Density Functional Theory Analysis Research Articles

Natural Flavonoids as Primary Amoebic Meningoencephalitis Inhibitor: Virtual Screening, Molecular Docking, MD Simulation, MMPBSA, Density Functional Theory, Principal Component, and Gibbs Free Energy Landscape Analyses

ABSTRACTFlavonoids have been showing diversified bioactivities. Primary amoebic meningoencephalitis is a brain inflammation caused by Naegleria fowleri brain eating amoeba. In this manuscript, we selected 93 flavonoids by extensive literature survey and 83 flavonoids passed drug likeness parameter. Selected flavonoids were molecular docked against primary amoebic meningoencephalitis N. fowleri CYP51 receptor considering voriconazole as standard. Beta naphthoflavone, abyssinone I, and abyssinone III showed maximum docking scores of −10.9 kcal/mol, −10.7 kcal/mol, and −10.6 kcal/mol, respectively, whereas voriconazole showed docking scores of −7.6 kcal/mol. Molecular dynamic simulation data showed that RMSD values attained almost a static value during the simulation, and all nearest interacting amino acid residues were fluctuated within limit. Molecular Mechanics Poisson‐Boltzmann Surface Area (MMPBSA) data of beta naphthoflavone abyssinone I, abyssinone III, and voriconazole showed free binding energies of −82.755 kJ/mol, −1924.193 kJ/mol, −1890.335 kJ/mol, and −540.141 kJ/mol, respectively. Frontier molecular orbital (FMO) analysis showed that abyssinone III was the chemically reactive molecule and beta naphthoflavone showed maximum electrophilicity. Molecular electrostatic potential (MEP) analysis portrayed possible nucleophilic‐electrophilic attack areas of the structures. PCA and free energy landscape (FEL) analysis data confirmed the stable conformations between flavonoids and receptor. Abyssinone I and III showed nontoxic behavior. These data confirmed that if we repurpose these flavonoids against primary amoebic meningoencephalitis, it will be beneficial for mankind.

Evaluating the electronic and structural basis of carbon selenide-based quantum dots as photovoltaic design materials: A DFT and ML analysis

We present a new study on the design, discovery and space generation of carbon selenide based photovoltaic (PV) materials. By extending acceptors and leveraging density functional theory (DFT) and machine learning (ML) analysis, we discover new QDs with remarkable PV properties. We employ various ML models, to correlate the exciton binding energy (Eb) of 938 relevant compounds from literature with their molecular descriptors of structural features that influence their performance. Our study demonstrates the potential of ML approaches in streamlining the design and discovery of high-efficiency PV materials. Also the RDKit computed molecular descriptors correlates with PV parameters revealed maximum absorption (λmax) ranges of 509–531 nm, light harvesting efficiency (LHE) above 92 %, Open Circuit Voltage (Voc) of 0.22–0.45 V, and short Circuit (Jsc) currents of 37.92–42.75 mA/cm2. Their Predicted Power Conversion Efficiencies (PCE) using the Scharber method reaches upto 09–13 %. This study can pave the way for molecular descriptor-based design of new PV materials, promising a paradigm shift in the development of high-efficiency solar energy conversion technologies.

Unveiling the Anti-convulsant Potential of Novel Series of 1,2,4-Triazine- 6H-Indolo[2,3-b]quinoline Derivatives: In Silico Molecular Docking, ADMET, DFT, and Molecular Dynamics Exploration.

