Negative Binding Energy Research Articles

Density Functional Theory Study of Triple Transition Metal Cluster Anchored on the C2N Monolayer for Nitrogen Reduction Reactions.

The electrochemical nitrogen reduction reaction (NRR) is an attractive pathway for producing ammonia under ambient conditions. The development of efficient catalysts for nitrogen fixation in electrochemical NRRs has become increasingly important, but it remains challenging due to the need to address the issues of activity and selectivity. Herein, using density functional theory (DFT), we explore ten kinds of triple transition metal atoms (M3 = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) anchored on the C2N monolayer (M3-C2N) as NRR electrocatalysts. The negative binding energies of M3 clusters on C2N mean that the triple transition metal clusters can be stably anchored on the N6 cavity of the C2N structure. As the first step of the NRR, the adsorption configurations of N2 show that the N2 on M3-C2N catalysts can be stably adsorbed in a side-on mode, except for Zn3-C2N. Moreover, the extended N-N bond length and electronic structure indicate that the N2 molecule has been fully activated on the M3-C2N surface. The results of limiting potential screen out the four M3-C2N catalysts (Co3-C2N, Cr3-C2N, Fe3-C2N, and Ni3-C2N) that have a superior electrochemical NRR performance, and the corresponding values are -0.61 V, -0.67 V, -0.63 V, and -0.66 V, respectively, which are smaller than those on Ru(0001). In addition, the detailed NRR mechanism studied shows that the alternating and enzymatic mechanisms of association pathways on Co3-C2N, Cr3-C2N, Fe3-C2N, and Ni3-C2N are more energetically favorable. In the end, the catalytic selectivity for NRR on M3-C2N is investigated through the performance of a hydrogen evolution reaction (HER) on them. We find that Co3-C2N, Cr3-C2N, Fe3-C2N, and Ni3-C2N catalysts possess a high catalytic activity for NRR and exhibit a strong capability of suppressing the competitive HER. Our findings provide a new strategy for designing NRR catalysts with high catalytic activity and selectivity.

One electron is enough: A chemical bonding approach on the hydrogen induced structural transformation in MPd3 (M = Mg, In, Tl) intermetallic compounds

It is crucial to understand the nature of the metal-hydrogen interactions in the intermetallic hydrides in order to develop new hydrogen storage materials with optimum metal-H interactions for desired hydrogen absorption-desorption kinetics. The MPd3 intermetallic compounds (M = Mg, In, Tl) transform to cubic anti-perovskite type (AuCu3-type with hydrogen in the octahedral intersect) structure from ZrAl3-type four-fold ccp-superstructure up on hydrogenation. According to the DFT-based orbital space electronic structure and chemical bonding analysis, this structural transformation is driven by maximizing the coordination of hydrogen surrounded by Pd, forming the Pd (4d) – H (1s), and … Pd–H–Pd … multicenter interactions. These interactions provide sufficient thermodynamic stability for the hydrides to form, with negative binding energies of hydrogen. The binding energies are found to be significantly low, with the possibility of the ease of hydrogen desorption within limited reaction conditions.

Adsorptive removal of oxytetracycline antibiotics on magnetic nanoparticles NiFe2O4/Au: Characteristics, mechanism and theoretical calculations

This investigation aims to develop a specialized adsorbent for the efficient removal of Oxytetracycline (OTC) from complex matrices. We employed a magnetic composite, NiFe2O4/Au (NFO/Au), as the adsorbent, which exhibited remarkable ease of material recovery due to the reasonable magnetic property of NFO. Simultaneously, gold nanoparticles (AuNPs) on the NFO surface amplified the material's adsorption capacity by demonstrating a strong affinity for the amine groups within the OTC structure. The crystal and morphological structure and surface chemistry of the prepared material were identified by XRD, TEM, BET, and XPS. Their magnetic and optical properties were studied by VSM and UV-VIS. Cubic or rectangular shapes (50–100 nm) of NFO were surrounded by spherical AuNPs (10–30 nm). The saturation magnetization slightly decreased from 33 emu/g to 30 emu/g upon coating the NFO surface with AuNPs, which still ensures good magnetism of the composite. A maximum adsorption capacity of 43.48 mg/g was achieved at optimum adsorption conditions. The novel adsorbent exhibits fast adsorption after 30 min, high adsorption capacity, and good reusability after five cycles. The adsorption equilibrium adhered to a monolayer Langmuir isotherm, while the adsorption kinetics followed pseudo-second-order kinetics and the intraparticle diffusion models. The first principle calculation based on the density functional theory revealed that the fundamental reason behind the enhanced adsorption capacity is through greater electron populations, more negative binding energy, and higher effective charge transfer. This composite material was employed to remove OTC from water samples taken from a shrimp pond, demonstrating an impressive adsorption efficiency of approximately 90 %.

