5 research outputs found
Оценка экологической опасности рассеивания газопылевого облака при массовых взрывах в карьерах
Heteroanion
(HA) moieties have a key role in templating of heteropolyoxometalate
(HPA) architectures, but clusters templated by two different templates
are rarely reported. Herein, we show how a cross-shaped HPA-based
architecture can self-sort the HA templates by pairing two different
guests into a divacant {XYW<sub>15</sub>O<sub>54</sub>} building block,
with four of these building block units being linked together to complete
the cross-shaped architecture. We exploited this observation to incorporate
HA templates into well-defined positions within the clusters, leading
to the isolation of a collection of mixed-HA templated cross-shaped
polyanions [(XYW<sub>15</sub>O<sub>54</sub>)<sub>4</sub>(WO<sub>2</sub>)<sub>4</sub>]<sup>32–/36–</sup> (X = H–P, Y
= Se, Te, As). The template positions have been unambiguously determined
by single crystal X-ray diffraction, NMR spectroscopy, and high-resolution
electrospray ionization mass spectrometry; these studies demonstrated
that the mixed template containing HPA clusters are the preferred
products which crystallize from the solution. Theoretical studies
using DFT calculations suggest that the selective self-sorting originates
from the coordination of the template in solution. The cross-shaped
polyoxometalate clusters are redox-active, and the ability of molecules
to accept electrons is slightly modulated by the HA incorporated as
shown by differential pulse voltammetry experiments. These results
indicate that the cross-shaped HPAs can be used to select templates
from solution, and themselves have interesting geometries, which will
be useful in developing functional molecular architectures based upon
HPAs with well-defined structures and electronic properties
Counterintuitive Adsorption of [PW<sub>11</sub>O<sub>39</sub>]<sup>7–</sup> on Au(100)
Understanding the
interaction between charged species and surfaces is one of the most
challenging topics in chemistry, given its wide involvement in several
fields such as electrocatalysis, stabilization of metal nanoparticles,
preparation of devices, etc. In general, these systems are particularly
complex to model because of the elevated number of factors that must
be taken into account. Here, we report a robust strategy based on
density functional theory for studying these interactions, which has
been applied to the highly charged lacunary [PW<sub>11</sub>O<sub>39</sub>]<sup>7–</sup> (PW<sub>11</sub>) adsorbed on gold
and silver surfaces. In this context, we find that, unlike the modeling
of polyoxoanions in solution, the incorporation of counterions in
the computational models is crucial for accurately reproducing the
properties of the system, even if an implicit solvent is used. Most
interestingly, we find that the PW<sub>11</sub> cluster does not preferentially
adsorb to the gold surface via its more nucleophilic monodefect face
but, rather, through less negatively charged terminal oxygen ligands,
with an orientation similar to that found for the nondefective Keggin
anion [SiW<sub>12</sub>O<sub>40</sub>]<sup>4–</sup>, induced
by the strong anion–cation interactions from the same and neighboring
units. This counterintuitive result is important for ongoing efforts
to understand and utilize the properties of polyoxometalate monolayers
on gold and other reactive metal surfaces
Constructing Transition Metal Single-Atom-Modified MoB<sub>2</sub>: Extraordinary Electrocatalytic Hydrogen Evolution and Mechanism Investigation
Developing
single-atom catalysts (SACs) and exploring the interaction
between a single atom and support are crucial for identifying the
active centers, clarifying the catalytic mechanisms, and deepening
understanding of SACs. Herein, by employing Anderson-type POMs as
molecular precursor, a series of transition metal (TM = Ni, Co, Fe)
single atoms anchored on MoB2 (TM-MoB2) with
high TM loading (∼6.91 wt %) are prepared. The decoration of
TM promotes the electrocatalytic hydrogen evolution activity of MoB2, of which Ni-MoB2 delivers the best performance
in both alkaline and acidic solutions, outperforming most TM boride-based
catalysts. Density functional theory simulation reveals that the introduction
of Ni single atoms endows the top Mo on the Ni-MoB2 surface
with low water dissociation barrier (∼0.62 eV) and optimal
H adsorption Gibbs free energy (∼0.02 eV), thus exhibiting
remarkable hydrogen evolution activity. This work offers a versatile
strategy for preparing TM-MoB2 SACs and paves the way to
recognize SACs with a new support platform
Self-Sorting of Heteroanions in the Assembly of Cross-Shaped Polyoxometalate Clusters
Heteroanion
(HA) moieties have a key role in templating of heteropolyoxometalate
(HPA) architectures, but clusters templated by two different templates
are rarely reported. Herein, we show how a cross-shaped HPA-based
architecture can self-sort the HA templates by pairing two different
guests into a divacant {XYW<sub>15</sub>O<sub>54</sub>} building block,
with four of these building block units being linked together to complete
the cross-shaped architecture. We exploited this observation to incorporate
HA templates into well-defined positions within the clusters, leading
to the isolation of a collection of mixed-HA templated cross-shaped
polyanions [(XYW<sub>15</sub>O<sub>54</sub>)<sub>4</sub>(WO<sub>2</sub>)<sub>4</sub>]<sup>32–/36–</sup> (X = H–P, Y
= Se, Te, As). The template positions have been unambiguously determined
by single crystal X-ray diffraction, NMR spectroscopy, and high-resolution
electrospray ionization mass spectrometry; these studies demonstrated
that the mixed template containing HPA clusters are the preferred
products which crystallize from the solution. Theoretical studies
using DFT calculations suggest that the selective self-sorting originates
from the coordination of the template in solution. The cross-shaped
polyoxometalate clusters are redox-active, and the ability of molecules
to accept electrons is slightly modulated by the HA incorporated as
shown by differential pulse voltammetry experiments. These results
indicate that the cross-shaped HPAs can be used to select templates
from solution, and themselves have interesting geometries, which will
be useful in developing functional molecular architectures based upon
HPAs with well-defined structures and electronic properties
Self-Sorting of Heteroanions in the Assembly of Cross-Shaped Polyoxometalate Clusters
Heteroanion
(HA) moieties have a key role in templating of heteropolyoxometalate
(HPA) architectures, but clusters templated by two different templates
are rarely reported. Herein, we show how a cross-shaped HPA-based
architecture can self-sort the HA templates by pairing two different
guests into a divacant {XYW<sub>15</sub>O<sub>54</sub>} building block,
with four of these building block units being linked together to complete
the cross-shaped architecture. We exploited this observation to incorporate
HA templates into well-defined positions within the clusters, leading
to the isolation of a collection of mixed-HA templated cross-shaped
polyanions [(XYW<sub>15</sub>O<sub>54</sub>)<sub>4</sub>(WO<sub>2</sub>)<sub>4</sub>]<sup>32–/36–</sup> (X = H–P, Y
= Se, Te, As). The template positions have been unambiguously determined
by single crystal X-ray diffraction, NMR spectroscopy, and high-resolution
electrospray ionization mass spectrometry; these studies demonstrated
that the mixed template containing HPA clusters are the preferred
products which crystallize from the solution. Theoretical studies
using DFT calculations suggest that the selective self-sorting originates
from the coordination of the template in solution. The cross-shaped
polyoxometalate clusters are redox-active, and the ability of molecules
to accept electrons is slightly modulated by the HA incorporated as
shown by differential pulse voltammetry experiments. These results
indicate that the cross-shaped HPAs can be used to select templates
from solution, and themselves have interesting geometries, which will
be useful in developing functional molecular architectures based upon
HPAs with well-defined structures and electronic properties