Epilepsy is a chronic neurological disorder caused by irregular electrical activity in the brain. To manage this disorder effectively, it is imperative to identify potential pharmacological targets and to understand the pathophysiology of epilepsy in depth. This research aimed to identify promising leads from a library of 1,2,4-triazine-6Hindolo[ 2,3-b]quinoline derivatives and optimize them using in silico and dynamic processes. We used computational studies to examine 1,2,4-Triazine-6H-indolo[2,3-b]quinoline derivatives. Some methods were used to strengthen the stability of binding sites, including Docking, ADMET, IFD, MMGBSA, Density Functional Theory (DFT), and Molecular Dynamics. HRSN24 and HRSN34 exhibited promising pharmacokinetic and pharmacodynamic characteristics compared to standard drugs (Carbamazepine and Phenytoin) and a co-crystal ligand (Diazepam). Both HRSN24 and HRSN34 presented notable Glide Xp docking scores (-4.528 and -4.633 Kcal/mol), IFD scores (-702.22 and -700.3 Kcal/mol), and MMGBSA scores (-45.71 and -14.46 Kcal/mol). HRSN24 was selected for molecular dynamics and DFT analysis. During MD, HRSN24 identified LYS21, GLY22, ASP24, ARG26, VAL53, MET55, and SER308 as the most important amino acid residues for hydrophobic interactions. A DFT computation was performed to determine the physicochemical properties of HRSN24, revealing a total energy of -1362.28 atomic units, a HOMO value of -0.20186, and a LUMO value of -0.01915. Based on computational modelling techniques, an array of 1,2,4-triazine-6H-indolo [2,3-b]quinoline derivatives were evaluated for their anti-convulsant properties. A stable compound within the GABAA receptor was identified by HRSN24, suggesting its affinity as an anti-convulsant.

Insight into uranyl binding by cyclic peptides from molecular dynamics and density functional theory

It is a challenging task to develop uranyl-chelating agents based on peptide chemistry. A recently developed cationic dummy atom model of uranyl in conjunction with the classical molecular dynamics simulation presents a helpful utility to study the chelation of uranyl by peptides with a low computational cost. In the present study, it was used to describe the chelation of uranyl by the cyclic decapeptide with 4 Glu residues cyc-GluArgGluProGlyGluTrpGluProGly and its derivatives containing two phosphorylated serines in place of two Glu, termed pS16, pS18, pS38, and pS68. The obtained structures were further studied by density functional theory (DFT) and subsequent density analysis. We show that a combination of steered molecular dynamics and simulated annealing, using standard forcefields for peptide with the cationic dummy atom model of uranyl, can quickly and reliably obtain binding modes of uranyl-peptide complexes. Classical molecular dynamics simulation in explicit water produces geometry very close to the DFT-optimized structure. The presence of uranyl completely changes the conformation of these cyclic peptides from unstructured to organised. The simulation of a peptide with two uranyl units explained why only the 1: 1 ratio of peptide and chelated-uranyl is observed experimentally in most cases, by the insufficiency of the anionic residues for the chelation of two UO22+ units, but that pS16 can accommodate two such units.

A novel electrochemical high-performance non-enzymatic glucose sensing based on face-centred cubic FeCoNiMnCr high entropy nano alloys encapsulated in NCNTs

Here, we report a novel approach for non-enzymatic glucose sensing, utilizing a FeCoNiMnCr High Entropy Nano Alloy (HENA) encapsulated within N-doped carbon nanotubes (NCNT). The encapsulation of HENA within NCNT offers multiple advantages such as high sensitivity, low Limit of Detection (LOD), and fast response time. A step forward, the practical viability of the sensor has been demonstrated by detecting glucose in saliva medium. This non-invasive method for monitoring blood sugar levels highlights the potential of HENA@NCNT for wearable or portable glucose monitoring devices. The material also serves as a highly effective electrocatalyst for the oxygen evolution reaction (OER), with performance comparable to state-of-the-art catalyst RuO2. This makes HENA@NCNT a promising candidate for fuel cell applications and other energy storage systems. Density Functional Theory (DFT) analysis provides a deeper understanding of the advantages conferred by NCNT encapsulation. The encapsulation enhances the stability, efficiency, and durability of HENA by optimizing electronic structure and charge transfer processes making it more effective for both glucose sensing and OER

Tetracoordinate Boron(III) Compound with BF2O2 Skeleton as Monomer for the Synthesis of Tetracoordinate Oligoboranes

