Rational Design of Reliable Computational Protocols for Predicting Dielectric Constants of Gaseous Molecules.

A rapid prediction of the dielectric constants from a wide range of organic compounds is of paramount importance given the pressing need to find alternatives to SF6, one of the seven greenhouse gases. However, the availability of a universally applicable equation for predicting dielectric constants remains limited. This study endeavors to systematically develop a universal equation for predicting the dielectric constants of gaseous organic molecules in a systematic manner. The reliability of these newly developed equational protocols is evaluated through both quantitative (i.e., root-mean-squared deviation) and qualitative (i.e., Spearman's rank correlation coefficient) analyses. Equational optimization of the traditionally unreliable Clausius-Mossotti equation highlights the critical role of selecting a suitable variable to be incorporated into an adapted Clausius-Mossotti equation, ultimately enhancing the predictive accuracy. Furthermore, it is revealed that the nature of the chosen variable has a more significant impact on prediction accuracy than the quantity of variables introduced. These findings shed light on the ongoing efforts of developing a dependable protocol for predicting not only dielectric constants but also other vital insulating properties, such as dielectric strength.

Switchable Design of Redox-Enhanced Nonaromatic Quinones Enabled by Conjugation Recovery.

An innovative switchable design strategy for modulating the electronic structures of quinones is proposed herein, leading to remarkably enhanced intrinsic redox potentials by restoring conjugated but nonaromatic backbone architectures. Computational validation of two fundamental hypotheses confirms the recovery of backbone conjugation and optimal utilization of the inductive effect in switched quinones, which affords significantly improved redox chemistry and overall performance compared to reference quinones. Geometric and electronic analyses provide strong evidence for the restored backbone conjugation and nonaromaticity in the switched quinones, while highlighting the reinforcement of the inductive effect and suppression of the resonance effect. This strategic approach facilitates the development of an exceptional quinone, viz. 2,6-naphthoquinone, with outstanding performance parameters (338.9 mAh g-1 and 912.9 mWh g-1). Furthermore, 2,6-anthraquinone with superior cyclic stability, demonstrates comparable performance (257.4 mAh g-1 and 702.8 mWh g-1). These findings offer valuable insights into the design of organic cathode materials with favorable redox chemistry in secondary batteries.

Computational Modulation in Electronic Structures of Halide Perovskites via Element/Dopant/Phase.

This study employs computational chemistry to investigate the electronic properties of halide perovskite materials, focusing on structural frameworks, elemental composition, surface engineering, and defect engineering. The tetragonal phase generally exhibits higher band gaps than the cubic phase due to conduction band differences, with LiPbCl3 showing the greatest band gap difference. The ionic radius of the A element influences band gaps for both phases, with Cs having the highest impact. Surface engineering significantly affects the electronic properties, and surface direction and composition play vital roles in determining band gaps. Defect engineering induces semiconducting-to-metallic transitions, impacting band gaps. Understanding these core variables is crucial for tailoring the electronic properties of halide perovskites for photovoltaic and optoelectronic applications.

Dopant-induced electronic design of redox-active elements in LiMn2O4 spinel structures.

Despite the importance of the electronic-level design of inorganic cathode materials for high-performance secondary batteries, studies attempting to clarify the correlation between the electronic structure and performance are relatively scarce compared to the broad range of inorganic cathode materials developed to date. This study highlights that the symmetricity/asymmetricity of eg/t2g orbitals in redox-active elements would be a core factor to determine the degree of the Jahn-Teller distortion of LiM0.125Mn1.875O4 (M = Mn, Co, Cr, Cu, Fe, and Ni) spinel-type cathode materials during the discharging process. The presence of redox-active Mn3+ ions accompanied by a significant collapse in the symmetry of orbital eg during the discharging process is highlighted as the main reason for poor structural durability and electrochemical performance of the cathode material. This limitation can be most effectively overcome by removing Mn3+ ions by adding Ni2+ as a carefully selected dopant. Further investigation reveals that the electrochemical impact of the introduced dopants strongly relies on the change in the symmetricity/asymmetricity of their eg/t2g orbital configurations during the discharging process and the resultant energy benefit/penalty.

