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1.
Hysteretic Four‐Step Spin Crossover within a Three‐Dimensional Porous Hofmann‐like Material
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Dr. John E. Clements Dr. Jason R. Price Dr. Suzanne M. Neville Prof. Cameron J. Kepert 《Angewandte Chemie (International ed. in English)》2016,55(48):15105-15109
Materials that display multiple stepped spin crossover (SCO) transitions with accompanying hysteresis present the opportunity for ternary, quaternary, and quinary electronic switching and data storage but are rare in existence. Herein, we present the first report of a four‐step hysteretic SCO framework. Single‐crystal structure analysis of a porous 3D Hofmann‐like material showed long‐range ordering of spin states: HS, HS0.67LS0.33, HS0.5LS0.5, HS0.33LS0.67, and LS. These detailed structural studies provide insight into how multistep SCO materials can be rationally designed through control of host–host and host–guest interactions. 相似文献
2.
Dr. Carlos Bartual‐Murgui Dr. Amal Akou Dr. Helena J. Shepherd Dr. Gábor Molnár Prof. Dr. J. Antonio Real Dr. Lionel Salmon Dr. Azzedine Bousseksou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):15036-15043
A study of the spin‐crossover (SCO) behavior of the tridimensional porous coordination polymer {Fe(bpac)[Pt(CN)4]} (bpac=bis(4‐pyridyl)acetylene) on adsorption of different mono‐ and polyhalobenzene guest molecules is presented. The resolution of the crystal structure of {Fe(bpac)[Pt(CN)4]} ? G (G=1,2,4‐trichlorobenzene) shows preferential guest sites establishing π???π stacking interactions with the host framework. These host–guest interactions may explain the relationship between the modification of the SCO behavior and both the chemical nature of the guest molecule (electronic factors) and the number of adsorbed molecules (steric factors). 相似文献
3.
《Angewandte Chemie (International ed. in English)》2017,56(20):5465-5470
A major challenge is the development of multifunctional metal–organic frameworks (MOFs), wherein magnetic and electronic functionality can be controlled simultaneously. Herein, we rationally construct two 3D MOFs by introducing the redox active ligand tetra(4‐pyridyl)tetrathiafulvalene (TTF(py)4) and spin‐crossover FeII centers. The materials exhibit redox activity, in addition to thermally and photo‐induced spin crossover (SCO). A crystal‐to‐crystal transformation induced by I2 doping has also been observed and the resulting intercalated structure determined. The conductivity could be significantly enhanced (up to 3 orders of magnitude) by modulating the electronic state of the framework via oxidative doping; SCO behavior was also modified and the photo‐magnetic behavior was switched off. This work provides a new strategy to tune the spin state and conductivity of framework materials through guest‐induced redox‐state switching. 相似文献
4.
Yonghwi Kim Dr. Sunirban Das Saurav Bhattacharya Soonsang Hong Dr. Min Gyu Kim Dr. Minyoung Yoon Prof. Dr. Srinivasan Natarajan Prof. Dr. Kimoon Kim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(52):16642-16648
A porous metal–organic framework, Mn(H3O)[(Mn4Cl)3(hmtt)8] (POST‐65), was prepared by the reaction of 5,5′,10,10′,15,15′‐hexamethyltruxene‐2,7,12‐tricarboxylic acid (H3hmtt) with MnCl2 under solvothermal conditions. POST‐65(Mn) was subjected to post‐synthetic modification with Fe, Co, Ni, and Cu according to an ion‐exchange method that resulted in the formation of three isomorphous frameworks, POST‐65(Co/Ni/Cu), as well as a new framework, POST‐65(Fe). The ion‐exchanged samples could not be prepared by regular solvothermal reactions. The complete exchange of the metal ions and retention of the framework structure were verified by inductively coupled plasma–atomic emission spectrometry (ICP‐AES), powder X‐ray diffraction (PXRD), and Brunauer–Emmett–Teller (BET) surface‐area analysis. Single‐crystal X‐ray diffractions studies revealed a single‐crystal‐to‐single‐crystal (SCSC)‐transformation nature of the ion‐exchange process. Hydrogen‐sorption and magnetization measurements showed metal‐specific properties of POST‐65. 相似文献
5.
