Search Results (49)

In this study, we synthesized novel donor–π–acceptor (D–π–A) functional dyes bearing a carbonyl-bridged bithiophene as a π-conjugated spacer and evaluated the absorption and fluorescence properties as well as the photostability. The developed dyes 1-CO–3-CO possess an N,N-diphenylaminophenyl electron donor unit and an electron acceptor unit such as a formyl group (1-CO), an (N,N-diethylthiobarbituryl)methylene moiety (2-CO), or a (3-dicyanomethylidene-1-indanon-2-yl)methylene moiety (3-CO). The absorption spectra of 1-CO–3-CO in dichloromethane at room temperature showed absorption maxima at 569 nm, 631 nm, and 667 nm, respectively, and the stronger acceptors in 2-CO and 3-CO led to enhancement of the ICT character. In addition, 2-CO and 3-CO had a second absorption band in the visible region, showing panchromatic absorption properties. Electrochemical analyses of the developed dyes revealed that the carbonyl bridging group in the π-spacer contributes to stabilization of the frontier orbitals such as the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO, respectively), in comparison with the referential dyes bearing a dibutylmethylene-bridged bithiophene spacer, 1-CBu₂–3-CBu₂. The HOMO/LUMO stabilization brought about high photostability in the doped poly(methyl methacrylate) film. Full article

Contact electrification (CE), or triboelectrification, is an electron transfer phenomenon occurring at the interface between dissimilar materials due to differences in polarity, holding significant research value in tribology. The microscopic mechanisms of CE remain unclear due to the complex coupling of multiple physical processes. Recently, with the rise of triboelectric nanogenerator (TENG) technology, solid–liquid contact electrification has demonstrated vast application potential, sparking considerable interest in its underlying mechanisms. Emerging experimental evidence indicates that at water–polymer CE interfaces, the process involves not only traditional ion adsorption but also electron transfer. Halogen-containing functional groups in the solid material significantly enhance the CE effect. To elucidate the microscopic mechanism of water–polymer CE, this study employed first-principles density functional theory (DFT) calculations, simulating the interfacial electrification process using unit cell models of water contacting polymers. We systematically and quantitatively investigated the charge transfer characteristics at interfaces between water and three representative polymers with similar backbones but different halogen-functionalized (F, Cl) side chains: fluorinated ethylene propylene (FEP), polyvinyl chloride (PVC), and polytetrafluoroethylene (PTFE), focusing on evaluating halogen’s influence and mechanism on interfacial electron transfer. The results reveal that electron transfer is primarily governed by the energy levels of the polymer’s lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO). Halogen functional groups modulate the material’s electron-donating/accepting capabilities by altering these frontier orbital energy levels. Consequently, we propose that the critical strategy for polymer chemical modification resides in lowering the LUMO energy level of electron-accepting materials. This study provides a novel theoretical insight into the charge transfer mechanism at solid–liquid interfaces, offers guidance for designing high-performance TENG interfacial materials, and holds significant importance for both the fundamental theory and the development of advanced energy devices. Full article

