Roland A. Fischer

Nanjing University of Technology, Nan-ching, Jiangsu Sheng, China

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Publications (412)2089.92 Total impact

  • Zhenlan Fang · Bart Bueken · Dirk E. De Vos · Roland A. Fischer
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    ABSTRACT: Review: overview of defects in coordination network compounds (CNCs) (including their classification and characterizations) and applications of defective CNCs/MOFs; 133 refs.
    ChemInform 08/2015; 46(31). DOI:10.1002/chin.201531257
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    ABSTRACT: A controlled secondary building unit approach (CSA) was employed to obtain a series of ruthenium metal-organic frameworks (MOFs) of the general formula [Ru3(BTC)2Xx]·Gg (BTC = 1,3,5-benzenetricarboxylate; X = counter-anion, G = guest molecules) which are structural analogues of [M3(BTC)2] (M = Cu, Zn, Ni, Cr, Mo). The compounds [Ru2(OOCR)4X] and [Ru2(OOCCH3)4]Y were varied as Ru sources for CSA; namely strong coordinating X (Cl–) and weakly coordinating Y ([BF4]– or [BPh4]–) as well as the alkyl groups at the carboxylate ligand [R = CH3 or C(CH3)3] were utilized. Four phase-pure Ru-MOFs were obtained: [Ru3(BTC)2Cl0.5(OH)]·(AcOH)1.5 (1), [Ru3(BTC)2Cl1.2(OH)0.3]·(H3BTC)0.15(AcOH)2.4(PivOH)0.45 (2), [Ru3(BTC)2F0.5(OH)]·(AcOH)1.0 (3) and [Ru3(BTC)2(OH)1.5]·(H3BTC)0.5·(AcOH)1.4 (4) {AcOH = CH3COOH, PivOH = (CH3)3CCOOH}. The series of characterization data support the analytical composition and isostructural nature of 1–4, i.e. powder X-ray diffraction (PXRD), IR- and 1H-NMR spectroscopy, thermal gravimetric analysis (TGA) and N2 sorption were employed. The valence state of the Ru-sites were studied by X-ray absorption spectroscopy (XAS). The chosen precursors for CSA and optimized synthesis, work-up and activation protocols allowed improvement of the overall crystallinity, purity (i.e., residual solvent molecules) and surface area of the Ru-MOF materials.
    Berichte der deutschen chemischen Gesellschaft 07/2015; DOI:10.1002/ejic.201500478
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    ABSTRACT: Host-guest inclusion properties of UiO-66 and UiO-67 metal-organic frameworks have been studied using ferrocene (FeCp2) as probe molecule. According to variable-temperature solid-state 1H and 13C CP-MAS-NMR, two different environments exist for adsorbed FeCp2 inside UiO-66 and UiO-67, which have been assigned to octahedral and tetrahedral cavities. At room temperature, a rapid exchange between these two adsorption sites occurs in UiO-67, while at –80 °C the intracrystalline traffic of FeCp2 through the triangular windows is largely hindered. In UiO-66, FeCp2 diffusion is already impeded at room temperature, in agreement with the smaller pore windows. Palladium nanoparticles (Pd NPs) encapsulated inside UiO-66 and UiO-67 have been prepared by chemical vapor infiltration of (allyl)Pd(Cp) followed by UV light irradiation. Infiltration must be carried out at low temperature (–10 °C) to avoid uncontrolled decomposition of the organometallic precursor and formation of Pd NPs at the external surface of the MOF. The resulting Pd-MOFs are shape selective catalysts, as shown for the hydrogenation of carbonyl compounds with different steric hindrance.