Chemical Engineering of Photoactivity in Heterometallic Titanium–Organic Frameworks by Metal Doping
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Dr. Neyvis Almora‐Barrios Dr. Josep Albero Dr. A. Rabdel Ruiz‐Salvador Dr. Javier González‐Platas Prof. Hermenegildo García Dr. Carlos Martí‐Gastaldo 《Angewandte Chemie (International ed. in English)》2018,57(28):8453-8457
We report a new family of titanium–organic frameworks that enlarges the limited number of crystalline, porous materials available for this metal. They are chemically robust and can be prepared as single crystals at multi‐gram scale from multiple precursors. Their heterometallic structure enables engineering of their photoactivity by metal doping rather than by linker functionalization. Compared to other methodologies based on the post‐synthetic metallation of MOFs, our approach is well‐fitted for controlling the positioning of dopants at an atomic level to gain more precise control over the band‐gap and electronic properties of the porous solid. Changes in the band‐gap are also rationalized with computational modelling and experimentally confirmed by photocatalytic H2 production. 相似文献
6.
Civan Avci Javier Ariñez‐Soriano Dr. Arnau Carné‐Sánchez Dr. Vincent Guillerm Dr. Carlos Carbonell Dr. Inhar Imaz Prof. Dr. Daniel Maspoch 《Angewandte Chemie (International ed. in English)》2015,54(48):14417-14421
Controlling the shape of metal–organic framework (MOF) crystals is important for understanding their crystallization and useful for myriad applications. However, despite the many advances in shaping of inorganic nanoparticles, post‐synthetic shape control of MOFs and, in general, molecular crystals remains embryonic. Herein, we report using a simple wet‐chemistry process at room temperature to control the anisotropic etching of colloidal ZIF‐8 and ZIF‐67 crystals. Our work enables uniform reshaping of these porous materials into unprecedented morphologies, including cubic and tetrahedral crystals, and even hollow boxes, by an acid–base reaction and subsequent sequestration of leached metal ions. Etching tests on these ZIFs reveal that etching occurs preferentially in the crystallographic directions richer in metal–ligand bonds; that, along these directions, the etching rate tends to be faster on the crystal surfaces of higher dimensionality; and that the etching can be modulated by adjusting the pH of the etchant solution. 相似文献
7.
Sequential Transformation of Zirconium(IV)‐MOFs into Heterobimetallic MOFs Bearing Magnetic Anisotropic Cobalt(II) Centers
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Dr. Shuai Yuan Dr. Jun‐Sheng Qin Jian Su Dr. Bao Li Jialuo Li Wenmiao Chen Hannah F. Drake Dr. Peng Zhang Dr. Daqiang Yuan Prof. Dr. Jinglin Zuo Prof. Dr. Hong‐Cai Zhou 《Angewandte Chemie (International ed. in English)》2018,57(38):12578-12583
Heterometallic metal–organic frameworks (MOFs) allow the precise placement of various metals at atomic precision within a porous framework. This new level of control by MOFs promises fascinating advances in basic science and application. However, the rational design and synthesis of heterometallic MOFs remains a challenge due to the complexity of the heterometallic systems. Herein, we show that bimetallic MOFs with MX2(INA)4 moieties (INA=isonicotinate; M=Co2+ or Fe2+; X=OH?, Cl?, Br?, I?, NCS?, or NCSe?) can be generated by the sequential modification of a Zr‐based MOF. This multi‐step modification not only replaced the linear organic linker with a square planar MX2(INA)4 unit, but also altered the symmetry, unit cell, and topology of the parent structure. Single‐crystal to single‐crystal transformation is realized so that snapshots for transition process were captured by successive single‐crystal X‐ray diffraction. Furthermore, the installation of Co(NCS)2(INA)4 endows field‐induced slow magnetic relaxation property to the diamagnetic Zr‐MOF. 相似文献
8.