Impact of Structural Flexibility of Amine Moieties as Bridges for Redox-Active Sites on Secondary Battery Performance.

Although environmentally benign organic cathode materials for secondary batteries are in demand, their high solubility in electrolyte solvents hinders broad applicability. In this study, a bridging fragment to link redox-active sites is incorporated into organic complexes with the aim of preventing dissolution in electrolyte systems with no significant performance loss. Evaluation of these complexes using an advanced computational approach reveals that the type of redox-active site (i. e., dicyanide, quinone, or dithione) is a key parameter for determining the intrinsic redox activity of the complexes, with the redox activity decreasing in the order of dithione>quinone>dicyanide. In contrast, the structural integrity is strongly reliant on the bridging style (i. e., amine-based single linkage or diamine-based double linkage). In particular, owing to their rigid anchoring effect, diamine-based double linkages incorporated at dithione sites allow structural integrity to be maintained with no significant decrease in the high thermodynamic performance of dithione sites. These findings provide insights into design directions for insoluble organic cathode materials that can sustain high performance and structural durability during repeated cycling.

Microwave-assisted design of nanoporous graphene membrane for ultrafast and switchable organic solvent nanofiltration.

Layered two-dimensional materials can potentially be utilized for organic solvent nanofiltration (OSN) membrane fabrication owing to their precise molecular sieving by the interlayer structure and excellent stability in harsh conditions. Nevertheless, the extensive tortuosity of nanochannels and bulky solvent molecules impede rapid permeability. Herein, nanoporous graphene (NG) with a high density of sp2 carbon domain was synthesized via sequential thermal pore activation of graphene oxide (GO) and microwave-assisted reduction. Due to the smooth sp2 carbon domain surfaces and dense nanopores, the microwave-treated nanoporous graphene membrane exhibited ultrafast organic solvent permeance (e.g., IPA: 2278 LMH/bar) with excellent stability under practical cross-flow conditions. Furthermore, the membrane molecular weight cut-off (MWCO) is switchable from 500 Da size of molecule to sub-nanometer-size molecules depending on the solvent type, and this switching occurs spontaneously with solvent change. These properties indicate feasibility of multiple (both binary and ternary) organic mixture separation using a single membrane. The nanochannel structure effect on solvent transport is also investigated using computation calculations.

In Situ Synthesis of Multivariate Zeolitic Imidazolate Frameworks for C2 H4 /C2 H6 Kinetic Separation.

Herein, a new approach for the in situ synthesis of zeolitic imidazolate framework (ZIF) nanoparticles with triple ligands, referred to as Sogang ZIF-8 (SZIF-8), is reported for enhanced C2 H4 /C2 H6 kinetic separation. SZIF-8 consists of tetrahedral zinc metals coordinated with tri-butyl amine (TBA), 2,4-dimethylimidazole (DIm), and 2-methylimidazole (MIm). SZIF-8(x) with different DIm contents in x (up to 23.2 mol%) are synthesized in situ because TBA preferably deprotonates DIm ligands due to the much lower pKa of DIm over MIm, allowing for the Zn-DIm coordination. The Zn-DIm coordination reduces the window size of ZIF-8 with suppressed linker flipping motion due to bulky DIm ligands and simultaneously enhances the interfacial interaction between 6FDA-DAM polyimide (6FDA) and SZIF-8 via electron donor-acceptor interactions. Consequently, 6FDA/SZIF-8(13) mixed matrix membrane exhibits an excellent C2 H4 permeability of 60.3 Barrer and C2 H4 /C2 H6 selectivity of 4.5. The temperature-dependent transport characterization reveals that such excellent C2 H4 /C2 H6 kinetic separation is attained by the enhancement in size discrimination-based energetic selectivity. Our hybrid multi-ligand approach can offer a useful tool for the fine-tuning of molecular structures and textural properties of other metal organic frameworks.

NaOH-assisted H2O2 post-modification as a novel approach to enhance adsorption capacity of residual coffee waste biochars toward radioactive strontium: Experimental and theoretical studies.

