Activation of α-Fe2 O3 for Photoelectrochemical Water Splitting Strongly Enhanced by Low Temperature Annealing in Low Oxygen Containing Ambient.

Photoelectrochemical (PEC) water splitting is a promising method for the conversion of solar energy into chemical energy stored in the form of hydrogen. Nanostructured hematite (α-Fe2 O3 ) is one of the most attractive materials for a highly efficient charge carrier generation and collection due to its large specific surface area and the short minority carrier diffusion length. In the present work, the PEC water splitting performance of nanostructured α-Fe2 O3 is investigated which was prepared by anodization followed by annealing in a low oxygen ambient (0.03 % O2 in Ar). It was found that low oxygen annealing can activate a significant PEC response of α-Fe2 O3 even at a low temperature of 400 °C and provide an excellent PEC performance compared with classic air annealing. The photocurrent of the α-Fe2 O3 annealed in the low oxygen at 1.5 V vs. RHE results as 0.5 mA cm-2 , being 20 times higher than that of annealing in air. The obtained results show that the α-Fe2 O3 annealed in low oxygen contains beneficial defects and promotes the transport of holes; it can be attributed to the improvement of conductivity due to the introduction of suitable oxygen vacancies in the α-Fe2 O3 . Additionally, we demonstrate the photocurrent of α-Fe2 O3 annealed in low oxygen ambient can be further enhanced by Zn-Co LDH, which is a co-catalyst of oxygen evolution reaction. This indicates low oxygen annealing generates a promising method to obtain an excellent PEC water splitting performance from α-Fe2 O3 photoanodes.

Spin-Crossover Phenomenon in Microcrystals and Nanoparticles of a [Fe(2-mpz)2Ni(CN)4] Two-Dimensional Hofmann-Type Polymer: A Detailed Nano-Topographic Study.

The diamagnetic two-dimensional Hofmann-type metal-organic framework [ZnII(2-mpz)2Ni(CN)4] has been successfully synthesized along with its isostructural hysteretic spin-crossover FeII analogue in the form of both bulk microcrystalline powder and nanoparticles. Detailed atomic force microscopy topographic study revealed a nanogrowth relationship between the height and length of the nanoparticle.

Emerging chemical strategies for imprinting magnetism in graphene and related 2D materials for spintronic and biomedical applications.

Graphene, a single two-dimensional sheet of carbon atoms with an arrangement mimicking the honeycomb hexagonal architecture, has captured immense interest of the scientific community since its isolation in 2004. Besides its extraordinarily high electrical conductivity and surface area, graphene shows a long spin lifetime and limited hyperfine interactions, which favors its potential exploitation in spintronic and biomedical applications, provided it can be made magnetic. However, pristine graphene is diamagnetic in nature due to solely sp2 hybridization. Thus, various attempts have been proposed to imprint magnetic features into graphene. The present review focuses on a systematic classification and physicochemical description of approaches leading to equip graphene with magnetic properties. These include introduction of point and line defects into graphene lattices, spatial confinement and edge engineering, doping of graphene lattice with foreign atoms, and sp3 functionalization. Each magnetism-imprinting strategy is discussed in detail including identification of roles of various internal and external parameters in the induced magnetic regimes, with assessment of their robustness. Moreover, emergence of magnetism in graphene analogues and related 2D materials such as transition metal dichalcogenides, metal halides, metal dinitrides, MXenes, hexagonal boron nitride, and other organic compounds is also reviewed. Since the magnetic features of graphene can be readily masked by the presence of magnetic residues from synthesis itself or sample handling, the issue of magnetic impurities and correct data interpretations is also addressed. Finally, current problems and challenges in magnetism of graphene and related 2D materials and future potential applications are also highlighted.

An Isolated Molecule of Iron(II) Phthalocyanin Exhibits Quintet Ground-State: A Nexus between Theory and Experiment.