Single Crystal to Single Crystal (SC‐to‐SC) Transformation from a Nonporous to Porous Metal–Organic Framework and Its Application Potential in Gas Adsorption and Suzuki Coupling Reaction through Postmodification
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Dr. Rupam Sen Debraj Saha Dr. Subratanath Koner Dr. Paula Brandão Dr. Zhi Lin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5962-5971
A new amino‐functionalized strontium–carboxylate‐based metal–organic framework (MOF) has been synthesized that undergoes single crystal to single crystal (SC‐to‐SC) transformation upon desolvation. Both structures have been characterized by single‐crystal X‐ray analysis. The desolvated structure shows an interesting 3D porous structure with pendent ?NH2 groups inside the pore wall, whereas the solvated compound possesses a nonporous structure with DMF molecules on the metal centers. The amino group was postmodified through Schiff base condensation by pyridine‐2‐carboxaldehyde and palladium was anchored on that site. The modified framework has been utilized for the Suzuki cross‐coupling reaction. The compound shows high activity towards the C?C cross‐coupling reaction with good yields and turnover frequencies. Gas adsorption studies showed that the desolvated compound had permanent porosity and was microporous in nature with a BET surface area of 2052 m2 g?1. The material also possesses good CO2 (8 wt %) and H2 (1.87 wt %) adsorption capabilities. 相似文献
9.
Rui Yang Lei Li Ying Xiong Dr. Jian‐Rong Li Prof. Dr. Hong‐Cai Zhou Prof. Dr. Cheng‐Yong Su 《化学:亚洲杂志》2010,5(11):2358-2368
Assembly of copper(I) halide with a new tripodal ligand, benzene‐1,3,5‐triyl triisonicotinate (BTTP4), afforded two porous metal–organic frameworks, [Cu2I2(BTTP4)]?2 CH3CN ( 1? 2 CH3CN) and [CuBr(BTTP4)]?(CH3CN ? CHCl3 ? H2O) ( 2? solvents), which have been characterized by IR spectroscopy, thermogravimetry (TG), single‐crystal, and powder X‐ray diffraction (PXRD) methods. Compound 1.CH3CN is a polycatenated 3D framework that consists of 2D (6,3) networks through inclined catenation, whereas 2 is a doubly interpenetrated 3D framework possessing the ThSi2‐type ( ths ) (10,3)‐b topology. Both frameworks contain 1D channels of effective sizes 9×12 and 10×10 Å2, which amounts to 43 and 40 % space volume accessible for solvent molecules, respectively. The TG and variable‐temperature PXRD studies indicated that the frameworks can be completely evacuated while retaining the permanent porosity, which was further verified by measurement of the desolvated complex [Cu2I2(BTTP4)] ( 1′ ). The subsequent guest‐exchange study on the solvent‐free framework revealed that various solvent molecules can be adsorbed through a single‐crystal‐to‐single‐crystal manner, thus giving rise to the guest‐captured structures [Cu2I2(BTTP4)]?C6H6 ( 1.benzene ), [Cu2I2(BTTP4)]?2 C7H8 ( 1.2toluene ), and [Cu2I2(BTTP4)]?2 C8H10 ( 1.2ethyl benzene ). The gas‐adsorption investigation disclosed that two kinds of frameworks exhibited comparable CO2 storage capacity (86–111 mL g?1 at 1 atm) but nearly none for N2 and H2, thereby implying its separation ability of CO2 over N2 and H2. The vapor‐adsorption study revealed the preferential inclusion of aromatic guests over nonaromatic solvents by the empty framework, which is indicative of selectivity toward benzene over cyclohexane. 相似文献
10.
