradation rate of 83.4% for formaldehyde under visible light irradiation for 24 h. ASTF, as a kind of eco-friendly coating material, could be used easily in domestic buildings for our daily life.

Fe(TPT)2/3{MI(CN)2}2]⋅nSolv (MI=Ag, Au): New Bimetallic Porous Coordination Polymers with Spin‐Crossover Properties

Two new heterobimetallic porous coordination polymers with the formula [Fe(TPT)(2/3){M(I)(CN)2}2]⋅nSolv (TPT = [(2,4,6-tris(4-pyridyl)-1,3,5-triazine]; M(I) = Ag (nSolv = 0, 1 MeOH, 2 CH2Cl2), Au (nSolv = 0, 2CH2Cl2)) have been synthesized and their crystal structures were determined at 120 K and 293 K by single-crystal X-ray analysis. These structures crystallized in the trigonal R-3m space group. The Fe(II) ion resides at an inversion centre that defines a [FeN6] coordination core. Four dicyanometallate groups coordinate at the equatorial positions, whilst the axial positions are occupied by the TPT ligand. Each TPT ligand is centred in a ternary axis and bridges three crystallographically equivalent Fe(II) ions, whilst each dicyanometallate group bridges two crystallographically equivalent Fe(II) ions that define a 3D network with the topology of NbO. There are two such networks, which interpenetrate each other, thereby giving rise to large spaces in which very labile solvent molecules are included (CH2Cl2 or MeOH). Crystallographic analysis confirmed the reversible structural changes that were associated with the occurrence of spin-crossover behaviour at the Fe(II) ions, the most significant structural variation being the change in unit-cell volume (about 59 Å(3) per Fe(II) ion). The spin-crossover behaviour has been monitored by means of thermal dependence of the magnetic properties, Mössbauer spectroscopy, and calorimetry.