Showing papers by "Masaki Takata published in 2010"
TL;DR: The effective selective sorption of dioxygen and nitric oxide is described by a structurally and electronically dynamic porous coordination polymer built from zinc centres and tetracyanoquinodimethane (TCNQ) as a linker.
Abstract: Porous coordination polymers are materials formed from metal ions that are bridged together by organic linkers and that can combine two seemingly contradictory properties-crystallinity and flexibility. Porous coordination polymers can therefore create highly regular yet dynamic nanoporous domains that are particularly promising for sorption applications. Here, we describe the effective selective sorption of dioxygen and nitric oxide by a structurally and electronically dynamic porous coordination polymer built from zinc centres and tetracyanoquinodimethane (TCNQ) as a linker. In contrast to a variety of other gas molecules (C(2)H(2), Ar, CO(2), N(2) and CO), O(2) and NO are accommodated in its pores. This unprecedented preference arises from the concerted effect of the charge-transfer interaction between TCNQ and these guests, and the switchable gate opening and closing of the pores of the framework. This system provides further insight into the efficient recognition of small gas molecules.
293 citations
278 citations
TL;DR: The present method of purification and crystallization of C(60)-based metallofullerenes provides a new C( 60) fullerene material that contains a metal atom that has a unique two-dimensional structure.
Abstract: If the physical properties of C(60) fullerene molecules can be controlled in C(60) products already in use in various applications, the potential for industrial development will be significant. Encapsulation of a metal atom in the C(60) fullerene molecule is a promising way to control its physical properties. However, the isolation of C(60)-based metallofullerenes has been difficult due to their insolubility. Here, we report the complete isolation and determination of the molecular and crystal structure of polar cationic Li@C(60) metallofullerene. The physical and chemical properties of Li@C(60) cation are compared with those of pristine C(60). It is found that the lithium cation is located at off-centre positions in the C(60)-I(h) cage interior and that the [Li(+)@C(60)] salt has a unique two-dimensional structure. The present method of purification and crystallization of C(60)-based metallofullerenes provides a new C(60) fullerene material that contains a metal atom.
240 citations
TL;DR: The existence of two superconductor packings of the same electronically active unit reveals that Tc scales universally in a structure-independent dome-like relationship with proximity to the Mott metal–insulator transition, which is governed by the role of electron correlations characteristic of high-temperature superconducting materials other than fullerides.
Abstract: The crystal structure of a solid controls the interactions between the electronically active units and thus its electronic properties. In the high-temperature superconducting copper oxides, only one spatial arrangement of the electronically active Cu(2+) units-a two-dimensional square lattice-is available to study the competition between the cooperative electronic states of magnetic order and superconductivity. Crystals of the spherical molecular C(60)(3-) anion support both superconductivity and magnetism but can consist of fundamentally distinct three-dimensional arrangements of the anions. Superconductivity in the A(3)C(60) (A = alkali metal) fullerides has been exclusively associated with face-centred cubic (f.c.c.) packing of C(60)(3-) (refs 2, 3), but recently the most expanded (and thus having the highest superconducting transition temperature, T(c); ref. 4) composition Cs(3)C(60) has been isolated as a body-centred cubic (b.c.c.) packing, which supports both superconductivity and magnetic order. Here we isolate the f.c.c. polymorph of Cs(3)C(60) to show how the spatial arrangement of the electronically active units controls the competing superconducting and magnetic electronic ground states. Unlike all the other f.c.c. A(3)C(60) fullerides, f.c.c. Cs(3)C(60) is not a superconductor but a magnetic insulator at ambient pressure, and becomes superconducting under pressure. The magnetic ordering occurs at an order of magnitude lower temperature in the geometrically frustrated f.c.c. polymorph (Neel temperature T(N) = 2.2 K) than in the b.c.c.-based packing (T(N) = 46 K). The different lattice packings of C(60)(3-) change T(c) from 38 K in b.c.c. Cs(3)C(60) to 35 K in f.c.c. Cs(3)C(60) (the highest found in the f.c.c. A(3)C(60) family). The existence of two superconducting packings of the same electronically active unit reveals that T(c) scales universally in a structure-independent dome-like relationship with proximity to the Mott metal-insulator transition, which is governed by the role of electron correlations characteristic of high-temperature superconducting materials other than fullerides.
