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2024 Volume 43 Issue 5
2024, 43(5): 100213
doi: 10.1016/j.cjsc.2023.100213
Abstract:
Planar cations or anions can form stacks in crystals or solutions, where the surrounding or environment plays a decisive role as demonstrated in previous studies. However, it remains unclear whether these counterintuitive interactions possess any inherent stability or are thoroughly repulsive if the constraint of environment is removed. In this work, we explored the inherent stability of π-π stacking between closed-shell ions of like charges with prototypes derived from experimental studies. The inherent metastability was identified by the characteristic local minima and the transition states preventing their dissociation and verified by ab initio molecular dynamics (AIMD) simulations. The nature of involved interactions was deciphered with the energy decomposition approach based on the block-localized wavefunction method (BLW-ED). Like the conventional neutral π-π stacking interactions, electron correlation is the most attractive energy component. But it is overturned by the Coulombic repulsion between net charges for all modes of dimerization, resulting in the overall repulsive inter-cation or anion interactions. Contributions from van der Waals interactions were also observed in the reduced density gradient analysis. The origin of the metastability was elucidated by examining the contributions of individual physical factors to the well-depths. The inherent metastability originates from the electron correlation, which dramatically increases due to the enhanced overlap between ions from a transition state to its corresponding minimum.
Planar cations or anions can form stacks in crystals or solutions, where the surrounding or environment plays a decisive role as demonstrated in previous studies. However, it remains unclear whether these counterintuitive interactions possess any inherent stability or are thoroughly repulsive if the constraint of environment is removed. In this work, we explored the inherent stability of π-π stacking between closed-shell ions of like charges with prototypes derived from experimental studies. The inherent metastability was identified by the characteristic local minima and the transition states preventing their dissociation and verified by ab initio molecular dynamics (AIMD) simulations. The nature of involved interactions was deciphered with the energy decomposition approach based on the block-localized wavefunction method (BLW-ED). Like the conventional neutral π-π stacking interactions, electron correlation is the most attractive energy component. But it is overturned by the Coulombic repulsion between net charges for all modes of dimerization, resulting in the overall repulsive inter-cation or anion interactions. Contributions from van der Waals interactions were also observed in the reduced density gradient analysis. The origin of the metastability was elucidated by examining the contributions of individual physical factors to the well-depths. The inherent metastability originates from the electron correlation, which dramatically increases due to the enhanced overlap between ions from a transition state to its corresponding minimum.
2024, 43(5): 100254
doi: 10.1016/j.cjsc.2024.100254
Abstract:
A novel classification scheme for inorganic cluster compounds is presented based on the characteristics of their electronic structures. In the classification scheme, five distinct categories have been introduced, including Jellium clusters, Wadian clusters, electron-precise clusters, π-donor ligated metal-metal bonded clusters, and antiferromagnetically coupled high-spin metal clusters.
A novel classification scheme for inorganic cluster compounds is presented based on the characteristics of their electronic structures. In the classification scheme, five distinct categories have been introduced, including Jellium clusters, Wadian clusters, electron-precise clusters, π-donor ligated metal-metal bonded clusters, and antiferromagnetically coupled high-spin metal clusters.
2024, 43(5): 100266
doi: 10.1016/j.cjsc.2024.100266
Abstract:
Molecular dynamics simulation is a powerful tool in the study of polymeric systems. Among various simulation methods, coarse-grained (CG) model is particularly impactful because it effectively reduces the computational complexity and enables the simulation of large-scale polymer systems. In this review, we briefly summarize recent progresses in our group on the development of CG simulation methods, models, as well as in the software development. By compiling the CG models and various simulation methods, we have successfully developed a GPU-accelerated large-scale molecular simulation toolkit (GALAMOST), which provides an efficient platform for polymer simulations. We further developed the new-generation PyGAMD (Python GPU-Accelerated MD Software, website: http://pygamd.com/) software based on the Python platform, which makes the polymer simulation more powerful, flexible and user-friendly. In addition, some recent application cases in different polymer systems are also introduced. The aspiration of this review is to assist researchers in understanding the role of molecular simulations in the design and development of advanced polymer materials not only for academic researches, but also for possible industrial applications.
