43 research outputs found
De Novo Tailoring Pore Morphologies and Sizes for Different Substrates in a Urea-Containing MOFs Catalytic Platform
To better understand
the structure–catalytic property relationship,
a platform of urea-containing MOFs with diverse topologies as hydrogen-bonding
(H-bond) catalyst has been well established in the present work. During
the construction of MOFs, we proposed a new strategy called the isoreticular
functionalization approach in which the desired topological net is
first considered as a blueprint, and then two predesigned functionalized
polydentate ligands link to four different metal clusters by de novo
routes to achieve the MOFs with expected pore structure and catalytic
sites. By means of this strategy, we successfully synthesized four
programmed MOFs (named as <b>URMOF-1–4</b>) with diverse
topologies, pore morphologies, and sizes and distribution of active
sites. Subsequently, we systematically investigated the Friedel–Crafts
reactions of 1-methylpyrrole or 1-methylindole with nitroalkene derivatives
with diverse sizes to assess the catalytic properties of the above-mentioned
URMOFs. These four URMOFs can act as reusable H-bond catalysts and
show varied catalytic capacities and size-selectivity properties.
Most significantly, the open morphologies of pores, large channels
in the framework, and effective distribution of active sites on the
wall of the channel are proved to facilitate catalysis. This urea-containing
MOF catalytic platform provides new insight into the catalytic properties
of MOFs with the same kind of active sites but diverse topologies,
pore morphologies, and sizes and distributions of catalytic sites
Engineering UiO-68-Typed Homochiral Metal–Organic Frameworks for the Enantiomeric Separation of Fmoc-AAs and Mechanism Study
Homochiral metal–organic frameworks (HMOFs) have
been widely
investigated in the application of enantiomeric separation. Nonetheless,
it remains a significant challenge to explore the effect of multiple
weak interactions between HMOF adsorbents and chiral adsorbates on
enantiomeric separation performance still. In this work, robust chiral
amine-alcohol-functionalized UiO-68-typed Zr-HMOFs 1–3 with the same hydrogen-bonding sites but slightly different
Ï€-binding sites were prepared for the enantioseparation of amino
acid derivatives (Fmoc-AAs) with large π-binding groups. As
a consequence of multiple host–guest interactions, these Zr-HMOFs
exhibit speedy adsorption and high adsorption capacity for Fmoc-L/D-AAs and dissimilar enantioselectivity
for the adsorption of their enantiomers. Materials 1 and 2 exhibit excellent enantioselective separation performance
for Fmoc-valine with a single terminal π-binding group, while
material 3 displays excellent enantioselective separation
performance for Fmoc-phenylalanine and Fmoc-tryptophan with π-binding
groups at both ends. As evidently demonstrated by our experimental
and density functional theory (DFT) computational results, when the
number of π-binding groups preset in the confined chiral space
of adsorbents matches the number of π-binding groups of chiral
adsorbates, the synergism of π–π or σ–π
interactions will increase enantioselectivity; otherwise, the competition
interactions from redundant identical binding sites will weaken enantioselectivity.
Our case not only provides a tremendously typical system for investigating
the collaborative discrimination of multiple weak interactions and
exploring the impact of relatively excessive binding sites of HMOF
adsorbents or chiral adsorbates on the enantioselective separation
performance but also provides guidance for targeted functional modifications
of high-performance chiral porous materials
Engineering UiO-68-Typed Homochiral Metal–Organic Frameworks for the Enantiomeric Separation of Fmoc-AAs and Mechanism Study
Homochiral metal–organic frameworks (HMOFs) have
been widely
investigated in the application of enantiomeric separation. Nonetheless,
it remains a significant challenge to explore the effect of multiple
weak interactions between HMOF adsorbents and chiral adsorbates on
enantiomeric separation performance still. In this work, robust chiral
amine-alcohol-functionalized UiO-68-typed Zr-HMOFs 1–3 with the same hydrogen-bonding sites but slightly different
Ï€-binding sites were prepared for the enantioseparation of amino
acid derivatives (Fmoc-AAs) with large π-binding groups. As
a consequence of multiple host–guest interactions, these Zr-HMOFs
exhibit speedy adsorption and high adsorption capacity for Fmoc-L/D-AAs and dissimilar enantioselectivity
for the adsorption of their enantiomers. Materials 1 and 2 exhibit excellent enantioselective separation performance
for Fmoc-valine with a single terminal π-binding group, while
material 3 displays excellent enantioselective separation
performance for Fmoc-phenylalanine and Fmoc-tryptophan with π-binding
groups at both ends. As evidently demonstrated by our experimental
and density functional theory (DFT) computational results, when the
number of π-binding groups preset in the confined chiral space
of adsorbents matches the number of π-binding groups of chiral
adsorbates, the synergism of π–π or σ–π
interactions will increase enantioselectivity; otherwise, the competition
interactions from redundant identical binding sites will weaken enantioselectivity.
