4 research outputs found
Step-by-Step Fabrication of a Highly Oriented Crystalline Three-Dimensional Pillared-Layer-Type Metal–Organic Framework Thin Film Confirmed by Synchrotron X-ray Diffraction
Fabrication of a crystalline ordered thin film based
on the porous
metal–organic frameworks (MOFs) is one of the practical applications
of the future functional nanomaterials. Here, we report the creation
of a highly oriented three-dimensional (3-D) porous pillared-layer-type
MOF thin film on a metal substrate using a step-by-step approach based
on liquid-phase epitaxy. Synchrotron X-ray diffraction (XRD) study
clearly indicates that the thin film is crystalline and its orientation
is highly controlled in both horizontal and vertical directions relative
to the substrate. This report provides the first confirmation of details
of not only the crystallinity but also the orientation of 3-D MOF
thin film using synchrotron XRD. Moreover, we also demonstrate its
guest adsorption/desorption behavior by using <i>in situ</i> XRD measurements. The results presented here would promise useful
insights for fabrication of MOF-based nanodevices in the future
Remarkable Lattice Shrinkage in Highly Oriented Crystalline Three-Dimensional Metal–Organic Framework Thin Films
Highly oriented crystalline thin
films of metal–organic frameworks (MOFs) have promising practical
applications, such as in gas separation, catalysis, and sensing. We
report on the successful fabrication of highly oriented crystalline
thin films of three-dimensional porous MOFs, FeÂ(pz)Â[MÂ(CN)<sub>4</sub>] (M = Ni, Pd; pz = pyrazine). Synchrotron X-ray diffraction studies
reveal not only the highly oriented crystalline nature but also the
remarkable shrunken structure of the thin films (∼3–7%
volume shrinkage) compared with bulk samples. Furthermore, because
of lattice shrinkage, these films exhibit large lattice expansions
upon guest adsorption, in marked contrast to the almost unchanged
lattice in the bulk samples
Guest-Induced Two-Way Structural Transformation in a Layered Metal–Organic Framework Thin Film
Fabrication
of thin films made of metal–organic frameworks
(MOFs) has been intensively pursued for practical applications that
use the structural response of MOFs. However, to date, only physisorption-induced
structural response has been studied in these films. Chemisorption
can be expected to provide a remarkable structural response because
of the formation of bonds between guest molecules and reactive metal
sites in host MOFs. Here, we report that chemisorption-induced two-way
structural transformation in a nanometer-sized MOF thin film. We prepared
a two-dimensional layered-type MOF FeÂ[PtÂ(CN)<sub>4</sub>] thin film
using a step-by-step approach. Although the as-synthesized film showed
poor crystallinity, the dehydrated form of this thin film had a highly
oriented crystalline nature (<b>Film-D</b>) as confirmed by
synchrotron X-ray diffraction (XRD). Surprisingly, under water and
pyridine vapors, <b>Film-D</b> showed chemisorption-induced
dynamic structural transformations to FeÂ(L)<sub>2</sub>[PtÂ(CN)<sub>4</sub>] thin films [L = H<sub>2</sub>O (<b>Film-H</b>), pyridine
(<b>Film-P</b>)], where water and pyridine coordinated to the
open Fe<sup>2+</sup> site. Dynamic structural transformations were
also confirmed by in situ XRD, sorption measurement, and infrared
reflection absorption spectroscopy. This is the first report of chemisorption-induced
dynamic structural response in a MOF thin film, and it provides useful
insights, which would lead to future practical applications of MOFs
utilizing chemisorption-induced structural responses
Fabrication and Structural Characterization of an Ultrathin Film of a Two-Dimensional-Layered Metal–Organic Framework, {Fe(py)<sub>2</sub>[Ni(CN)<sub>4</sub>]} (py = pyridine)
We report the fabrication
and characterization of the first example of a tetracyanonickelate-based
two-dimensional-layered metal–organic framework, {FeÂ(py)<sub>2</sub>NiÂ(CN)<sub>4</sub>} (py = pyridine), thin film. To fabricate
a nanometer-sized thin film, we utilized the layer-by-layer method,
whereby a substrate was alternately soaked in solutions of the structural
components. Surface X-ray studies revealed that the fabricated film
was crystalline with well-controlled growth directions both parallel
and perpendicular to the substrate. In addition, lattice parameter
analysis indicated that the crystal system is found to be close to
higher symmetry by being downsized to a thin film