Konrad Hindelang Alexander Kronast Dr. Sergei I. Vagin Prof. Bernhard Rieger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(25):8244-8252
For the first time, the adaptability of the C?C double bond as a versatile precursor for the postsynthetic modification (PSM) of microporous materials was extensively investigated and evaluated. Therefore, an olefin‐tagged 4,4′‐bipyridine linker was synthesized and successfully introduced as pillar linker within a 9,10‐triptycenedicarboxylate (TDC) zinc paddle‐wheel metal–organic framework (MOF) through microwave‐assisted synthesis. Different reactions, predominately used in organic chemistry, were tested, leading to the development of new postsynthetic reactions for the functionalization of solid materials. The postsynthetic oxidation of the olefin side groups applying osmium tetroxide (OsO4) as a catalyst led to the formation of a microporous material with free vicinal diol functionalities. The epoxidation with dimethyldioxirane (DMDO) enabled the synthesis of epoxy‐functionalized MOFs. In addition to that, reaction procedures for a postsynthetic hydroboration with borane dimethyl sulfide as well as a photoinduced thiol–ene click reaction with ethyl mercaptan were developed. For all of these PSMs, yields of more than 90 % were obtained, entirely maintaining the crystallinity of the MOFs. Since the direct introduction of the corresponding groups by means of pre‐synthetic approaches is hardly possible, these new PSMs are useful tools for the functionalization of porous solids towards applications such as selective adsorption, separation, and catalysis. 相似文献
11.
Complete Transmetalation in a Metal–Organic Framework by Metal Ion Metathesis in a Single Crystal for Selective Sensing of Phosphate Ions in Aqueous Media
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K S Asha Rameswar Bhattacharjee Dr. Sukhendu Mandal 《Angewandte Chemie (International ed. in English)》2016,55(38):11528-11532
A complete transmetalation has been achieved on a barium metal–organic framework (MOF), leading to the isolation of a new Tb‐MOF in a single‐crystal (SC) to single‐crystal (SC) fashion. It leads to the transformation of an anionic framework with cations in the pore to one that is neutral. The mechanistic studies proposed a core–shell metal exchange through dissociation of metal–ligand bonds. This Tb‐MOF exhibits enhanced photoluminescence and acts as a selective sensor for phosphate anion in aqueous medium. Thus, this work not only provides a method to functionalize a MOF that can have potential application in sensing but also elucidates the formation mechanism of the resulting MOF. 相似文献
12.
Host–Guest [2+2] Cycloaddition Reaction: Postsynthetic Modulation of CO2 Selectivity and Magnetic Properties in a Bimodal Metal–Organic Framework
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Dr. Arpan Hazra Dr. Satyanarayana Bonakala Karteek K. Bejagam Prof. Dr. Sundaram Balasubramanian Prof. Dr. Tapas Kumar Maji 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7792-7799
Simultaneous tuning of permanent porosity and modulation of magnetic properties by postsynthetic modification (PSM) with light in a metal–organic framework is unprecedented. With the aim of achieving such a photoresponsive porous magnetic material, a 3D photoresponsive biporous framework, MOF1, which has 2D channels occupied by the guest 1,2‐bis(4‐pyridyl)ethylene (bpee), H2O, and EtOH molecules, has been synthesized. The guest bpee in 1 is aligned parallel to pillared bpee with a distance of 3.9 Å between the ethylenic groups; this allows photoinduced PSM of the pore surface through a [2+2] cycloaddition reaction to yield MOF2. Such photoinduced PSM of the framework structure introduces enhanced CO2 selectivity over that of N2. The higher selectivity in MOF2 than that of MOF1 is studied through theoretical calculations. Moreover, MOF2 unveils reversible changes in Tc with response to dehydration–rehydration. This result demonstrates that photoinduced PSM is a powerful tool for fabricating novel functional materials. 相似文献
13.