Molecular dynamics simulation is a powerful tool in the study of polymeric systems. Among various simulation methods, coarse-grained (CG) model is particularly impactful because it effectively reduces the computational complexity and enables the simulation of large-scale polymer systems. In this review, we briefly summarize recent progresses in our group on the development of CG simulation methods, models, as well as in the software development. By compiling the CG models and various simulation methods, we have successfully developed a GPU-accelerated large-scale molecular simulation toolkit (GALAMOST), which provides an efficient platform for polymer simulations. We further developed the new-generation PyGAMD (Python GPU-Accelerated MD Software, website: http://pygamd.com/) software based on the Python platform, which makes the polymer simulation more powerful, flexible and user-friendly. In addition, some recent application cases in different polymer systems are also introduced. The aspiration of this review is to assist researchers in understanding the role of molecular simulations in the design and development of advanced polymer materials not only for academic researches, but also for possible industrial applications.
2024, 43(5): 100267
doi: 10.1016/j.cjsc.2024.100267
Abstract:
This work highlights two different strategies for functionalizing amino groups in MOF-808: directly binding amino acid to zirconium cluster and polyamine incorporation via nucleophilic substitution. The synthesized MOF-808-AAs and MOF-808-PAs exhibit remarkable CO2 uptake capacity with amino group. Furthermore, under humidity condition, such capacity is greatly enhanced by dynamic breakthrough measurements. This research reveals that amine-functionalized MOF-808 are promising sorbents for direct air capture of CO2 and propose a new strategy for functionalizing MOFs with post-modification for other applications.
This work highlights two different strategies for functionalizing amino groups in MOF-808: directly binding amino acid to zirconium cluster and polyamine incorporation via nucleophilic substitution. The synthesized MOF-808-AAs and MOF-808-PAs exhibit remarkable CO2 uptake capacity with amino group. Furthermore, under humidity condition, such capacity is greatly enhanced by dynamic breakthrough measurements. This research reveals that amine-functionalized MOF-808 are promising sorbents for direct air capture of CO2 and propose a new strategy for functionalizing MOFs with post-modification for other applications.
2024, 43(5): 100269
doi: 10.1016/j.cjsc.2024.100269
Abstract:
The successful implementation of direct anodic epoxidation relies on the compatibility of electrolyte system with specific catalysts and alkene substrates. In the oxidation of various alkene substrates using a water-acetonitrile mixed electrolyte, acetonitrile enhances the solubility of hydrophobic substrates, but organic solvents may increase the overall resistance of the electrolyte. When water is used as the sole solvent, gas-diffusion electrodes can address the low solubility issue of propylene. Therefore, water electrolyte is sufficient for epoxide production. PdPtOx/C catalyst on a gas-diffusion electrode exhibited an average Faradaic efficiency of approximately 60% for propylene epoxidation at a potential of 1.65 V (vs. SHE).
The successful implementation of direct anodic epoxidation relies on the compatibility of electrolyte system with specific catalysts and alkene substrates. In the oxidation of various alkene substrates using a water-acetonitrile mixed electrolyte, acetonitrile enhances the solubility of hydrophobic substrates, but organic solvents may increase the overall resistance of the electrolyte. When water is used as the sole solvent, gas-diffusion electrodes can address the low solubility issue of propylene. Therefore, water electrolyte is sufficient for epoxide production. PdPtOx/C catalyst on a gas-diffusion electrode exhibited an average Faradaic efficiency of approximately 60% for propylene epoxidation at a potential of 1.65 V (vs. SHE).
2024, 43(5): 100271
doi: 10.1016/j.cjsc.2024.100271
Abstract:
In conclusion, LVOs have been shown the feasibility as Ca2+ host materials, but it is worthwhile to consider how to accelerate the ion and electron transfer rates and enhance structural stability simultaneously with a view to realizing high specific capacities, long cycling stability and fast charging/discharging capability (Fig. 2). “Every cloud has a silver lining”. Although improvement strategies, such as interlayer engineering, nanostructural design, etc., have exhibited significant enhancement, more attention should be paid to their negative effects and operation difficulties. Additionally, we would like to emphasize that LVOs have been widely used in other multivalent ion (e.g., Zn2+, Al2+) batteries, but the experiences and knowledge obtained cannot be directly applied to CIBs because the discrepancies of various multivalent ions like charge density and ionic radius may result in significantly different charge storage behaviors regardless of the physical/chemical similarities. As an emerging battery technology, CIBs also remain elusory issues in anode/electrolyte interphase. The surface of the Ca metal anode is easily passivated in most conventional electrolytes with sluggish and poorly reversible Ca stripping/plating behaviors. The modification of cathode materials is suggested to be in combination with electrolyte design to achieve further improvements in CIBs.