Background/Objectives: Helicobacter pylori infects approximately half of the global population, causing chronic gastritis, peptic ulcers, and gastric cancer, a leading cause of cancer mortality. While current therapies face challenges from rising antibiotic resistance, particularly to clarithromycin, alongside treatment complexity and costs, the World Health Organization has prioritized the development of new antibiotics to combat this high-risk pathogen. In this study, we employed computer-aided drug design (CADD) methodologies, including molecular docking, Molecular Mechanics-Generalized Born Surface Area (MM-GBSA) analysis, molecular dynamics (MD) simulations, and Density Functional Theory (DFT) calculations, to explore the potential repurposing of FDA-approved agents as inhibitors of Helicobacter pylori shikimate kinase (HpSK). Methods: Using the Glide module, the HTVS method was initially applied to screen 1615 FDA-approved agents followed by extra-precision (XP) docking for the obtained 111 hits. The obtained XP scores were used to confine the results to those hits with a score above the reference ligand, shikimate, score. This yielded 31 final hits with an XP score above −5.867. MM-GBSA calculations were performed on these top candidates and the reference ligand to refine the analysis and compounds’ prioritization. Results: The 31 compounds displayed binding free energy (ΔG_bind) values ranging from 3.61 to −55.92 kcal/mol, with shikimate exhibiting a ΔG_bind of −34.24 kcal/mol and 10 hits having a lower ΔG_bind value. Out of these ten, three drugs—Dolutegravir, Cangrelor, and Isavuconazonium—were selected for further analysis based on their drug-like properties. Robust and stable binding profiles for both Isavuconazonium and Cangrelor were verified via molecular dynamics simulation. Additionally, Density Functional Theory (DFT) analysis was conducted, and the Highest Occupied Molecular Orbitals (HOMOs), Lowest Unoccupied Molecular Orbitals (LUMOs), and the energy gap (HLG) between them were calculated. All three drug candidates displayed lower HLG values than shikimate, suggesting higher reactivity and more efficient electronic transitions than the reference ligand. Conclusions: These findings suggest that the identified drugs, although not optimal for direct repurposing, would serve as promising leads against Helicobacter pylori shikimate kinase. These drugs could be valuable leads for experimental assessment and further optimization, particularly with no prototype yet identified. In terms of potential for clinical repurposing, the results point to diflunisal as a promising candidate for further testing. Full article

Cisplatin-based platinum compounds are important clinical chemotherapeutic agents that participate in most tumor chemotherapy regimens. Through density-functional theory calculations, the formation and stability of the inorganic oxide carrier, the mechanisms of the hydrolysis reaction of the activated platinum compound, and its binding mechanism with DNA bases can be studied. The higher the oxidation state of Pt (II to IV), the more electrons transfer from the magnesia–gold composite material to the platinum compound. After adsorption on the composite carrier, 5d←2p coordination bonds of Pt-N are strengthened. For flat and oblique adsorption modes of cisplatin, there is no significant difference in the density of states of the gold and magnesium oxide film, indicating the maintenance of the heterojunction structural framework. However, there are significant changes in the electronic states of cisplatin itself with different adsorption configurations. In the flat configuration, the band gap width of cisplatin is larger than that of the oblique configuration. The Cl-Pt bond range in the Pt(III) compound shows a clear charge reduction on the magnesia film, indicating the Cl-Pt bond is an active site with the potential for decomposition and hydrolysis. The substitution of chloride ions by water can lead to hydrolysis products, enhancing the polarization of the composite and showing strong charge separation. The hydrolysis of the free platinum compound is endothermic by 0.309 eV, exceeding the small activation energy barrier of 0.399 eV, indicating that hydrolysis of this platinum compound is easily achievable. ADME (absorption, distribution, metabolism, and excretion) prediction parameters indicate that hydrolysis products have good ESOL (Estimated SOLubility) solubility and high gastrointestinal absorption, consistent with Lipinski’s rule. During the coordination reaction process, there are significant changes in the distribution of frontier molecular orbitals, with the HOMO (highest occupied molecular orbital) of the initial state primarily located on the purine base, providing the possibility for electron transfer to the empty orbitals of the platinum compound in the LUMO (lowest unoccupied molecular orbital). The HOMO and HOMO-1 of the transition state and product are mainly distributed on the platinum compound, indicating clear electron transfer and orbital rearrangement. The activation energy barrier for the purine coordination reaction with the hydrolysis products is reduced to 0.61 eV, and the dipole moment gradually decreases to 6.77 Debye during the reaction, indicating a reduction in the system’s charge separation and polarization. This contribution is anticipated to provide a new theoretical clue for developing inorganic oxide carriers of platinum compounds. Full article