    Berichte der deutschen chemischen Gesellschaft 07/2015; DOI:10.1002/ejic.201500299
  • The Journal of Physical Chemistry C 07/2015; 119(28-28):16276-16285. DOI:10.1021/acs.jpcc.5b01078 · 4.77 Impact Factor
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    Zhenlan Fang · Bart Bueken · Dirk E. De Vos · Roland A. Fischer
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    ABSTRACT: Defect engineering in metal-organic frameworks (MOFs) is an exciting concept for tailoring material properties, which opens up novel opportunities not only in sorption and catalysis, but also in controlling more challenging physical characteristics such as band gap as well as magnetic and electrical/conductive properties. It is challenging to structurally characterize the inherent or intentionally created defects of various types, and there have so far been few efforts to comprehensively discuss these issues. Based on selected reports spanning the last decades, this Review closes that gap by providing both a concise overview of defects in MOFs, or more broadly coordination network compounds (CNCs), including their classification and characterization, together with the (potential) applications of defective CNCs/MOFs. Moreover, we will highlight important aspects of "defect-engineering" concepts applied for CNCs, also in comparison with relevant solid materials such as zeolites or COFs. Finally, we discuss the future potential of defect-engineered CNCs. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
    Angewandte Chemie International Edition 06/2015; 54. DOI:10.1002/anie.201411540 · 11.26 Impact Factor
  • Zhenlan Fang · Bart Bueken · Dirk E. De Vos · Roland A. Fischer
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    ABSTRACT: Die gezielte Manipulation Metall-organischer Gerüste (MOFs) ist ein interessantes Konzept zur Entwicklung maßgeschneiderter Materialeigenschaften, das nicht nur in den Gebieten der Sorption und Katalyse neue Möglichkeiten schafft, sondern auch bei der Kontrolle anspruchsvollerer physikalischer Merkmale wie der Bandlücke sowie magnetischer und elektrischer Eigenschaften. Bisher gab es wenig Bemühungen, die intrinsischen oder absichtlich geschaffenen Defekte verschiedenster Art zu charakterisieren. Basierend auf Veröffentlichungen aus den letzten Jahrzehnten schließt dieser Aufsatz die Lücke, indem er einen prägnanten Überblick über Defekte in MOFs, oder weiter gefasst in Koordinationsnetzwerk-Verbindungen (CNCs), gibt und deren Klassifikation und Charakterisierung sowie (mögliche) Anwendungen der defekthaltigen CNCs/MOFs einschließt. Außerdem werden wir wichtige Aspekte des Konzepts der “Defektmanipulation” in Anwendung an CNCs hervorheben, auch in Gegenüberstellung mit relevanten Feststoffen wie Zeolithen oder kovalenten organischen Gerüsten (COFs). Zuletzt werden wir das Potenzial der defektmanipulierten CNCs für die Zukunft diskutieren.
    Angewandte Chemie 06/2015; DOI:10.1002/ange.201411540
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    Min Tu · Suttipong Wannapaiboon · Kira Khaletskaya · Roland A. Fischer
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    ABSTRACT: Thin films of sodalite-type zeolitic-imidazolate frameworks (ZIFs, ZIF-7, 8, 9, 67, 90, and ZIF-65-Zn) with different metal centers and functional moieties are fabricated on SiO2 coated quartz crystal microbalance (QCM) substrates using automatic program controlled repeated direct growth method. The repeated direct growth procedure manipulated here shows great applicability for rapid growth of uniform ZIF thin films with controllable thickness. The fabricated ZIF/QCM devices are used to detect vapor phase volatile organic compounds including alcohol/water, BTEX compounds (benzene, toluene, ethylbenzene and xylene isomers), and hexane isomers. The ZIF/QCM devices exhibit selective detection behavior upon exposure to these chemical vapors. The effects of ZIF pore size, limited pore diameter, surface functionality, and structural flexibility on the sensing performances of ZIF/QCM devices are systematically investigated, which would be beneficial for the practical application of ZIF sensors based on array-sensing technology. Furthermore, the selective adsorption behavior suggests that these ZIF materials have great potentials in the applications of biofuel recovery and the separation of benzene/cyclohexane, xylene, and hexane isomers.
    Advanced Functional Materials 06/2015; DOI:10.1002/adfm.201500760 · 11.81 Impact Factor
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    ABSTRACT: A new titanium precursor, [Ti(OPri)2(deacam)2] (deacam = N,N-diethylacetoacetamide), was developed by the reaction of the parent Ti alkoxide with the β-ketoamide. The compound, obtained as a monomeric six-coordinated complex, was used in metal organic chemical vapor deposition (MOCVD) of TiO2 both as a single source precursor (SSP) and in the presence of oxygen. The high thermal stability of [Ti(OPri)2(deacam)2] enabled the fabrication of TiO2 films over a wide temperature range, with steady growth rates between 500 and 800 °C. The microstructure of the obtained systems was analyzed by X-ray diffraction (XRD) and Raman spectroscopy, whereas atomic force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) measurements were performed to investigate the surface morphology and nanoorganization. Film composition was investigated by complementary techniques like Rutherford backscattering spectrometry (RBS), nuclear reaction analysis (NRA), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS). The electrical properties of the layers were investigated by performing capacitance voltage (C–V) and leakage current measurements.