A new neutral tetracoordinate boron(III) compound 1 containing a BF2O2 skeleton was used as a monomer to produce a mixture of oligoboranes featuring sp3 B–B bonds via the Wurtz-type coupling reaction with metallic sodium in boiling toluene. 1, which is a difluoroboron compound that contains an O,O-donor ligand, showed intense greenish light emission in crystalline form with fluorescence quantum yield (ΦF) of 0.56 and aggregation-induced emission (AIE) phenomenon with ΦF of 0.25. The molecular structure of 1 was characterized by single-crystal X-ray diffraction and confirmed by 1H, 11B, 13C, 19F NMR and elemental analysis, while the mixture of oligomers was characterized by solution 1H, 11B, 13C, and 19F NMR and in the solid-state by 11B MAS NMR analysis. The Matrix-Assisted Laser Desorption/Ionization-Time-Of-Flight (MALDI-TOF) analysis confirmed that the oligoboranes are composed of a mixture of diborane and triborane species. Both in the solution and the solid state, 11B NMR analysis confirmed the boron atoms maintain the tetracoordination with sp3 hybridization. The Density Functional Theory (DFT) analysis was used to get more insights into the molecular structure of the diborane and triborane species.

Structural characteristics of biochars made from different parts of corn straw and their adsorption performances for methylene blue

Corn straw husk-derived biochars (HBC), corn straw leaf-derived biochars (LBC), and corn straw pith-derived biochars (PBC) were prepared through a hydrothermal carbonization method and subsequently employed for the dye wastewater. The different adsorption behaviors of three biochars on Methylene blue (MB) were investigated through adsorption kinetics, adsorption isotherms, pH influence, and ion coexistence experiments. The surface characterization results indicated that PBC showed a relatively rough surface, while HBC and LBC exhibited smooth strip and block-like structures. The pseudo-second-order kinetic model and the Langmuir model could describe the adsorption process of the three biochars more accurately. The adsorption capacities of three corn straw biochar (CSBC) for MB were 251.08 mg/g PBC, 134.79 mg/g HBC, and 99.9 mg/g LBC, respectively. Furthermore, the removal efficiency of MB by PBC remained as high as 82.6 % after five adsorption-desorption cycles, indicating that PBC was an efficient and renewable adsorbent. Based on the characterization of biochar combined with Density Functional Theory (DFT) analysis, it was proposed that the main adsorption mechanisms include electrostatic attraction, hydrogen bonding, ion exchange, and π-π conjugation.

Organic modes of occurrence and evolution mechanism of germanium and lithium in coal: Insights from density functional theory

Critical elements in coal, such as Ge and Li, recently have attracted attention due to their economic significance. Modes of occurrence of these critical elements are academically and practically important, because they can not only provide evidence for sources of elements and minerals in coal and regional geological background information, but also help with design of recovery methods. However, conventional analytical methods are unable to observe precisely the organic binding sites of Ge and Li in coal, and this limits the understanding of their enrichment mechanism and the improvements for recovery techniques. In this study, organic modes of occurrence and evolution mechanism of Ge4+ and Li+ were investigated at the atom level by constructing molecular models of Ge- and Li-rich coals combined with density functional theory (DFT) methods. The solid-state 13C nuclear magnetic resonance spectroscopy (NMR), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and helium pycnometry analyses indicate that the molecular formulas of Ge- and Li-rich coals are C166H162N2O32 and C153H174N2O24S, respectively. The DFT analysis reveals that the binding sites for Ge4+ in Ge-rich coal are located near the carboxyl group (-COOH) and the pyrrole ring, while those for Li+ in Li-rich coal are near the carbonyl group (-C=O) and the pyrrole ring. The Ge4+ is immobilized in the Ge-rich coal molecular model through coordination bonds with the O atom in the -COOH and the C atom in the pyrrole ring, while being away from the N atom in the pyrrole ring. Li+ forms a coordination bond with the O atom in the -C=O and additional coordination bond with the nearby hydroxyl group during binding to the pyrrole ring. The impact of coal rank on the organic modes of occurrence of Ge4+ and Li+ was investigated using Wender coals of different ranks, which were one of the earliest proposed coal models. At the lignite stage, oxygen-containing functional groups and aromatic rings show a strong binding ability to Ge4+ and Li+, facilitating their enrichment in coals. Along with coal rank advance to bituminous coal, the reduction of oxygen-containing functional groups (e.g., -COOH and -C=O) and the relatively low condensation of aromatic rings decrease binding sites for Ge4+ and Li+, and the binding ability also decline, resulting in a decrease in their concentration. In anthracite stage, highly condensed aromatic rings provide binding sites for Ge4+ and Li+. The strong binding ability of aromatic rings to Ge4+ indicates that it is probably enriched in anthracite, whereas Li+ is difficult to enrich owing to its relatively weak binding ability to aromatic rings. The low content of oxygen-containing functional groups in anthracite reduces their effect on the organic modes of occurrence of Ge4+ and Li+. This study elucidates the organic modes of occurrence and evolution mechanism of Ge4+ and Li+ from the perspective of coal structure, providing fundamental insights for future research on the interaction between organic and inorganic matter within coal.

