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[Takayuki Nakane](https://orcid.org/0000-0003-0282-169X), [Takashi Naka](https://orcid.org/0000-0002-0645-6952), Kazuyoshi Sato, [Noriki Terada](https://orcid.org/0000-0002-8676-5586), Pascal Manuel, Ahmed Ibrahim, Shiro Kubuki, Chiya Numako, Dimitry Khalyavin, Anne de Visser, Hiroya Abe

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[Quasi-one-dimensional magnetism of transition metal oxide in Fe-based inorganic–organic hybrid nanosheets](https://mdr.nims.go.jp/datasets/f25c7206-0e07-47dd-ae47-5faa564b04ec)

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Quasi-one-dimensional magnetism of transition-metal oxide in Fe-based inorganic–organic hybrid nanosheets5934 |  J. Mater. Chem. C, 2026, 14, 5934–5941 This journal is © The Royal Society of Chemistry 2026Cite this: J. Mater. Chem. C,2026, 14, 5934Quasi-one-dimensional magnetism of transition-metal oxide in Fe-based inorganic–organic hybridnanosheetsTakayuki Nakane, *a Takashi Naka,ba Kazuyoshi Sato,c Noriki Terada,aPascal Manuel,d Ahmed Ibrahim,e Shiro Kubuki, e Chiya Numako,fDimitry Khalyavin, d Anne de Visserg and Hiroya AbehLow dimensionality provides an exciting research field for investigating quantum effects in functionalmaterials. This work reports a novel quasi one-dimensional (1D) spin system configured in an inorganic–organic hybrid nanosheet. This nanosheet was solvothermally synthesized from FeCl3, CH3COOK, and ethy-lene glycol (C2H6O2) as the solvent. The minimum chemical composition of this hybrid nanosheet isFe7O4.77(C2H4O2)9, and the quantum magnetic properties arise from a quasi-1D spin system of Fe3+. Remark-ably, this quasi-1D antiferromagnetism exhibits a critical temperature at 21 K, implying a relatively low mag-netic fluctuation state compared with an ideal 1D spin system. The unique characteristics of this novelinorganic–organic hybrid nanosheet are therefore considered attractive for tailoring novel low-dimensionalquantum devices.1. IntroductionLow-dimensional materials provide an exciting research platformfor investigating functional quantum phenomena,1–9 such assuperconductivity,1,2 metal–insulator transitions,3 and multistagemagnetic ordering.4 The unique characteristics and potential ofone-dimensional (1D) materials were actively predicted in theearly stages of modern materials science.10–14 However, the fabri-cation of 1D materials and the detection of their distinctivefeatures were challenging, although recent advances in nanotech-nology have drastically boosted this research field.Quantum properties generally arise in nanoscale regions.Consequently, the functional signal from an individual quan-tum region is typically weak. Therefore, the effective alignmentof quantum regions to bundle these weak responses is ofparamount importance for investigating the functionality of1D materials. To address this issue, fabrication techniques ofhybrid nanomaterials have recently come to the fore as effectiveapproaches to tailor novel quantum materials.15–18 A hybridnanomaterial is generally defined as a compound consistingof a nanostructured matrix within a framework of organicmolecules.19,20 Thus, it is not a simple mixture of components;rather, the constituents form an original crystal structure throughchemical bondings.Here, we report the discovery of a novel hybrid material in aprecursor nanosheet used for synthesizing shape-controlledFe3O4 microcrystals.21 The uniqueness of this hybrid nanosheetresides in its quasi-1D properties, displaying a phase transitionthat originates from the distinctive structure of the iron oxidewithin the material. The crystal structure remains to be clarified.This work precisely characterizes this novel hybrid nanosheetinvolving a quasi-1D spin system of Fe3+ (HNS-1DFe).2. Experiments2.1. Synthesis and fundamental characterizationHNS-1DFe was solvothermally synthesized from 0.5 M FeCl3(96.0%, Kanto Chemical: Japan) and 3 M CH3COOK (97.0%,Kishida Chemical: Japan) in dehydrated anhydrous ethyleneglycol (EG: 99.8%, Sigma-Aldrich: USA) as the solvent.21 Thesesolutions were mixed, sealed into a reaction tube with a highallowable inner pressure, and heated at 180 1C for 2 h in an oilbath. After synthesis, the product was extracted, washed threea National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japanb University of the Ryukyus, 1 Senbaru, Nishihara-cho, Nakagami-gun, Okinawa903-0213, Japanc Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japand ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire,OX11 0QX, UKe Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachi-Oji, Tokyo 192-0397,Japanf Graduate School of Science, Chiba University, Chiba 263-8522, Japang University of Amsterdam, Science Park 904, 1098 XH, The Netherlandsh Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, JapanReceived 22nd October 2025,Accepted 8th February 