Metal–organic frameworks with Zr6 nodes, UiO-66 and NU-1000, were investigated as supports for Ir(CO)2 and Ir(C2H4)2 complexes. A single bonding site for the iridium is identified on the nodes of ...NU-1000, whereas two sites are identified on UiO-66, although at low iridium loadings only one site is occupied. Density functional theory calculations provide structural results that are in good agreement with infrared and X-ray absorption fine-structure spectra. The reactivity of node-supported Ir(CO)2 with C2H4 and the catalytic activity and selectivity of the species initially present as Ir(C2H4)2 for ethylene hydrogenation and dimerization were investigated both experimentally and computationally and shown to be strongly influenced by the node.
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The synthesis of molybdenum oxo-amidinate complexes MoO
2
(R
2
AMD)
2
AMD =
N
,
N
′-di-R-acetamidinate; R = Cy (
2
; cyclohexyl) and
i
Pr (
3
), and their characterization by
1
H,
13
C NMR, X-ray ...diffraction, and thermogravimetric analysis is reported. Quartz-crystal microbalance and X-ray photoelectron spectroscopic studies confirm that
3
is an improved ALD precursor
versus
the R =
t
-butyl derivative for MoO
3
film growth. Complex
3
is accessible in higher yields (80%+), is easier to handle without mass loss, and in conjunction with O
3
as the second ALD reagent, yields nitride-free MoO
3
films.
The synthesis and characterization of molybdenum oxo-amidinate ALD precursors MoO
2
(R
2
AMD)
2
AMD =
N
,
N
′-di-R-acetamidinate; R = Cy (
2
; cyclohexyl) and
i
Pr (
3
) is reported.
To grow films of Cu2O, bis-(dimethylamino-2-propoxide)Cu(ii), or Cu(dmap), is used as an atomic layer deposition precursor using only water vapor as a co-reactant.
To grow films of Cu2O, bis-(dimethylamino-2-propoxide)Cu(ii), or Cu(dmap), is used as an atomic layer deposition precursor using only water vapor as a co-reactant.
Here, the synthesis of molybdenum oxo-amidinate complexes MoO2(R2AMD)2 AMD = N,N'-di-R-acetamidinate; R = Cy (2; cyclohexyl) and iPr (3), and their characterization by 1H, 13C NMR, X-ray diffraction, ...and thermogravimetric analysis is reported. Quartz-crystal microbalance and X-ray photoelectron spectroscopic studies confirm that 3 is an improved ALD precursor versus the R = t-butyl derivative for MoO3 film growth. Complex 3 is accessible in higher yields (80%+), is easier to handle without mass loss, and in conjunction with O3 as the second ALD reagent, yields nitride-free MoO3 films.
Metal–organic frameworks (MOFs) with Lewis acid catalytic sites, such as zirconium‐based MOFs (Zr‐MOFs), comprise a growing class of phosphatase‐like nanozymes that can degrade toxic organophosphate ...pesticides and nerve agents. Rationally engineering and shaping MOFs from as‐synthesized powders into hierarchically porous monoliths is essential for their use in emerging applications, such as filters for air and water purification and personal protection gear. However, several challenges still limit the production of practical MOF composites, including the need for sophisticated reaction conditions, low MOF catalyst loadings in the resulting composites, and poor accessibility to MOF‐based active sites. To overcome these limitations, a rapid synthesis method is developed to introduce Zr‐MOF nanozyme coating into cellulose nanofibers, resulting in the formation of processable monolithic aerogel composites with high MOF loadings. These composites contain Zr‐MOF nanozymes embedded in the structure, and hierarchical macro‐micro porosity enables excellent accessibility to catalytic active sites. This multifaceted rational design strategy, including the selection of a MOF with many catalytic sites, fine‐tuning the coating morphology, and the fabrication of a hierarchically structured monolithic aerogel, renders synergistic effects toward the efficient continuous hydrolytic detoxification of organophosphorus‐based nerve agent simulants and pesticides from contaminated water.
A rapid synthesis method is developed to introduce Zr‐MOF nanozyme coating into cellulose nanofibers, resulting in the formation of processable macro‐micro porous aerogel composites with high metal–organic framework (MOF) loadings. The hierarchically structured MOF nanozymes monolithic aerogel enables excellent accessibility to catalytic active sites for fast and efficient hydrolytic detoxification of organophosphorus‐based nerve agent simulants and pesticides from contaminated water.