    Physica Status Solidi (A) Applications and Materials 05/2015; DOI:10.1002/pssa.201532271 · 1.62 Impact Factor
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    ABSTRACT: Porosity switching in the crystalline solid state is a unique phenomenon observed only in a limited number of materials. The switching behavior of two metal-organic frameworks as well as their respective solid solutions of composition [Zn2(BME-bdc)x(DB-bdc)2-xdabco]n (x = 2; 1.5; 1.0; 0.5; 0) is studied in situ during the adsorption of CO2 and Xe using X-ray diffraction and NMR techniques. The diffraction data, measured during the adsorption suggest a direct one-step phase transition (switching) from the narrow pore phase to the large pore phase beyond the transition pressure. An intermediate phase was found only in one compound within a narrow pressure range around the phase transition pressure region. In situ high-pressure 13C NMR spectroscopy of adsorbed CO2 also allowed following the gating behavior of the studied materials by monitoring the signal of adsorbed CO2. The 13C NMR spectra exhibit a pronounced broadening indicating a certain degree of order for the adsorbed molecules inside the pores. This ordering effect and the resulting line broadening depend on the linker functionalization as could be confirmed by corresponding molecular dynamics (MD) simulations.
    Microporous and Mesoporous Materials 03/2015; DOI:10.1016/j.micromeso.2015.02.042 · 3.21 Impact Factor
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    ABSTRACT: Thin films of metal-organic frameworks (MOFs) enable various applications ranging from membrane separations over sensor techniques to potential (micro-) electronic uses. Recent progresses of thin and homogenous surface-mounted MOF (SURMOF) films, which are prepared in a well-defined layer-by-layer fashion on a solid substrate surface, are highlighted in this review. Various substrate surfaces, ranging from plain metal, metal-oxide and polymer surfaces over metal-oxide membranes to magnetic nanoparticles, can be coated with SURMOFs. Multilayered SURMOF films with either identical or different MOF lattice constants or even different MOF structures were prepared, enabling the preparation of functional surface coatings. This allows, by incorporating photoswitchable azobenzene in the MOF structure, the preparation of multilayered, nanoporous films with remote-controllable properties. By means of crosslinking the SURMOF structure employing post-synthetic modifications, water stable thin films, SURGELs, can be prepared. Their thin and homogenous morphology also makes SURMOFs perfectly suited as coatings for electrochemical and electronic applications, where the small dielectric constant k as well as the option to tune the conductivity by loading the pores are very promising features of these porous solids. Furthermore, SURMOFs are very well suited for investigations of MOF-specific properties, since e.g. photoelectron spectroscopies can be applied to these thin films in a straightforward fashion. In additions, mass transfer and diffusion properties in MOFs can be studied for such thin films with high precision using a quartz-crystal microbalance (QCM).
    Microporous and Mesoporous Materials 03/2015; DOI:10.1016/j.micromeso.2015.03.018 · 3.21 Impact Factor
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    ABSTRACT: Die dreieckigen Cluster [Zn3Cp*3]+ und [Zn2CuCp*3] wurden durch Addition der in situ generierten, elektrophilen und isolobalen Spezies [ZnCp*]+ und [CuCp*] an das Carmona-Reagens [Cp*ZnZnCp*] synthetisiert, wobei die Zn-Zn-Bindung des Letzteren erhalten blieb. Die Verwendung von nichtkoordinierenden fluorierten aromatischen Lösungsmitteln ist dabei essenziell. Die Bindungssituation der ligandenstabilisierten Cluster wurde mit quantenchemischen Methoden untersucht, wobei sich ein hohes Maß an σ-Aromatizität zeigte, ähnlich der Bindungssituation im Triwasserstoffkation [H3]+. Die neuen Spezies dienen als molekulare Bausteine für CunZnm-Cluster (Nanomessing), die auch im LIFDI-Massenspektrum der neuen Verbindungen detektiert werden können.
