12 research outputs found
Insight and Control of the Crystal Growth of Zeolitic Imidazolate Framework ZIF-67 by Atomic Force Microscopy and Mass Spectrometry
Combination of electrospray
ionization mass spectrometry (ESI-MS)
and in situ atomic force microscopy (AFM) are applied to provide the
first nanoscopic study of the crystal growth of zeolitic imidazolate
framework ZIF-67. ZIF-67 is found to form through a process of nucleation
and spreading of metastable unenclosed substeps to form stable surface
steps of the enclosed framework structure and demonstrates that isostructural
MOFs, ZIF-67 and ZIF-8, undergo identical crystal growth mechanisms.
The information on the crystal growth species obtained from the AFM
experiments correlates well with the solution species identified by
ESI-MS indicating that the species involved in the growth under low
supersaturation conditions are methylimidazole/methylimidazolate,
monomeric nonmethylimidazole/methylimidazolate complexed Co<sup>2+</sup> ions and monomeric complexed [CoÂ(methylimidazole/methylimidazolate)<sub>1‑2</sub>] ions. Combination of the use of low supersaturation
growth solutions and in situ AFM has also allowed the successful extraction
of the synthetic conditions necessary for formation of ZIF-67 nanodots
that possesses a maximum vertical dimension of 1.2 nm which is the
smallest dimension reported for a stable ZIF-67 entity. This methodology
may be expanded to understand the formation of, and to form, complex
crystal forms of other MOFs for new or improved functionality
Growth Mechanism of Microporous Zincophosphate Sodalite Revealed by In Situ Atomic Force Microscopy
Microporous zincophosphate sodalite crystal growth has
been studied
in situ by atomic force microscopy. This simple model system permits
an in depth investigation of some of the axioms governing crystal
growth of nanoporous framework solids in general. In particular, this
work reveals the importance of considering the growth of a framework
material as the growth of a dense phase material where the framework
structure, nonframework cations, and hydrogen-bonded water must all
be considered. The roles of the different components of the structure,
including the role of strict framework ordering, are disentangled,
and all of the growth features, both crystal habit and nanoscopic
surface structure, are explained according to a simple set of rules.
The work describes, for the first time, both ideal growth and growth
leading to defect structures on all of the principal facets of the
sodalite structure. Also, the discovery of the presence of anisotropic
friction on a framework material is described
Growth Mechanism of Microporous Zincophosphate Sodalite Revealed by In Situ Atomic Force Microscopy
Microporous zincophosphate sodalite crystal growth has
been studied
in situ by atomic force microscopy. This simple model system permits
an in depth investigation of some of the axioms governing crystal
growth of nanoporous framework solids in general. In particular, this
work reveals the importance of considering the growth of a framework
material as the growth of a dense phase material where the framework
structure, nonframework cations, and hydrogen-bonded water must all
be considered. The roles of the different components of the structure,
including the role of strict framework ordering, are disentangled,
and all of the growth features, both crystal habit and nanoscopic
surface structure, are explained according to a simple set of rules.
The work describes, for the first time, both ideal growth and growth
leading to defect structures on all of the principal facets of the
sodalite structure. Also, the discovery of the presence of anisotropic
friction on a framework material is described
Growth Mechanism of Microporous Zincophosphate Sodalite Revealed by In Situ Atomic Force Microscopy
Microporous zincophosphate sodalite crystal growth has
been studied
in situ by atomic force microscopy. This simple model system permits
an in depth investigation of some of the axioms governing crystal
growth of nanoporous framework solids in general. In particular, this
work reveals the importance of considering the growth of a framework
material as the growth of a dense phase material where the framework
structure, nonframework cations, and hydrogen-bonded water must all
be considered. The roles of the different components of the structure,
including the role of strict framework ordering, are disentangled,
and all of the growth features, both crystal habit and nanoscopic
surface structure, are explained according to a simple set of rules.
The work describes, for the first time, both ideal growth and growth
leading to defect structures on all of the principal facets of the
sodalite structure. Also, the discovery of the presence of anisotropic
friction on a framework material is described
Growth Mechanism of Microporous Zincophosphate Sodalite Revealed by In Situ Atomic Force Microscopy
Microporous zincophosphate sodalite crystal growth has
been studied
in situ by atomic force microscopy. This simple model system permits
an in depth investigation of some of the axioms governing crystal
growth of nanoporous framework solids in general. In particular, this
work reveals the importance of considering the growth of a framework
material as the growth of a dense phase material where the framework
structure, nonframework cations, and hydrogen-bonded water must all
be considered. The roles of the different components of the structure,
including the role of strict framework ordering, are disentangled,
and all of the growth features, both crystal habit and nanoscopic
surface structure, are explained according to a simple set of rules.
The work describes, for the first time, both ideal growth and growth
leading to defect structures on all of the principal facets of the
sodalite structure. Also, the discovery of the presence of anisotropic
friction on a framework material is described
Growth Mechanism of Microporous Zincophosphate Sodalite Revealed by In Situ Atomic Force Microscopy
Microporous zincophosphate sodalite crystal growth has
been studied
in situ by atomic force microscopy. This simple model system permits
an in depth investigation of some of the axioms governing crystal
growth of nanoporous framework solids in general. In particular, this
work reveals the importance of considering the growth of a framework
material as the growth of a dense phase material where the framework
structure, nonframework cations, and hydrogen-bonded water must all
be considered. The roles of the different components of the structure,
including the role of strict framework ordering, are disentangled,
and all of the growth features, both crystal habit and nanoscopic
surface structure, are explained according to a simple set of rules.
