7 research outputs found
Water-stable zirconium-based metal-organic framework material with high-surface area and gas-storage capacities.
We designed, synthesized, and characterized a new Zr-based metal-organic framework material, NU-1100, with a pore volume of 1.53â
ccg(-1) and Brunauer-Emmett-Teller (BET) surface area of 4020â
m(2) g(-1) ; to our knowledge, currently the highest published for Zr-based MOFs. CH4 /CO2 /H2 adsorption isotherms were obtained over a broad range of pressures and temperatures and are in excellent agreement with the computational predictions. The total hydrogen adsorption at 65â
bar and 77â
K is 0.092â
gâg(-1) , which corresponds to 43â
gâL(-1) . The volumetric and gravimetric methane-storage capacities at 65â
bar and 298â
K are approximately 180â
vSTP /v and 0.27â
gâg(-1) , respectively.OKF, JTH and RQS thank DOE ARPA-E and the Stanford Global Climate and Energy Project for support of work relevant to methane and CO2, respectively. TY acknowledges support by the U. S. Department of Energy through BES Grant No. DE-FG02-08ER46522. WB acknowledges support from the Foundation for Polish Science through the âKolumbâ Program. DFJ acknowledges the Royal Society (UK) for a University Research Fellowship. This material is based upon work supported by the National Science Foundation (grant CHE-1048773).This is the accepted manuscript. The final version is available as 'Water-Stable Zirconium-Based MetalâOrganic Framework Material with High-Surface Area and Gas-Storage Capacities' from Wiley at http://onlinelibrary.wiley.com/doi/10.1002/chem.201402895/abstract
1,3,4-Oxadiazoles for Crystal Engineering. Convenient Synthesis and Self-Assembly: Nonchiral Chains versus Chiral Helices
A series of new 1,3,4-oxadiazoles
containing carboxylic and halogen groups and a double bond have been
synthesized in good yields and a multigram scale. This was achieved
at room temperature from readily available 1,2-diacylhydrazines using
a cheap condensation reagent (the solution of P<sub>2</sub>O<sub>5</sub> in H<sub>2</sub>SO<sub>4</sub>). Single-crystal X-ray diffraction
analysis has shown that all studied 1,3,4-oxadiazole-containing acids
are self-assembled by intermolecular H-bonds into supramolecular zigzag
chains or helices, depending on the tecton molecular structure and
the type of H-bonding. Factors affecting helix formation have been
found, and a Cambridge Structural Database (CSD) survey has been performed
to support these findings. Moreover, it has been demonstrated that
the tuning of the crystal structure leading to spontaneous symmetry
breaking for supramolecular helices based on nonchiral molecules is
possible even by as little change in molecular structure as a shift
from an isopropyl substituent to a cyclopropyl. Subsequently, the
studied 1,3,4-oxadiazole-containing acids and related compounds are
found to be easily accessible building blocks for crystal engineering
of new chiral materials with tunable supramolecular arrangement
1,3,4-Oxadiazoles for Crystal Engineering. Convenient Synthesis and Self-Assembly: Nonchiral Chains versus Chiral Helices
A series of new 1,3,4-oxadiazoles
containing carboxylic and halogen groups and a double bond have been
synthesized in good yields and a multigram scale. This was achieved
at room temperature from readily available 1,2-diacylhydrazines using
a cheap condensation reagent (the solution of P<sub>2</sub>O<sub>5</sub> in H<sub>2</sub>SO<sub>4</sub>). Single-crystal X-ray diffraction
analysis has shown that all studied 1,3,4-oxadiazole-containing acids
are self-assembled by intermolecular H-bonds into supramolecular zigzag
chains or helices, depending on the tecton molecular structure and
the type of H-bonding. Factors affecting helix formation have been
found, and a Cambridge Structural Database (CSD) survey has been performed
to support these findings. Moreover, it has been demonstrated that
the tuning of the crystal structure leading to spontaneous symmetry
breaking for supramolecular helices based on nonchiral molecules is
possible even by as little change in molecular structure as a shift
from an isopropyl substituent to a cyclopropyl. Subsequently, the
studied 1,3,4-oxadiazole-containing acids and related compounds are
found to be easily accessible building blocks for crystal engineering
of new chiral materials with tunable supramolecular arrangement
MetalâOrganic Framework (MOF) Defects under Control: Insights into the Missing Linker Sites and Their Implication in the Reactivity of Zirconium-Based Frameworks
For
three-dimensional (3D) metalâorganic frameworks (MOFs),
the presence and nature of structural defects has been recognized
as a key factor shaping the materialâs physical and chemical
behavior. In this work, the formation of the âmissing linkerâ
defects has been addressed in the model biphenyl-4,4âČ-dicarboxylate
(bpdc)-based Zr MOF, UiO-67. The defect showed strong dependence on
the nature of the modulator acid used in the MOF synthesis; the defects,
in turn, were found to correlate with the MOF physical and chemical
properties. The dynamic nature of the Zr6 (node)-monocarboxylate bond
showed promise in defect functionalization and âhealingâ,
including the formation of X-ray-quality âdefect-freeâ
UiO-67 single crystals. Chemical transformations at defect sites have
also been explored. The study was also extended to the isoreticular
UiO-66 and UiO-68âČ systems
Computational Design of MetalâOrganic Frameworks Based on Stable Zirconium Building Units for Storage and Delivery of Methane
A metalâorganic framework
(MOF) with high volumetric deliverable
capacity for methane was synthesized after being identified by computational
screening of 204 hypothetical MOF structures featuring (Zr<sub>6</sub>O<sub>4</sub>)Â(OH)<sub>4</sub>(CO<sub>2</sub>)<sub>n</sub> inorganic
building blocks. The predicted MOF (<b>NU-800</b>) has an <b>fcu</b> topology in which zirconium nodes are connected via ditopic
1,4-benzenedipropynoic acid linkers. Based on our computer simulations,
alkyne groups adjacent to the inorganic zirconium nodes provide more
efficient methane packing around the nodes at high pressures. The
high predicted gas uptake properties of this new MOF were confirmed
by high-pressure isotherm measurements over a large temperature and
pressure range. The measured methane deliverable capacity of <b>NU-800</b> between 65 and 5.8 bar is 167 ccÂ(STP)/cc (0.215 g/g),
the highest among zirconium-based MOFs. High-pressure uptake values
of H<sub>2</sub> and CO<sub>2</sub> are also among the highest reported.
These high gas uptake characteristics, along with the expected highly
stable structure of <b>NU-800</b>, make it a promising material
for gas storage applications
NâPhosphorylated Azolylidenes: Novel Ligands for Dinuclear Complexes of Coinage Metals
Dinuclear silverÂ(I) complexes with bridging N-phosphorylated
azolylidene
ligands have been synthesized. Subsequent transfer of the ligands
to other group 11 metal centers (Cu, Au) has been accomplished, highlighting
the usefulness of the silver complexes as an easy to handle, air-
and moisture-stable source of these ligands. Preliminary results indicate
that dinuclear copperÂ(I) complexes with N-phosphorylated imidazolylidene
ligands display notable catalytic efficiency in nitrene transfer reactions