Phenothiazine-based photosensitizers bear the intrinsic potential to substitute various expensive organometallic dyes owing to the strong electron-donating nature of the former. If coupled with a strong acceptor unit and the length of N-alkyl chain is appropriately chosen, they can easily produce high efficiency levels in dye-sensitized solar cells. Here, three novel D-A dyes containing 1H-tetrazole-5-acrylic acid as an acceptor were synthesized by varying the N-alkyl chain length at its phenothiazine core and were exploited in dye-sensitized solar cells. Differential scanning calorimetry showed that the synthesized phenothiazine derivatives exhibited behavior characteristic of molecular glasses, with glass transition and melting temperatures in the range of 42–91 and 165–198 °C, respectively. Based on cyclic and differential pulse voltammetry measurements, it was evident that their lowest unoccupied molecular orbital (LUMO) (−3.01–−3.14 eV) and highest occupied molecular orbital (HOMO) (−5.28–−5.33 eV) values were fitted to the TiO₂ conduction band and the redox energy of I⁻/I₃⁻ in electrolyte, respectively. The experimental results were supported by density functional theory, which was also utilized for estimation of the adsorption energy of the dyes on the TiO₂ and its size. Finally, the compounds were tested in dye-sensitized solar cells, which were characterized based on current–voltage measurements. Additionally, for the compound giving the best photovoltaic response, the efficiency of the DSSCs was optimized by a photoanode modification involving the use of cosensitization and coadsorption approaches and the introduction of a blocking layer. Subsequently, two types of tandem dye-sensitized solar cells were constructed, which resulted in an increase in photovoltaic efficiency to 6.37%, as compared to DSSCs before modifications, with a power conversion value of 2.50%. Full article

Cardiovascular diseases (CVD) pose a significant global health challenge, requiring innovative therapeutic strategies. Vasodilators, which are central to vasodilation and blood pressure reduction, play a crucial role in cardiovascular treatment. This study integrates quantitative structure– (QSAR) modeling and molecular dynamics (MD) simulations to predict the biological activity and interactions of vasodilatory compounds with the aim to repurpose drugs already known and estimateing their potential use as vasodilators. By exploring molecular descriptors, such as electronegativity, softness, and highest occupied molecular orbital (HOMO) energy, this study identifies key structural features influencing vasodilatory effects, as it seems molecules with the same mechanism of actions present similar frontier orbitals pattern. The QSAR model was built using fifty-four Food Drugs Administration-approved (FDA-approved) compounds used in cardiovascular treatment and their activities in rat thoracic aortic rings; several molecular descriptors, such as electronic, thermodynamics, and topographic were used. The best QSAR model was validated through robust training and test dataset split, demonstrating high predictive accuracy in drug design. The validated model was applied on the FDA dataset and molecules in the application domain with high predicted activity were retrieved and filtered. Thirty molecules with the best-predicted pKI50 were further analyzed employing molecular orbital frontiers and classified as angiotensin-I or β1-adrenergic inhibitors; then, the best scoring values obtained from molecular docking were used to perform a molecular dynamics simulation, providing insight into the dynamic interactions between vasodilatory compounds and their targets, elucidating the strength and stability of these interactions over time. According to the binding energies results, this study identifies novel vasodilatory candidates where Dasabuvir and Sertindole seem to have potent and selective activity, offering promising avenues for the development of next-generation cardiovascular therapies. Finally, this research bridges computational modelling with experimental validation, providing valuable insight for the design of optimized vasodilatory agents to address critical unmet needs in cardiovascular medicine. Full article