    Angewandte Chemie 02/2015; 127(14). DOI:10.1002/ange.201410737
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    ABSTRACT: The triangular clusters [Zn3 Cp*3 ](+) and [Zn2 CuCp*3 ] were obtained by addition of the in situ generated, electrophilic, and isolobal species [ZnCp*](+) and [CuCp*] to Carmona's compound, [Cp*ZnZnCp*], without splitting the ZnZn bond. The choice of non-coordinating fluoroaromatic solvents was crucial. The bonding situations of the all-hydrocarbon-ligand-protected clusters were investigated by quantum chemical calculations revealing a high degree of σ-aromaticity similar to the triatomic hydrogen ion [H3 ](+) . The new species serve as molecular building units of Cun Znm nanobrass clusters as indicated by LIFDI mass spectrometry. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Angewandte Chemie International Edition in English 02/2015; 54(14). DOI:10.1002/anie.201410737 · 13.45 Impact Factor
  • Hung Banh · Christian Gemel · Rüdiger W. Seidel · Roland A. Fischer
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    ABSTRACT: The synthesis and characterisation of the solvent-stabilized salt [Zn2(THF)6]2+[BAr4F]2− (1) is presented, which features the dizinc dication [Zn2]2+ as an analogue of the calomel dication [Hg2]2+. The labile tetrahydrofuran (THF) solvate molecules of 1 can be readily substituted by other ligands. Reaction with the strong donor ligand PMe3 (Me = CH3) leads to the Zn(II) complex [Zn(PMe3)4]2+[BAr4F]2− by disproportionation, while the π-acceptor-ligand phenylisocyanide (PhNC) gives the substitution product [Zn2(PhNC)6]2+[BAr4F]2− (2) with an intact Zn–Zn bond.
    Chemical Communications 01/2015; 51(11). DOI:10.1039/C4CC08850F · 6.83 Impact Factor
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    ABSTRACT: The synthesis and characterization of the cationic mixed metal Ga/Zn cluster [Zn2(GaCp*)6](2+) (1) is presented. The reaction of [Zn2Cp*2] with [Ga2Cp*][BAr4(F)] leads to the formation of the novel complex being the first example of a [Zn2](2+) core exclusively ligated by metalloid group-13 organyl-ligands. Compound 1 exhibits two different coordination modes: In the solid state, two of the six GaCp* ligands occupy bridging positions, whereas VT (1)H NMR indicates the coexistence of a second isomer in solution featuring six terminal GaCp* ligands. Quantum chemical calculations have been carried out to assign the gallium and zinc positions; the bonding situation in 1 is characterized and the importance of dispersion forces is discussed.
    Inorganic Chemistry 12/2014; 54(1). DOI:10.1021/ic502532g · 4.79 Impact Factor
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    ABSTRACT: The zinc-imidazolate-based framework ZIF-8 was loaded with preformed surfactant-stabilized bimetallic Pd/Au nanoparticles and its corresponding monometallic counterparts Au and Pd by a controlled encapsulation process during the ZIF-8 crystal growth. The nanoparticle-loaded materials were characterized by powder X-ray diffraction (PXRD), FTIR spectroscopy, N2-sorption measurements, as well as by transmission electron microscopy (TEM). The ZIF-8 matrix material remained intact and the NP@ZIF-8 materials revealed the permanent porosity of Brunauer–Emmett–Teller (BET) surface areas above 1100 m2 g–1. The nanoparticles are exclusively found inside the volume of the nanocrystals and exhibit unchanged composition and size distribution as revealed by TEM investigations. Additionally, scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray spectroscopy (EDX) confirmed the solid solution-type alloying of Pd and Au in the embedded Pd/Au nanoparticles. The materials were briefly evaluated in aqueous-phase aerobic alcohol oxidation to investigate the synergetic effects of alloyed Pd/Au nanoparticles and the microporous, hydrophobic matrix ZIF-8.