In this study, NaOH-assisted H2O2 post-modification was proposed as a novel strategy to enhance the adsorption of radioactive strontium (Sr) onto residual coffee waste biochars (RCWBs). To validate its viability, the adsorption capacities and mechanisms of Sr(II) using pristine (RCWBP), H2O2 post-modified (RCWBHP), and NaOH-assisted H2O2 post-modified residual coffee waste biochars (RCWBNHP) were experimentally and theoretically investigated. The highest adsorption capacity of Sr(II) for RCWBNHP (10.91 mg/g) compared to RCWBHP (5.57 mg/g) and RCWBP (5.07 mg/g) was primarily attributed to higher negative surface zeta potential (RCWBNHP = -5.66 → -30.97 mV; RCWBHP = -0.31 → -11.29 mV; RCWBP = 1.90 → -10.40 mV) and decoration of Na on the surfaces of RCWBP via NaOH-assisted H2O2 post-modification. These findings agree entirely with the theoretical observations that the adsorption of Sr(II) onto RCWBP and RCWBHP was controlled by electrostatic interactions involving carbonyls whereas enriched carboxylic acids and decorated Na on the surfaces of RCWBNHP through the replacement of Mg and K by NaOH-assisted H2O2 modification stimulated electrostatic interactions and cation exchanges governing the adsorption of Sr(II). Hence, NaOH-assisted H2O2 post-modification seemed to be practically applicable for improving the adsorption capacity of Sr(II) using RCWB-based carbonaceous adsorbents in real water matrices.

Development of computational design for reliable prediction of dielectric strengths of perfluorocarbon compounds.

The development of robust computational protocols capable of accurately predicting the dielectric strengths of eco-friendly insulating gas candidates is crucial; however, it lacks relevant efforts significantly. Consequently, a series of computational protocols are employed in this study to enable the computational prediction of polarizability and ionization energy of eco-friendly, perfluorinated carbon-based candidates, followed by the equation-based prediction of their dielectric strength. The validation process associated with the prediction of the afore-mentioned variables for selected datasets confirms the suitability of the B3LYP-based prediction protocol for reproducing experimental values. Subsequently, the validation of dielectric strength prediction outlines the following three conclusions. (1) The referenced equation adopted from a previous study is incapable of predicting the dielectric strengths of 137 organic compounds present in our database. (2) Parameterization of the coefficients in the referenced equation leads to the accurate prediction of the dielectric strengths. (3) Incorporation of a novel variable, viz. molecular weight, into the referenced equation combined with the parameterization of the coefficients leads to a robust protocol capable of predicting dielectric strengths with high efficiencies even with a significantly smaller fitting dataset. This implies the development of a comprehensive solution capable of accurately predicting the dielectric strengths of a substantially large dataset.

Fabrication of junction-free Cu nanowire networks via Ru-catalyzed electroless deposition and their application to transparent conducting electrodes.

Over the past few years, metal nanowire networks have attracted attention as an alternative to transparent conducting oxide materials such as indium tin oxide for transparent conducting electrode applications. Recently, electrodeposition of metal on nanoscale template is widely used for formation of metal network. In the present work, junctionless Cu nanowire networks were simply fabricated on a substrate by forming a nanostructured Ru with 80 nm width as a seed layer, followed by direct electroless deposition of Cu. By controlling the density of Ru nanowires or the electroless deposition time, we readily achieve desired transmittance and sheet resistance values ranging from ∼1 kΩ sq-1at 99% to 9 Ω sq-1at 89%. After being transferred to flexible substrates, the nanowire networks exhibited no obvious increase in resistance during 8000 cycles of a bending test to a radius of 2.5 mm. The durability was verified by evaluation of its heating performance. The maximum temperature was greater than 180 °C at 3 V and remained constant after three repeated cycles and for 10 min. Transmission electron microscopy and x-ray diffraction studies revealed that the adhesion between the electrolessly deposited Cu and the seed Ru nanowires strongly influenced the durability of the core-shell structured nanowire-based heaters.

Tailored Design of Electrochemically Degradable Anthraquinone Functionality toward Organic Cathodes.