Iron(II) phthalocyanine (FePc) is an important member of the phthalocyanines family with potential applications in the fields of electrocatalysis, magnetic switching, electrochemical sensing, and phototheranostics. Despite the importance of electronic properties of FePc in these applications, a reliable determination of its ground-state is still challenging. Here we present combined state of the art computational methods and experimental approaches, that is, Mössbauer spectroscopy and Superconducting Quantum Interference Device (SQUID) magnetic measurements to identify the ground state of FePc. While the nature of the ground state obtained with density functional theory (DFT) depends on the functional, giving mostly the triplet state, multi-reference complete active space second-order perturbation theory (CASPT2) and density matrix renormalization group (DMRG) methods assign quintet as the FePc ground-state in gas-phase. This has been confirmed by the hyperfine parameters obtained from 57 Fe Mössbauer spectroscopy performed in frozen monochlorobenzene. The use of monochlorobenzene guarantees an isolated nature of the FePc as indicated by a zero Weiss temperature. The results open doors for exploring the ground state of other metal porphyrin molecules and their controlled spin transitions via external stimuli.

Noncovalent Grafting of a DyIII2 Single-Molecule Magnet onto Chemically Modified Multiwalled Carbon Nanotubes.

While synthetic methods for the grafting of nanoparticles or photoactive molecules onto carbon nanotubes (CNTs) have been developed in the last years, a very limited number of reports have appeared on the grafting of single-molecule magnets (SMMs) onto CNTs. There are many potential causes, mainly focused on the fact that the attachment of molecules on surfaces remains not trivial and their magnetic properties are significantly affected upon attachment. Nevertheless, implementation of this particular type of hybrid material in demanding fields such as spintronic devices makes of utmost importance the investigation of new synthetic protocols for effective grafting. In this paper, we demonstrate a new experimental protocol for the noncovalent grafting of DyIII2 SMM, [Dy2(NO3)2(saph)2(DMF)4], where H2saph = N-salicylidene- o-aminophenol and DMF = N, N-dimethylformamide, onto the surface of functionalized multiwalled CNTs (MWCNTs). We present a simple wet chemical method, followed by an extensive washing protocol, where the cross-referencing of data from high-resolution transmission electron microscopy combined with electron energy loss spectroscopy, conventional magnetic measurements (direct and alternating current), X-ray photoelectron spectroscopy, and Raman spectroscopy was used to investigate the physical properties, chemical nature, and overall magnetic behavior of the resulting hybrids. A key point to the whole synthesis involves the functionalization of MWCNTs with carboxylic groups, which proved to be a powerful strategy for enhancing the ability to process MWCNTs and facilitating the preparation of hybrid composites. While in the majority of analogous hybrid materials the raw carbon material (multiwalled or single-walled nanotubes) is heavily treated to minimize the contribution of contaminant traces of magnetic nanoparticles with important effects on their electronic properties, this method can lead easily to elimination of the largest part of the impurities and provide an effective way to investigate/discriminate the magnetic contribution of the SMM molecules.

Targeted Drug Delivery with Polymers and Magnetic Nanoparticles: Covalent and Noncovalent Approaches, Release Control, and Clinical Studies.

Targeted delivery combined with controlled drug release has a pivotal role in the future of personalized medicine. This review covers the principles, advantages, and drawbacks of passive and active targeting based on various polymer and magnetic iron oxide nanoparticle carriers with drug attached by both covalent and noncovalent pathways. Attention is devoted to the tailored conjugation of targeting ligands (e.g., enzymes, antibodies, peptides) to drug carrier systems. Similarly, the approaches toward controlled drug release are discussed. Various polymer-drug conjugates based, for example, on polyethylene glycol (PEG), N-(2-hydroxypropyl)methacrylamide (HPMA), polymeric micelles, and nanoparticle carriers are explored with respect to absorption, distribution, metabolism, and excretion (ADME scheme) of administrated drug. Design and structure of superparamagnetic iron oxide nanoparticles (SPION) and condensed magnetic clusters are classified according to the mechanism of noncovalent drug loading involving hydrophobic and electrostatic interactions, coordination chemistry, and encapsulation in porous materials. Principles of covalent conjugation of drugs with SPIONs including thermo- and pH-degradable bonds, amide linkage, redox-cleavable bonds, and enzymatically-cleavable bonds are also thoroughly described. Finally, results of clinical trials obtained with polymeric and magnetic carriers are analyzed highlighting the potential advantages and future directions in targeted anticancer therapy.

Doping with Graphitic Nitrogen Triggers Ferromagnetism in Graphene.