Synthesis and characterization of magnetic aluminum metal-organic frameworks encapsulated with chitosan and carboxymethyl cellulose for effective elimination of atrazine from aqueous solutions: Adsorption evaluation, DFT calculations and Box-Behnken design optimization

The discharge of herbicides is a primary contributor to water contamination, presenting significant environmental and public health hazards. Encapsulating herbicides in a chemical compound called MAl-MOF/CS-CMC hydrogel bead (MACC) made from magnetic aluminum metal-organic frameworks (MAl-MOF) and crosslinked with chitosan (CS) and carboxymethyl cellulose (CMC) shows promise for potential use. The research successfully developed and examined MACC microspheres, utilizing various analytical techniques including PXRD, FESEM, TEM, FT-IR, and XPS. The efficiency of MACC in eliminating atrazine (ATZ) from wastewater was also simulated. Additionally, density functional theory (DFT) was employed to assess the electrical characteristics, reactivity, and arrangement of ATZ at a structural level. The results of the DFT analysis demonstrate a significant relationship between the locations of nucleophilic and electrophilic attacks and the molecular orbitals of the HOMO and LUMO. Using MACC as an adsorbent provides considerable advantages due to its expansive surface area of 860.92 m2/g and a pore size of 1.48 nm, meeting the mesoporous classification criteria outlined by IUPAC standards. In addition, it possesses a pore volume of 1.22 cm3/g. Nevertheless, following the adsorption procedure, the pore volume reduced to 0.78 cm3/g, and the surface area decreased to 650.42 m2/g. Several factors contributing to the capacity to attract and retain substances were analyzed. These factors encompass temperature, duration of contact, quantity of the attracting substance, initial atrazine (ATZ) concentration, and solution pH. The primary method of adsorption that was determined is chemisorption, as evidenced by the calculated adsorption energy of 29.3 kJ per mole. The thermodynamic analysis indicates that the adsorption of ATZ by the micropores of MACC occurs spontaneously and is characterized as endothermic, as evidenced by the positive ΔHo value and negative ΔGo value. It has been proposed that a range of adsorption mechanisms, including chemisorption, π-π interactions, pore filling, hydrogen bonding, and electrostatic interactions, may be responsible for removing the herbicide from the MACC material.

A DFT analysis of the antioxidant capacity of scopolin and scopoletin.

