Wachstumsmechanismen Metall‐organischer Gerüststrukturen: Einblicke in die Keimbildung anhand einer schrittweisen Methodik

Shekhah, Osama; Wang, Hui; Zacher, Denise; Fischer, Roland A.; Wöll, Christof

doi:10.1002/ange.200900378

Cited by 48 publications

(18 citation statements)

References 34 publications

(52 reference statements)

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“…[7] Clearly, layer-based PCPs (Figure 2) are structurally more or less related to the Hofmann clathrates and should be particularly suited for LbL growth, since the pronounced anisotropy of this class of PCPs is highly compatible with the boundary conditions dictated by a nucleating, two-dimensional substrate. However, only very few such cases have been reported so far, including [Fe(pz){Pt(CN) 4 }] (pz = pyrazin) [8] and [ZnA C H T U N G T R E N N U N G (bdc)A C H T U N G T R E N N U N G (bipy) 0.5 ] (MOF-508; bdc = 1,4-benzenedicarboxylic acid). [5] This is unfortunate, because layer-based PCPs or MOFs are very promising as novel materials for selective gas sorption and sensing applications.…”

Section: A C H T U N G T R E N N U N G (Btc) 2 -A C H T U N G T R E Nmentioning

confidence: 98%

“…[3] Later, continuous, extremely smooth, and defect-free multilayer films of HKUST-1 with well-defined thicknesses grown in either the crystallographic [100] or [111] direction were obtained by a self-terminating, liquid-phase, quasi-epitaxial layer-by-layer (LbL) growth process. [4] This LbL fabrication of so-called "SURMOFs" (i.e., surface grown, crystalline metal-organic frameworks) has a number of interesting perspectives. For instance, it allows the control of interpenetration, a phenomenon limiting the pore size when the conventional solvothermal synthesis scheme is employed.…”

Section: A C H T U N G T R E N N U N G (Btc) 2 -A C H T U N G T R E Nmentioning

confidence: 99%

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Liquid‐Phase Epitaxy of Multicomponent Layer‐Based Porous Coordination Polymer Thin Films of [M(L)(P)0.5] Type: Importance of Deposition Sequence on the Oriented Growth

Zacher¹,

Yusenko²,

Bétard³

et al. 2011

Chemistry A European J

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164

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The progressive liquid-phase layer-by-layer (LbL) growth of anisotropic multicomponent layer-based porous coordination polymers (PCPs) of the general formula [M(L)(P)(0.5)] (M: Cu(2+), Zn(2+); L: dicarboxylate linker; P: dinitrogen pillar ligand) was investigated by using either pyridyl- or carboxyl-terminated self-assembled monolayers (SAMs) on gold substrates as templates. It was found that the deposition of smooth, highly crystalline, and oriented multilayer films of these PCPs depends on the conditions at the early growth cycles. In the case of a two-step process with an equimolar mixture of L and P, growth along the [001] direction is strongly preferred. However, employing a three-step scheme with full separation of all components allows deposition along the [100] direction on carboxyl-terminated SAMs. Interestingly, the growth of additional layers on top of previously grown oriented seeding layers proved to be insensitive to the particular growth scheme and full retention of the initial orientation, either along the [001] or [100] direction, was observed. This homo- and heteroepitaxial LbL growth allows full control over the orientation and the layer sequence, including introduction of functionalized linkers and pillars.

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Section: A C H T U N G T R E N N U N G (Btc) 2 -A C H T U N G T R E Nmentioning

confidence: 98%

Section: A C H T U N G T R E N N U N G (Btc) 2 -A C H T U N G T R E Nmentioning

confidence: 99%

Liquid‐Phase Epitaxy of Multicomponent Layer‐Based Porous Coordination Polymer Thin Films of [M(L)(P)0.5] Type: Importance of Deposition Sequence on the Oriented Growth

Zacher¹,

Yusenko²,

Bétard³

et al. 2011

Chemistry A European J

Self Cite

164

183

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“…[12,13] Several studies have reported on the different stages of the crystallisation process of MOFs with real time studies often providing the greatest information on the processes occurring. [12][13][14][15][16][17][18][19][20][21][22][23][24][25] Atomic force microscopy (AFM) has proved itself as one of the most useful techniques in deciphering the crystal growth process of crystallisation due to its ability to scan surface features with a vertical resolution < 1 and the capacity to perform in situ studies. [20][21][22][26][27][28][29][30][31] In situ AFM studies of dif-Abstract: Crystal growth of the metalorganic framework MOF-5 was studied by atomic force microscopy (AFM) for the first time.…”

Section: Introductionmentioning

confidence: 99%

Crystal Growth Mechanisms and Morphological Control of the Prototypical Metal–Organic Framework MOF‐5 Revealed by Atomic Force Microscopy