This study focuses on NMC 811 (LiNi_0.8Mn_0.1Co_0.1O₂), a promising material for high-capacity batteries, and investigates the challenges associated with its use, specifically the formation of the cathode electrolyte interphase (CEI) layer due to chemical reactions. This layer is a consequence of the position of the Lowest Unoccupied Molecular Orbital (LUMO) energy level of NMC 811 that is close to the Highest Occupied Molecular Orbital (HOMO) level of liquid electrolytes, resulting in electrolyte oxidation and cathode surface alterations during charging. A stable CEI layer can mitigate further degradation by reducing the interaction between the reactive cathode material and the electrolyte. Our research analyzed the CEI layer on NMC 811 using advanced techniques, such as 4D-STEM ACOM (automated crystal orientation mapping) and STEM-EDX, focusing on the effects of different charging voltages (4.3 V and 4.5 V). The findings revealed varying degrees of degradation and the formation of a fluorine-rich layer on the secondary particles. Detailed analysis showed that the composition of this layer differed based on the voltage: only LiF at 4.5 V and a combination of lithium fluoride (LiF) and lithium hydroxide (LiOH) at 4.3 V. Despite LiF’s known stability as a CEI protective layer, our observations indicate that it does not effectively prevent degradation in NMC 811. The study concluded that impurities and unwanted chemical reactions leading to suboptimal CEI formation are inevitable. Therefore, future efforts should focus on developing protective strategies for NMC 811, such as the use of specific additives or coatings. Full article

The two-dimensional layered heterostructure have been demonstrated as an effective method for achieving efficient photocatalytic hydrogen production. In this work, we propose, for the first time, the creation of van der Waals heterostructures from monolayers of SiH and g-C₃N₄ using first-principle calculations. We also systematically investigated additional properties for the first time, such as the electronic structure and optical behavior of van der Waals heterostructures composed of SiH and g-C₃N₄ monolayers. The results of this study show that the SiH/g-C₃N₄ heterostructure is categorized as a type-II heterostructure, which has a bandgap of 2.268 eV. Furthermore, the SiH/g-C₃N₄ heterostructure interface was observed to efficiently separate and transfer photogenerated charges, resulting in an enhanced photocatalytic redox performance. Moreover, the calculation of HOMO (Highest occupied molecular orbital) and LUMO (Least unoccupied molecular orbital) and charge density difference can further confirm that the SiH/g-C₃N₄ heterojunction is a type-II heterojunction, which has excellent photocatalytic hydrogen production and water decomposition performance. In addition, the SiH/g-C₃N₄ heterostructure exhibited excellent HER (Hydrogen evolution reaction) efficiency. This is essential for the process of photocatalytic water splitting. In SiH/g-C₃N₄ heterojunctions, the redox potential required for water splitting is spanned by the band edge potential. Calculating the absorption spectra, it was discovered that the SiH/g-C₃N₄ heterostructure possesses outstanding optical properties within the visible-light range, implying its high efficiency in photocatalytic hydrogen production. This research provides a broader research direction for the investigation of novel efficient photocatalysts and offers effective theoretical guidance for future efficient photocatalysts. Full article

We prepared ternary organic solar cells (OSCs) by incorporating the medium wavelength absorption polymer PSEHTT into the PM6:L8-BO binary system. The power conversion efficiency (PCE) is improved from 15.83% to 16.66%. Although the fill factor (FF) is slightly reduced, the short-circuit current density (J_SC) and open-circuit voltage (V_OC) are significantly increased at the same time. A small amount of PSEHTT has a broad absorption spectrum in the short wavelength region and has good compatibility with PM6, which is conducive to fine-tuning the photon collection and improving the J_SC. In addition, the highest occupied molecular orbital (HOMO) energy level of PSEHTT is deeper than that of PM6, which broadens the optical bandgap. This study provides an effective method to fabricate high-performance ternary OSCs by using a lower concentration of PSEHTT with PM6 as a hybrid donor material, which ensures a better surface and bulk morphology, improves photon collection, and broadens the optical bandgap. Full article