189 citations
183 citations
TL;DR: A new strategy to achieve a crystalline porous material with the pore surface regularly decorated with highly reactive 'bare' nitrenes that are photonically generated from stable 'dormant' precursors at will is shown.
Abstract: Porous compounds are ubiquitous and indispensable in daily life as adsorbents and catalysts. The discovery of a new porous compound with unique properties based on intrinsic nanosized space and surface functionalities is scientifically and technologically important. However, the functional species used in this context are limited to those that are sufficiently inert to not spoil the porous structures. Here, we show a new strategy to achieve a crystalline porous material with the pore surface regularly decorated with highly reactive 'bare' nitrenes that are photonically generated from stable 'dormant' precursors at will. The bare triplet nitrenes were accessible to and reacted with adsorbed oxygen or carbon monoxide molecules, which showed not only activation of the pore surface, but also a high probability of chemical trapping and conversion of guest molecules by light stimulation on demand.
170 citations
TL;DR: It is shown that, upon one-step hot-pressing with uniaxially stretched Teflon sheets, a polymer brush carrying azobenzene-containing mesogenic side chains self-assembles into a freestanding film, where the polymer backbone aligns homeotropically to the film plane and the side chains align horizontally.
Abstract: Rational molecular design and processing, enabling large-area molecular ordering, are important for creating high-performance organic materials and devices. We show that, upon one-step hot-pressing with uniaxially stretched Teflon sheets, a polymer brush carrying azobenzene-containing mesogenic side chains self-assembles into a freestanding film, where the polymer backbone aligns homeotropically to the film plane and the side chains align horizontally. Such an ordered structure forms through translation of a one-dimensional molecular order of the Teflon sheet and propagates from the interface macroscopically on both sides of the film. The resultant wide-area bimorph configuration allows the polymer film to bend rapidly and reversibly when the azobenzene units are photoisomerized. The combination of polymer brushes with hot-pressing and Teflon sheets provides many possibilities in designing functional soft materials.
152 citations
TL;DR: The successfully obtained Pd-Pt solid-solution nanoparticles with a Pt content of 8-21 atom % had a higher hydrogen-storage capacity than Pd nanoparticles and can be tuned by changing the composition of Pd and Pt.
Abstract: We have achieved the creation of a solid-solution alloy where Pd and Pt are homogeneously mixed at the atomic level, by a process of hydrogen absorption/desorption as a trigger for core (Pd)/shell (Pt) nanoparticles. The structural change from core/shell to solid solution has been confirmed by in situ powder X-ray diffraction, energy dispersive spectra, solid-state 2H NMR measurement, and hydrogen pressure−composition isotherms. The successfully obtained Pd−Pt solid-solution nanoparticles with a Pt content of 8−21 atom % had a higher hydrogen-storage capacity than Pd nanoparticles. Moreover, the hydrogen-storage capacity of Pd−Pt solid-solution nanoparticles can be tuned by changing the composition of Pd and Pt.
143 citations
TL;DR: In this article, a temperature responsive 1-dimensional porous compound (CPL-11) is presented, which changes its structural uniformity in response to ambient temperature, which gives rise to changes in the effective pore size.
Abstract: Selective adsorption, so called “molecular sieving”, is one of the significant functions of porous materials because it can play an important role in separation processes to obtain highly pure gases or petroleum. One of the next outstanding challenges of porous materials is the achievement of controllable “molecular sieving” in response to external environments. Here, we show a new temperature responsive 1-dimensional porous compound (CPL-11) which changes its structural uniformity in response to ambient temperature, which gives rise to changes in the effective pore size. As a result of the structural responsiveness, the seeming adsorption properties of CPL-11 are apparently opposite to conventional porous compounds expected from thermodynamic law, resulting in a highly selective adsorption for O2 compared to Ar. This unexpected adsorption behavior indicates that the adsorption properties can be controlled by changing the channel uniformity of a porous framework depending on the ambient temperature.
86 citations
TL;DR: In this paper, a crystallographic and magnetic phase diagram of SmFeAsO1−xFx is determined as a function of x in terms of temperature based on electrical transport and magnetization, synchrotron powder x-ray diffraction, 57Fe Mossbauer spectra (MS), and 149Sm nuclear resonant forward scattering (NRFS) measurements.