In efforts to design organic cathode materials for rechargeable batteries, a fundamental understanding of the redox properties of diverse non-carbon-based functionalities incorporated into 9,10-anthraquinone is lacking despite their potential impact. Herein, a preliminary investigation of the potential of anthraquinones with halogenated nitrogen-based functionalities reveals that the Li-triggered structural collapse observed in the early stage of discharging can be ascribed to the preference toward the strong Lewis acid-base interaction of N-Li-X (X = F or Cl) over the repulsive interaction of the electron-rich N-X bond. A further study of three solutions (i.e., substitution of NX2 with (i) BX2, (ii) NH2, and (iii) BH2) to the structural decomposition issue highlights four conclusive remarks. First, the replacement of N and/or X with electron-deficient atom(s), such as B and/or H, relieves the repulsive force on the N-X bond without the assistance of Li, and thus, no structural decomposition occurs. Second, the incorporation of BH2 is verified to be the most beneficial for improving the theoretical performance. Third, all the redox properties are better correlated with electron affinity and solvation energy than the electronegativity of functionality, implying that these key parameters cooperatively contribute to the electrochemical redox potential; additionally, solvation energy plays a crucial role in determining cathodic deactivation. Fourth, the improvement to the Li storage capability of anthraquinone using the third solution can primarily be ascribed to solvation energy remaining at a negative value even after the binding of more Li atoms than the other derivatives.

Improvement of Electrical Conductivity in Conjugated Polymers through Cascade Doping with Small-Molecular Dopants.

Doping capability is primitively governed by the energy level offset between the highest occupied molecular orbital (HOMO) of conjugated polymers (CPs) and the lowest unoccupied molecular orbital (LUMO) of dopants. A poor doping efficiency is obtained when doping directly using NOBF4 forming a large energy offset with the CP, while the devised doping strategy is found to significantly improve the doping efficiency (electrical conductivity) by sequentially treating the NOBF4 to the pre-doped CP with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquino-dimethane (F4TCNQ), establishing a relatively small energy level offset. It is verified that the cascade doping strategy requires receptive sites for each dopant to further improve the doping efficiency, and provides fast reaction kinetics energetically. An outstanding electrical conductivity (>610 S cm-1 ) is achieved through the optimization of the devised doping strategy, and spectroscopy analysis, including Hall effect measurement, supports more efficient charge carrier generation via the devised cascade doping.

Insights on Redox Properties of Sumanene Derivatives for High-Performance Organic Cathodes.

Despite the potential of large organic molecules for insoluble cathode materials in lithium-ion batteries, they have attracted less attention owing to the penalty in the molecular weight. Herein, an advanced computational modeling approach is employed to comprehensively explore the electrochemical characteristics and theoretical charge/energy storage capability for a series of sumanene derivatives. It is highlighted from this investigation that the carbonyl moiety is generally beneficial to the improvement of the redox properties for the sumanenes. The sumanene with hexagon rings fully functionalized by six carbonyls particularly exhibits both the remarkably high redox potential (3.53 V vs Li/Li+) and performance parameters (454 mAh/g and 1129 mWh/g), implying its candidacy as high-potential organic cathodes. It is further demonstrated from a universal relationship of redox potential-electronic property-solvation property that a sumanene derivative would experience a two-stage discharging behavior. This indicates that the sumanene derivative would be cathodically inactive due to a sudden increase of solvation energy.

Pyrenetetrone Derivatives Tailored by Nitrogen Dopants for High-Potential Cathodes in Lithium-Ion Batteries.

To overcome limited information on organic cathode materials for lithium-ion batteries, we studied the electrochemical redox properties of pyrenetetrone and its nitrogen-doped derivatives. Three primary conclusions are highlighted from this study. First, the redox potential increases as the number of electron-withdrawing nitrogen dopants increases. Second, the redox potentials of pyrenetetrone derivatives continuously decrease with the number of bound Li atoms during the discharging process owing to the decrease in the reductive ability until the compounds become cathodically deactivated exhibiting negative redox potentials. Notably, pyrenetetrone with four nitrogen dopants loses its cathodic activity after the binding of five Li atoms, indicating remarkably high performance (496 mAh/g and 913 mWh/g). Last, the redox potential is strongly correlated not only with electronic properties but also with solvation energy. This highlights that pyrenetetrone derivatives would follow two-stage transition behaviors during the discharging process, implying a crucial contribution of solvation energy to their cathodic deactivation.