Due to its high carrier mobility and electron transmission, the phenyl-C₆₁-butyric acid methyl ester (PC₆₁BM) is usually used as an electron transport layer (ETL) in perovskite solar cell (PSC) configurations. However, PC₆₁BM films suffer from poor coverage on perovskite active layers because of their low solubility and weak adhesive ability. In this work, to overcome the above-mentioned shortcomings, 30 nm thick PC₆₁BM ETLs with different concentrations were modeled. Using a 30 nm thick PC₆₁BM ETL with a concentration of 50 mg/mL, the obtained performance values of the PSCs were as follows: an open-circuit voltage (V_oc) of 0.87 V, a short-circuit current density (J_sc) of 20.44 mA/cm², a fill factor (FF) of 70.52%, and a power conversion efficiency (PCE) of 12.54%. However, undesired fine cracks present on the PC₆₁BM surface degraded the performance of the resulting PSCs. To further improve performance, multiple different thicknesses of ZnO interface layers were deposited on the PC₆₁BM ETLs to release the fine cracks using a thermal evaporator. In addition to the pavement of fine cracks, the ZnO interface layer could also function as a hole-blocking layer due to its larger highest occupied molecular orbital (HOMO) energy level. Consequently, the PCE was improved to 14.62% by inserting a 20 nm thick ZnO interface layer in the PSCs. Full article

In this study, we investigated the electronic properties and selective adsorption for CO₂ of nickel boride clusters (NiB)_n, (n = 1~10) using the first principles method. We optimized the structures of the clusters and analyzed their stability based on binding energy per atom. It was observed that (NiB)_n clusters adopt 3D geometries from n = 4, which were more stable compared to the plane clusters. The vertical electron affinity, vertical ionization energy, chemical potential, and highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap were calculated. Our results revealed that (NiB)₆ and (NiB)₁₀, with high chemical potential, exhibit a higher affinity for CO₂ adsorption due to a charge delivery channel that forms along the Ni→B→CO₂ path. Notably, (NiB)₁₀ demonstrated a more practical CO₂ desorption temperature, as well as a broader window for the selective adsorption of CO₂ over N₂. The density of states analysis showed that the enhanced CO₂ adsorption on (NiB)₁₀ can be attributed to the synergistic effect between Ni and B, which provides more active sites for CO₂ adsorption and promotes the electron transfer from the surface to the CO₂ molecule. Our theoretical results imply that (NiB)₁₀ should be a promising candidate for CO₂ capture. Full article

Efficient energy-level alignment is crucial for achieving high performance in organic electronic devices. Because the electronic structure of an organic semiconductor is significantly influenced by its molecular orientation, comprehensively understanding the molecular orientation and electronic structure of the organic layer is essential. In this study, we investigated the interface between a 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN) hole injection layer and a zinc-phthalocyanine (ZnPc) p-type organic semiconductor. To determine the energy-level alignment and molecular orientation, we conducted in situ ultraviolet and X-ray photoelectron spectroscopies, as well as angle-resolved X-ray absorption spectroscopy. We found that the HAT-CN molecules were oriented relatively face-on (40°) in the thin (5 nm) layer, whereas they were oriented relatively edge-on (62°) in the thick (100 nm) layer. By contrast, ZnPc orientation was not significantly altered by the underlying HAT-CN orientation. The highest occupied molecular orbital (HOMO) level of ZnPc was closer to the Fermi level on the 100 nm thick HAT-CN layer than on the 5 nm thick HAT-CN layer because of the higher work function. Consequently, a considerably low energy gap between the lowest unoccupied molecular orbital level of HAT-CN and the HOMO level of ZnPc was formed in the 100 nm thick HAT-CN case. This may improve the hole injection ability of the anode system, which can be utilized in various electronic devices. Full article

