Molecular Model Systems Research Articles

Graph-neural-network potential energy surface to speed up Monte Carlo simulations of water cluster anions

Regression of potential energy functions stands as one of the most prevalent applications of machine learning in the realm of materials simulation, offering the prospect of accelerating simulations by several orders of magnitude. Recently, graph-based architectures have emerged as particularly adept for modeling molecular systems. However, the development of robust and transferable potentials, leading to stable simulations for different sizes and physical conditions, remains an ongoing area of investigation. In this study, we compare the performance of several graph neural networks for predicting the energy of water cluster anions, a system of fundamental interest in Chemistry and Biology. Following the identification of the graph attention network as the optimal aggregation procedure for this task, we obtained an efficient and accurate energy model. This model is then employed to conduct Monte Carlo simulations of clusters across different sizes, demonstrating stable behavior. Notably, the predicted surface-to-interior state transition point and the bulk energy of the system are consistent with findings from other investigations, at a computational cost three-orders of magnitude lower.

Robust superhydrophobic self-cleaning coating prepared by silane modified multi-walled carbon nanotubes: A combined experimental and molecular dynamics study

As a functional material, superhydrophobic coating has been widely studied in the field of self-cleaning. However, obtaining superhydrophobic coatings with robustness through simple preparation processes remains a challenge. In this paper, a robust superhydrophobic coating is prepared based on multi-walled carbon nanotubes modified by octyltrimethoxysilane, and its performance and hydrophobic mechanism are studied by experiments and molecular dynamics simulation. The superhydrophobic coating is prepared by one-step spraying method. The coating is characterized and analyzed by scanning electron microscopy and Fourier transform infrared spectroscopy, and the properties of the coating are tested by experiments. Molecular dynamics simulation is used in the study to construct a molecular model system, and the molecular modification mechanism and coating wettability are simulated under the COMPASSII force field. The results show that octyltrimethoxysilane successfully modified carbon nanotubes, and the hydroxyl groups at the head of the molecular chain are bound to the surface of the carbon nanotubes in the form of hydrogen bonds, while the tail of the molecular chain is far away from the surface. After modification, the surface of carbon nanotubes changed from hydrophilic to hydrophobic. The prepared superhydrophobic coating not only has excellent self-cleaning properties, but also exhibits corrosion resistance to acid and alkali solutions. The coating still has superhydrophobic when the wear length is in the range of 400 cm. It can be seen that a robust superhydrophobic self-cleaning coating is successfully prepared by a simple one-step spraying method. The modification mechanism and the hydrophobic mechanism of the coating were obtained by the combination of experiment and molecular dynamics simulation, which provided theoretical support for the superhydrophobic of the coating at the micro level.

Study of Ammonia Adsorption on Magnetite Surfaces with Molecular Dynamics Simulations.

The present study proposes an atomistic molecular dynamics model system of a magnetite (Fe3O4) {111} surface. The effect of temperature on the adsorption process of ammonia (NH3) at low concentrations in the aqueous phase has been considered. The molecular dynamics simulations were carried out using the Clay force field (Clay FF) with a modification for the iron atoms in the NPT ensemble at a pressure of 90 bar. The considered system was heated in a temperature range from 293 to 473 K, and additional relaxations were performed at temperatures of interest. Within the scope of this study, the basic parameters of the magnetite surface were calculated and the distances between the ammonia molecules and the surface were determined. A general idea of the degree and rate of adsorption at specific temperatures was obtained. The calculation results were compared to the experimental data where possible and to other available simulations of adsorption processes on metal oxides.