2026DOI: 10.1039/d5tc03791crsc.li/materials-cJournal ofMaterials Chemistry CPAPERhttps://orcid.org/0000-0003-0282-169Xhttps://orcid.org/0000-0001-8255-7811https://orcid.org/0000-0002-6724-7695http://crossmark.crossref.org/dialog/?doi=10.1039/d5tc03791c&domain=pdf&date_stamp=2026-02-16https://rsc.li/materials-cThis journal is © The Royal Society of Chemistry 2026 J. Mater. Chem. C, 2026, 14, 5934–5941 |  5935times with EG using centrifugation under 10 000 G for 10 min,and finally dried for 1 week. This fabrication procedure repro-ducibly yielded a dark yellow nanosheet powder; however, thecolour was slightly different among samples synthesized ondifferent days. Therefore, all evaluations in this study wereconducted using a single sample batch to maintain consistencyin the discussion.The chemical composition of the product HNS-1DFe wasevaluated by inductively coupled plasma optical emissionspectroscopy (ICP-OES: Ultima-2, HORIBA: Japan) and organicelemental analysis (OEA: TruSpec Micro CHN, LECo: USA). Thtthermal stability of HNS-1DFe was verified by thermogravimetricanalysis (TG: TGD-7000RH/SP, ULVAC: Japan) under flowing N2.2.2. Morphology and structural characterizationsThe morphology of HNS-1DFe was observed by field-emissionscanning electron microscopy (FE-SEM: SU-8000, Hitachi High-Tech: Japan), and the crystal structure was verified from field-emission transmission electron microscopy (FE-TEM: JEM-2000F, Japan Electron: Japan) images acquired with an accel-erating voltage of 200 kV.Spectroscopic structural analysis was also carried out usingFourier transform infrared spectroscopy (FT-IR: FT/IR-680 Plus,JASCO: Japan) with the specimen prepared as KBr pellets, andRaman spectroscopy (NanoFinder-1000, Tokyo Instrument:Japan) with a 532 nm excitation laser, respectively. The powderX-ray diffraction (XRD) pattern was measured using a conven-tional diffractometer (MiniFlex-600, RIGAKU: Japan) with copperKa radiation. Powder Neutron diffraction (PND) measurementswere conducted on a long-wavelength diffractometer (WISH, ISISNeutron and Muon Source: UK), which covers long d-spacingvalues up to 100 Å in magnetic and large unit-cell systems.22The main valence state of iron ions and their cationicconfigurations in HNS-1DFe were also evaluated by Fe K-edgeX-ray absorption fine structure (XAS) spectra measured at BL-9A, photon factory, KEK, Japan, using the transmissionmethod. Data processing of the X-ray absorption near-edgestructure (XANES) region and extended X-ray absorption finestructure (EXAFS) region in the XAS spectra was carried outusing the data processing program, ATHENA.23 Measurementsof 57Fe Mössbauer spectra were carried out under constantacceleration mode. A g-ray source of 57Co(Rh) (1.85 GBq,MCo7.124/74/20, Rietverc, verified on 02.12. 2020) was attachedto the transducer, and a-Fe (30 mm thickness, MRA 2.6/30.20)was used as a reference for zero-velocity and velocity-scalecalibration, with the sample placed in front of the proportionalcounter (45431, Niki-Kogei). For the measurements, 40 mg ofthe well-pulverized sample was shaped into a 10 mm diameterpellet and fixed on cellophane tape. The g-ray from the sourcethrough the sample was detected by the proportional counterunder an applied voltage of 2 kV supplied by a high-voltagepower supply (556, ORTEC: USA).2.3. Measurement of physical propertiesThe physical properties of HNS-1DFe were characterized interms of dc-magnetization and specific heat by using aMagnetic Properties Measurement System (MPMS-XL, QuantumDesign: USA) and a Physical Properties Measurement System(PPMS Dynacool, Quantum Design: USA), respectively. The mag-netic contribution of Fe3+ ions in the specific heat, Cmag, wasestimated as Cmag/T = [Cmol – Clattice]/T for HNS-1DFe. Here,Clattice denotes the lattice contribution to the specific heat, andthe estimation procedure is given in the SI (SI-4). Then, themagnetic entropy, Smag(T), was calculated as follows.SmagðTÞ ¼ðTTminCmagTdT (1)here, Tmin E 1.9 K is the lowest experimental temperature. Onthe other hand, the temperature dependence of Cmag, Cmag(T),followed the power law Cmag = d00Ta (aE 3),24 and Cmag(T) was fitto determine the d00 and a values. The d00 serves as a prefactor. Theexponent a is discussed as dmag/n, where dmag is the dimension ofthe spin system and n is an index indicating ferromagnetic (n = 2)or AF (n = 1) interactions between spins.243. Results3.1. Verification of the hybrid structureThe solvothermal synthesis in this study yielded a dark yellowpowder as the product (HNS-1DFe) with each particle innanosheet form (see Fig. 1(a)). Details of this fundamentalcharacterization are described in the SI (SI-1). The HNS-1DFeshows a flake-like morphology with a size of 1–5mm. The thicknessof HNS-1DFe can be estimated from Fig. 1(b) and is about50–100 nm. Compositional analysis for HNS-1DFe revealed theminimum chemical composition as Fe7O4.77(C2H4O2)9. This resultindicates the existence of an organic component, which is addi-tionally verified by spectral analysis. Fig. 1(c) shows FT-IR andRaman spectra of HNS-1DFe and ethylene glycol (EG, C2H6O2)used as the solvent during synthesis. Most of the peaks above800 cm�1 for HNS-1DFe can be assigned to EG, while several finestructures with peak splitting and small shifts in wavenumber arealso observed. The difference between the peaks of HNS-1DFe andFig. 