Locating Gases in Porous Materials: Cryogenic Loading of Fuel‐Related Gases Into a Sc‐based Metal–Organic Framework under Extreme Pressures
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Jorge Sotelo Dr. Christopher H. Woodall Dr. Dave R. Allan Eugene Gregoryanz Dr. Ross T. Howie Konstantin V. Kamenev Dr. Michael R. Probert Prof. Paul A. Wright Dr. Stephen A. Moggach 《Angewandte Chemie (International ed. in English)》2015,54(45):13332-13336
An alternative approach to loading metal organic frameworks with gas molecules at high (kbar) pressures is reported. The technique, which uses liquefied gases as pressure transmitting media within a diamond anvil cell along with a single‐crystal of a porous metal–organic framework, is demonstrated to have considerable advantages over other gas‐loading methods when investigating host–guest interactions. Specifically, loading the metal–organic framework Sc2BDC3 with liquefied CO2 at 2 kbar reveals the presence of three adsorption sites, one previously unreported, and resolves previous inconsistencies between structural data and adsorption isotherms. A further study with supercritical CH4 at 3–25 kbar demonstrates hyperfilling of the Sc2BDC3 and two high‐pressure displacive and reversible phase transitions are induced as the filled MOF adapts to reduce the volume of the system. 相似文献
14.
Tuning the Spin‐Crossover Behaviour of a Hydrogen‐Accepting Porous Coordination Polymer by Hydrogen‐Donating Guests
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Jin‐Yan Li Yan‐Cong Chen Ze‐Min Zhang Wei Liu Dr. Zhao‐Ping Ni Prof. Ming‐Liang Tong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(4):1645-1651
A Hoffman‐like coordination polymer with appreciable porosity and uncoordinated pyridyl groups, namely, [Fe(2,5‐bpp){Au(CN)2}2] ? x Solv (2,5‐bpp=2,5‐bis(pyrid‐4‐yl)pyridine; Solv=solvent), was synthesised and characterised. A series of fascinating spin‐crossover behaviours with abrupt, stepwise and hysteretic features were obtained by exchange with a range of protic solvents (ethanol, n‐propanol, isopropyl alcohol, sec‐butanol and isobutanol). Guest–host hydrogen‐bonding interactions involving the H‐accepting site of the framework are primarily responsible for the pronounced cooperativity of these spin‐crossover behaviours. Meanwhile, the tunable critical temperatures over a range of about 130 K are presumably attributable to a certain degree of competition between internal pressure and local electronic influences of solvents. 相似文献
15.
Byeongchan Lee Dohyun Moon Jinhee Park 《Angewandte Chemie (International ed. in English)》2020,59(33):13793-13799
We report the dual postsynthetic modification (PSM) of a metal–organic framework (MOF) involving the microscopic conversion of C?H bonds into C?C bonds and the mesoscopic introduction of hierarchical porosity. MOF crystals underwent single‐crystal‐to‐single‐crystal transformations during the electrophilic aromatic substitution of Co2(m‐DOBDC) (m‐DOBDC4?=4,6‐dioxo‐1,3‐benzenedicarboxylate) with alkyl halides and formaldehyde. The steric hindrance caused by the proximity of the introduced functional groups to the coordination bonds reduced bond stability and facilitated the transformation into hierarchically porous mesostructures by etching with in situ generated protons (hydroniums) and halides. The numerous defect sites in the mesostructural MOFs are potential water‐sorption sites. However, since the introduced functional groups are close to the main adsorption sites, even methyl groups are able to considerably decrease water adsorption, whereas hydroxy groups increase adsorption at low vapor pressures. 相似文献
16.
Uniaxial Movements of a Metal–Cyanide Framework Switched by Weak Interactions through Dehydration and Rehydration
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Bin Wei Ran Shang Xi Zhang Xiu‐Dan Shao Prof. Ye‐Feng Yao Prof. Zhe‐Ming Wang Prof. Ren‐Gen Xiong Prof. Wen Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8269-8273
A metal–cyanide framework undergoes a dehydration–rehydration triggered reversible single‐crystal‐to‐single‐crystal transformation. The resulting accordion‐like contraction–expansion corresponds to a size change along the c axis as much as 24 %. This anisotropic response arises from the cooperativity among the water molecules, K ions, and CN groups between the unique two‐dimensional bimetallic layers through weak interactions of hydrogen bonds and electrostatic (ionic) interactions. The key role of the water molecules in the dehydration–rehydration process is revealed by solid‐state 1H NMR spectroscopy and dielectric measurements. 相似文献
17.