In conclusion, LVOs have been shown the feasibility as Ca2+ host materials, but it is worthwhile to consider how to accelerate the ion and electron transfer rates and enhance structural stability simultaneously with a view to realizing high specific capacities, long cycling stability and fast charging/discharging capability (Fig. 2). “Every cloud has a silver lining”. Although improvement strategies, such as interlayer engineering, nanostructural design, etc., have exhibited significant enhancement, more attention should be paid to their negative effects and operation difficulties. Additionally, we would like to emphasize that LVOs have been widely used in other multivalent ion (e.g., Zn2+, Al2+) batteries, but the experiences and knowledge obtained cannot be directly applied to CIBs because the discrepancies of various multivalent ions like charge density and ionic radius may result in significantly different charge storage behaviors regardless of the physical/chemical similarities. As an emerging battery technology, CIBs also remain elusory issues in anode/electrolyte interphase. The surface of the Ca metal anode is easily passivated in most conventional electrolytes with sluggish and poorly reversible Ca stripping/plating behaviors. The modification of cathode materials is suggested to be in combination with electrolyte design to achieve further improvements in CIBs.
2024, 43(5): 100273
doi: 10.1016/j.cjsc.2024.100273
Abstract:
In conclusion, we apply four aromaticity indices, including NICS, ACID-π, EDDB and HOMA methods, to evaluate (anti-)aromaticity of DHP systems for the S0 and T1/S1 states. All the four indices agree that DHP systems experience aromaticity reversal when excited to T1 state. More importantly, the MCSCF-GIAO method demonstrates that Baird's rule holds for both T1 and S1 states of such systems from a theoretical point of view. Furthermore, we find that t-Bu-DHP would undergo aro[1]matic reduction in S0 states when conjugated moieties like acetylenyl are introduced as its side-chain groups according to corresponding values. These findings may shed light on the design and development of materials concerning photochemical reactions. In addition, their radical character is also studied, and we discover that t-Bu-DHP is more likely to form radicaloids during excitation when an acetylenyl group is introduced. It should be noted that, however, quantitatively reliable NICS for excited-state acety-t-Bu-DHP is not guaranteed by the above computation, since MCSCF-GIAO can't afford the description of full valence π space in this system, which would be indispensable for excited states. When involving large active space, more accurate NICS calculation has to overcome the exponential growth of the FCI expansion. Therefore, DMRG's marriage to MCSCF-GIAO is supposed to be put on the agenda, and our laboratory is striving to be their matchmaker.
In conclusion, we apply four aromaticity indices, including NICS, ACID-π, EDDB and HOMA methods, to evaluate (anti-)aromaticity of DHP systems for the S0 and T1/S1 states. All the four indices agree that DHP systems experience aromaticity reversal when excited to T1 state. More importantly, the MCSCF-GIAO method demonstrates that Baird's rule holds for both T1 and S1 states of such systems from a theoretical point of view. Furthermore, we find that t-Bu-DHP would undergo aro[1]matic reduction in S0 states when conjugated moieties like acetylenyl are introduced as its side-chain groups according to corresponding values. These findings may shed light on the design and development of materials concerning photochemical reactions. In addition, their radical character is also studied, and we discover that t-Bu-DHP is more likely to form radicaloids during excitation when an acetylenyl group is introduced. It should be noted that, however, quantitatively reliable NICS for excited-state acety-t-Bu-DHP is not guaranteed by the above computation, since MCSCF-GIAO can't afford the description of full valence π space in this system, which would be indispensable for excited states. When involving large active space, more accurate NICS calculation has to overcome the exponential growth of the FCI expansion. Therefore, DMRG's marriage to MCSCF-GIAO is supposed to be put on the agenda, and our laboratory is striving to be their matchmaker.
2024, 43(5): 100274
doi: 10.1016/j.cjsc.2024.100274
Abstract:
In conclusion, a set of high-accuracy global coupled PESs of X ̃ and B ̃ state of H2O has been improved by adding more ab initio points in O+H2 channel to the previous calculation data reported by Jiang et al. and fitting all points by the PIP-NN method. The structural, energetic and spectroscopic properties of PESs are in good agreement with experimental measurements. The quantum dynamical calculations were implemented by using a Chebyshev real wave packet method, and the total cross section is consistent with the latest experimental measurements. The branching ratio of hydrogen generation is very small, and the product H2 mainly distributes at the vibrational ground state with only X ̃ and B ̃ states considered. While diverting the initial wave packet from Frank-Condon region to B ̃-D ̃ conical intersection, the calculated branching ratio of H2 generation channel increases obviously, which indicates an important role of higher D ̃ state on the dynamics for O+H2 channel. It should be pointed out that a more accurate dynamical characterization of the X ̃-B ̃-D ̃ three-state model as well as more experimental work will be helpful to better understand the production of O(1D)+H2(X ̃1~Σg+) from water photodissociation at different wavelengths.
