Search Results (159)

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

We report a computational investigation on the reachability of the molecular similarity index (MSI) approach for predicting the relative drug strength of methylcarbamate derivatives. Traditional MSI values have been obtained by calculating the overlap integral of total electron momentum densities between one molecule and another. Furthermore, we have proposed and tested orbital-specific MSI (OS-MSI) values, obtained by doing the same but with electron momentum densities of a selected molecular orbital (MO) such as the highest occupied MO (HOMO) and the lowest unoccupied MO (LUMO). In the calculations, a Boltzmann-weighted electron momentum density estimated by a theoretical probability distribution of rotamers was used, while the solvation effect was considered using the polarizable continuum model. It is shown that the traditional MSI values as well as the OS-MSI values for the HOMO do not have any correlation with experimental relative toxicity of the methylcarbamate derivatives. In contrast, it has been observed and found that the OS-MSI values for the LUMO exhibit a noticeable correlation with the experimental data. The reason behind this observation is discussed in relation to the drug reaction mechanism of the methylcarbamate derivatives. 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

This study explores the chemical composition and synergistic anti-fungal properties of essential oils from the aerial parts of Satavari (Asparagus racemosus Willd.), Dill (Anethum graveolens L.), and lemongrass (Cymbopogon citratus Stapf), along with the peels of Lime (Citrus aurantifolia (Christm.)) and Kaffir lime (Citrus hystrix DC), as well as the leaves of Citrus hystrix DC, against Malassezia furfur, a yeast linked to dandruff and seborrheic dermatitis. Gas chromatography-mass spectrometry (GC-MS) identified key volatile compounds within these oils. In vitro anti-fungal assays evaluated their efficacy individually and in combinations using checkerboard dilution techniques to assess synergy. Results indicated significant antifungal activity, with lemongrass exhibiting the strongest effect (MIC of 0.125% v/v). Notably, a 1:1 combination of lemongrass and kaffir lime essential oils showed synergism, reducing the MIC to 0.0625% v/v. The antifungal activity was primarily attributed to citral and citronellal, with MICs of 0.03125% v/v and 0.125% v/v, respectively. Molecular orbital analysis revealed that the higher energy levels of the lowest unoccupied molecular orbitals (LUMOs) in citral correlate with greater antifungal efficacy, likely due to its enhanced electrophilicity, facilitating nucleophilic interactions with M. furfur’s cellular components. These findings highlight potential applications of essential oil combinations in antifungal therapies. Full article

Our first-principles calculations have unveiled a profound influence of varied external charges on the energy levels and spin distributions of zero-, one-, and two-dimensional carbon nanomaterials. By leveraging the Fermi distribution formula, we systematically analyze the temperature-dependent electron occupancy probabilities of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). Notably, configurations with specific additional electron loads exhibit a stable total occupancy of HOMO + LUMO equal to 1 across a wide temperature range, forming a robust basis for orbital qubits. This stability persists even under Fermi energy corrections, demonstrating minimal temperature sensitivity up to 300 K. Furthermore, we identify a universal criterion—E_HOMO + E_LUMO = 2E_Fermi—that governs qubit feasibility across diverse carbon nanostructures, independent of dimensionality or atom count. Experimental validation via charge injection methods (e.g., gate modulation or electron beam irradiation) is supported by existing precedents in carbon-based quantum devices. Our findings establish low-dimensional carbon nanomaterials as versatile, scalable platforms for quantum computing, combining thermal stability and dimensional adaptability, thus bridging theoretical insights with practical quantum engineering. Full article