Comparative analysis of the RVA VP7 and VP4 antigenic epitopes circulating in Iran and the Rotarix and RotaTeq vaccines

Analyzing the lineages and detecting antigenic variation in immunogenic motifs of Group A Rotavirus (RVA) variants is crucial because it can impact vaccine efficacy. This study investigated the circulating lineages of VP4 and VP7 proteins of human RVA isolates and their phylogeny in ≤24-month-old symptomatic, rotavirus-positive children with transudative diarrhea within 48 h of admission to Mofid Children's Hospital between December 2020 and March 2022 in Tehran, Iran. Antigen detection was performed by ELISA, RNA extraction, and semi-nested multiplex PCR for G/P genotypes, followed by sequencing and bioinformatic analysis using multiple sequence alignments in MEGA and phylogenetic analysis by Geneious Prime. The similarity of VP7 and VP4 amino acids with the RotaTeq and Rotarix vaccine strains for cytotoxic T cell and antigenic epitopes was evaluated using the UCSF Chimera Molecular Modeling System. Overall, 27.3 % of the samples were RVA positive, showing untypeable (2.5 %), single (76.9 %), and mixed (20.5 %) genotypic characteristics. The strains clustered in the G1/II, G2/IV, G3/I, G4/I, G9/III, P[8]/III, P[4]/V, and P[6]/I lineages. Comparative analysis of VP7 antigenic epitopes showed that the G1/II strains were completely conserved, while the G2/IV, G3/I, G4/I, G6, G9/III strains contained 2, 3–5, 2, 4 and 9 amino acid substitutions, respectively. The P[8]/III genotypes differed by 3 amino acids, while the P[6]/I genotype had the most substitutions. CTL epitopes were completely conserved in G3/I strains, but other genotypes differed by 1–4 amino acids compared to the vaccine strains. Given the diversity of circulating RVA genotypes and the observed mutations in neutralizing and CTL epitopes, immune escape by some of the strains is likely in Iran. This finding underscores the importance of evaluating the effect of rotavirus vaccines on local genotypes and related lineages before implementing a vaccination program.

Electrical Wiring of Malarial Parasite Intermediate Hematin on a Tailored N-Doped Carbon Nanomaterial Surface and Its Bioelectrocatalytic Hydrogen Peroxide Reduction and Sensing.

Hematin, an iron-containing porphyrin compound, plays a crucial role in various biological processes, including oxygen transport, storage, and functionality of the malarial parasite. Specifically, hematin-Fe interacts with the nitrogen atom of antimalarial drugs, forming an intermediate step crucial for their function. The electron transfer functionality of hematin in biological systems has been scarcely investigated. In this study, we developed a biomimicking electrical wiring of hematin-Fe with a model N-drug system, represented as {hematin-Fe---N-drug}. We achieved this by immobilizing hematin on a multiwalled carbon nanotube (MWCNT)/N-graphene quantum dot (N-GQD) modified electrode (MWCNT/N-GQD@Hemat). N-GQD serves as a model molecular drug system containing nitrogen atoms to mimic the {hematin-Fe---N-drug} interaction. The prepared bioelectrode exhibited a distinct redox peak at a measured potential (E1/2) of -0.410 V vs Ag/AgCl, accompanied by a surface excess value of 3.54 × 10-9 mol cm-2. This observation contrasts significantly with the weak or electroinactive electrochemical responses documented in literature-based hematin systems. We performed a comprehensive set of physicochemical and electrochemical characterizations on the MWCNT/N-GQD@Hemat system, employing techniques including FESEM, TEM, Raman spectroscopy, IR spectroscopy, and AFM. To evaluate the biomimetic electrode's electroactivity, we investigated the selective-mediated reduction of H2O2 as a model system. As an important aspect of our research, we demonstrated the use of scanning electrochemical microscopy to visualize the in situ electron transfer reaction of the biomimicking electrode. In an independent study, we showed enzyme-less electrocatalytic reduction and selective electrocatalytic sensing of H2O2 with a detection limit of 319 nM. We achieved this using a batch injection analysis-coupled disposable screen-printed electrode system in physiological solution.