1 Typical characteristics indicating a hybrid structured nanosheet forHNS-1DFe. (a) and (b) Typical SEM images. (c) Raman and FT-IR spectra.These spectra are compared with those of EG. (d) Weight loss measured byTG under heating and cooling procedures in N2.Paper Journal of Materials Chemistry C5936 |  J. Mater. Chem. C, 2026, 14, 5934–5941 This journal is © The Royal Society of Chemistry 2026those of simple EG is attributed to the solidification of EGmolecules.25 For example, absorption bands at around 3700,2900 and 1060 cm�1 are assigned to strong stretching modes ofOH, CH, and C–O, respectively, in the case of liquid-state EG.However, the strong absorbance of the OH stretching-vibration atB3700 cm�1 is diminished in HNS-1DFe. This indicates that HNS-1DFe includes EG-derived organic molecules lacking hydrogenatoms.Fig. 1(d) shows the weight loss of HNS-1DFe as a function ofincreasing and decreasing temperature. The weight loss startsat around 300 1C. This temperature is apparently higher thanthe boiling point of EG (E 198 1C), and it defines the phaseformation point of Fe3O4 from HNS-1DFe.21 These observationslead to the conclusion that EG in HNS-1DFe does not exist as anadsorbed organic molecule but instead forms chemical bondsthat allow its stabilization within the structure.For characterizing the nanostructured matrix in HNS-1DFe,XAS and Mössbauer spectra were measured. The results areshown in Fig. 2. Fig. 2(a) compares the XANES spectrum ofHNS-1DFe with those of a-Fe2O3 and FeAl2O4 measured asreference materials,26 indicating Fe3+ and Fe2+, respectively.Pre-edge peaks observed at around 7115 eV are due to 1s-to-3dforbidden transition of Fe K-edge absorption, and the positionis almost the same for HNS-1DFe and a-Fe2O3. This peakposition is known to depend on the valence state of ironions.27,28 Hence, these data indicate that the valence state ofFe in HNS-1DFe is similar to that in a-Fe2O3 rather thanFeAl2O4. This trend is also identified from the absorption edgeof XANES spectra. The absorption edge of HNS-1DFe is almostidentical to that of a-Fe2O3, which shows that the valence stateof Fe ions are all 3+ with the spin state, S = 5/2, in HNS-1DFe.Mössbauer spectra shown in Fig. 2(b) further support thisobservation; Fe2+ was not identified. Analysis details are givenin SI (SI-2).Fig. 2(c) plots the radial distribution function against theradial distance with respect to the XAS spectra of Fe in HNS-1DFe and in that of a-Fe2O3. For a-Fe2O3, the origin of the firstpeaks (red area) is assigned to Fe–O distances (distances to thenearest-neighbour anions), and that of the second peaks (greenarea) is assigned to Fe–Fe distances (distances to the nearest-neighbour cations). This figure reveals that the radial distancesof Fe–O bonds in a-Fe2O3 are almost the same as those betweenFe and the nearest-neighbour-atom in HNS-1DFe, even thoughthe densities differ. The average distance between Fe and itsnearest-neighbour atoms is clearly shorter than the value inmetallic iron (E2.5 Å)29–31 and in iron-based complexes(E2.0 Å).31–33 Therefore, the nanostructured matrix of HNS-1DFe is inferred to be an iron oxide.3.2. Evaluation of low dimensionality of HNS-1DFeTemperature dependence of the magnetic susceptibility, w(T),of HNS-1DFe is presented in Fig. 3(a) (see also SI-3 in SI). Thefield-cooled (FC) w(T), measured in a field of 10 kOe, shows around maximum at Tmax E 120 K and a kink at around 21 K.The kink is indicative of a magnetic transition, while the broadmaximum at higher temperature suggests magnetic order withlow dimensionality of the spin system.34 Therefore, weattempted to fit the data with 1D and 2D models for antiferro-magnetic (AF) spin systems by applying the Fisher classicalmodel35 and the Lines model,36 respectively, instead of theconventional Curie–Weiss law, which is established for 3DFig. 2 Structural characteristics of HNS-1DFe. (a) XANES spectra of HNS-1DFe, a-Fe2O3 and FeAl2O4 as reference materials. (b) Mössbauer spectrameasured at different temperatures. (c) Relationship between the radialdistance and the radial distribution function calculated from XAS spectra.Fig. 3 Physical properties indicating low-dimensional spin system inHNS-1DFe. (a) Temperature dependence of normalized magneticsusceptibility for 1 mol of Fe3+ (S = 5/2). (b) Temperature dependence ofthe magnetic contribution of Fe3+ ions in the specific heat, divided