Improving the Understanding of the Redox Properties of Fluoranil Derivatives for Cathodes in Sodium-Ion Batteries.

Despite the potential of organic cathodes in sodium-ion batteries, their redox properties still need to be explored. In this study, a density functional theory modeling approach is employed to comprehensively investigate the redox properties and theoretical performance parameters for a selected set of fluoranil derivatives as cathode materials. The redox properties are further correlated with various characteristics including structural variations, electronic properties, and solvation. Three primary conclusions are drawn. First, the incorporation of bulky trifluoromethyl functional group(s) into fluoranil increases its redox potential but significantly decreases its gravimetric charge capacity. This suggests that the trifluoromethyl functional group(s) would be detrimental to the design of high-performance batteries. Second, fluoranil exhibits significant enhancements in terms of redox properties and theoretical performance compared with its hydrogenated form, benzoquinone, suggesting a desired strategy for designing high-performance batteries. Third, the redox properties of fluoranil derivatives would strongly rely not only on structural variations (e.g., bulkiness) and electronic properties (e.g., functionality) but also on solvation energy. It is further verified that cathodic deactivation could be completed by solvation energy. The new understanding will provide us with guidelines for an efficient design of promising organic cathode materials.

Li-Binding Thermodynamics and Redox Properties of BNOPS-Based Organic Compounds for Cathodes in Lithium-Ion Batteries.

Cyclic organic compounds with pentagon rings have been paid less attention for cathodes in lithium-ion batteries as compared with aromatic compounds. In this study, we investigate the Li-binding thermodynamics, redox properties, and theoretical performance for a selected set of heteroatom-containing, pentagon-shaped, organic compounds, namely borole, pyrrole, furan, phosphole, thiophene, and their derivatives to assess their potential for organic cathode materials. This investigation provides us with three important findings. First, the Li-binding thermodynamics and redox properties for the organic compounds would be systematically tailored by the type of the incorporated heteroatom and backbone length, exhibiting both the strongest Li-binding and the highest redox potential for borole. Second, it is highlighted that borole can store up to two Li atoms per molecule exhibiting the exceptionally high charge capacity (839 mA h/g) despite the absence of any well-known redox-active moieties (e.g., carbonyl). Third, dibenzothiophene exhibits weak and comparable Li-binding strengths at multiple feasible binding configurations with an indication of its low Li-storage capability, while the others dominantly bind with Li at their most stable binding configurations. All these findings will provide an insight into the guidelines for the systematic design of promising heterocyclic organic compounds (i.e., borole-based insoluble polymeric forms) for cathodes in secondary batteries.

Clinicopathological characteristics of miscarriages featuring placental massive perivillous fibrin deposition.

INTRODUCTION: Massive perivillous fibrin deposition (MPFD) is frequently associated with detrimental pregnancy outcomes, and extensive perivillous fibrin deposition results in severe placental dysfunction and loss of maternofetal interface. Unfortunately, the fundamental pathogenesis of MPFD remains unknown, and systematic analyses of MPFD in miscarriage is lacking. We analyzed the frequency and clinicopathological characteristics of MPFD in first trimester miscarriages. METHODS: We analyzed a consecutive series of miscarriages (n = 582) gathered between March 2012 and June 2016. MPFD was classified as fibrin-type (f-MPFD) and matrix-type (m-MPFD) by immunostaining for fibrin and collagen type IV. The control group consisted of miscarriage cases (MC, n = 18) that were matched to f-MPFD with normal chromosome (f-MPFD-nc) for number of previous miscarriages and placental chromosomal status. RESULTS: MPFD was identified in 2.7% of miscarriages. f-MPFD was associated with recurrent abortions. Compared with miscarriages without fibrin deposition, MPFD cases had higher proportion of those with normal placental chromosome (69.2% vs. 27.4%, P < 0.005) and higher frequency of villous syncytiotrophoblast C4d deposition (73.3% vs. 33.9%, P < 0.005). All C4d(+) f-MPFD patients had more than three recurrent miscarriages, whereas C4d(-) f-MPFD patients had no history of recurrent miscarriage (P < 0.05). Patients with f-MPFD-nc had significantly higher HLA PRA immunopositivity rate than did MC patients (P = 0.005). DISCUSSION: MPFD was more common in miscarriages than in preterm and term pregnancies. Placental massive fibrin-type fibrinoid deposition and villous C4d immunoreactivity were associated with recurrent miscarriage.