    Berichte der deutschen chemischen Gesellschaft 11/2014; 2014(32). DOI:10.1002/ejic.201402409
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    ABSTRACT: The novel all-hydrocarbon ligand-stabilized binuclear clusters of metal-core composition Ni2Zn7E, [(η(5)-Cp*)Ni2(ZnMe)6(ZnCp*)(ECp*)] (1-Zn, E = Zn; 1-Ga, E = Ga) and [(η(6)-toluene)Ni2(ZnCp*)2(ZnMe)6] (2; Cp* = pentamethylcyclopentadienyl), were obtained via Ga/Zn and Al/Zn exchange reactions using the starting compounds [Ni2(ECp*)3(η(2)-C2H4)2] (E = Al/Ga) and an excess of ZnMe2 (Me = CH3). Compounds 1-Zn and 1-Ga are very closely related and differ only by one Zn or Ga atom in the group 12/13 metal shell (Zn/Ga) around the two Ni centers. Accordingly, 1-Zn is EPR-active and 1-Ga is EPR-silent. The compounds were derived as a crystalline product mixture. All new compounds were characterized by (1)H and (13)C NMR and electron paramagnetic resonance (EPR) spectroscopy, mass spectrometric analysis using liquid-injection field desorption ionization, and elemental analysis, and their molecular structures were determined by single-crystal X-ray diffraction studies. In addition, the electronic structure has been investigated by DFT and QTAIM calculations, which suggest that there is a Ni1-Ni2 binding interaction. Similar to Zn-rich intermetallic phases of the Hume-Rothery type, the transition metals (here Ni) are distributed in a matrix of Zn atoms to yield highly Zn-coordinated environments. The organic residues, ancillary ligands (Me, Cp*, and toluene), can be viewed as the "protecting" shell of the 10-metal-atom core structures. The soft and flexible binding properties of Cp* and transferability of Me substituents between groups 12 and 13 are essential for the success of this precedence-less type of cluster formation reaction.
    Inorganic Chemistry 09/2014; 53(19). DOI:10.1021/ic5014335 · 4.79 Impact Factor
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    Min Tu · Roland A. Fischer
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    Min Tu · Christian Wiktor · Christoph Rösler · Roland A. Fischer
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    ABSTRACT: Solvent mixture controlled rapid room temperature syntheses for facile access to uniform zeolitic-imidazolate framework nanocrystals (ZIF-7, ZIF-65-Zn and ZIF-71) are reported. ZIF thin film devices for sensing volatile organic chemicals were fabricated by dip-coating nano-ZIF (80-130 nm) suspensions.
    Chemical Communications 09/2014; 50(87). DOI:10.1039/C4CC06491G · 6.83 Impact Factor
  • Denise Zacher · Roman Nayuk · Ralf Schweins · Roland A. Fischer · Klaus Huber
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    ABSTRACT: A small angle neutron scattering (SANS) study is presented, which investigates the impact of a modulator on nucleation and growth of MOF-5 nanopartides. Two DMF solutions, one with the secondary building unit Zn4O(C6H5COO)(6) (SBU) and one with terephthalic acid (BDC) as a linker, were mixed, and 5 min after generation of the mixture, monodentate 4-n-decylbenzoic acid was added as a modulator agent. Time-resolved SANS during the initial stages of the particle formation process offered insight into morphological transformations during the first hours. Subsequently, it could be demonstrated that a shell is formed by the modulator wrapping around the growing MOF-5 particles while directing the formation of MOP-5 nanopartides. This has been made possible by an identification of a mixture of deuterated and hydrogenated solvent (DMF), which matches the scattering contrast of MOF-5, thus giving access to the scattering signal of the modulator.
    Crystal Growth & Design 09/2014; 14(9):4859-4863. DOI:10.1021/cg501025g · 4.56 Impact Factor

Publication Stats

7k Citations
2,089.92 Total Impact Points

Institutions

  • 2015
    • Nanjing University of Technology
      Nan-ching, Jiangsu Sheng, China
  • 1998–2015
    • Ruhr-Universität Bochum
      • • Inorganic Chemistry
      • • Fakultät für Chemie und Biochemie
      Bochum, North Rhine-Westphalia, Germany
  • 1998–2014
    • Philipps University of Marburg
      • Faculty of Chemistry
      Marburg, Hesse, Germany
  • 1999
    • Hochschule Bochum
      Bochum, North Rhine-Westphalia, Germany
  • 1996–1997
    • Universität Heidelberg
      • Institute of Inorganic Chemistry
      Heidelburg, Baden-Württemberg, Germany
    • Technische Universität München
      München, Bavaria, Germany
  • 1980–1996
    • Deutsches Herzzentrum München
      München, Bavaria, Germany
  • 1988
    • Hochschuelerschaft an der Technischen Universitaet Graz
      FRG, New York, United States