bytemperature, measured at various applied fields for HNS-1DFe. Inset showsthe field variation of the maximum temperature indicated in the Cmol/Tcurves as TC. (c) Temperature dependence of the magnetic contribution tothe specific heat and the relationship between temperature and themagnetic entropy of HNS-1DFe at 0 Oe. (d) Logarithmic plot of themagnetic contribution in the specific heat used to fit a power law.Journal of Materials Chemistry C PaperThis journal is © The Royal Society of Chemistry 2026 J. Mater. Chem. C, 2026, 14, 5934–5941 |  5937materials. For the Fisher classical model, w(T) of a 1D AFmaterial, w1D(T), was calculated from formulas (2) and (3).w1DðTÞ ¼ Ng2mB2SðS þ 1Þ3kBT� �� ð1þ uÞð1� uÞ� �(2)u ¼ coth2JSðS þ 1ÞkBT� �� kBT2JSðS þ 1Þ (3)On the other hand, the Lines model calculates the w(T) of 2DAF material, w2D(T), by formulas (4) and (5).w2DðTÞ ¼ SðS þ 1Þ Ng2mB23kBT� �� 1þ A3yþ B3y2þ C3y3þ D3y4þ E3y5þ F3y6� ��1 (4)y ¼ kBTJSðS þ 1Þ (5)here, S = 5/2 (Fe3+), g = 2, and the nearest-neighbour exchangeinteraction J/kB is empirically determined as the fitting para-meter. Then, A = 4, B = 1.448, C = 0.228, D = 0.262, E = 0.119, andF = 0.017 are used as the optimized parameters for S = 5/2.36Each fitting processes was conducted for the measured w(T) asw(T) = w1D(T) and w(T) = w2D(T), respectively. Fig. 3(a) shows thatthe 1D model (blue line) provides a better fit than the 2D model(red line), even though a sizeable diamagnetic depression mustbe taken into account. Here, the value of J/kB was determined asJ/kB = �13.6 K to fit the position of Tmax. The magnitude of thediamagnetic shift for HNS-1DFe is quite large and cannot beexplained by the influence of EG molecules. These fitting issuessuggest the existence of an inter-chain interaction, J0, betweenthe 1D chains of the spin system, and the magnetism of HNS-1DFe is more precisely considered as quasi-1D antiferromag-netism. Therefore, we considered the influence of J0 for fittingthe data of w(T). Here, w(T) was taken as the origin of themagnetism of the sample, and M and H were defined as themagnetization of the sample and the applied magnetic field,respectively. That is, w(T) = M/H. On the other hand, w1D(T) isconsidered to be the response to the effective magnetic field,H + lM. Here, l is the molecular field coefficient including thecontribution of J0, and it is expected to be la 0 in the case of J0a 0. In this case, w1D(T) is expressed as w1D(T) = M/(H + lM).These two equations give rise to formula (6).wðTÞ ¼w1DðTÞ1� lw1DðTÞ (6)Fig. 3(a) shows the successful fit by the modified 1D model(orange line) obtained by applying formula (6) with lE �0.6 tow1D(T) with J/kB = �13.6 K. These results indicate quasi-1Dantiferromagnetism with the contribution of J0 in HNS-1DFe.Low dimensionality of the spin system in HNS-1DFe wasalso verified by heat capacity measurements. First, Fig. 3(b)shows the specific heat divided by temperature, Cmol/T. A smallpeak appears at 20.4 K, corresponding to the critical transitiontemperature, TC, in Fig. 3(a). This peak temperature is slightlydepressed by applying a magnetic field (see the inset inFig. 3(b)). Next, the magnetic contribution of Fe3+ ions to thespecific heat, Cmag, is plotted in Fig. 3(c). Remarkably, Cmag(T)exhibits a broad maximum at Tmax E 44 K above the magnetictransition at TC. This indicates that the magnetic degrees offreedom of Fe3+ ions persist at high temperatures, T c TC.Thus, the existence of strong AF spin correlations or low-dimensional spin fluctuations in the spin system is consideredthe origin of the broad maximum in Cmag(T). This point isverified by a theoretical calculation for the 1D AF spin system,38and the computed line is drawn (bold dashed blue line) inFig. 3(c). Here, theoretical calculations reproduce draw theCmag(T) behaviour using formulas (7) and (8). Then, a2 =11.097, a2 = 11.097, a3 = �0.8511, a4 = 0.1799, b1 = 0.0195,b2 = 0.5845, and g = 1.8081 are used as the optimized para-meters for S = 5/2.37CmagðTÞ ¼a2K2 þ a3K3 þ a4K41þ b1K þ b2K2ð Þg (7)K ¼ JSðS þ 1ÞkBT(8)The model curve does not represent the experimental curvewell, and this discrepancy is attributed to the existence of J0between the 1D chains of the spin system in HNS-1DFe.The magnetic entropy, Smag(T), is also plotted in Fig. 3(c). Itis worth noting that Smag(T) reaches a saturation value of Smag =15 J K�1 molFe�1 at temperatures as high as T = 100 K, whichcorresponds well to the theoretically expected value of Sspin =Rln(2S + 1) = 14.9 J K�1 molFe�1 for S = 5/2. This is consistentwith the previous results.On the other hand, the kink at 21 K is remarkable becausesuch a transition phenomenon is not expected for a typical 1DAF spin system.38 This is further evidence of the intrinsicquasi-1D characteristics of the spin system in HNS-1DFe. TheCmag(T) at T { TC is expected to follow a cubic power law,Cmag = d00Ta (aE 3).24 In our