Nitrogen doping opens possibilities for tailoring the electronic properties and band gap of graphene toward its applications, e.g., in spintronics and optoelectronics. One major obstacle is development of magnetically active N-doped graphene with spin-polarized conductive behavior. However, the effect of nitrogen on the magnetic properties of graphene has so far only been addressed theoretically, and triggering of magnetism through N-doping has not yet been proved experimentally, except for systems containing a high amount of oxygen and thus decreased conductivity. Here, we report the first example of ferromagnetic graphene achieved by controlled doping with graphitic, pyridinic, and chemisorbed nitrogen. The magnetic properties were found to depend strongly on both the nitrogen concentration and type of structural N-motifs generated in the host lattice. Graphenes doped below 5 at. % of nitrogen were nonmagnetic; however, once doped at 5.1 at. % of nitrogen, N-doped graphene exhibited transition to a ferromagnetic state at ∼69 K and displayed a saturation magnetization reaching 1.09 emu/g. Theoretical calculations were used to elucidate the effects of individual chemical forms of nitrogen on magnetic properties. Results showed that magnetic effects were triggered by graphitic nitrogen, whereas pyridinic and chemisorbed nitrogen contributed much less to the overall ferromagnetic ground state. Calculations further proved the existence of exchange coupling among the paramagnetic centers mediated by the conduction electrons.

Two-Step Spin-Crossover with Three Inequivalent FeII Sites in a Two-Dimensional Hofmann-Type Coordination Polymer.

An unprecedented two-step spin-crossover behavior with the sequence of γHS =1↔γHS =3/4↔γHS =1/4 was observed in two-dimensional Hofmann type coordination polymer [Fe(isoq)2 {Ag(CN)2 }2 ] (isoq=isoquinoline), which resulted from three crystallographically inequivalent FeII sites with distinct transition temperatures.

Colloidal Surface Active Maghemite Nanoparticles for Biologically Safe Cr(VI) Remediation: from Core-Shell Nanostructures to Pilot Plant Development.

The present study is aimed at the exploration of achievable improvements for Cr(VI) ex situ and in situ water remediation by using novel naked colloidal maghemite (γ-Fe2 O3 ) nanoparticles (surface active maghemite nanoparticles, SAMNs). The reliability of SAMNs for Cr(VI) binding and removal was demonstrated, and SAMN@Cr(VI) complex was characterized, as well as the covalent nature of the absorption was unequivocally proved. SAMNs were structurally and magnetically well conserved after Cr(VI) binding. Thus, in consideration of their affinity for Cr(VI) , SAMNs were exploited in a biological model system, mimicking a real in situ application. The assay evidenced a progressive reduction of revertant colonies of Salmonella typhimurium TA100 strain, as maghemite nanoparticles concentration increased, till the complete suppression of Cr(VI) mutagen effect. Finally, an automatic modular pilot system for continuous magnetic removal and recovery of Cr(VI) from water is proposed. SAMNs, thanks to their colloidal, binding, and catalytic properties, represent a promising tool as a reliable nanomaterial for water remediation by Cr(VI) .

Electrocatalytic Nanostructured Ferric Tannates: Characterization and Application of a Polyphenol Nanosensor.

A novel core-shell hybrid nanomaterial composed of peculiar maghemite nanoparticles (surface-active maghemite nanoparticles (SAMNs)) as the core and tannic acid (TA) as the shell was developed by self-assembly of ferric tannates onto the surface of SAMNs by simple incubation in water. The hybrid nanomaterial (SAMN@TA) was characterized by using UV/Vis, FTIR, and Mössbauer spectroscopies, magnetization measurements, and X-ray powder diffraction, which provide evidence of a drastic reorganization of the iron oxide surface upon reaction with TA and the formation of an outer shell that consists of a cross-linked network of ferric tannates. According to a Langmuir isotherm analysis, SAMN@TA offers one of most stable iron complexes of TA reported in the literature to date. Moreover, SAMN@TA was characterized by using electrical impedance spectroscopy, voltammetry, and chronoamperometry. The nanostructured ferric tannate interface showed improved conductivity and selective electrocatalytic activity toward the oxidation of polyphenols. Finally, a carbon-paste electrode modified with SAMN@TA was used for the determination of polyphenols in blueberry extracts by square-wave voltammetry.

Impact of inorganic buffering ions on the stability of Fe(vi) in aqueous solution: role of the carbonate ion.