Solar energy harvesting using semiconductor photocatalysis offers an enticing solution to two of the biggest societal challenges, energy scarcity and environmental pollution. After decades of effort, no photocatalyst exists which can simultaneously meet the demand for excellent absorption, high quantum efficiency and photochemical resilience/durability. While CdS is an excellent photocatalyst for hydrogen evolution, pollutant degradation and organic synthesis, photocorrosion of CdS leads to the deactivation of the catalyst. Surface passivation of CdS with 2D graphitic carbon nitrides (CN) such as g-C₃N₄ and C₃N₅ has been shown to mitigate the photocorrosion problem but the poor oxidizing power of photogenerated holes in CN limits the utility of this approach for photooxidation reactions. We report the synthesis of exfoliated 2D nanosheets of a modified carbon nitride constituted of tris-s-triazine (C₆N₇) linked pyromellitic dianhydride polydiimide (CN:PDI) with a deep oxidative highest occupied molecular orbital (HOMO) position, which ensures sufficient oxidizing power for photogenerated holes in CN. The heterojunction formed by the wrapping of mono-/few layered CN:PDI on CdS nanorods (CdS/CN:PDI) was determined to be an excellent photocatalyst for oxidation reactions including photoelectrochemical water splitting, dye decolorization and the photocatalytic conversion of benzyl alcohol to benzaldehyde. Extensive structural characterization using HR-TEM, Raman, XPS, etc., confirmed wrapping of few-layered CN:PDI on CdS nanorods. The increased photoactivity in CdS/CN:PDI catalyst was ascribed to facile electron transfer from CdS to CN:PDI in comparison to CdS/g-C₃N₄, leading to an increased electron density on the surface of the photocatalyst to drive chemical reactions. Full article

Predicting the dielectric strengths of organic compounds is critical for identifying potential insulating gases. However, experimental evaluation techniques are time-consuming, and current computational protocols are limited in scope. In this study, to develop a reliable prediction protocol for the dielectric strengths of a broad array of perfluorocarbon (PFC) and non-PFC compounds, systematic linear regression is combined with computational calculations of relevant core factors. The designed equation-based protocol is demonstrated to have four core factors, including two high-correlation factors (polarizability and molecular weight) and two critical factors (ionization energy and highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap). The two critical factors are crucial for determining a suitable protocol, as reliable predictions of dielectric strength are only possible if the ionization energy and HOMO–LUMO gap are maintained within specified ranges for all the compounds. These findings can act as design guidelines for future computational protocols to predict the insulating properties of PFC and non-PFC compounds. Full article

A linear–shaped small organic molecule (E)-4-(5-(3,5-dimethoxy-styryl)thiophen-2-yl)-7-(5″-hexyl-[2,2′:5′,2″-terthiophen]-5-yl)benzo[c][1,2,5]thiadiazole (MBTR) comprising a benzothiadiazole (BTD) acceptor linked with the terminal donors bithiophene and dimethoxy vinylbenzene through a π-bridge thiophene was synthesized and analyzed. The MBTR efficiently tuned the thermal, absorption, and emission characteristics to enhance the molecular packing and aggregation behaviors in the solid state. The obtained optical bandgap of 1.86 eV and low-lying highest occupied molecular orbital (HOMO) level of −5.42 eV efficiently lowered the energy losses in the fabricated devices, thereby achieving enhanced photovoltaic performances. The optimized MBTR:PC₇₁BM (1:2.5 w/w%) fullerene-based devices showed a maximum power conversion efficiency (PCE) of 7.05%, with an open-circuit voltage (V_OC) of 0.943 V, short-circuit current density (J_SC) of 12.63 mA/cm², and fill factor (FF) of 59.2%. With the addition of 3% 1,8-diiodooctane (DIO), the PCE improved to 8.76% with a high V_OC of 1.02 V, J_SC of 13.78 mA/cm², and FF of 62.3%, which are associated with improved charge transport at the donor/acceptor interfaces owing to the fibrous active layer morphology and favorable phase separation. These results demonstrate that the introduction of suitable donor/acceptor groups in molecular design and device engineering is an effective approach to enhancing the photovoltaic performances of organic solar cells. Full article