Instantaneous Detection of Trichlorinated Carbon via Photo-Induced Electron Transfer toward Chemosensor for Toxic Organochlorides.

Despite the usefulness of organochlorides as raw materials for organic synthesis, they cause several issues in the human body, such as hepatic dysfunction, tumor, and heavy damage to the central nervous system. Especially when organochlorides contain three or more chlorinated carbons, they tend to be more toxic to the human body possibly owing to relatively high reactivity. Several electron donors (TPCAs) are designed to devise a novel detection system for toxic organochlorides containing trichlorinated carbons, and the detection mechanism of the devised sensor system is systematically identified by EPR measurement and the analysis of the solution after the detection of chloroform, which is used as a model compound. Since the detection system simultaneously utilizes the radical-generation capability and the low LUMO level of the trichlorinated carbon, it provides high selectivity against most of the common organic compounds including other organochlorides containing mono- or dichlorinated carbons, and the outstanding selectivity of the designed sensor has been verified with Mirex composed of numerous chlorinated carbons. In addition, the detection system exhibits immediate sensing capability because only electron transfer and radical reaction are involved in the detection process. Finally, when diphosgene is detected with the devised sensing platform, a noticeable change in fluorescence intensities can be identified within 5 s even for a diphosgene concentration of less than 1 ppm.

Observation of Olefin/Paraffin Selectivity in Azo Compound and Its Application into a Metal-Organic Framework.

Olefin/paraffin separation is an important and challenging issue because the two molecules have similar physicochemical properties. Although a couple of olefin adsorbents have been developed by introducing inorganic nanoparticles into metal-organic frameworks (MOFs), there has been no study on the development of an olefin adsorbent by introducing a certain organic functional group into a MOF. In this study, we posited that azo compounds could offer olefin/paraffin selectivity. We have revealed using first-principles calculations that the simplest aromatic azo compound (azobenzene, Azob) has an unusual propylene/propane selectivity due to special electrostatic interactions between Azob and propylene molecules. On the basis of this interesting discovery, we have synthesized a novel propylene adsorbent, MIL-101(Cr)_DAA, by grafting 4,4'-diaminoazobenzene (DAA) into open metal sites in a mesoporous MIL-101(Cr). Remarkably, MIL-101(Cr)_DAA exhibited enhanced propylene/propane selectivity as well as considerably higher propylene heat of adsorption compared to pristine MIL-101(Cr) while maintaining the high working capacity of MIL-101(Cr). This clearly indicates that azo compounds when introduced into MOFs can provide propylene selectivity. Moreover, MIL-101(Cr)_DAA showed good C3H6/C3H8 separation and easy regeneration performances from packed-bed breakthrough experiments and retained its propylene adsorption capacity even after exposure to air for 12 h. As far as we know, this is the first study that improves the olefin selectivity of MOF by postsynthetically introducing an organic functional group.

Density Functional Theory - Machine Learning Approach to Analyze the Bandgap of Elemental Halide Perovskites and Ruddlesden-Popper Phases.

In this study, we have developed a protocol for exploring the vast chemical space of possible perovskites and screening promising candidates. Furthermore, we examined the factors that affect the band gap energies of perovskites. The Goldschmidt tolerance factor and octahedral factor, which range from 0.98 to 1 and from 0.45 to 0.7, respectively, are used to filter only highly cubic perovskites that are stable at room temperature. After removing rare or radioactively unstable elements, quantum mechanical density functional theory calculations are performed on the remaining perovskites to assess whether their electronic properties such as band structure are suitable for solar cell applications. Similar calculations are performed on the Ruddlesden-Popper phase. Furthermore, machine learning was utilized to assess the significance of input parameters affecting the band gap of the perovskites.