An iron compound of +6 oxidation state (Fe(VI)O4(2-), Fe(vi)) is a green molecule for various applications (water oxidation catalyst, organic transformation for synthesis, and water remediation agent). However, its use is hindered because of its inherent decay in aqueous solution. This study presents a systematic kinetics investigation of the decay of ferrate(vi) in the presence of inorganic buffering ions (borate, phosphate, and carbonate) at a pH range from 6.0 to 9.0. When the heterogeneous decay of Fe(vi) on ferric products was inhibited by phosphate, detailed kinetic analysis revealed that the carbonate anion enhanced the Fe(vi) decay rate, compared to phosphate and borate ions. The order of the Fe(vi) decay rate under neutral solution conditions was carbonate > phosphate ≥ borate. In alkaline solution, the decay rates of Fe(vi) were similar for the studied buffering ions. The decay of Fe(vi) in the presence of the carbonate ion was described by mixed first- and second-order kinetics and the first-order rate constant (k1') had a linear relationship with the concentration of the carbonate ion at a neutral pH (k1' = 0.023 + 3.54 × [carbonate] L mol(-1) s(-1)). The analysis of the Fe(vi) decay intermediates/products (˙O2(-), H2O2, and O2) suggests similar decay pathways in the presence of different buffering anions. The impact of carbonate ions on the size of the nanoparticles of the Fe(iii) precipitate, the final reduced form of Fe(vi), was studied using transmission electron microscopy, (57)Fe Mössbauer spectroscopy, and magnetization measurements. The results indicated that carbonate ions induce the formation of ultrasmall iron(iii) oxyhydroxide nanoparticles (<5 nm), which apparently contribute to increased decay of Fe(vi) due to their larger specific surface area. The described homogeneous reaction of carbonate with Fe(vi) has important implications in the efficiency of environmental Fe(vi) applications. On the other hand, the observed low reactivity of borate with Fe(vi) demonstrates that borate is the least reactive buffer in studies of Fe(vi) reactivity in neutral solutions.

Synthesis, physical properties and application of the zero-valent iron/titanium dioxide heterocomposite having high activity for the sustainable photocatalytic removal of hexavalent chromium in water.

A magnetic photocatalytic material composed of nanoscale zero-valent iron (nZVI) homogeneously distributed over a mesoporous nanocrystalline TiO2 matrix has been prepared by a multistage chemical process, including sol-gel technique, wet impregnation, and chemical reduction. X-ray powder diffraction and Raman spectroscopy were used for the structural and chemical characterization of the magnetic photocatalyst, while bulk magnetization measurements and scanning/transmission electron microscopy were employed to determine the physical and textural properties of the photocatalyst. The synthesized nZVI@TiO2 photocatalyst shows very high efficiency in the removal of hexavalent chromium, Cr(vi), from water. The degradation rate follows a pseudo-first-order kinetic model. Most importantly, the remarkable efficiency of the photocatalyst is found to be due to the synergistic contributions of both counterparts, nZVI and TiO2, as validated by comparative experiments with neat TiO2 and nZVI@TiO2 under UV-C irradiation and without irradiation. New insights into the mechanism of synergistic degradation of chromium(vi) and suppressed oxidation of nZVI particles in the composite material are proposed and therein discussed.

High-valent iron (Fe(VI), Fe(V), and Fe(IV)) species in water: characterization and oxidative transformation of estrogenic hormones.

This paper presents solid state synthesis and characterization of tetra-oxy iron(iv) and iron(v) species in their salt forms (Na4FeO4-Fe(IV) and K3FeO4-Fe(V)). Stability of the synthesized salts, commonly called ferrates, in water was determined by applying the (57)Fe Mössbauer spectroscopy technique. Within 2 s in water, Fe(IV) converted into Fe(III) while Fe(V) transformed into Fe(VI) and Fe(III) at pH = 8.2. Comparatively, Fe(VI) (bought as K2FeO4) remained stable in aqueous solution during the short time period. The oxidative removal efficiency of the high-valent iron species was then tested against five environmentally important estrogenic hormones (estron (E1), 17-ß-estradiol (E2), estriol (E3), 17-α-ethinylestradiol (EE2), and diethylstibestrol (DES)) in effluent water of a wastewater treatment plant. Three dosages of iron species (1, 10, and 100 mg L(-1)) were applied to the effluent water. An increase in the concentration of dosages enhanced the removal of estrogens. Both Fe(V) and Fe(VI) were effective in degrading estrogens, but Fe(IV) showed limited oxidation capacity to transform estrogens. The oxidized products of the estrogens were analyzed using Raman spectroscopy and high-performance liquid chromatography-mass spectrometry (HPLC-MS) techniques. Results demonstrated the transformation of estrogens into low molecular weight oxygenated compounds such as quinone-like and opened-aromatic ring species. A detailed study on E1 by using excess Fe(VI) showed the mineralization of the parent compound. The results demonstrate great potential of high-valent iron species in the degradation of endocrine disruptor chemicals like estrogens with several superior aspects including fast reactions, complete degradation and/or formation of benign organic species, and environmentally-acceptable iron oxide by-products.