Linear conjugated polymer photocatalysts are still hampered by challenges involving low charge separation efficiency and poor water dispersibility, which are crucial factors during the photocatalytic water splitting process. Herein, we synthesized Poly thieno[3,2-b]thiophene (PTT) nanoparticles with excellent visible light response characteristic. Subsequently, we constructed the gun–bullet model PTT/graphitic carbon nitride (PTT/g-C₃N₄) heterojunctions for photocatalytic hydrogen production, where PTT with good visible light response characteristic serves as the bullets and g-C₃N₄ with good water dispersibility serves as the guns. The as-prepared PTT/g-C₃N₄ heterojunctions show greatly accelerated charge separation and excellent photocatalytic hydrogen production performance. Specifically, 10PTT/g-C₃N₄ demonstrates extraordinary hydrogen production performance, reaching 6.56 mmol g⁻¹ h⁻¹ (2 wt% Pt loading, 0.1 M AA as sacrificial agent, λ > 420 nm), calculated to be 15.3 and 22.6 times those of PTT and g-C₃N₄, respectively. Mechanistic studies reveal that the significantly improved performance of PTT/g-C₃N₄ heterojunctions is ascribed to the accelerated charge transfer, which originates from the C…S/N…S noncovalent interactions among PTT and g-C₃N₄. The C…S/N…S noncovalent interactions act as an efficient interface charge transmission channel (ICTC), accelerating the steady stream of excited electron transfer from the lowest unoccupied molecular orbital (LUMO) of PTT to that of g-C₃N₄. The gun–bullet model heterojunctions proposed here provide a practical strategy for achieving exceptional visible light photocatalytic hydrogen production by combining charge separation with water dispersibility in polymer/polymer heterojunctions via noncovalent interactions. Full article

In this work, the structural and optical properties of calcium monochalcogenide nanoparticles were numerically examined by using Density Functional Theory and Time Dependent Density Functional Theory. The composition of the examined nanoparticles was obtained from an initial cubic-like building block of the form Ca₄Y₄, where Y could be one of the chalcogen elements sulfur, selenium, and tellurium, after its proper numerical examination to check their structural stability. The examined nanoparticles were then created from these initial cubic-like building blocks after their elongation along one, two, and three perpendicular directions. Τhe Absorption Spectrum, the Binding Energy, together with the highest occupied-lowest unoccupied molecular orbital (HOMO-LUMO) gap, were included in the calculations of the studied calcium monochalcogenides. The calculations provided numerical evidence regarding the existence of stable structures for a wide range of morphologies. In addition, the examination of the properties of such nanostructures after placing different kinds of defects was also included in the calculations, thus leading to new groups of nanoparticles with several potential uses in technological applications, such as hydrogen storage, CO₂ capture, and ultraviolet-responsive devices. Full article

The structural and electronic properties at organic/organic interfaces determine the functionality of organic electronics. Here, we investigated the structural and electronic properties at interfaces between methyl-substituted dicyanovinyl-quinquethiophenes (DCV5T-Me₂) and other electron acceptor molecules, namely fullerene (C₆₀) and tetracyanoquinodimethane (TCNQ), by using low-temperature scanning tunneling microscopy/spectroscopy (STM/STS). Upon adsorption on Au(111), DCV5T-Me₂ molecules self-assemble into compact islands at sub-monolayer coverage through hydrogen bonding and electrostatic interactions. A similar bonding configuration dominates in the second layer of a bilayer film, where DCV5T-Me₂ possesses higher-lying LUMO (lowest unoccupied molecular orbital) and LUMO+1 in energy due to a decoupling effect. The co-deposition of DCV5T-Me₂ and C₆₀ does not result in ordered hybrid assemblies at the sub-monolayer coverage on Au(111). On the other hand, C₆₀ molecules can self-assemble into ordered islands on top of the DCV5T-Me₂ monolayer. The dI/dV spectra reveal that the LUMO of decoupled C₆₀ is 400 mV lower in energy than the LUMO of decoupled DCV5T-Me₂. This energy difference facilitates electron transfer from DCV5T-Me₂ to C₆₀. The co-deposition of DCV5T-Me₂ and TCNQ leads to the formation of hybrid nanostructures. A tip-induced electric field can manipulate the charging and discharging of TCNQ by surrounding DCV5T-Me₂, manifested as sharp peaks and dips in dI/dV spectra recorded over TCNQ. Full article

