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  • 1. Cheung, Ocean
    et al.
    Zhang, Peng
    Frykstrand, Sara
    Zheng, Haoquan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yang, Taimin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sommariva, Marco
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Strømme, Maria
    Nanostructure and pore size control of template-free synthesised mesoporous magnesium carbonate2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 78, p. 74241-74249Article in journal (Refereed)
    Abstract [en]

    The structure of mesoporous magnesium carbonate (MMC) first presented in 2013 is investigated using a bottom-up approach. MMC is found to be built from the aggregation of nanoparticles of amorphous MgCO3 and MgO with a coating of amorphous MgCO3. The nanoparticles have dimensions of approximately 2-5 nm as observed using transmission electron microscopy and the aggregation of the particles creates the pore structure of MMC. We further show that the average pore diameter of MMC can be controlled by varying the temperature during the powder formation process and demonstrate that altering the pore size opens the possibility to tune the amorphous phase stabilisation properties that MMC exerts on poorly soluble drug compounds. Specifically, we show the loading and release of the antifungal drug itraconazole using MMC as a drug carrier.

  • 2. Lee, Hwajun
    et al.
    Shin, Jiho
    Choi, Wanuk
    Choi, Hyun June
    Yang, Taimin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hong, Suk Bong
    PST-29: A Missing Member of the RHO family of Embedded Isoreticular Zeolites2018In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 30, no 19, p. 6619-6623Article in journal (Refereed)
  • 3.
    Lin, Junzhong
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cichocka, Magdalena O.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Peng, Fei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yang, Taimin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Peking University, P. R. China.
    Hierarchical Shell‐Like ZSM‐5 with Tunable Porosity Synthesized by using a Dissolution–Recrystallization Approach2018In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 56, p. 14974-14981Article in journal (Refereed)
    Abstract [en]

    Zeolites have been widely used in various fields in industry, such as catalysis, separation, and adsorption, etc. The small pore size of the micropores in the zeolite could lead to severe diffusion resistance in mass transfer. Numerous efforts have been dedicated to imposing hierarchical pore systems into zeolites by using templates or leaching methods. Here, we report the synthesis of single‐crystalline hierarchical shell‐like ZSM‐5 by utilizing a dissolution–recrystallization post‐treatment on mesoporous ZSM‐5. Tetrapropylammonium hydroxide solution was used in the post‐treatment. The hierarchical porosity in the crystalline shell can be controlled by adding sodium cations into the synthesis system. The hierarchical shell‐like ZSM‐5 reported here shows higher catalytic activity in acetalization reactions containing bulky molecules.

  • 4.
    Lin, Junzhong
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yang, Taimin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lin, Cong
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hierarchical MFI zeolite synthesized via regulating the kinetic of dissolution-recrystallization and their catalytic properties2018In: Catalysis communications, ISSN 1566-7367, E-ISSN 1873-3905, Vol. 115, p. 82-86Article in journal (Refereed)
    Abstract [en]

    Hierarchical MFI zeolites with open pores were synthesized by a temperature programmed dissolution-recrystallization post-treatment. By controlling the temperature of post-treatment using TPAOH, open macropores and mesopores were created by simply regulating the kinetics of dissolution and recrystallization. Benzyl alcohol self-etherification reaction, which only occurs in micropores, was tested on ZSM-5 to understand the effect of hierarchical pore system. The catalytic activity of hierarchical TS-1 was tested with cyclohexanone ammoximation. Hierarchical ZSM-5 and TS-1 zeolites with open pores showed higher catalytic activity compared with both hollow and conventional ones. The increased catalytic activities can be ascribed to the enhanced diffusion.

  • 5. Seo, Seungwan
    et al.
    Yang, Taimin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Shin, Jiho
    Jo, Donghui
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hong, Suk Bong
    Two Aluminophosphate Molecular Sieves Built from Pairs of Enantiomeric Structural Building Units2018In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 57, no 14, p. 3727-3732Article in journal (Refereed)
    Abstract [en]

    Herein we report the synthesis and structures of two new small-pore aluminophosphate molecular sieves PST-13 and PST-14 with mutually connected 8-ring channels. The structure of PST-13, synthesized using diethylamine as an organic structure-directing agent, contains penta-coordinated framework Al atoms bridged by hydroxy groups and thus edge-sharing 3- and 5-rings. Upon calcination, PST-13 undergoes a transformation to PST-14 with loss of bridging hydroxy groups and occluded organic species. The structures of both materials consist nonjointly of pairs of previously undiscovered 1,5- and 1,6-open double 4-rings (d4rs) which are mirror images of each other. We also present a series of novel chemically feasible hypothetical structures built from 1-open d4r (sti) or 1,3-open d4r (nsc) units, as well as from these two enantiomeric structural building units.

  • 6.
    Wang, Bin
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Rhauderwiek, Timo
    Inge, Andrew Kentaro
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Xu, Hongyi
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yang, Taimin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Huang, Zhehao
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Stock, Norbert
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A Porous Cobalt Tetraphosphonate Metal-Organic Framework: Accurate Structure and Guest Molecule Location Determined by Continuous-Rotation Electron Diffraction2018In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 66, p. 17429-17433Article in journal (Refereed)
    Abstract [en]