Scopolin and scopoletin belong to the class of coumarins and have experimentally proven natural antioxidants. Natural antioxidants are crucial in mitigating the impact of oxidants in the human body through radical scavenging. Even though scopolin and scopoletin are proven antioxidants by experimental results, their antioxidant mechanisms still remained unexplained. In this study, Density functional theory (DFT) calculations were used to study the radical scavenging mechanisms of both scopolin and scopoletin using kinetic and thermodynamics parameters. The global parameters indicated that both scopolin and scopoletin have antioxidant properties. The band gap energy revealed that scopoletin (4.18eV) has strong antioxidant activity compared to scopolin (4.31eV). These studies found that hydrogen atom transfer (HAT) is the primary mechanism for CH3OO• radical scavenging at the C-H bond in scopolin (91.98kcal.mol-1) and the O-H bond in scopoletin (77.05kcal.mol-1) due to their lowest bond dissociation energies. The calculated activation energy ( ) for the radical scavenging reaction, reconfirmed scopoletin ( =11.19kcal.mol-1) performed as a better antioxidant compared to scopolin ( =20.91kcal.mol-1). In this study, the results of DFT calculations confirmed that scopoletin exhibits a higher antioxidant capacity, and HAT mechanism is the most effective radical scavenging mechanism. The antioxidant activity of scopolin and scopoletin was determined by DFT at the B3LYP/6-31G(d) level of theory. Global parameter calculations and frontier molecular orbital analysis were conducted to assess these compounds' capacity for scavenging radicals. Hydrogen atom transfer (HAT), sequential electron transfer proton transfer (SETPT), and sequential proton loss electron transfer (SPLET) mechanisms were the three main mechanisms that were taken into consideration. The potential energy surface (PES) verified the most appropriate processes shown by the enthalpy calculations.

A Bifunctional Iron-Nickel Oxygen Reduction/Oxygen Evolution Catalyst for High-Performance Rechargeable Zinc-Air Batteries.

Efficient and robust electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial for fuel cells, metal-air batteries, and other energy technologies. Here, a highly stable, efficient bifunctional OER/ORR electrocatalyst (FeNi-NC@MWCNTs) is reported and demonstrated its integration and robust performance in an aqueous Zinc-air battery (ZAB). The catalyst is based on neighboring iron/nickel sites (FeNiN6) which are atomically dispersed on porous nitrogen-doped carbon particles. The particles are wrapped in electrically conductive multi-walled carbon nanotubes for enhanced electrical conductivity. Electrocatalytic analyses show high OER and ORR performance (OER/ORR voltage difference = 0.69V). Catalyst integration in a ZAB results in excellent performance metrics, including an open circuit voltage of 1.44V, a specific capacity of 782 mAh g-1 (at j = 15mA cm-2), a peak power density of 218mW cm-2 (at j = 260mA cm-2) and long-term durability over 600 charge/discharge cycles. Combined experimental and theoretical (density functional theory) analyses provide an in-depth understanding of the physical and electronic structure of the catalyst and the role of the FeNi dual atom reaction site. The study therefore provides critical insights into the structure and reactivity of high-performance bifunctional OER/ORR catalysts based on atomically dispersed non-critical metals.

Carotenoids Interaction with PCSK9: Exploring Novel Cholesterol-Lowering Strategies

Background/Objectives: This study investigated the potential of green algae-derived carotenoids as natural inhibitors of the proprotein convertase subtilisin/kexin type 9 (PCSK9), a key regulator of cholesterol metabolism. PCSK9 promotes the degradation of low-density lipoprotein receptors (LDLR), thereby increasing blood cholesterol levels and elevating the risk of cardiovascular diseases. Methods/Results: We screened the pharmacophore fit score of 27 carotenoids with PCSK9 and identified 14 that were analyzed for binding affinity and molecular interactions. Astaxanthin, siphonaxanthin, and prasinoxanthin were identified as the top candidates, demonstrating strong binding affinity (−10.5, −10.3, and −9.4 Kcal/mol, respectively) and stable interactions with several known key residues within the active site of PCSK9, including Pro-331, Arg-357, Cys-358, Val-359, Asp-360, Ile-416, Leu-436, Thr-437, Pro-438, Leu-440, Arg-458, Val-460, Trp-461, Arg-476, Cys-477, Ala-478, Ala-649, Val-650, and Asp-651. Density functional theory analysis confirmed the stability of astaxanthin and its favorable electronic properties, suggesting its potential as an effective inhibitor. Molecular dynamics simulations of the PCSK9–astaxanthin complex revealed sustained structural stability and key interactions critical for maintaining the functional integrity of the protein. Conclusions: These findings provide evidence that specific carotenoids, particularly astaxanthin, may offer a cost-effective alternative to existing PCSK9 inhibitors, providing a potential approach for managing cholesterol levels and reducing cardiovascular risk. Pre-clinical and clinical validations are required to confirm the therapeutic potential of these compounds.