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Bottom-up construction of highly intricate structures from simple building blocks remains one of the most difficult challenges in chemistry. We report a structurally complex, mesoporous uranium-based ...metal-organic framework (MOF) made from simple starting components. The structure comprises 10 uranium nodes and seven tricarboxylate ligands (both crystallographically nonequivalent), resulting in a 173.3-angstrom cubic unit cell enclosing 816 uranium nodes and 816 organic linkers—the largest unit cell found to date for any nonbiological material. The cuboctahedra organize into pentagonal and hexagonal prismatic secondary structures, which then form tetrahedral and diamond quaternary topologies with unprecedented complexity. This packing results in the formation of colossal icosidodecahedral and rectified hexakaidecahedral cavities with internal diameters of 5.0 nanometers and 6.2 nanometers, respectively—ultimately giving rise to the lowest-density MOF reported to date.
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Titanium dioxide (TiO2) thin films have been utilized in a wide range of applications in optoelectronics and solar energy conversion. In particular, TiO2 has been exclusively used in photovoltaic ...devices and photoelectrochemical cells owing to its ability to efficiently transport electrons and passivate photoactive materials against aqueous media. However, TiO2 exhibits optimal transport properties in the crystalline anatase phase, and thus requires a high temperature annealing, which significantly limits its application in temperature sensitive substrates or active materials (e.g. organic-inorganic hybrid perovskites). Moreover, while high resistance of TiO2 films necessitates the need for ultrathin films to reduce series resistance in PV devices, the synthesis of ultrathin pinhole-free TiO2 films remains a challenge through conventional deposition methods. To address these issues, TiO2 compact layers for planar perovskite PV devices were deposited via atomic layer deposition (ALD) - a chemically diverse vapor phase deposition technique with the capability to synthesize ultrathin pinhole-free films.
The rapid, discriminative, and portable detection of highly toxic chemical warfare agents is extremely important for response to public security emergencies but remains a challenge. One plausible ...solution involves the integration of porous molecular traps onto a photoelectrochemical (PEC) sensor. Here, a fast and facile protocol is developed to fabricate sub‐1 nm AgNPs encapsulated hydrogen‐bonded organic framework (HOF) nanocomposite materials through an in situ photoreduction and subsequent encapsulation process. Compared to traditional semiconductors and selected metal–organic frameworks (MOF) materials, these AgNPs@HOFs show significantly enhanced photocurrent. Most importantly, the portable PEC device based on AgNPs@HOF‐101 can selectively recognize 13 different mustard gas simulants, including 2‐chloroethyl ethyl sulfide (CEES), based on synergistic size‐exclusion and specific recognition. The extremely low detection limit for CEES (15.8 nmol L−1), reusability (at least 30 cycles), and long‐term working stability (at least 30 d) of the portable PEC device warrant its use as a chemical warfare agents (CWAs) sensor in practical field settings. More broadly, this work indicates that integrating porous molecular traps onto PEC sensors offers a promising strategy to further develop portable devices for CWAs detection with both ultrahigh sensitivity and selectivity.
An in situ photoreduction and subsequent encapsulation process affords nanocomposite materials comprising sub‐1 nm Ag nanoparticles (AgNPs) encapsulated in hydrogen‐bonded organic frameworks (HOFs). Compared to traditional semiconductors and selected metal–organic framework materials, the AgNPs@HOFs exhibit significantly enhanced photocurrent. A portable photoelectrochemical (PEC) device based on AgNPs@HOF‐101 detects chemical warfare agent (CWA) simulants with both nanomolar sensitivity and excellent selectivity.
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We report the design and synthesis of a metal–organic framework (MOF)–polythiophene composite that has comparable electronic conductivity to reported conductive 3-D MOFs, but with display and ...retention of high porosity, including mesoporosity. A robust zirconium MOF, NU-1000, was rendered electronically conductive by first incorporating, via solvent-assisted ligand incorporation (SALI), a carefully designed pentathiophene derivative at a density of one pentamer per hexa-zirconium node. Using a cast film of the intermediate composite (termed pentaSALI) on conductive glass, the incorporated oligothiophene was electrochemically polymerized to yield the conductive composite, Epoly. Depending on the doping level of the polythiophene in the composite, it can be tuned from an insulating state to a semiconduting state with conductivity of 1.3 × 10–7 (S cm–1), which is comparable to values reported for 3-D conductive MOFs. The porosity of the thin-film MOF–polythiophene composite was assessed using decane vapor uptake as determined by quartz crystal microgravimetry (QCM). The results indicate a porosity (pore volume) for Epoly essentially identical to that of bulk pentaSALI, and ∼74% of that of unmodified NU-1000. PentaSALI, and by inference Epoly, displays both micro- and mesoporosity, and features a BET surface area of nearly 1,600 m2·g–1, i.e., substantially larger than yet reported for any other electronically conductive MOF.
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