    Single-crystal electron diffraction has shown to be powerful for structure determination of nano- and submicron-sized crystals that are too small to be studied by single-crystal X-ray diffraction. However, it has been very challenging to obtain high quality electron diffraction data from beam sensitive crystals such as metal-organic frameworks (MOFs). It is even more difficult to locate guest species in the pores of MOF crystals. Here, we present synthesis of a novel porous cobalt MOF with 1D channels, [Co-2(Ni-H4TPPP)]center dot 2DABCO center dot 6H(2)O, (denoted Co-CAU-36; DABCO=1,4-diazabicyclo[2.2.2]octane), and its structure determination using continuous rotation electron diffraction (cRED) data. By combining a fast hybrid electron detector with low sample temperature (96 K), high resolution (0.83-1.00 angstrom) cRED data could be obtained from eight Co-CAU-36 crystals. Independent structure determinations were conducted using each of the eight cRED datasets. We show that all atoms in the MOF framework could be located. More importantly, we demonstrate for the first time that organic molecules in the pores, which were previously difficult to find, could be located using the cRED data. A comparison of eight independent structure determinations using different datasets shows that structural models differ only on average by 0.03(2) angstrom for the framework atoms and 0.10(6) and 0.16(12) angstrom for DABCO and water molecules, respectively.

  • 7.
    Wang, Yunchen
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yang, Taimin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Xu, Hongyi
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    On the quality of the continuous rotation electron diffraction data for accurate atomic structure determination of inorganic compounds2018In: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 51, p. 1094-1101Article in journal (Refereed)
    Abstract [en]

    The continuous rotation electron diffraction (cRED) method has the capability of providing fast three-dimensional electron diffraction data collection on existing and future transmission electron microscopes; unknown structures could be potentially solved and refined using cRED data collected from nano-and submicrometre-sized crystals. However, structure refinements of cRED data using SHELXL often lead to relatively high R1 values when compared with those refined against single-crystal X-ray diffraction data. It is therefore necessary to analyse the quality of the structural models refined against cRED data. In this work, multiple cRED data sets collected from different crystals of an oxofluoride (FeSeO3F) and a zeolite (ZSM-5) with known structures are used to assess the data consistency and quality and, more importantly, the accuracy of the structural models refined against these data sets. An evaluation of the precision and consistency of the cRED data by examination of the statistics obtained from the data processing software DIALS is presented. It is shown that, despite the high R1 values caused by dynamical scattering and other factors, the refined atomic positions obtained from the cRED data collected for different crystals are consistent with those of the reference models refined against single-crystal X-ray diffraction data. The results serve as a reference for the quality of the cRED data and the achievable accuracy of the structural parameters.

  • 8.
    Xu, Hongyi
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lebrette, Hugo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Yang, Taimin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Srinivas, Vivek
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Hovmöller, Sven
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Högbom, Martin
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A Rare Lysozyme Crystal Form Solved Using Highly Redundant Multiple Electron Diffraction Datasets from Micron-Sized Crystals2018In: Structure, ISSN 0969-2126, E-ISSN 1878-4186, Vol. 26, no 4, p. 667-675Article in journal (Refereed)
    Abstract [en]

    Recent developments of novel electron diffraction techniques have shown to be powerful for determination of atomic resolution structures from micronand nano-sized crystals, too small to be studied by single-crystal X-ray diffraction. In this work, the structure of a rare lysozyme polymorph is solved and refined using continuous rotation MicroED data and standard X-ray crystallographic software. Data collection was performed on a standard 200 kV transmission electron microscope (TEM) using a highly sensitive detector with a short readout time. The data collection is fast (similar to 3 min per crystal), allowing multiple datasets to be rapidly collected from a large number of crystals. We show that merging data from 33 crystals significantly improves not only the data completeness, overall I/sigma and the data redundancy, but also the quality of the final atomic model. This is extremely useful for electron beam-sensitive crystals of low symmetry or with a preferred orientation on the TEM grid.

  • 9.
    Xu, Hongyi
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yang, Taimin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Waitschat, Steve
    Inge, Andrew Kentaro
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Stock, Norbert
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Electron Crystallography Method for Rapid and Accurate Structure Determination of Small Organic MoleculesManuscript (preprint) (Other academic)
  • 10.
    Yang, Taimin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    3D Electron Microscopy Methods and Applications: Structures from Atomic Scale to Mesoscale2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The crystal structure determines the physical properties of a material. The structure can be analysed at different levels, from atomic level, mesoscale level, all the way up to the macroscale level. Transmission Electron Microscope (TEM) is a powerful tool for studying the structure of materials at atomic scale level and mesoscale level because of the short wavelength of the electrons. At atomic scale level, structure determination using TEM can be performed in diffraction mode. The recent developments in 3D electron diffraction methods make structure determination from nano- and micron-sized crystals much easier than before. However, due to the strong interactions, electrons can be scattered multiple times through the crystal, causing the measured intensities to be less accurate than that in the X-ray case.

    In this thesis, we use the continuous rotation electron diffraction (cRED) developed in our group to investigate the structure of materials and the accuracy of this method. In the third chapter, we use cRED method to determine the structure of two aluminophosphate zeolites, PST-13 and PST-14. We presented that these structures can be built from two pairs of enantiomeric structural building units. In the fourth chapter, we show that despite the inaccuracy in measured intensities originated from dynamical effect, it is still possible to determine the structure accurately. We show that the atomic coordinates of ZSM-5 and sucrose crystal structure determined by multiple electron diffraction datasets is identical to that determined from X-ray data or neutron data. We also assessed the linearity between calculated structure factor and observed structure factor and use this as a coarse assessment indicator for diffraction data quality for protein crystals.

    Apart from atomic structure, mesoscale structures, such as mesopores, can also determine the property of materials. For the 3D structures of these nanoscale structures, we can also use TEM electron tomography techniques to investigate. In chapter five, we performed electron tomography for two different materials with mesoporous structure and illustrated the formation mechanism of mesoporous magnesium carbonate and the internal tunnel structure of hierarchical TS-1 zeolite.

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