Electro-activated peroxymonosulfate based on hollow cubic skeleton nanoflower cathode catalyst MoSe2/cubic nanocage (CNC) for enhanced degradation of norfloxacin: Performance, mechanism, degradation pathways and toxicity

Recently, antibiotic wastewater pollution has become increasingly serious. In this study, a novel hollow cubic framework self-supported nanoflower-like cathode catalyst (MoSe2/CNC) based on Co Fe prussian blue analogues (CoFePBA)-derived cubic nanocage (CNC) loaded with MoSe2 was successfully prepared and utilized in an electro-activated peroxymonosulfate (PMS) system for norfloxacin (NOR) degradation. Benefit from the combined structures of MoSe2, MoC, and Co/FeNC, the electrocatalytic activity and specific surface area were greatly improved. The effects of catalyst dosage and ratio, current, PMS concentration, electrolyte type, pH, as well as initial concentration were comprehensively investigated. Under the optimal conditions, NOR and TOC removal reached 92.70% and 82.17%, respectively, which was superior to the previous studies. Additionally, ·O2− was proved to be the primary reactive species for NOR degradation.·Based on density functional theory (DFT) and intermediates analysis, NOR underwent substitution and ring-opening reactions in the piperazine ring, substitution of fluoride ions, and cleavage of the carboxyl group and tetrahydropyridine ring, ultimately converting into water, carbon dioxide, and inorganic ions. Moreover, toxicity assessment and seed germination experiments demonstrated that the toxicity of NOR and intermediates were strongly decreased by electro-activated PMS system based on MoSe2/CNC cathode. Overall, this study not only contributes to the evolution of efficient and sustainable wastewater purification technology, but also provides valuable insights into the degradation of antibiotic wastewater.

Design and synthesis of camphor-thiazole derivatives as potent antifungal agents: structure-activity relationship and preliminary mechanistic study.

Plant pathogenic fungi pose a severe threat to crop yield and food security. This study aims to investigate the potential antifungal activity and mechanism of action of camphor-thiazole derivatives against six plant pathogenic fungi. A novel series of camphor-thiazole derivatives were designed, synthesized and evaluated for their antifungal effects against Rhizoctonia solani, Fusarium graminearum, Valsa mali, Alternaria solani, Colletotrichum orbiculare and Botryitis cinerea. Most of the synthesized camphor-thiazole derivatives exhibited notable antifungal activity. Amongst them, compounds C5, C10 and C17 showed significant activity against R. solani with median effective concentrations (EC50) values in the range 3-4 μg mL-1, demonstrating superior antifungal efficacy to the control drug boscalid (EC50 = 1.23 μg mL-1). Structure-activity relationship and density functional theory analysis emphasized the critical role of substituent selection in optimizing the biological activity of these compounds. Moreover, preliminary mechanistic studies revealed that compound C5 induced abnormal mycelial and cellular morphology in R. solani as observed using scanning and transmission electron microscopy, and triggered the production and accumulation of reactive oxygen species. Additionally, the increased concentration of C5 resulted in enhanced cell membrane permeability. In this study, the designed and optimized compound C5 emerged as a promising candidate for potent antifungal agents. The results demonstrate that synthesized camphor-thiazole derivatives possess potent antifungal activity and can serve as lead compounds for further optimization in antifungal agent development. © 2024 Society of Chemical Industry.