Abstract: A crystallographic and magnetic phase diagram of SmFeAsO1−xFx is determined as a function of x in terms of temperature based on electrical transport and magnetization, synchrotron powder x-ray diffraction, 57Fe Mossbauer spectra (MS), and 149Sm nuclear resonant forward scattering (NRFS) measurements. MS revealed that the magnetic moments of Fe were aligned antiferromagnetically at ~144 K (TN(Fe)). The magnetic moment of Fe (MFe) is estimated to be 0.34 μB/Fe at 4.2 K for undoped SmFeAsO; MFe is quenched in superconducting F-doped SmFeAsO. 149Sm NRFS spectra revealed that the magnetic moments of Sm start to order antiferromagnetically at 5.6 K (undoped) and 4.4 K (TN(Sm)) (x=0.069). Results clearly indicate that the antiferromagnetic (AF) Sm sublattice coexists with the superconducting phase in SmFeAsO1−xFx below TN(Sm), while the AF Fe sublattice does not coexist with the superconducting phase.
77 citations
TL;DR: In this paper, it was shown that the network formation in the glass is governed by the interplay of tetrahedra and polyhedra in PbO-SiO glass and that the distribution of non-network units is inhomogeneous.
Abstract: It is well known that ${\text{PbO-SiO}}_{2}$ exhibits a wide glass formation composition range, up to $90\text{ }\text{mol}\text{ }\mathrm{%}$ PbO. Earlier studies suggest that the existence of ${\text{PbO}}_{3}$ or ${\text{PbO}}_{4}$ structural units, which act like network formers, may be the reason for the wide glass formation range but the structure beyond short-range order is still unclear. Here we found that the network formation in the glass is governed by the interplay of ${\text{SiO}}_{4}$ tetrahedra and ${\text{PbO}}_{x}$ polyhedra ($x=3--5$, $x=4$ is major) as a network former while the distribution of other (non-network) units is inhomogeneous. The inhomogeneous distribution of ${\text{PbO}}_{x}$ polyhedra in the $34\text{ }\text{mol}\text{ }\mathrm{%}$ PbO glass and that of ${\text{SiO}}_{4}$ tetrahedra in the $65\text{ }\text{mol}\text{ }\mathrm{%}$ PbO glass yield a prepeak at $Ql1.5\text{ }{\text{\AA{}}}^{\ensuremath{-}1}$, a sign of a characteristic length of the inhomogeneity in the diffraction patterns. Furthermore, ${\text{PbO-SiO}}_{2}$ glasses contain extraordinarily large amounts of free volume (voids), which cannot be found in conventional binary silicate glasses (network former---network modifier) but only in network-former glasses such as ${\text{SiO}}_{2}$ glass and in its mixtures with another network former such as ${\text{GeO}}_{2}$. We classify ${\text{PbO-SiO}}_{2}$ glass as a ``binary network-former glass'' with large amounts of free volume.
23 Jun 2010
TL;DR: In this article, a high-resolution Debye-Scherrer camera at the RIKEN materials science beamline, BL44B2 of SPring‐8, was designed to be equipped with the hybrid X-ray detector system.
Abstract: In order to visualize molecular interaction by the experimental electrostatic potential analysis we have optimized the optical parameters and developed the high‐resolution Debye‐Scherrer camera at the RIKEN materials science beamline, BL44B2 of SPring‐8. For the purpose the camera was designed to be equipped with the hybrid X‐ray detector system. One is the conventional detector, the imaging plate readout off‐line to carry out high d (interplanar spacing)‐resolution measurements and the other is the CCD detector, which can be operated in a camera at variable distances for high angle‐resolution measurements. In addition we have been developing an in‐situ properties measurement system to visualize the electrostatic interaction completely synchronized with material functions.
06 Jul 2010
TL;DR: In this paper, a large cylindrical camera was installed at the BL02B1/SPring‐8. In conceptual design, the image plate (IP) was selected as the detector, because such IP will not only detect wide range in one shot but also yield reliable data.
Abstract: The investigation of accurate structure at charge density level will not only understand the function mechanism of physical property but also lead to design new functional materials. We have successfully installed large cylindrical camera at the BL02B1/SPring‐8. In conceptual design, the image plate (IP) was selected as the detector, because such IP will not only detect wide range in one shot but also yield reliable data. In commissioning, the performance of this camera demonstrated to be suitable for the direct observation of d‐electron system.
TL;DR: A fan-shaped molecule, carrying hydrogen-bonding amide groups in proximity to its polar aromatic core, self-assembles into a columnar liquid crystalline mesophase, which unprecedentedly possesses a spontaneous macroscopic polarization along the columnar axis.