Evaluation of the binding efficacy of flavonol derivatives on estrogen receptors (ER) with respect to ring B hydroxylation

RationaleFlavonols are a class of flavonoids, consist of two aromatic rings (A and B) connected by a three-carbon bridge, forming a closed pyran ring (C) with a hydroxyl group at position 3. Galangin is a form of flavonols formed with additional hydroxyl groups at ring A positions 5 and 7. The hydroxylation at ring B of galangin may result in resonance and delocalization of electrons and the formation of different derivatives like kaempferol, quercetin, and myricetin. Most of these flavonols have a similarity to 17β-estradiol, the steroid sex hormone which bound to estrogen receptors (ER), a class of nuclear transcription factors involved in the regulation of many complex pathophysiological processes including breast cancer genesis and progression. Various studies have reported that most of the flavonols are antiestrogenic and show anticancer potential, but the mechanisms may be varied like estrogenic, anti-estrogenic, non-estrogenic, and biphasic activities and their mechanisms of action have not been systematically evaluated. AimThe goal of this study is to ascertain the possible interactions of flavonol derivatives to ER with respect to ring B hydroxylation and the unsaturation degree of the C2′=C3′ bond. MethodsThe variations in structure, frontier molecular orbital, molecular electrostatic potential maps, Mullikan charge population of derivatives was determined by Density functional theory (DFT) calculations at B3LYP/6-311G (d,p) level on model molecular systems. A deep insight into these interactions with ER was described by molecular docking studies. Results and discussionResults shows that the flavonol was found more affinity to ERβ and the efficacy was increased with respect to the OH group on ring B. The hydroxyl group at position 3 and 5 in ring A and C are not found much relevant. The site of ERβ is more hydrophilic while binding ligand and the electropositive and electronegative area of the molecule was increased and reaches a maximum for quercetin with the 3 OH group; after that, it found to diminish. Moreover, the reduced cavity size of ERβ and the replacement of LEU384 with polar HIE475 and MET336 increased the polarity and hydrophilicity of the cavity and led to more electrostatic interaction with ligands. ERα is found to be hydrophobic and the polar interaction between the ligands and ERα is less due to open confirmation of the cavity and bulk empty space. The results also emphasize that myricetin and quercetin require less energy to activate while accounting for the values of Gibbs free energy, the electronic configuration of frontier molecular orbitals, and entropy. ConclusionThe hydroxylation on ring B has a significant importance in the chemical reactivity as well as estrogenic activity of flavonol.

Interaction Mechanisms Between Nitrogen‐Containing Groups and Alkali Metals with Molecular Model System of HATCN**

AbstractTo enable the practical implementation of alkali metal batteries (AMBs), significant endeavors have been focused on enhancing the stability of alkali metal anodes (AMAs) using a range of strategies, such as optimizing electrolyte compositions, constructing anode deposition hosts, and establishing artificial protective layers. Despite significant progress in enhancing battery performance, limited attention has been given to comprehending the interaction mechanisms between alkali metals and protective materials, which is pivotal for the informed development of novel protective materials. Thus, aiming to enhance the comprehension of interaction processes between AMAs and organic protective materials containing various nitrogen groups, we conducted a mechanism study utilizing 1,4,5,8,9,11‐hexaazatriphenylenehexacarbonitrile (HATCN) as the model material, based on in‐situ x‐ray and ultraviolet photoelectron spectroscopy (XPS/UPS), and near edge x‐ray absorption fine structure (NEXAFS), as well as density functional theory (DFT) calculations. Through the investigation of interaction processes between HATCN and Li/Na, we find that Li or Na interacts with the two different nitrogen‐containing groups of HATCN in the same order: preferentially interacts with the inner imine groups of HATCN before interacting with the outer nitrile groups. Interestingly, our findings also reveal that the two distinct nitrogen‐containing groups exhibit a smaller difference in their sodiophilicity compared to their difference in lithiophilicity. These valuable insights shed light on the intricate interactions between nitrogen‐containing protective materials and AMAs, paving the way for the development of more effective protective materials in the future.

Graph Partitions in Chemistry.

We study partitions (equitable, externally equitable, or other) of graphs that describe physico-chemical systems at the atomic or molecular level; provide examples that show how these partitions are intimately related with symmetries of the systems; and discuss how such a link can further lead to insightful relations with the systems' physical and chemical properties. We define a particular kind of graph partition, which we call Chemical Equitable Partition (CEP), accounting for chemical composition as well as connectivity and associate it with a quantitative measure of information reduction that accompanies its derivation. These concepts are applied to model molecular and crystalline solid systems, illustrating their potential as a means to classify atoms according to their chemical or crystallographic role. We also cluster materials in meaningful manners that take their microstructure into account and even correlate them with the materials' physical properties.