Dicyanovinyl (DCV)-substituted oligothiophenes consist of both electron donor and acceptor ligands, which makes them promising materials for organic electronics. Here, we studied the structural and electronic properties of methyl-substituted dicyanovinyl-quinquethiophenes (DCV5T-Me₂) adsorbed on different metal surfaces, namely Au(111), Ag(111), and Cu(111), by using low-temperature scanning tunneling microscopy/spectroscopy (STM/STS). It is found that the assembled structures of DCV5T-Me₂ and the corresponding electronic properties vary depending on the underlying substrates. On Au(111) and Ag(111), compact organic islands are formed through intermolecular hydrogen bonding and electrostatic interactions. The lowest unoccupied molecular orbital (LUMO) and LUMO+1 of DCV5T-Me₂ are lower in energy on Ag(111) than those on Au(111), due to the stronger molecule–surface interaction when adsorbed on Ag(111). Moreover, orbital distributions of the LUMO and LUMO+1 in dI/dV maps on Au(111) and Ag(111) are the same as the DFT-calculated orbital distributions in gas phase, which indicates physisorption. In contrast, chemisorption dominates on Cu(111), where no ordered assemblies of DCV5T-Me₂ could be formed and resonances from the LUMO and LUMO+1 vanish. The present study highlights the key role of molecule–substrate interactions in determining the properties of organic nanostructures and provides valuable insights for designing next-generation organic electronics. 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

The introduction of functional groups, such as graphene oxide, can improve the reactivity between molecules, increasing the potential for their use in many fields such as gas sensing and adsorption. It was reported that that graphene materials are actively utilized in toxic gas sensor materials by modifying the surface with their chemical and structural stability. In order to understand the mechanisms of graphene and graphene oxides for adsorbing the hazardous gases, we classified the four gases (H₂S, NH₃, HF and COS) with their phases (two asymmetric and two linear), and conducted density functional theory calculations to determine the adsorption affinity, which represents the binding energy, bond distance, energy charge (Mulliken and Hirshfeld methods) and band gap between the HOMO (Highest Occupied Molecular Orbital) and the LUMO (Lowest Unoccupied Molecular Orbital). The results showed that introducing a functional group enhanced the binding energy with a narrowed band gap in asymmetric gas adsorption (H₂S and NH₃), while the results of the linear gases (HF and COS) showed lowered binding energy with a narrowed band gap. It is judged that the oxygen functional groups can narrow the band gap by introducing localized states between the valence and conduction bands or by forming new hybrid states through interactions with all the gases. However, from the differences in the phases, the linear gases stably interacted with a defect-free, porous and flat structure like with π–π interactions. In short, the theoretical findings confirm that the oxidation functional groups narrowed the band gap with a local interaction; however, linear gases showed enhanced binding energies with pristine graphene, which highlights the importance of surface material selection dependent on the target gases. 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

Singlet fission (SF) is a photophysical process where one singlet exciton splits into two triplet excitons. To construct design guidelines for engineering directional triplet exciton migration, we investigated the SF dynamics in symmetric linear heterotrimer systems consisting of different unsubstituted or 6,13-disubstituted pentacene derivatives denoted as X/Y (X, Y: terminal and center monomer species). Time-dependent density functional theory (TDDFT) calculations clarified that the induction effects of the substituents, represented as Hammett’s para-substitution coefficients ${\sigma }_p$, correlated with both the excitation energies of S₁ and T₁ states, in addition to the energies of the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO). Electronic coupling calculations and quantum dynamics simulations revealed that the selectivity of spatially separated TT states for heterotrimers increased over 70%, superior to that in the homotrimer: an optimal region of the difference in ${\sigma }_p$ between the substituents of X and Y for the increase in SF rate was found. The origin of the rise in SF rate is explained by considering the quantum interference effect: reduction in structural symmetry opens new interaction paths, allowing the S₁-TT mixing, which contributes to accelerating the hetero-fission between the terminal and center molecules. Full article

Energies of the atomic and molecular orbitals belonging to one and two atom systems from the fourth and fifth periods of the periodic table have been calculated using ab initio quantum mechanical calculations. The energies of selected occupied and unoccupied orbitals surrounding the highest occupied and lowest unoccupied orbitals (HOMOs and LUMOs) of each system were selected and used as input for our artificial intelligence (AI) software. Using the AI software, correlations between orbital parameters and selected chemical and physical properties of bulk materials composed of these elements were established. Using these correlations, the materials’ bulk properties were predicted. The Q² correlation for the single-atom predictions of first ionization potential, melting point, and boiling point were 0.3589, 0.4599, and 0.1798 respectively. The corresponding Q² correlations using orbital parameters describing two-atom systems increased the capability to predict the experimental properties to the respective values of 0.8551, 0.8207, and 0.7877. The accuracy in predicting materials’ bulk properties was increased up to four-fold by using two atoms instead of one. We also present results of the prediction of molecules for materials relevant to energy systems. Full article