Abstract: A fan-shaped molecule (2), carrying hydrogen-bonding amide groups in proximity to its polar aromatic core, self-assembles into a columnar liquid crystalline mesophase, which unprecedentedly possesses a spontaneous macroscopic polarization along the columnar axis. Due to its polar nature, the mesophase displays a signal of second harmonic generation (SHG), which disappears on phase transition to an isotropic melt and then retrieves its original intensity on subsequent cooling.
TL;DR: Flash-photolysis time-resolved microwave conductivity measurements, in conjunction with transient absorption spectroscopy, clearly indicate that the nanofiber of 2(Amphi) intrinsically allows for better carrier generation and transport properties than the microfibrous assembly of 2 (Lipo).
Abstract: To tailor organic p/n heterojunctions with molecular-level precision, a rational design strategy using side-chain incompatibility of a covalently connected donor acceptor (D-A) dyad has been successfully carried out. An oligothiophene-perylenediimide dyad, when modified with triethylene glycol side chains at one terminus and dodecyl side chains at the other (2(Amphi)), self-assembles into nanofibers with a long-range D/A heterojunction. In contrast, when the dyad is modified with dodecyl side chains at both termini (214), ill-defined microfibers result. In steady-state measurements using microgap electrodes, a cast film of the nanofiber of 2(Amphi) displays far better photoconducting properties than that of the microfiber of 2(Lipo).. Flash-photolysis time-resolved microwave conductivity measurements, in conjunction with transient absorption spectroscopy, clearly indicate that the nanofiber of 2(Amphi) intrinsically allows for better carrier generation and transport properties than the microfibrous assembly of 2(Lipo).
06 Jul 2010
TL;DR: Submicrometer single crystal diffractometry for highly accurate structure determination was developed using the extremely stable and highly brilliant synchrotron radiation from SPring‐8 as discussed by the authors, which was achieved using a microbeam focusing system and the submicrometers precision low-eccentric goniometer system.
Abstract: Submicrometer single crystal diffractometry for highly accurate structure determination was developed using the extremely stable and highly brilliant synchrotron radiation from SPring‐8. This was achieved using a microbeam focusing system and the submicrometer precision low‐eccentric goniometer system. We demonstrated the structure analyses with 2×2×2 μm3 cytidine, 600×600×300 nm3 BaTiO3, and 1×1×1 μm3 silicon. The observed structure factors of the silicon crystal were in agreement with the structure factors determined by the Pendellosung method and do not require absorption and extinction corrections.
TL;DR: In this paper, two novel coordination polymers, where pzdc is pyrazine-2,3-dicarboxylate and L is 2,7-diazapyrene (CPL-3) and 1,2-azopyridine (cPL-4), have been proposed.
Abstract: Two novel coordination polymers, {[Cu2(pzdc)2L]·mH2O}n where pzdc is pyrazine-2,3-dicarboxylate and L is 2,7-diazapyrene (CPL-3) and 1,2-azopyridine (CPL-4), respectively, having 3D pillared-layer ...
TL;DR: Under appropriate conditions, st(rich)-2 regularly self-assembles, not only in the solid state but also in solution, into nanofibers that eventually give rise to physical gelation of halogenated solvents such as CH(2)Cl(2).
Abstract: Cyclopolymerization of isopropylidene diallylmalonate (1) in CH2Cl2 using as the initiator a crystallographically defined α-diimine Pd(II) complex with a trans-azobenzene strap (trans-3) proceeds stereospecifically to give a cycloolefinic polymer that is rich in threo-disyndiotactic sequences (strich-2; syndiotactic tetrad content = 60% at −10 to 0 °C). Polymer 2, when perfectly threo-disyndiotactic, adopts a “barb”-shaped geometry with its cyclic malonate pendants sticking out alternately up and down along the rigid main chain. Under appropriate conditions, strich-2 regularly self-assembles, not only in the solid state but also in solution, into nanofibers that eventually give rise to physical gelation of halogenated solvents such as CH2Cl2. In sharp contrast, a reference polymer 2 that is rich in threo-diisotactic sequences (itrich-2), which likely adopts a helical geometry, has poor self-assembly capability in solution and neither forms nanofibers nor induces physical gelation of CH2Cl2.
TL;DR: In this article, a multipole model division of overlapping reflection intensities is proposed to limit the spherical-atom bias in structure factors extracted from overlapping powder data using conventional sphericalatom Rietveld refinement, and both the structure factors and derived density are compared with results from ab initio theoretical calculations.