Hysteretic Spin Crossover in Two-Dimensional (2D) Hofmann-Type Coordination Polymers.

Three new two-dimensional (2D) Hofmann-type coordination polymers with general formula [Fe(3-NH2py)2M(CN)4] (3-NH2py = 3-aminopyridine, M = Ni (1), Pd (2), Pt (3)) have been synthesized. Magnetic susceptibility measurements show that they exhibited cooperative spin crossover (SCO) with remarkable hysteretic behaviors. Their hysteresis widths are 25, 37, and 30 K for 1-3, respectively. The single-crystal structure of 1 suggest that the pseudo-octahedral Fe sites are equatorially bridged by [M(CN)4](2-) to form 2D grids and axially coordinated by 3-NH2py ligands. The intermolecular interactions between layers (the offset face-to-face π···π interactions, hydrogen bonds, and weak N(amino)···Ni(II) contacts) together with the covalent bonds bridged by [M(CN)4](2-) units are responsible to the significant cooperativity.

Ferrate(VI)-prompted removal of metals in aqueous media: mechanistic delineation of enhanced efficiency via metal entrenchment in magnetic oxides.

The removal efficiency of heavy metal ions (cadmium(II), Cd(II); cobalt(II), Co(II); nickel(II), Ni(II); copper(II), Cu(II)) by potassium ferrate(VI) (K2FeO4, Fe(VI)) was studied as a function of added amount of Fe(VI) (or Fe) and varying pH. At pH = 6.6, the effective removal of Co(II), Ni(II), and Cu(II) from water was observed at a low Fe-to-heavy metal ion ratio (Fe/M(II) = 2:1) while a removal efficiency of 70% was seen for Cd(II) ions at a high Fe/Cd(II) weight ratio of 15:1. The role of ionic radius and metal valence state was explored by conducting similar removal experiments using Al(III) ions. The unique combination of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), in-field Mössbauer spectroscopy, and magnetization measurements enabled the delineation of several distinct mechanisms for the Fe(VI)-prompted removal of metal ions. Under a Fe/M weight ratio of 5:1, Co(II), Ni(II), and Cu(II) were removed by the formation of MFe2O4 spinel phase and partially through their structural incorporation into octahedral positions of γ-Fe2O3 (maghemite) nanoparticles. In comparison, smaller sized Al(III) ions got incorporated easily into the tetrahedral positions of γ-Fe2O3 nanoparticles. In contrast, Cd(II) ions either did not form the spinel ferrite structure or were not incorporated into the lattic of iron(III) oxide phase due to the distinct electronic structure and ionic radius. Environmentally friendly removal of heavy metal ions at a much smaller dosage of Fe than those of commonly applied iron-containing coagulants and the formation of ferrimagnetic species preventing metal ions leaching back into the environment and allowing their magnetic separation are highlighted.

Efficient synthesis of a maghemite/gold hybrid nanoparticle system as a magnetic carrier for the transport of platinum-based metallotherapeutics.

The preparation and thorough characterization of a hybrid magnetic carrier system for the possible transport of activated platinum-based anticancer drugs, as demonstrated for cisplatin (cis-[Pt(NH3)2Cl2], CDDP), are described. The final functionalized mag/Au-LA-CDDP* system consists of maghemite/gold nanoparticles (mag/Au) coated by lipoic acid (HLA; LA stands for deprotonated form of lipoic acid) and functionalized by activated cisplatin in the form of cis-[Pt(NH3)2(H2O)2]2+ (CDDP*). The relevant techniques (XPS, EDS, ICP-MS) proved the incorporation of the platinum-containing species on the surface of the studied hybrid system. HRTEM, TEM and SEM images showed the nanoparticles as spherical with an average size of 12 nm, while their superparamagnetic feature was proven by 57Fe Mössbauer spectroscopy. In the case of mag/Au, mag/Au-HLA and mag/Au-LA-CDDP*, weaker magnetic interactions among the Fe3+ centers of maghemite, as compared to maghemite nanoparticles (mag), were detected, which can be associated with the non-covalent coating of the maghemite surface by gold. The pH and time-dependent stability of the mag/Au-LA-CDDP* system in different media, represented by acetate (pH 5.0), phosphate (pH 7.0) and carbonate (pH 9.0) buffers and connected with the release of the platinum-containing species, showed the ability of CDDP* to be released from the functionalized nanosystem.