Cubillas

Anderson

Attfield

2012

Chemistry A European J

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Crystal growth of the metal-organic framework MOF-5 was studied by atomic force microscopy (AFM) for the first time. Growth under low supersaturation conditions was found to occur by a two-dimensional or spiral crystal growth mechanism. Observation of developing nuclei during the former reveals growth occurs through a process of nucleation and spreading of metastable and stable sub-layers revealing that MOFs may be considered as dense phase structures in terms of crystal growth, even though they contain sub-layers consisting of ordered framework and disordered non-framework components. These results also support the notion this may be a general mechanism of surface crystal growth at low supersaturation applicable to crystalline nanoporous materials. The crystal growth mechanism at the atomistic level was also seen to vary as a function of the growth solution Zn/H(2)bdc ratio producing square terraces with steps parallel to the <100> direction or rhombus-shaped terraces with steps parallel to the <110> direction when the Zn/H(2)bdc ratio was >1 or about 1, respectively. The change in relative growth rates can be explained in terms of changes in the solution species concentrations and their influence on growth at different terrace growth sites. These results were successfully applied to the growth of as-synthesized cube-shaped crystals to increase expression of the {111} faces and to grow octahedral crystals of suitable quality to image using AFM. This modulator-free route to control the crystal morphology of MOF-5 crystals should be applicable to a wide variety of MOFs to achieve the desired morphological control for performance enhancement in applications.

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“…[5] In principle, MOFs crystallized as anisotropic crystallographic systems should exhibit distinct adsorption kinetics for adsorbates approaching from different directions owing to varied pore openings. [10] Thin films of the jungle-gym structured [M 2 (L) 2 (P)] (M = Cu 2+ , Zn 2+ , Co 2+ , Ni 2+ ; L = dicarboxylate, P = dinitrogen pillar ligand) [11] were regulated into [100] and [001] orientations by carboxylate-and pyridyl-terminated SAMs, respectively, on substrates. In contrast, the anisotropic nature of MOF crystals is averaged.…”

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confidence: 99%

Metal–Organic Framework Thin Films: Crystallite Orientation Dependent Adsorption

Liu

Fischer

2013

Angew Chem Int Ed

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Porous metal-organic frameworks (MOFs) have risen to their fame in material science in the past decades owing to their intrinsic porosities, diversified topologies, and tailored structures and properties, all of which are attractive for a wide spectrum of promising applications for gas storage/separation, greenhouse gas capture, catalysis and sensors, as well as newly established applications in membranes, thin film devices, and biomedical imaging. [1] MOFs as adsorbents, especially for H 2 , CO 2 , and volatile organic compounds (VOCs, typical hydrocarbons and alcohols, etc.) separation have attracted attention for energy and environmental technologies. Sterics (size/shape exclusion), thermodynamic equilibrium, as well as kinetic and quantum sieving effects are dominant factors in a separation process involving porous materials. Like other kinds of porous materials such as carbon, [2] zeolites, [3] and silica films, [4] MOFs provide interesting potential for selective adsorption and separation at the molecular level because of their pore structures and sizes which can be precisely controlled at the molecular level. [5] In principle, MOFs crystallized as anisotropic crystallographic systems should exhibit distinct adsorption kinetics for adsorbates approaching from different directions owing to varied pore openings. Nevertheless, most property studies of MOFs have dealt with nanoscale bulky powder or singlecrystal samples with randomly distributed crystallite orientations, which exhibits overall adsorption kinetics from all orientations. In contrast, the anisotropic nature of MOF crystals is averaged. One of the very few examples is the anisotropic [{Cu 2 (bza) 4 (pyz)} n ] (bza = benzoate; pyz = pyrazine) as a single-crystal membrane for gas separation, in which the aligned channels gave rise to a much higher permeance and permeation selectivity for H 2 and CO 2 than observed for the nonporous direction. [6] Nevertheless, this study on one single crystal may have limited importance for direct applications since it is challenging to grow large single crystals of MOFs. Advanced thin film/membrane technologies have been coupled with MOFs, and typical examples are ZIF-based membranes. [7] Such membranes displayed superior gas separation performance, and could provide an alternative way of using MOF materials in separation technologies. Although adsorption properties on some well-oriented MOF thin films/membranes have been reported, [8] to the best of our knowledge, no orientation-dependent adsorption on MOF thin films or homogenous ensembles of oriented MOF crystallites attached to surfaces (SURMOFs) has ever been studied.To investigate anisotropic properties, the first task was to prepare a MOF thin-film material, or better said, a homogeneous sample of MOF crystallites attached to a suitable surface with controlled, uniform orientation.Step-by-step liquid-phase epitaxy (LPE) is suited for this purpose, and involves the oriented growth of MOF nano-and microsized crystallites regulated by the functionality of self-...

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Wachstumsmechanismen Metall‐organischer Gerüststrukturen: Einblicke in die Keimbildung anhand einer schrittweisen Methodik

Cited by 48 publications

References 34 publications

Liquid‐Phase Epitaxy of Multicomponent Layer‐Based Porous Coordination Polymer Thin Films of [M(L)(P)0.5] Type: Importance of Deposition Sequence on the Oriented Growth

Liquid‐Phase Epitaxy of Multicomponent Layer‐Based Porous Coordination Polymer Thin Films of [M(L)(P)0.5] Type: Importance of Deposition Sequence on the Oriented Growth

Crystal Growth Mechanisms and Morphological Control of the Prototypical Metal–Organic Framework MOF‐5 Revealed by Atomic Force Microscopy

Metal–Organic Framework Thin Films: Crystallite Orientation Dependent Adsorption

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