Abstract: Accurate structure factors are extracted from synchrotron powder diffraction data measured on crystalline diamond based on a novel multipole model division of overlapping reflection intensities. The approach limits the spherical-atom bias in structure factors extracted from overlapping powder data using conventional spherical-atom Rietveld refinement. The structure factors are subsequently used for multipole electron-density modelling, and both the structure factors and the derived density are compared with results from ab initio theoretical calculations. Overall, excellent agreement is obtained between experiment and theory, and the study therefore demonstrates that synchrotron powder diffraction can indeed provide accurate structure-factor values based on data measured in minutes with limited sample preparation. Thus, potential systematic errors such as extinction and twinning commonly encountered in single-crystal studies of small-unit-cell inorganic structures can be overcome with synchrotron powder diffraction. It is shown that the standard Hansen-Coppens multipole model is not flexible enough to fit the static theoretical structure factors, whereas fitting of thermally smeared structure factors has much lower residuals. If thermally smeared structure factors (experimental or theoretical) are fitted with a slightly wrong radial model (s(2)p(2) instead of sp(3)) the radial scaling parameters (kappa' parameters) are found to be inadequate and the ;error' is absorbed into the atomic displacement parameter. This directly exposes a correlation between electron density and thermal parameters even for a light atom such as carbon, and it also underlines that in organic systems proper deconvolution of thermal motion is important for obtaining correct static electron densities.
TL;DR: In this article, a structural phase transition at the Fermi level in a triangular lattice with modified triangular lattices was studied and it was found that the electrical resistivity jumps by three orders of magnitude and a gap opens up in the optical conductivity spectrum.
Abstract: A structural phase transition at ${T}_{c}\ensuremath{\sim}130\text{ }\text{K}$ in ${\text{BaV}}_{10}{\text{O}}_{15}$ containing modified ${\text{V}}^{3+}$ $(3{d}^{2})$ triangular lattices was studied. It was found that the electrical resistivity jumps by three orders of magnitude and a gap opens up in the optical conductivity spectrum at ${T}_{c}$. It was also found from synchrotron x-ray powder-diffraction measurement that the trimerization of the V ions occurs below ${T}_{c}$. These results indicate that the orbital ordering of $\text{V}\text{ }{t}_{2g}$ states occurs at ${T}_{c}$ and that induces a charge gap near the Fermi level in the electronic states of ${\text{BaV}}_{10}{\text{O}}_{15}$.
TL;DR: In this paper, a mold with a line pattern was imprinted onto a thin film of poly{2-(perfluorooctyl)ethyl acrylate} with long crystalline fluoroalkyl groups, and the nanoimprinting characteristics of PFA-C8 thin films were investigated.
Abstract: A mold with a line pattern was imprinted onto a thin film of poly{2-(perfluorooctyl)ethyl acrylate} with long crystalline fluoroalkyl groups (PFA-C8), and the nanoimprinting characteristics of PFA-C8 thin films were investigated. It was revealed that nanostructures could be imprinted on PFA-C8 at room temperature because of the weak interaction among the fluoroalkyl groups in crystallites. The nanotextured PFA-C8 film with a line pattern exhibited anisotropic wetting behavior. The anisotropic wetting behavior was attributed to the difference between the energy barriers of wetting in the direction parallel and orthogonal to the lines. Fabricated nanostructures were stable for annealing below its melting point and were stable at room temperature (RT) for several months.
TL;DR: In this article, a flexible microporous coordination polymer, CPL-2 [Cu 2 (pzdc) 2 (bpy)]·(pzhdc = pyrazine-2,3-dicarboxylate; bpy = 4,4'-bipyridine), possessing bellows-shaped one-dimensional channels was measured.
TL;DR: The structural findings suggest that the structural modulation and the site-selective LS → HS excitation are highly correlated.
Abstract: The photo-induced superstructure of polymorph C of trans-[Fe(abpt)2(NCS)2] (abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole) is discovered as a commensurate modulated structure by single-crystal X-ray diffraction under irradiation. The crystal structure at 25 K before the photo-irradiation composed of two crystallographically independent iron molecules, one of which exhibits high spin (HS) state and the other at low spin (LS) state. Under green laser light (λ = 532 nm) irradiation, the LS molecule (Fe1) is found to be excited to a metastable HS state and gives rise to a commensurate tripled superstructure along the c axis. In addition, it is confirmed that this modulation persists until the HS → LS relaxation temperature beyond 52 K. Our structural findings suggest that the structural modulation and the site-selective LS → HS excitation are highly correlated.