case, Cmag(T) follows the power lawCmag = d00T 2.69(1) with d00 = 3.09(7) mJ K�2.69 below 10 K(Fig. 3(d)). The theoretical exponent is discussed as dmag/n,24where dmag is the dimension of the spin system and n is anindex indicating ferromagnetic (n = 2) or AF (n = 1) interactionsbetween spins. That is, the exponent value of a ferromagneticspin system should be 0.5–1.5 and that of a 3D AF systemshould be E3. An exponent value of 2.69(1) is much higherthan 1.5 and clearly lower than 3. This result is in-line with alow-dimensional AF systems with the existence of J0 in the low-temperature phase of HNS-1DFe.3.3. Structural characterization of HNS-1DFeExperimental details and the raw data are presented in SI (SI-5).In Fig. 4(a), the XRD and PND patterns of HNS-1DFe are plottedagainst the lattice distance, d. This figure truncates the extre-mely intense peak observed at d E 8.05 Å in order to focus onother small peaks. There are several sharp peaks in the XRDpattern, which can be assigned to fractional numbers of thePaper Journal of Materials Chemistry C5938 |  J. Mater. Chem. C, 2026, 14, 5934–5941 This journal is © The Royal Society of Chemistry 2026main intense peak considered to originate from the iron oxidematrix (see the red line in Fig. 4(a)). This series of peaks can beindexed as 00l, with a lattice constant of E8.05 Å. On the otherhand, both diffraction patterns display many broad peaks thatcan be attributed to the organic molecules in HNS-1DFe.However, assignment of these peaks is not as easy as that ofthe 00l peaks; hence, HNS-1DFe appears to belong to a crystalsystem with an axial angle a901. Fig. 4(a) shows the position ofthese typical peaks to clarify the characteristic distances inHNS-1DFe.The nanosheet surface of HNS-1DFe was studied by TEMobservation. The most frequently observed surface area isshown in Fig. 4(b), while Fig. 4(c) and the mesophases (specu-lated) between them were also observed in the surroundingregions. Gerber et al. reported a hybrid nanosheet of 1D ironoxide synthesized under similar conditions to those used forHNS-1DFe.39 Their hybrid nanosheet configures zebra arraystructure, in which organic molecules and 1D iron oxide alignalternately along the nanosheet surface. However, our TEMobservation couldn’t find this zebra array structure for HNS-1DFe. Instead, Fig. 4(b), which is a typical TEM image of HNS-1DFe, shows a hexagonal arrangement of atoms, where theobserved atoms are considered to be Fe. The symbolic lengthsdescribed in Fig. 4(b) as d1 and d2 are estimated as 10 and 8 Å,respectively. (Note that it cannot be concluded that theselengths correspond to 8.05 Å and 10.2 Å, obtained from XRDand PND data. The atomic planes with d E 8 Å have anotheratomic plane between them, which will scatter in anti-phase,making the intensity of the reflection at 8 Å zero.) In this case,the distance between two Fe atoms was about 5 Å, significantlylonger than the typical distance (o4 Å) in iron oxides. Addi-tionally, it is much longer than the calculated radial distanceextracted from Fig. 2(c) (E2.8 Å).On the other hand, we were able to observe other views forHNS-1DFe. Fig. 4(c) shows that atoms form short-bond stackingwhile sliding their positions uniformly. In that case, distancesof 8 Å, 14 Å, and 20 Å (E8.05 Å, E13.7 Å, and o22 Å)corresponding to d3, d4, and d5 drawn in Fig. 4(c), respectively.This image is considered to relate to the periodicity of the 1Diron oxide chain.4. Discussion4.1. Low-dimensional structure of iron oxideIn the previous sections we have demonstrated that the spinsystem in HNS-1DFe orders with a quasi-1D nature. This isattributed to the magnetic moments of Fe3+ in the iron oxidematrix. Magnetism in transition-metal oxides is usually mediatedby superexchange interaction; hence a 1D (or quasi-1D) network ofthe chemical bonds between Fe3+ and O2� should structurally existin HNS-1DFe. However, this does not directly indicate the struc-tural low dimensionality of iron oxide matrix in HNS-1DFe. Thissection discusses the structural low dimensionality of HNS-1DFein more detail.This low dimensionality of iron oxide in HNS-1DFe isinferred from the Mössbauer data described in SI (SI-2). Here,the isomer shift, d, of Fe3+ is relatively small (=0.316 mm s�1 at294.2 K) compared to the typical value for Fe3+-based oxides.Based on the general understanding of the analysis of 57FeMössbauer spectra for 3D materials, this small d suggests thatFe3+ in HNS-1DFe locally has a tetrahedral coordination ratherthan an octahedral one. However, this is not common forsimple Fe3+ oxides. In contrast, the small d value is reasonableif the iron oxide matrix has a low-dimensional configurationwith a relatively small number of surrounding anions. Thisresult indicates the structural low dimensionality of iron oxidein HNS-1DFe, since the origin of the magnetism is only Fe3+ inthe case of this material. The Debye