Can zero-valent iron nanoparticles remove waterborne estrogens?

Steroidal estrogens are one of the most challenging classes of hazardous contaminants as they can cause adverse effects to biota in extremely low concentrations. They emerge in both waste waters and surface waters serving as a source of drinking water. Environmental Quality Standards for 17ß-estradiol (E2) and 17α-ethinylestradiol (EE2), promulgated within the EU Water Framework Directive, are 0.4 and 0.035 ng L(-1), respectively. Because nanoscale zero-valent iron (nZVI) particles have been previously used in numerous remediation technologies and have the advantage of possible magnetic separation, interaction of nZVI with E2 and EE2 in water was investigated to assess the potential role of nZVI in removing steroidal estrogens. A mixture of E2 and EE2 dissolved in water was shaken with varying doses of nZVI for 1-5 h. Concentration-dependent removal of the estrogens was observed but removal did not increase significantly with time. Concentrations of the estrogens were determined by HPLC/MS/MS and a biodetection reporter gene assay. Sorption and nonspecific oxygen-mediated oxidation of estrogens were identified as the most probable removal mechanisms. Two independent experiments confirmed that significant decrease of estrogens concentration is achieved when at least 2 g L(-1) of nZVI is applied. The presented study provides insights into the mechanisms of nZVI interaction with steroidal estrogens under aerobic conditions prevailing in currently applied water treatment technologies.

4-aminobenzoic acid-coated maghemite nanoparticles as potential anticancer drug magnetic carriers: a case study on highly cytotoxic Cisplatin-like complexes involving 7-azaindoles.

This study describes a one-pot synthesis of superparamagnetic maghemite-based 4-aminobenzoic acid-coated spherical core-shell nanoparticles (PABA@FeNPs) as suitable nanocomposites potentially usable as magnetic carriers for drug delivery. The PABA@FeNPs system was subsequently functionalized by the activated species (1* and 2*) of highly in vitro cytotoxic cis-[PtCl2(3Claza)2] (1; 3Claza stands for 3-chloro-7-azaindole) or cis-[PtCl2(5Braza)2] (2; 5Braza stands for 5-bromo-7-azaindole), which were prepared by a silver(I) ion assisted dechlorination of the parent dichlorido complexes. The products 1*@PABA@FeNPs and 2*@PABA@FeNPs, as well as an intermediate PABA@FeNPs, were characterized by a combination of various techniques, such as Mössbauer, FTIR and EDS spectroscopy, thermal analysis, SEM and TEM. The results showed that the products consist of well-dispersed maghemite-based nanoparticles of 13 nm average size that represent an easily obtainable system for delivery of highly cytotoxic cisplatin-like complexes in oncological practice.

Fe3O4 nanocrystals tune the magnetic regime of the Fe/Ni molecular magnet: a new class of magnetic superstructures.

A new class of organometallic-inorganic magnetic material was engineered by a sonochemically assisted self-assembly process between magnetite nanoparticles (biogenic Fe3O4, hard constituent) functionalized with isonicotinic acid and a metamagnetic organometallic complex ([Ni(en)2]3[Fe(CN)6]2·3H2O, soft constituent). In such bottom-up methodology, hard and soft counterparts form well-organized microdimensional clusters that showed morphological fingerprints and magnetic behavior clearly distinct from those of the initial building units. In the engineered soft-hard material, the magnetite nanocrystals induced ferromagnetic ordering at room temperature of closer contact layers of [Ni(en)2]3[Fe(CN)6]2·3H2O, thus demonstrating the ability to sensibly modify the [Ni(en)2]3[Fe(CN)6]2·3H2O paramagnetic regime. The magnetic ordering of [Ni(en)2]3[Fe(CN)6]2·3H2O was triggered by the intrinsic local field of the hard magnetic nanocrystals, which resembled, to some extent, the effects promoted by large, external magnetic fields.