TL;DR: In this paper, a single-crystalline thin film of an iridium dioxide polymorph Ir2O4 has been fabricated by the pulsed laser deposition of LixIr 2O4 precursor and the subsequent Li-deintercalation using soft chemistry.
Abstract: Single-crystalline thin film of an iridium dioxide polymorph Ir2O4 has been fabricated by the pulsed laser deposition of LixIr2O4 precursor and the subsequent Li-deintercalation using soft chemistry. Ir2O4 crystallizes in a spinel (AB2O4) without A cations in the tetrahedral site, which is isostructural to λ-MnO2. Ir ions form a pyrochlore sublattice, which is known to give rise to a strong geometrical frustration. This Ir spinel was found to be a narrow gap insulator, in remarkable contrast to the metallic ground state of rutile-type IrO2. We argue that an interplay of a strong spin-orbit coupling and a Coulomb repulsion gives rise to an insulating ground state as in a layered perovskite Sr2IrO4.
TL;DR: Calculations based on the density functional theory revealed that these materials are compound semiconductors with very narrow band gaps.
Abstract: The crystal structures of GeSb(6)Te(10) and GeBi(6)Te(10) were scrutinized using an X-ray powder diffraction method, which revealed that these compounds crystallize in trigonally distorted cubic close-packed structures with a 51-layer period (R3m). Each layer consists of a triangular atomic net; Te atoms occupy their own specific layers, whereas Ge, Sb and Bi atoms are located in the other layers. In these pseudobinary compounds, random atomic occupations of Ge and Sb/Bi are observed and the layers form two kinds of elemental structural blocks by their successive stacking along the c axis. These compounds can be presumed to be isostructural. It is known that the chemical formula of the chalcogenide compounds with the homologous structures found in these pseudobinary systems can be written as (GeTe)(n)(Sb(2)Te(3))(m) or (GeTe)(n)(Bi(2)Te(3))(m) (n, m: integer); the GeSb(6)Te(10) and GeBi(6)Te(10) investigated in this study, which correspond to the case in which n = 1 and m = 3, naturally have 3 x l = 51-layer structures according to a formation rule l = 2n + 5m commonly found in the compounds of these chalcogenide systems (l represents the number of layers in the basic structural unit). Calculations based on the density functional theory revealed that these materials are compound semiconductors with very narrow band gaps.
TL;DR: In this paper, simultaneous measurements of WAXD, SAXS, and Raman spectra have been performed during the water-induced phase transitions of poly(ethylenimine) (PEI).
Abstract: Simultaneous measurements of WAXD, SAXS, and Raman spectra have been performed during the water-induced phase transitions of poly(ethylenimine) (PEI). As is well-known, PEI transforms among four ki...
TL;DR: Glyde et al. as mentioned in this paper presented a study on Access to Major International Facilities (AODF) for the American Physical Society (APS) Committee on International Scientific Affairs.
Abstract: Recently, the American Physical Society (APS) Committee on International Scientific Affairs commissioned a study on Access to Major International Facilities. The study members were Henry Glyde (Chair; University of Delaware), Robert Briber (University of Maryland), and Sunil Sinha (University of California San Diego).
TL;DR: The suppression of magnetic susceptibility with trimerization and the existence of a Curie tail at low temperatures, together with the result of NMR measurement, indicate that the V trimers are spin singlet, whereas the untrimerized V ions have a magnetic moment.
Abstract: We found that in ${A}_{2}{\mathrm{V}}_{13}{\mathrm{O}}_{22}$ ($A=\mathrm{Ba}$, Sr), which contains a trilayer slab of VO in the sodium-chloride structure with periodically missing ions, the trimerization of V ions occurs at 290 K ($A=\mathrm{Ba}$) and 380 K ($A=\mathrm{Sr}$). V trimers form a three-dimensional network, but some V ions remain untrimerized in these compounds. The suppression of magnetic susceptibility with trimerization and the existence of a Curie tail at low temperatures, together with the result of NMR measurement, indicate that the V trimers are spin singlet, whereas the untrimerized V ions have a magnetic moment; i.e., there is a spontaneous separation between nonmagnetic and magnetic ions in the crystal.