temperature, YD, calcu-lated from the Mössbauer spectra also implies this trend. Thecalculated YD of HNS-1DFe is 245 K, consistent with the valueYD = 237 K obtained from the fitting process of Cmol (see SI SI-2and SI-4). These YD values are smaller than those of Fe2O3(300–330 K)40 and suggest weaker bonds around Fe3+ in HNS-1DFe than those in Fe2O3 with a 3D structure.On the other hand, Fig. 2(c) shows that the density of thedistances to the nearest-neighbour cation (assigned as Fe–Fedistances) of Fe3+ in HNS-1DFe is smaller than that in a-Fe2O3.This indicates that the number of surrounding ions is relativelysmall in the case of Fe3+ in HNS-1DFe. This observation is inagreement with the structural low dimensionality of the ironoxide matrix in HNS-1DFe.From these data, we consider that the magnetic low dimen-sionality of HNS-1DFe is strongly correlated with the structuraluniqueness of the 1D iron oxide matrix.4.2. Quasi-1D structure of iron oxideThe preceding section argues for the structural uniqueness ofthe 1D iron oxide matrix in HNS-1DFe. In general, a 1D networkis assumed to be a continuous straight chain structure, andthus of the term ‘‘chain’’ is used to describe the 1D network forclarity. However, some experimental data of HNS-1DFe indicatethe contribution of J0 to overall 1D magnetism. This requiresfurther structural verification for the 1D network of Fe3+ andFig. 4 Structural information relating to the 1D iron oxide matrix in HNS-1DFe. (a) Diffraction patterns plotted against lattice distance, d, of XRD andPND measurements for HNS-1DFe. The PND measurement yielded twopatterns corresponding to different detector set points, enabling collec-tion of a wide range of diffraction data. (b) Typical high-resolution imagesobserved by TEM of the nanosheet surface. (c) TEM image observed in thevicinity of the typical images shown in (b).Journal of Materials Chemistry C PaperThis journal is © The Royal Society of Chemistry 2026 J. Mater. Chem. C, 2026, 14, 5934–5941 |  5939O2�. Therefore, this section examines the structure of the 1Dnetwork.The simplest structural model for the 1D iron oxide is acontinuous straight chain (see the illustration in Fig. 5(a)).However, Fig. 2(c) indicates that the average distance betweenFe3+ and O2� is about 1.55 Å. Then, the average distancebetween Fe3+ and Fe3+ is about 2.8 Å. Therefore, if one calcu-lates a bond angle of Fe–O–Fe bonds, it is about 1291. Thisindicates that the 1D iron oxide in HNS-1DFe is not a straightchain like that shown in Fig. 5(a) but instead has at least azigzag structure. Additionally, the chemical composition ofHNS-1DFe would be expected to be Fe7O7(C2H4O2)9 in the caseof a simple continuous chain. However, the oxygen content ofthe 1D iron oxide in HNS-1DFe is calculated as 4.77, which isconsidered smaller than expected. The oxygen content was notdirectly measured, and thus the accuracy is limited. There is thepossibility that the residual oxygen content is 7 if we measuredit exactly. However, further evidence for a residual oxygencontent of 4.7 comes from considering the isolated 1D ironoxides in the inorganic–organic hybrid structure. For example,atomic ordering as shown in Fig. 5(b) may generate quasi-1Diron oxide with some magnetic frustration, and the chemicalcomposition becomes Fe3O2. The chemical composition ofFe3O2 can correspond to Fe7O4.7 if the Fe content is calculatedas 7, taking into account Fe7O4.77(C2H4O2)9 as the minimumchemical composition of HNS-1DFe. This possibility is there-fore also reasonable for explaining the origin of the phasetransition phenomenon at TC E 21 K, since the quasi-1D ironoxide structure is expected to be more rigid than a simplechain. Fig. 5(b) is a 2D image drawn with 1201 of Fe–O–Febonds, and HNS-1DFe involves organic molecules of EG in thehybrid structure; therefore, the real crystal structure is consid-ered more complex. However, this speculation implies thepossibility that the 1D iron oxides in HNS-1DFe form a quasi-1D structure rather than simple zigzag chains.5. SummaryThis investigation reports the discovery of HNS-1DFe as a novelhybrid nanosheet. Interestingly, the spin system of this mate-rial shows quasi-1D magnetism. This characteristic propertywas carefully verified through several experiments performedindependently, and the obtained results were all consistentwith the proposed structural model.Notably, the results indicate that the iron oxide matrix inHNS-1DFe has the potential to give rise to a phase-transitionphenomenon, since its quasi-1D structure is expected to bemore rigid than a simple 1D straight chain. Transition-metaloxides are widely known as effective platforms for investigatingnovel functional materials. Therefore, the rigid structure of ironoxide in HNS-1DFe is expected to pave the way for tailoring low-dimensional functional properties. HNS-1DFe is a hybrid nano-material, and the hybrid