Discovery of novel CDK2 inhibitors for cancer treatment: integrating ligand-based pharmacophore modelling, molecular docking, DFT, ADMET, and molecular dynamics simulation studies

BackgroundThe global landscape of public health faces significant challenges attributed to the prevalence of cancer and the emergence of treatment resistance. This study addresses these challenges by focusing on Cyclin-dependent Kinase 2 (CDK2) and employing a systematic computational approach for the discovery of novel cancer therapeutics.ResultsInitial ligand-based pharmacophore modelling, utilizing a training set of five reported CDK2 inhibitors, yielded a robust model characterized by Aro|Hyd| and |Acc|Don| features. Screening this validated model against the ZINC database identified 1881 hits, which were further subjected to molecular docking studies. The top 10 compounds (Z1–Z10) selected from the docking studies underwent Pharmacokinetic parameters Absorption, Distribution, Metabolism, Excretion and Toxicity profiling, Density Functional Theory (DFT) studies and the top two went for 100ns molecular dynamics (MD) simulations by comparing them with the standard Roscovitine. Compounds Z1 and Z2 emerged as the most promising, with docking scores of − 8.05 kcal/mol and − 8.02 kcal/mol, respectively. DFT analysis of the top 10 compounds revealed minimal variations in highest occupied molecular orbital–lowest unoccupied molecular orbital energy gaps, indicating consistent electronic stability and reactivity across the candidates. MD simulations of Z1 and Z2 confirmed their stable interactions with CDK2, with root mean square deviation (RMSD) values ranging from 1.4 to 2.5 Å for Z1 and 1.5 to 2.4 Å for Z2.ConclusionThe current research identified compounds Z1 and Z2, which demonstrated significant potential as potent CDK2 inhibitors for cancer therapy, providing valuable insights into the development of more effective CDK2 inhibitors and addressing the critical need for innovative therapeutic strategies in cancer treatment.Graphical abstract

Synergistic Configuration of Binary Rhodium Single Atoms in Carbon Nanofibers for High-Performance Alkaline Water Electrolyzer.

Electrochemical alkaline water electrolysis offers significant economic advantages; however, these benefits are hindered by the high kinetic energy barrier of the water dissociation step and the sluggish kinetics of the hydrogen evolution reaction (HER) in alkaline media. Herein, the ensemble effect of binary types of Rh single atoms (Rh-Nx and Rh-Ox) on TiO2-embedded carbon nanofiber (Rh-TiO2/CNF) is reported, which servesas potent active sites for high-performance HER in anion exchange membrane water electrolyzer (AEMWE). Density functional theory (DFT) analyses support the experimental observations, highlighting the critical role of binary types of Rh single atoms facilitated by the TiO2 sites. The Rh-TiO2/CNF demonstrates an impressive areal current density of 1 A cm-2, maintaining extended durability for up to 225 hin a single-cell setup. Furthermore, a 2-cell AEMWE stack utilizing Rh-TiO2/CNF is tested under industrial-scale conditions. This research makes a significant contribution to the commercialization of next-generation high-performance and durable AEMWE stacks for clean hydrogen production.

Investigation of the atomic layer etching mechanism for Al2O3 using hexafluoroacetylacetone and H2 plasma.