Effect of thermal fluctuations on the electronic excitation energies of linear polyenes: A combined molecular dynamics and TD‐DFT study

AbstractIn the present study, thermally averaged electronic excitation energies (the so‐called dynamic approach) are quantitatively assessed for a model molecular system composed of a series of increasingly longer chains of simple linear polyenes. The molecular dynamics trajectories are calculated using the semi‐empirical “Geometry, Frequency, Noncovalent, eXtended Tight Binding” (GFN2‐xTB) method, while TD‐DFT vertical excitation energies of selected snapshots are obtained with the spin‐component‐scaled double hybrid density functional SCS‐wPBEPP86. Boltzmann weighted average excitation energies were then calculated in order to take into account the contribution of thermal motions. Excitation energies via the dynamic approach are compared with that of the static approach in which thermal fluctuations are not considered. The differences between the dynamic and the static approaches were found to be around the range to eV for polyenes up to 44 carbon atoms. This range of errors is relatively small in comparison with typical errors produced by using different density functionals and/or basis sets. Therefore, the electronic excited states of small to medium lengths of linear polyenes (less than 50 carbon atoms) can be safely modeled via the static approach. However, extrapolation of the results to longer polyenes indicates that the difference between both approaches is estimated to be 0.05 eV for polyenes containing 100 carbon atoms, which suggests that considering thermal motions in the calculations of excitation energies is recommended for such long conjugated molecular systems.

Molecular Subtype Classification of Postmenopausal Osteoporosis and Immune Infiltration Microenvironment Based on Bioinformatics Analysis of Osteoclast-Regulatory Genes.

Osteoporosis is common in postmenopausal women but is often asymptomatic until a fracture occurs, highlighting the importance of early screening and preventive interventions. This study aimed to develop molecular subtype risk stratification of postmenopausal osteoporosis and analyze the immune infiltration microenvironment. Microarray data for osteoporosis were downloaded and analyzed. Logistic and least absolute shrinkage and selection operator (LASSO) regression analyses were used to construct the molecular risk model. Circulating blood samples were collected from 10 enrolled participants to validate the key differentially expressed genes, and consistent clustering based on the expression profiles of candidate genes was performed to obtain molecular subtypes. Three key genes, CTNNB1, MITF, and TNFSF11, were obtained as variables and used to construct the risk model. External experimental validation showed substantial differences in the three key genes between patients with osteoporosis and the controls (p < 0.05). Three subtypes were obtained based on dimensionality reduction clustering results. Cluster 3 had significantly more patients with low bone mineral density (BMD), whereas Cluster 2 had significantly more patients with high BMD (p < 0.05). This study introduced a novel molecular risk model and subtype classification system, which is an evidence-based screening strategy that will guide the active prevention, early diagnosis, and treatment of osteoporosis in high-risk postmenopausal women.

Homozygous Missense Variants in FOXI1 and TMPRSS3 Genes Associated with Non-syndromic Deafness in Moroccan Families.

One of the most prevalent sensorineural disorders, autosomal recessive non-syndromic hearing loss (ARNSHL) which can affect all age groups, from the newborn (congenital) to the elderly (presbycusis). Important etiologic, phenotypic, and genotypic factors can cause deafness. So far, the high genetic variability that explains deafness makes molecular diagnosis challenging. In Morocco, the GJB2 gene is the primary cause of non-syndromic hereditary deafness, while the existence of a variant in the LRTOMT gene is the second cause of this condition. After excluding these two frequently occurring GJB2 and LRTOMT variants, whole-exome sequencing was carried out in two Moroccan consanguineous families with hearing loss. As a result, two novel variants in the TMPRSS3 (c.1078G>A, p. Ala 360Thr) and FOXI1 (c.6C>G, p. Ser 2Arg) genes have been discovered in deaf patients and the pathogenic effect has been anticipated by several bioinformatics and molecular modeling systems. For the first time, these variants are identified in the Moroccan population, showing the population heterogeneity and demonstrating the value of the WES in hearing loss diagnosis.