nanomaterial has an advantage forcontrolling the overall structure by arranging the organicmolecules. The potential for tailoring novel functional devicesusing this nanosheet warrants a future detailed investigation ofHNS-1DFe.Author contributionsThe manuscript was written through the contributions of allauthors. T. Nakane, T. Naka and HA contributed equally to thiswork. Material preparations were performed by HA. Funda-mental evaluations were exhibited by HA, T. Nakane and KS.Structural characterization and the analysis were exhibited byT. Nakane, NT, DDK and PM. Measurement of XAS spectra andthe analysis was performed by CN and T. Naka. On the otherhand, evaluation of the magnetism and the analysis was con-ducted by T. Naka and T. Nakane. Specific heat measurementand the analysis was exhibited and analysed by T. Naka andAdV. Mössbauer spectra were collected and analysed by AI andSK. Finally, all authors have approved the final version of themanuscript.Conflicts of interestThe authors declare that they have no competing interest.Data availabilityAll relevant data are within the manuscript and supplementaryinformation (SI). Supplementary information is available. SeeDOI: https://doi.org/10.1039/d5tc03791c.AcknowledgementsThis work was supported by a Grant-in-Aid for the CooperativeResearch Project of Design & Engineering by Joint InverseInnovation for Materials Architecture (DEJI2MA) of the Ministryof Education, Culture, Sports, Science and Technology (MEXT),and JSPS KAKENHI Grant Number (21H01637, 16K13999 and24K08507). This work was conducted with experimental sup-ports of the NIMS Electron Microscopy Unit and the NIMSSurface and Bulk Analysis Unit.References1 D. Jérome, A. Mazaud, M. Ribault and K. Bechgaard, Super-conductivity in a synthetic organic conductor (TMTSF)2PF6,J. Phys., Lett., 1980, 41, L95–L98.2 M. Fujioka, M. Jeem, K. Sato, M. Tanaka, K. Morita,T. Shibuya, K. Takahashi, S. Iwasaki, A. Miura, M. Nagao,Fig. 5 Simplified model of the 1D iron oxide structure in HNS-1DFe. (a)Continuous straight chain model. (b)Modified model with Fe3O2 composition.Paper Journal of Materials Chemistry Chttps://doi.org/10.1039/d5tc03791c5940 |  J. Mater. Chem. C, 2026, 14, 5934–5941 This journal is © The Royal Society of Chemistry 2026S. Demura, H. Sakata, M. Ono, H. Kaiju and J. Nishii,Intercalation on Transition Metal Trichalcogenides via aQuasi-Amorphous Phase with 1D Order, Adv. Funct. Mater.,2023, 33, 2208702.3 F. Kagawa, T. Itou, K. Miyagawa and K. Kanoda, Transportcriticality of the first-order Mott transition in the quasi-two-dimensional organic conductor k-(BEDT-TTF)2Cu[N(CN)2]Cl,Phys. Rev. B: Condens. Matter Mater. Phys., 2004, 69, 64511.4 Y. Shimizu, K. Miyagawa, K. Kanoda, M. Maesato andG. Saito, Spin Liquid State in an Organic Mott Insulatorwith a Triangular Lattice, Phys. Rev. Lett., 2003, 91, 107001.5 A. Ishii and A. Miyasaka, A. Direct detection of circularpolarized light in helical 1D perovskite-based photodiode,Sci. Adv., 2020, 6, eabd3274.6 A. F. Santander-Syro, O. Copie, T. Kondo, F. Fortuna,S. Pailhès, R. Weht, X. G. Qiu, F. Bertran, A. Nicolaou,A. Taleb-Ibrahimi, P. Le Fèvre, G. Herranz, M. Bibes,N. Reyren, Y. Apertet, P. Lecoeur, A. Barthélémy andM. J. Rozenberg, Two-dimensional electron gas with uni-versal subbands at the surface of SrTiO3, Nature, 2011, 469,189–193.7 S. Iijima, Helical microtubules of graphitic carbon, Nature,1991, 354, 56–58.8 H. Ishii, H. Kataura, H. Shiozawa, H. Yoshioka, H. Otsubo,Y. Takayama, T. Miyahara, S. Suzuki, Y. Achiba,M. Nakatake, T. Narimura, M. Higashiguchi, K. Shimada,H. Namatame and M. Taniguchi, Direct observation ofTomonaga–Luttinger-liquid state in carbon nanotubes atlow temperatures, Nature, 2003, 426, 540–544.9 A. K. Geim and K. S. Novoselov, The Rise of Graphene, Nat.Mater., 2007, 6, 183–191.10 S. Tomonaga, Remarks on Bloch’s Method of Sound Wavesapplied to Many-Fermion Problems, Prog. Theor. Phys.,1950, 5, 544–569.11 J. M. Luttinger, An Exactly Soluble Model of a Many-Fermion System, J. Math. Phys., 1963, 4, 1154–1162.12 D. C. Mattis and E. H. Lieb, Exact Solution of a Many-Fermion System and Its Associated Boson Field, J. Math.Phys., 1965, 6, 304–312.13 F. D. M. Haldane, Continuum dynamics of the 1-D Heisen-berg antiferromagnet: Identification with the O(3) nonlinearSigma model, Phys. Lett. A, 1983, 93, 464–468.14 F. D. M. Haldane, Nonlinear Field Theory of Large-SpinHeisenberg Antiferromagnets: Semiclassically QuantizedSolitons of the One-Dimensional Easy-Axis Néel State, Phys.Rev. Lett., 1983, 50, 1153–1156.15 A. Kojima, K. Teshima, Y. Shirai and T. Miyasaka, Organo-metal Halide Perovskites as Visible-Light Sensitizers forPhotovoltaic Cells, J. Am. Chem. Soc., 2009, 131, 6050–6051.16 M. G. Yamada, H. Fujita and M. Oshikawa, Designing KitaevSpin Liquids in Metal-Organic Frameworks, Phys. Rev. Lett.,2017, 119, 057202.17 