New 3 D Tubular Porous Structure of an Organic–Zincophosphite Framework with Interesting Gas Adsorption and Luminescence Properties
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Prof. Chih‐Min Wang Dr. Li‐Wei Lee Tsung‐Yuan Chang Bing‐Lun Fan Chih‐Ling Wang Prof. Hsiu‐Mei Lin Prof. Kuang‐Lieh Lu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(45):16099-16102
A new 3D tubular zinc phosphite, Zn2(C22H22N8)0.5(HPO3)2?H2O ( 1 ), incorporating a tetradentate organic ligand was synthesized under hydro(solvo)thermal conditions and structurally characterized by single‐crystal X‐ray diffraction. Compound 1 is the first example of inorganic zincophosphite chains being interlinked through 1,2,4,5‐tetrakis(imidazol‐1‐ylmethyl)benzene to form a tubular porous framework with unusual organic–inorganic hybrid channels. The thermal and chemical stabilities, high capacity for CO2 adsorption compared to that for N2 adsorption, and interesting optical properties of LED devices fabricated using this compound were also studied. 相似文献
18.
Chen Tan Michelle C. Lee Mohammad Arshadi Morteza Azizi Alireza Abbaspourrad 《Angewandte Chemie (International ed. in English)》2020,59(24):9506-9513
Processing metal–organic frameworks (MOFs) into hierarchical macroscopic materials can greatly extend their practical applications. However, current strategies suffer from severe aggregation of MOFs and limited tuning of the hierarchical porous network. Now, a strategy is presented that can simultaneously tune the MOF loading, composition, spatial distribution, and confinement within various bio‐originated macroscopic supports, as well as control the accessibility, robustness, and formability of the support itself. This method enables the good dispersion of individual MOF nanoparticles on a spiderweb‐like network within each macrovoid even at high loadings (up to 86 wt %), ensuring the foam pores are highly accessible for excellent adsorption and catalytic capacity. Additionally, this approach allows the direct pre‐incorporation of other functional components into the framework. This strategy provides precise control over the properties of both the hierarchical support and MOF. 相似文献
19.
A Metal–Organic Framework with a Pore Size/Shape Suitable for Strong Binding and Close Packing of Methane
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Dr. Jiao‐Min Lin Chun‐Ting He Yan Liu Pei‐Qin Liao Dong‐Dong Zhou Prof. Dr. Jie‐Peng Zhang Prof. Dr. Xiao‐Ming Chen 《Angewandte Chemie (International ed. in English)》2016,55(15):4674-4678
Much effort has been devoted to develop new porous structures for methane storage. We report a new porous coordination framework showing exceptional methane uptakes (e.g. 263 v/v at 298 K and 65 bar) and adsorption enthalpies (21.6 kJ mol?1) as high as current record holders functionalized by open metal sites. Computational simulations demonstrated that the hierarchical pore structure consisting of single‐wall nanocages has suitable sizes/shapes and organic binding sites to enforce not only strong host–methane and methane–methane interactions but also dense packing of methane molecules. 相似文献
20.
Katherine Self Michael Telfer Dr. Heather F. Greer Prof. Wuzong Zhou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):19090-19095
RHO zeolitic imidazolate framework (ZIF), Zn1.33(O.OH)0.33(nim)1.167(pur), crystals with a rhombic dodecahedral morphology were synthesized by a solvothermal process. The growth of the crystals was studied over time using scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X‐ray diffraction (PXRD) and Brunauer–Emmett–Teller (BET) analyses, and a reversed crystal growth mechanism was revealed. Initially, precursor materials joined together to form disordered aggregates, which then underwent surface recrystallization forming a core–shell structure, in which a disordered core is encased in a layer of denser, less porous crystal. When the growth continued, the shell became less and less porous, until it was a layer of true single crystal. The crystallization then extended from the surface to the core over a six‐week period until, eventually, true single crystals were formed. 相似文献