Poisson’s ratio of fluorapatite crystals

Introduction. It is known that in the pathogenesis of caries and non-carious lesions of teeth, an important role is played by enamel resistance, which is determined by numerous factors, among which the structure and physical and mechanical properties of tooth tissues are considered to be among the most important. This report summarizes the literature data on the Poisson’s ratio of fluorapatite (FAp), a biomaterial and one of the mineral components of dental hard tissues. The literature search was carried out in electronic databases Scopus, Web of Science, PubMed, Medline, Elibrary, MatWeb for the period from January 1970 to March 2023 inclusive. Some of the data are supplemented by our own calculations based on formulas for crystalline hexagonal systems (systems). As is known, Poisson’s ratio determines the volumetric response of materials and biological tissues to mechanical load, but its anisotropic properties have not been studied in detail. Material and methods. Calculations of the Poisson’s ratio of fluorapatite were carried out in the computer algebra system Mathcad 15.0, using the online analysis of elasticity tensors ELATE, and an integrated molecular modeling system was used - the graphic package VESTA (Visualization for Electronic and STructural Analisis). Results and discussion. The Poisson’s ratio values of fluorapatite crystals varied: minimum values 0.057–0.283, maximum values 0.302–0.494, average values obtained by integration in all directions 0.24–0.308. The coefficient of elastic anisotropy of the fluorapatite crystal lattice, calculated based on the values of Poisson’s ratio, is 1.21–5.29. The results obtained were compared with those of hydroxyapatite (HAp) crystals, dentin, enamel and filling materials. The highest values of the parameters μ and μmax are found in dentin (0.312 and 0.54), the lowest μmin are also found in dentin (0.13). Conclusions. Fluorapatite crystals are elastically anisotropic, and Poisson’s ratio μmax/μmin varies over a wide range. The Poisson’s ratio of fluorapatite showed similarity with the transverse strain coefficient of isomorphic hydroxyapatite crystals (0.207–0.374), dentin (0.13–0.54), enamel (0.16–0.47) and dental composite filling materials (0.24–0 ,35). The latter should help improve the quality of restorations using filling materials for replacing hard dental tissues. It has been established that the organic component of dentin increases its Poisson’s ratio as a biocomposite and the anisotropy of elastic properties.

Aggregation-Induced Asymmetric Charge States of Amino Acids in Supramolecular Nanofibers.

Electrostatic interactions contribute critically to the kinetic pathways and thermodynamic outcomes of peptide self-assembly involving one or more than one charged amino acids. While it is well understood in protein folding that those amino acids with acidic/basic side chains could shift their pKas when placed in a hydrophobic microenvironment, to what extent aggregation of monomeric peptide units from the bulk solution could alter their charged status and how this change in pKa values would reciprocally impact their assembly outcomes. Here, we design and analyze two solution systems containing peptide amphiphiles with hydrocarbon chains of different lengths to determine the factor of deprotonation on assembly. Our results suggest that models of supramolecular nanofibers with uniformly distributed, fully charged amino acids are oversimplified. We demonstrate, with molecular dynamics simulations, and validate with experimental results that asymmetric, different protonation states of the peptides lead to distinct nanostructures after self-assembly. The results give estimates on the electrostatic interactions in peptide amphiphiles required for their self-assembly and shed light on modeling molecular assembly systems containing charged amino acids.

The contribution of Compton ionization to ultrafast x-ray scattering.

We investigate the role of Compton ionization in ultrafast non-resonant x-ray scattering using a molecular model system, which includes the ionization continuum via an orthonormalized plane wave ansatz. Elastic and inelastic components of the scattering signal, as well as coherent-mixed scattering that arises from electron dynamics, are calculated. By virtue of a near-quantitative distinction between scattering related to electronic transitions into bound and continuum states, we demonstrate how Compton ionization contributes to the coherent-mixed component. Analogous to inelastic scattering, the contribution to the coherent-mixed signal is significant and particularly manifests at intermediate and high-momentum transfers. Strikingly, for molecules with inversion symmetry, the exclusion of bound or continuum transitions may lead to the prediction of spurious coherent-mixed signals. We conclude that qualitative and quantitative accuracies of predicted scattering signals on detectors without energy resolution require that elements of the two-electron density operator are used. This approach inherently accounts for all accessible electronic transitions, including ionization.