The work describes, for the first time, both ideal growth and growth
leading to defect structures on all of the principal facets of the
sodalite structure. Also, the discovery of the presence of anisotropic
friction on a framework material is described
Growth Mechanism of Microporous Zincophosphate Sodalite Revealed by In Situ Atomic Force Microscopy
Microporous zincophosphate sodalite crystal growth has
been studied
in situ by atomic force microscopy. This simple model system permits
an in depth investigation of some of the axioms governing crystal
growth of nanoporous framework solids in general. In particular, this
work reveals the importance of considering the growth of a framework
material as the growth of a dense phase material where the framework
structure, nonframework cations, and hydrogen-bonded water must all
be considered. The roles of the different components of the structure,
including the role of strict framework ordering, are disentangled,
and all of the growth features, both crystal habit and nanoscopic
surface structure, are explained according to a simple set of rules.
The work describes, for the first time, both ideal growth and growth
leading to defect structures on all of the principal facets of the
sodalite structure. Also, the discovery of the presence of anisotropic
friction on a framework material is described
Growth Mechanism of Microporous Zincophosphate Sodalite Revealed by In Situ Atomic Force Microscopy
Microporous zincophosphate sodalite crystal growth has
been studied
in situ by atomic force microscopy. This simple model system permits
an in depth investigation of some of the axioms governing crystal
growth of nanoporous framework solids in general. In particular, this
work reveals the importance of considering the growth of a framework
material as the growth of a dense phase material where the framework
structure, nonframework cations, and hydrogen-bonded water must all
be considered. The roles of the different components of the structure,
including the role of strict framework ordering, are disentangled,
and all of the growth features, both crystal habit and nanoscopic
surface structure, are explained according to a simple set of rules.
The work describes, for the first time, both ideal growth and growth
leading to defect structures on all of the principal facets of the
sodalite structure. Also, the discovery of the presence of anisotropic
friction on a framework material is described
Disorder and Sorption Preferences in a Highly Stable Fluoride-Containing Rare-Earth <i>fcu</i>-Type Metal–Organic Framework
Rare-earth (RE) metal–organic
frameworks (MOFs) synthesized
in the presence of fluorine-donating modulators or linkers are an
important new subset of functional MOFs. However, the exact nature
of the REaXb core of the molecular building block (MBB) of the MOF, where X is
a μ2 or 3-bridging group, remains unclear.
Investigation of one of the archetypal members of this family with
the stable fcu framework topology, Y-fum-fcu-MOF (1), using a combination of experimental
techniques, including high-field (20 T) solid-state nuclear magnetic
resonance spectroscopy, has determined two sources of framework disorder
involving the μ3-X face-capping group of the MBB
and the fumarate (fum) linker. The core of the MBB of 1 is shown to contain a mixture of μ3-F– and (OH)− groups with preferential occupation
at the crystallographically different face-capping sites that result
in different internally lined framework tetrahedral cages. The fum
linker is also found to display a disordered arrangement involving
bridging– or chelating–bridging bis-bidentate modes
over the fum linker positions without influencing the MBB orientation.
This linker disorder will, upon activation, result in the creation
of Y3+ ions with potentially one or two additional uncoordinated
sites possessing differing degrees of Lewis acidity. Crystallographically
determined host–guest relationships for simple sorbates demonstrate
the favored sorption sites for N2, CO2, and
CS2 molecules that reflect the chemical nature of both
the framework and the sorbate species with the structural partitioning
of the μ3-groups apparent in determining the favored
sorption site of CS2. The two types of disorder found within 1 demonstrate the complexity of fluoride-containing RE-MOFs
and highlight the possibility to tune this and other frameworks to
contain different proportions and segregations of μ3-face-capping groups and degrees of linker disorder for specifically
tailored applications
Disorder and Sorption Preferences in a Highly Stable Fluoride-Containing Rare-Earth <i>fcu</i>-Type Metal–Organic Framework
Rare-earth (RE) metal–organic
frameworks (MOFs) synthesized
in the presence of fluorine-donating modulators or linkers are an
important new subset of functional MOFs. However, the exact nature
of the REaXb core of the molecular building block (MBB) of the MOF, where X is
a μ2 or 3-bridging group, remains unclear.
Investigation of one of the archetypal members of this family with
the stable fcu framework topology, Y-fum-fcu-MOF (1), using a combination of experimental
techniques, including high-field (20 T) solid-state nuclear magnetic
resonance spectroscopy, has determined two sources of framework disorder
involving the μ3-X face-capping group of the MBB
and the fumarate (fum) linker. The core of the MBB of 1 is shown to contain a mixture of μ3-F– and (OH)− groups with preferential occupation
at the crystallographically different face-capping sites that result
in different internally lined framework tetrahedral cages. The fum
linker is also found to display a disordered arrangement involving
bridging– or chelating–bridging bis-bidentate modes
over the fum linker positions without influencing the MBB orientation.
This linker disorder will, upon activation, result in the creation
of Y3+ ions with potentially one or two additional uncoordinated
sites possessing differing degrees of Lewis acidity. Crystallographically
determined host–guest relationships for simple sorbates demonstrate
the favored sorption sites for N2, CO2, and
CS2 molecules that reflect the chemical nature of both
the framework and the sorbate species with the structural partitioning
of the μ3-groups apparent in determining the favored
sorption site of CS2. The two types of disorder found within 1 demonstrate the complexity of fluoride-containing RE-MOFs
and highlight the possibility to tune this and other frameworks to
contain different proportions and segregations of μ3-face-capping groups and degrees of linker disorder for specifically
tailored applications