Atomic layer etching (ALE) is required to fabricate the complex 3D structures for future integrated circuit scaling. To enable ALE for a wide range of materials, it is important to discover new processes and subsequently understand the underlying mechanisms. This work focuses on an isotropic plasma ALE process based on hexafluoroacetylacetone (Hhfac) doses followed by H2 plasma exposure. The ALE process enables accurate control of Al2O3 film thickness with an etch rate of 0.16 ± 0.02 nm per cycle, and an ALE synergy of 98%. The ALE mechanism is investigated using Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) simulations. Different diketone surface bonding configurations are identified on the Al2O3 surface, suggesting that there is competition between etching and surface inhibition reactions. During the Hhfac dosing, the surface is etched before becoming saturated with monodentate and other hfac species, which forms an etch inhibition layer. H2 plasma is subsequently employed to remove the hfac species, cleaning the surface for the next half-cycle. On planar samples no residue of the Hhfac etchant is observed by FTIR after H2 plasma exposure. DFT analysis indicates that the chelate configuration of the diketone molecule is the most favorable surface species, which is expected to leave the surface as volatile etch product. However, formation of the other configurations is also energetically favorable, which explains the buildup on an etch inhibiting layer. The ALE process is thus hypothesized to work via an etch inhibition and surface cleaning mechanism. It is discussed that such a mechanism enables thickness control on the sub-nm scale, with minimal contamination and low damage.

Synthesis, mechanistic insights, and anticancer evaluation of novel 2-aroylbenzo[b]thiophen-3-ols: A DFT and Hirshfeld surface analysis

A simple one-pot reaction was employed for the synthesis of 2-aroylbenzo[b]thiophene derivatives by reacting 2-mercaptobenzoic acid with substituted bromomethyl aryl ketones in the presence of triethylamine and DMF in significant yield and purity. The structure of the product was elucidated through spectroscopic data and confirmed through single crystal X-ray diffraction data. The benzo[b]thiophene ring was found to be nearly coplanar with the adjacent carbonyl group and conformationally stabilized by intramolecular hydrogen bonding. The key intramolecular cyclization takes place via an in-situ generated enol, which is most likely formed and reacts at the carboxylic group mediated by the conjugate acid, triethylammonium bromide. Density functional theory (DFT) was employed to investigate the energy profile of the reaction at the B3LYP/6–31G(d,p) level. Finally, all the synthesized 2-aroylbenzo[b]thiophene-3-ols were screened in vitro against HCT116 (colorectal) and MCF-7 (breast) cancer cell lines at 25 μM and 50 μM treatments, indicating the antiproliferative potential of several derivatives.

Conformational dynamics of the pyrene excimer.

The conformational dynamics of the pyrene excimer play a critical role in its unique fluorescence properties. Yet, the influence of multiple local minima on its excited-state behavior remains underexplored. Using a combination of time-dependent density functional theory (TD-DFT) and unsupervised machine learning analysis, we have identified and characterized a diverse set of stable excimer geometries in the first excited state. Our analysis reveals that rapid structural reorganization towards the most stable stacked-twisted conformer dominates the excimer's photophysics, outcompeting radiative relaxation. This conformer, which is primarily responsible for the characteristic red-shifted, structureless fluorescence emission, reconciles experimental observations of long fluorescence lifetimes and emission profiles. These findings provide new insights into the excited-state dynamics of excimers. They may inform the design of excimer-based materials in fields ranging from organic electronics to molecular sensing.

Investigation of cross-association behavior in water-ethanol solutions: A combined computational-ATR spectroscopy study.

The water/ethanol system possesses complexities at the molecular level, which render its description a difficult task. For the elucidation of the system's hydrogen bonding features that are the key factors in its complex behavior, we conduct a Density Functional Theory analysis on relevant water/ethanol clusters inside implicit solvent cavities for the determination of the ethanol donor hydrogen bond strength. We record Attenuated Total Reflectance spectra of water/ethanol-OD solutions and utilize our density and refractive index measurements for post-processing. The application of the Badger-Bauer rule reveals a minimum in the strength of the ethanol donor hydrogen bond for a composition of xwater = 0.74. We attempt to analyze further this result by estimating the effect of the implicit solvent on the ethanol donor hydrogen bond strength, finding it to be incremental. A brief analysis of different cluster conformations is carried out to determine the cooperativity conditions that can potentially explain the observed minimum in the ethanol donor hydrogen bond strength. These observations are related to notions of microheterogeneity in water/alcohol mixtures and provide context toward a more elaborate picture of association in heteroclusters.