Designed Tetranuclear Iron‐oxo Clusters with Redox Activity for High‐Performance Lithium Storage

AbstractPolyoxometalates (POMs) are considered as promising catalysts with unique redox activity at the molecular level for energy storage. However, eco‐friendly iron‐oxo clusters with special metal coordination structures have rarely been reported for Li‐ion storage. Herein, three novel redox‐active tetranuclear iron‐oxo clusters have been synthesized using the solvothermal method with different ratios of Fe3+ and SO42−. Further, they can serve as anode materials for Li‐ion batteries. Among them, cluster H6[Fe4O2(H2O)2(SO4)7]⋅H2O, the stable structure extended by SO42− with a unique 1D pore, displays a specific discharge capacity of 1784 mAh g−1 at 0.2 C and good cycle performance (at 0.2 C and 4 C). This is the first instance of inorganic iron‐oxo clusters being used for Li‐ion storage. Our findings present a new molecular model system with a well‐defined structure and offer new design concepts for the practical application of studying the multi‐electron redox activity of iron‐oxo clusters.

Designed Tetranuclear Iron-oxo Clusters with Redox Activity for High-Performance Lithium Storage.

Polyoxometalates (POMs) are considered as promising catalysts with unique redox activity at the molecular level for energy storage. However, eco-friendly iron-oxo clusters with special metal coordination structures have rarely been reported for Li-ion storage. Herein, three novel redox-active tetranuclear iron-oxo clusters have been synthesized using the solvothermal method with different ratios of Fe3+ and SO4 2- . Further, they can serve as anode materials for Li-ion batteries. Among them, cluster H6 [Fe4 O2 (H2 O)2 (SO4 )7 ]⋅H2 O, the stable structure extended by SO4 2- with a unique 1D pore, displays a specific discharge capacity of 1784 mAh g-1 at 0.2 C and good cycle performance (at 0.2 C and 4 C). This is the first instance of inorganic iron-oxo clusters being used for Li-ion storage. Our findings present a new molecular model system with a well-defined structure and offer new design concepts for the practical application of studying the multi-electron redox activity of iron-oxo clusters.

Tracing the pathway toward decomposition: Crystal structure of Ag3(PO2NH)3 and K3(PO2NH)3 as a function of temperature

Trimetaphosphimates are both molecular model systems for oxonitridophosphates and oxonitridic glasses as well as precursors for their syntheses. The decomposition of both K3(PO2NH)3 and Ag3(PO2NH)3 afford amorphous products. Analysis of the atomic displacement parameter as a function of the temperature revealed a higher increase just before decomposition, especially with respect to stretching vibrations. This is more pronounced for the P3N3 ring in Ag3(PO2NH)3, indicating that the ring is predetermined for decomposition, whereas there are no conspicuous sites in the potassium compound. Libration corrections for trimetaphosphimate anions result in rather small changes of bond lengths, most pronounced for P–O bonds at high temperatures.

Gatekeeping Effect of Ancillary Ligand on Electron Transfer in Click Chemistry‐Linked Tris‐Heteroleptic Ruthenium(II) Donor–Photosensitizer–Acceptor Triads

Stable charge‐separated states are key features for using light in various types of solar cells and a broad range of photocatalytic applications. So far, molecular systems often suffer from increased charge recombination after initial excitation. Herein, the scope of molecular model systems for intramolecular electron transfer and charge separation by applying copper‐catalyzed click chemistry to covalently functionalize tris‐heteroleptic ruthenium(II) complexes to yield donor–photosensitizer–acceptor triads with 1,4‐dihydro‐N‐benzyl‐nicotinamide (BNAH) as donor and N‐methyl‐4,4´‐bipyridinium (MQ+) as acceptor is studied. Two triads with electron‐withdrawing or electron‐donating ancillary 2,2´‐bipyridyl ligands are synthesized and their light‐induced intramolecular electron transfer and long‐lived charge‐separated states (τ = 0.8 ms and τ = 1.5 ms) are characterized using steady‐state and time‐resolved spectroscopy and electrochemistry. Additionally, it is found that the charge‐separated state resides on different parts of the molecule within these two triads, allowing for selective directionality of charge transfer within a molecule.