In conclusion, a set of high-accuracy global coupled PESs of X ̃ and B ̃ state of H2O has been improved by adding more ab initio points in O+H2 channel to the previous calculation data reported by Jiang et al. and fitting all points by the PIP-NN method. The structural, energetic and spectroscopic properties of PESs are in good agreement with experimental measurements. The quantum dynamical calculations were implemented by using a Chebyshev real wave packet method, and the total cross section is consistent with the latest experimental measurements. The branching ratio of hydrogen generation is very small, and the product H2 mainly distributes at the vibrational ground state with only X ̃ and B ̃ states considered. While diverting the initial wave packet from Frank-Condon region to B ̃-D ̃ conical intersection, the calculated branching ratio of H2 generation channel increases obviously, which indicates an important role of higher D ̃ state on the dynamics for O+H2 channel. It should be pointed out that a more accurate dynamical characterization of the X ̃-B ̃-D ̃ three-state model as well as more experimental work will be helpful to better understand the production of O(1D)+H2(X ̃1~Σg+) from water photodissociation at different wavelengths.
2024, 43(5): 100275
doi: 10.1016/j.cjsc.2024.100275
Abstract:
The luminescent properties of uranyl complexes have been extensively studied; however, fewer investigations have explored their potential applications in ionizing radiation detection. This study delves into the synthesis and structures of a series of uranyl-organic hybrids, as well as their promising use for X-ray scintillation. The combination of uranyl cations with 3-(pyridin-4-yl) benzoate (pba–) organic ligands has yielded a new uranyl-organic hybrid with a 2D network. Notably, U-pba exhibits a distinct radioluminescence, with intensities linearly correlated to X-ray dose rates across a broad dynamic range (36.7–4545.7 μGy s−1) with a detection limit of 38.12 μGy s−1. Additionally, it demonstrates high radiation hardness and excellent hydrolytical stability, rendering it as a promising candidate for X-ray scintillation. This work demonstrates that uranyl-organic hybrids represent a promising platform for ionizing radiation detection.
The luminescent properties of uranyl complexes have been extensively studied; however, fewer investigations have explored their potential applications in ionizing radiation detection. This study delves into the synthesis and structures of a series of uranyl-organic hybrids, as well as their promising use for X-ray scintillation. The combination of uranyl cations with 3-(pyridin-4-yl) benzoate (pba–) organic ligands has yielded a new uranyl-organic hybrid with a 2D network. Notably, U-pba exhibits a distinct radioluminescence, with intensities linearly correlated to X-ray dose rates across a broad dynamic range (36.7–4545.7 μGy s−1) with a detection limit of 38.12 μGy s−1. Additionally, it demonstrates high radiation hardness and excellent hydrolytical stability, rendering it as a promising candidate for X-ray scintillation. This work demonstrates that uranyl-organic hybrids represent a promising platform for ionizing radiation detection.
2024, 43(5): 100287
doi: 10.1016/j.cjsc.2024.100287
Abstract:
In summary, the sulfated Pt/TiO2-S catalysts were preparedby impregnating with sulfuric acid solution. The sulfation of TiO2 causes the supported Pt/TiO2-S catalysts to severely deactivate towards methane combustion. It is found that sulfation of TiO2 supports suppresses the formation and stability of highly reactive Pt2+ species during methane oxidation process, weakens the adsorption of CH4 molecule, and raises activation energy barrier of the first C-H bond, eventually leading to a sharp decline in activity.
In summary, the sulfated Pt/TiO2-S catalysts were preparedby impregnating with sulfuric acid solution. The sulfation of TiO2 causes the supported Pt/TiO2-S catalysts to severely deactivate towards methane combustion. It is found that sulfation of TiO2 supports suppresses the formation and stability of highly reactive Pt2+ species during methane oxidation process, weakens the adsorption of CH4 molecule, and raises activation energy barrier of the first C-H bond, eventually leading to a sharp decline in activity.