T. Takenaka, K. Ishihara, M. Roppongi, Y. Miao,Y. Mizukami, T. Makita, J. Tsurumi, S. Watanabe,J. Takeya, M. Yamashita, K. Torizuka, Y. Uwatoko,T. Sasaki, X. Huang, W. Xu, D. Zhu, N. Su, J. G. Cheng,T. Shibauchi and K. Hashimoto, Strongly correlated super-conductivity in a copper-based metal-organic frameworkwith a perfect kagome lattice, Sci. Adv., 2021, 7, eabf3996.18 K. Wang, L. Jin, Y. Gao, A. Liang, B. P. Finkenauer, W. Zhao,Z. Wei, C. Zhu, T. F. Guo, L. Huang and L. Dou, Lead-FreeOrganic�Perovskite Hybrid Quantum Wells for Highly StableLight-Emitting Diodes, ACS Nano, 2021, 15, 6316–6325.19 M. Kondo, T. Yoshitomi, K. Seki, H. Matsuzaka andS. Kitagawa, Three-Dimensional Framework with Channel-ing Cavities for Small Molecules: {[M2(4, 4’-bpy)3(NO3)4]�xH2O}n (M = Co, Ni, Zn), Angew. Chem., Int. Ed. Engl.,1997, 36, 1725–1727.20 H. Li, M. Eddaoudi, T. L. Groy and O. M. Yaghi, EstablishingMicroporosity in Open Metal�Organic Frameworks: Gas Sorp-tion Isotherms for Zn(BDC) (BDC = 1,4-Benzenedicarboxylate),J. Am. Chem. Soc., 1998, 120, 8571–8572.21 H. Abe, T. Naka, K. Sato, K. Suzuki and M. Nakano, Shape-Controlled Syntheses of Magnetite Microparticles and TheirMagnetorheology, Int. J. Mol. Sci., 2019, 20, 3617–3627.22 L. C. Chapon, P. Manuel, P. G. Radaelli, C. Benson,L. Perrott, S. Ansell, N. J. Rhodes, D. Raspino, D. Duxbury,E. Spill and J. Norris, Wish: The new powder and singlecrystal magnetic diffractometer on the second target sta-tion, Neutron News, 2011, 22, 22–25.23 B. Ravel and M. Newville, ATHENA, ARTEMIS, HEPHAES-TUS: data analysis for X-ray absorption spectroscopy usingIFEFFIT, J. Synchrotron. Rad., 2005, 12, 537–541.24 L. J. de Jongh and A. R. Miedema, Experiments on simplemagnetic model systems, Adv. Phys., 1974, 23, 1–260.25 K. Krishman and R. S. Krishman, Raman and InfraredSpectra of Ethylene Glycol, Proc. Indian Acad. Sci. Sect. A,1966, 64, 111–122.26 T. Nakane, S. Ishii, T. Naka and T. Uchikoshi, Influence ofFabrication Conditions on the Structural Characteristicsand the Magnetic Properties of FeAl2O4, J. Am. Ceram.Soc., 2023, 106, 2317–2325.27 M. Wilke, F. Farges, P.-E. Petit, G. E. Brown and F. Martin,Oxidation state and coordination of Fe in minerals: An Fe K-XANES spectroscopic study, Am. Mineral., 2001, 86, 714–730.28 R. Murao, T. Harano, M. Kimura and I.-H. Jung, Thermo-dynamic Modeling of the SFCA Phase Ca2(Fe,Ca)6(Fe,Al,Si)6O20, ISIJ Int., 2018, 58, 259–266.29 N. V. Ershov, Y. A. Babanov and V. R. Galakhov, EXAFS Study ofCrystalline Cu, Ni, and Fe, Phys. Stat. Solidi B, 1983, 117, 749–753.30 P. Srivastava, L. Lemke, H. Wende, R. Chauvistré, N. Haack,K. Baberschke, J. Hunter-Dunn, D. Arvanitis, N. Mårten-sson, A. Ankudinov and J. J. Rehr, Magnetic extended x-rayabsorption fine structure at the L3,2 edges of Fe and Co onCu(001), J. Appl. Phys., 1998, 83, 7025–7027.31 N. Parsai and A. Mishra, Study of XAFS of some Fe com-pounds and determination of first shell radial distance,J. Phys.: Conf. Ser., 1998, 836, 012045.32 V. G. Vlasenko, A. T. Shuvaev, T. I. Nedoseikina,A. L. Nivorozhkin, A. I. Uraev, A. D. Garnovskii andO. Y. Korshunov, EXAFS studies of the novel iron(III) com-plexes with an N/S(Se) chromophore simulating ligandJournal of Materials Chemistry C PaperThis journal is © The Royal Society of Chemistry 2026 J. Mater. Chem. C, 2026, 14, 5934–5941 |  5941environment of the active site of nitrile hydratase,J. Synchrotron Rad., 1999, 6, 406–408.33 Y. T. Chen, K. H. C. Chen and M. Fukuda, DFT Study forEvaluation of the Interraction of Coordinated Molecule toFe(III) in Various Iron(III)Chloride Complexes, J. Comput.Chem. Jpn., 2017, 16, 1–16.34 H. Lu, T. Yamamoto, W. Yoshimune, N. Hayashi,Y. Kobayashi, Y. Ajiro and H. A. Kageyama, Nearly IdealOne-Dimensional S = 5/2 Antiferromagnet FeF3(4,4-bpy)(4,4-bpy =4,4-bipyridyl) with Strong Intrachain Interactions,J. Am. Chem. Soc., 2015, 137, 9804–9807.35 M. E. Fisher, Magnetism in One-Dimensional Systems - TheHeisenberg Model for Infinite Spin, Am. J. Phys., 1964, 32,343–346.36 M. E. Lines, The quadratic-layer antiferromagnet, J. Phys.Chem. Solids, 1970, 31, 101–116.37 T. de Neef, A. J. M. Kuipers and K. Kopinga, Magneticspecific heat of isotropic linear chains for S p 5/2, J. Phys.A: Math., Nucl. Gen., 1974, 7, L171–L175.38 E. Ijing, Beitrag zur Theorie des Ferromagnetismus, Z. Phys.,1925, 31, 253–258.39 O. Gerber, B. P. Pichon, D. Ihiawakrim, I. Florea,S. Moldovan, O. Ersen, D. Begin, J.-M. Grenèche,S. Lemonnier, E. Barraud and S. Begin-Colin, Synthesisengineering of iron oxide raspberry-shaped nanostructures,Nanoscale, 2017, 9, 305–313.40 A. Ibrahim, K. Tani, K. Hashi, B. Zhang, Z. Homonnay,E. Kuzmann, A. Bafti, L. Pavić, S. Krehula, M. Marciuš andS. Kubuki, Debye Temperature Evaluation for SecondaryBattery Cathode of a-SnxFe1�xOOH Nanoparticles Derivedfrom the 57Fe- and 119Sn-Mössbauer Spectra, Int. J. Mol.Sci., 2024, 25, 2488–2513.Paper Journal of Materials Chemistry C