Selective Generation of Electroreduction C 1 –C 2 Products Through Self-Regulation of Catalytically Active Cu Sites on the Same Coordination Cluster Catalyst

Open AccessCCS ChemistryRESEARCH ARTICLES14 Dec 2022Selective Generation of Electroreduction C1-C2 Products through Self-Regulation of Catalytically Active Cu Sites on The Same Coordination Cluster Catalyst Rui Wang, Jiang Liu, Long-Zhang Dong, Jie Zhou, Qing Huang, Yi-Rong Wang, Jing-Wen Shi and Ya-Qian Lan Rui Wang Google Scholar More articles by this author , Jiang Liu Google Scholar More articles by this author , Long-Zhang Dong Google Scholar More articles by this author , Jie Zhou Google Scholar More articles by this author , Qing Huang Google Scholar More articles by this author , Yi-Rong Wang Google Scholar More articles by this author , Jing-Wen Shi Google Scholar More articles by this author and Ya-Qian Lan Google Scholar More articles by this author https://doi.org/10.31635/ccschem.022.202202316 SectionsSupplemental MaterialAboutPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Well-defined crystalline coordination compound catalysts have showcased distinct advantages in the regulation of the species and selectivity of electrocatalytic CO2 reduction products. However, the systematic study of the crystal-facet effect of crystalline coordination compound on the performance of electrocatalytic CO2 reduction has not yet been reported. Herein, a stable hexanuclear copper cluster (Cu6) catalyst model system is designed and synthesized. By effectively regulating the growth size (micro-nano size) and morphology of Cu6 single crystal, Cu6(P) with the main (100) facet, Cu6(H) with the main (100) and (001) facet, and Cu6(S) with the main (001) facet are obtained. From Cu6(P)via Cu6(H) to Cu6(S), there is a shift from the predominantly exposed the (100) facet (involving two nonadjacent active Cu sites) to (001) facet ((involving three adjacent active Cu sites), which directly affects the adsorption direction of the key *CO intermediate and the potential of C-C coupling, thus enabling effective regulation of the selectivity of C1 (CO and CH4) and C2 (C2H4) reduction products. This work provides an essential molecular model system and a novel design perspective for the systematic study of the crystal-facet effect of coordination compounds on the species and selectivity of CO2RR products. Download figure Download PowerPoint Previous articleNext article FiguresReferencesRelatedDetails Issue AssignmentNot Yet AssignedSupporting Information Copyright & Permissions© 2022 Chinese Chemical Society Downloaded 77 times PDF downloadLoading ...

Tailored Charge Transfer Kinetics in Precursors for Organic Radical Batteries: A Joint Synthetic-Theoretical Approach.

The development of sustainable energy storage devices is crucial for the transformation of our energy management. In this scope, organic batteries attracted considerable attention. To overcome the shortcomings of typically applied materials from the classes of redox-active conjugated polymers (i. e., unstable cell voltages) and soft matter-embedded stable organic radicals (i. e., low conductivity), a novel design concept was introduced, integrating such stable radicals within a conductive polymer backbone. In the present theory-driven design approach, redox-active (2,2,6,6-tetramethylpiperidin-1-yl)oxyls (TEMPOs) were incorporated in thiophene-based polymer model systems, while structure-property relationships governing the thermodynamic properties as well as the charge transfer kinetics underlying the charging and discharging processes were investigated in a systematical approach. Thereby, the impact of the substitution pattern, the length as well as the nature of the chemical linker, and the ratio of TEMPO and thiophene units was studied using state-of-the-art quantum chemical and quantum dynamical simulations for a set of six molecular model systems. Finally, two promising candidates were synthesized and electrochemically characterized, paving the way to applications in the frame of novel organic radical batteries.