Our case not only provides a tremendously typical system for investigating
the collaborative discrimination of multiple weak interactions and
exploring the impact of relatively excessive binding sites of HMOF
adsorbents or chiral adsorbates on the enantioselective separation
performance but also provides guidance for targeted functional modifications
of high-performance chiral porous materials
Engineering UiO-68-Typed Homochiral Metal–Organic Frameworks for the Enantiomeric Separation of Fmoc-AAs and Mechanism Study
Homochiral metal–organic frameworks (HMOFs) have
been widely
investigated in the application of enantiomeric separation. Nonetheless,
it remains a significant challenge to explore the effect of multiple
weak interactions between HMOF adsorbents and chiral adsorbates on
enantiomeric separation performance still. In this work, robust chiral
amine-alcohol-functionalized UiO-68-typed Zr-HMOFs 1–3 with the same hydrogen-bonding sites but slightly different
Ï€-binding sites were prepared for the enantioseparation of amino
acid derivatives (Fmoc-AAs) with large π-binding groups. As
a consequence of multiple host–guest interactions, these Zr-HMOFs
exhibit speedy adsorption and high adsorption capacity for Fmoc-L/D-AAs and dissimilar enantioselectivity
for the adsorption of their enantiomers. Materials 1 and 2 exhibit excellent enantioselective separation performance
for Fmoc-valine with a single terminal π-binding group, while
material 3 displays excellent enantioselective separation
performance for Fmoc-phenylalanine and Fmoc-tryptophan with π-binding
groups at both ends. As evidently demonstrated by our experimental
and density functional theory (DFT) computational results, when the
number of π-binding groups preset in the confined chiral space
of adsorbents matches the number of π-binding groups of chiral
adsorbates, the synergism of π–π or σ–π
interactions will increase enantioselectivity; otherwise, the competition
interactions from redundant identical binding sites will weaken enantioselectivity.
Our case not only provides a tremendously typical system for investigating
the collaborative discrimination of multiple weak interactions and
exploring the impact of relatively excessive binding sites of HMOF
adsorbents or chiral adsorbates on the enantioselective separation
performance but also provides guidance for targeted functional modifications
of high-performance chiral porous materials
In Situ Construction of a Coordination Zirconocene Tetrahedron
The
current study describes the first in situ synthesis and characterization
of a new family of cationic coordination tetrahedra of both the V<sub>4</sub>F<sub>4</sub> and V<sub>4</sub>E<sub>6</sub> type, which are
constructed by a new building block based on a trinuclear zirconocene
moiety and the dicarboxylate or tricarboxylate anions
A Water and Thermally Stable Metal–Organic Framework Featuring Selective CO<sub>2</sub> Adsorption
A 2-fold
interpenetrated microporous MOF [Ni<sub>2</sub>(C<sub>2</sub>O<sub>4</sub>)Â(L)<sub>2</sub>]<sub><i>n</i></sub>·6<i>n</i>H<sub>2</sub>O (HL = 4,2′:4″,2′-terpyridine-4′-carboxylic
acid) (<b>1</b>) was synthesized and structurally characterized. <b>1</b> has obvious 1D channels along the crystallographic <i>a</i> and <i>c</i> axes with a pore size of 5.7 to
6.9 Ã…. Topological analysis shows that the framework of <b>1</b> can be interpreted as a (3,4)-connected net with point symbol
(6<sup>3</sup>)Â(6<sup>5</sup>·8). <b>1</b> exhibits high
water and thermal stability, which is demonstrated by TGA, PXRD, and
VT-PXRD. Additionally, the high temperature structure of <b>1</b>′ (433 K) undoubtedly demonstrates the stability of the framework.
More importantly, <b>1</b> shows high selectivities for CO<sub>2</sub> over N<sub>2</sub>, H<sub>2</sub>, and CH<sub>4</sub> at
low pressure and 273 K
In Situ Construction of a Coordination Zirconocene Tetrahedron
The
current study describes the first in situ synthesis and characterization
of a new family of cationic coordination tetrahedra of both the V<sub>4</sub>F<sub>4</sub> and V<sub>4</sub>E<sub>6</sub> type, which are
constructed by a new building block based on a trinuclear zirconocene
moiety and the dicarboxylate or tricarboxylate anions
In Situ Construction of a Coordination Zirconocene Tetrahedron
The
current study describes the first in situ synthesis and characterization
of a new family of cationic coordination tetrahedra of both the V<sub>4</sub>F<sub>4</sub> and V<sub>4</sub>E<sub>6</sub> type, which are
constructed by a new building block based on a trinuclear zirconocene
moiety and the dicarboxylate or tricarboxylate anions
Adsorptive Separation of Methylfuran and Dimethylfuran by a Robust Porous Organic Cage
As vital raw materials in the chemical industry, 2-methylfuran
(MeF) and 2,5-dimethylfuran (DMeF) are commonly
produced as mixtures. The selective separation of MeF and DMeF is crucial yet challenging, with significant
industrial and economic implications. This study presents an energy-efficient
separation technique using a robust calix[4]resorcinarene-based supramolecular
porous organic cage (POC), CPOC-301, to effectively capture DMeF from an equimolar MeF/DMeF mixture
within 2 h, yielding 95.3% purity. The exceptional separation efficiency
stems from the superior structural stability of CPOC-301, maintaining its initial porous crystalline structure during separation.
Calculations show that CPOC-301 forms more C–H···π
hydrogen bonds with DMeF versus MeF, accounting
for its DMeF selectivity. CPOC-301 can be
easily regenerated via heat under a vacuum and reused for over five
adsorption–desorption cycles without significant performance
loss. This work introduces an approach to separate similar organic
molecules effectively using POC materials
Stabilization of Allylic Amine N‑Oxide through Cocrystallization with Pyrogallol[4]arene
An
active allylic amine N-oxide (ANO) molecule was cocrystallized
with pyrogallol[4]Âarene through intermolecular hydrogen bonds and
π···π interactions. Interestingly, [2,3]-Meisenheimer
rearrangement of the ANO was suppressed, which was analyzed in detail
in the solid state by single crystal X-ray crystallography in varying
temperatures. Additionally, this work provides not only a new strategy
to stabilize reactive chemicals, but also a unique method to elucidate
their structures