In silico analysis: Fulleropyrrolidine derivatives against HIV-PR mutants and SARS-CoV-2 Mpro

Abstract Approximately 37.9 million people living with HIV (PLWH) are at risk of severe consequences from COVID-19. Urgent development of tailored treatments for PLWH, who have historically been excluded from vaccine trials, is crucial. The present study introduces some modified fulleropyrrolidine derivatives with chalcogen atoms (O, S, or Se) and hydroxymethylcarbonyl (HMC) groups to target 11 single and double HIV-1 protease (HIV-PR) mutations and the main protease of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2 Mpro). The inhibitory activities of these derivatives are computationally examined through molecular docking, molecular dynamic simulations for 200 ns, and Lipinski’s rule of five (RO5). Fourier-transform infrared spectroscopy spectra and thermodynamic properties are calculated and analyzed using Density Functional Theory B88-PW91 method. The results indicate that the suggested O-compounds obey three parameters of the RO5 and HMC forms hydrogen bonds with studied viral proteases. Compounds with O and S additives display a high binding affinity with negative binding energy values for HIV-PR mutations (A71V-I84V, V77I-I84V, and I84V-L90M) and SARS-CoV-2 Mpro. The compounds with S and Se additives shift to lower frequencies of the major vibrational bands. Specifically, compound 1, with two oxygen additives, emerges as the most effective in inhibiting both HIV-PR mutations and SARS-CoV-2 Mpro.

Rational Approach toward COVID-19's Main Protease Inhibitors: A Hierarchical Biochemoinformatics Analysis.

This study investigated the potential of selected compounds as inhibitors of SARS-CoV-2 Mpro through pharmacokinetic and toxicological analyses, molecular docking, and molecular dynamics simulations. In silico molecular docking simulations revealed promising ligands with favorable binding affinities for Mpro, ranging from -6.2 to -9.5 kcal/mol. Moreover, molecular dynamics simulations demonstrated the stability of protein-ligand complexes over 200 ns, maintaining protein secondary structures. MM-PBSA analysis revealed favorable interactions between ligands and Mpro, with negative binding energy values. Hydrogen bond formation capacity during molecular dynamics was confirmed, indicating consistent interactions with Mpro catalytic residues. Based on these findings, selected ligands show promise for future studies in developing COVID-19 treatments.

Effect of intermolecular interactions and pharmacokinetic profile of antidiabetic agent (E)-N,N‑diethyl-2-(5(3‑hydroxy-4-methoxybenzylidene)-2,4-dioxothiazolidin-3-yl) acetamide

Diabetes is a prevalent disease in South India, posing a severe threat to public health. To tackle this issue, researchers are focusing on developing multi-targeted ligands, and one promising candidate is (E)-N,N‑diethyl-2-(5(3‑hydroxy-4-methoxybenzylidene)-2,4-dioxothiazolidin-3-yl)acetamide (DMDA). Geometry optimization of DMDA was carried out using density functional theory with 6–311+G(d, p) basis set to develop a theoretical model close to the previously synthesized and reported DMDA. Natural Bond Orbital analysis was conducted to scrutinize the phenomena of charge delocalization and electronic exchange interactions governing both intermolecular and intramolecular associations. Moreover, the vibrational characteristics of the molecule were elucidated through FT-IR and FT-Raman spectra. Lowest Unoccupied Molecular Orbital and Highest Occupied Molecular Orbital have also been explored to enhance understanding of the molecule's electronic structure and reactivity. Hirshfeld surface analysis was utilized to investigate the interactions between molecules within the crystalline lattice. Absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis elucidates the potential pharmacokinetic profile of DMDA. Molecular docking was performed to predict the binding site responsible for various interactions with the targeted protein. By combining these techniques, a comprehensive molecular description of DMDA has been generated.There are three prominent intramolecular interactions within the ambit of van der Waals radii, leading to stability of the molecule. The presence of a broad and shallow band with a significant red shift provides evidence for the strong intermolecular OH hydrogen bonding. DMDA complies with Lipinski's Rule of Five, highlighting its favorable characteristics for pharmaceutical efficacy. The negative binding energies determined by docking studies ascertain the potential sites of ligand-protein interaction leading to inhibition of α-amylase and α-glucosidase enzyme.

2D biphenylene-based nanostructures as prospective drug delivery carriers of carvedilol and levosim: DFT study

Drug delivery using 2D biphenylene-based nanostructures is investigated using DFT calculations. The explored nanostructures are energetically and dynamically stable with negative binding energies and real vibration frequencies. The high adsorption energy of ∼ -2.1 eV indicates the successful loading of the heart drugs (carvedilol and levosim). The chemical modification promotes adsorption by adding new adsorption sites at the edges. Surprisingly, no substantial change in the electronic structure following drug adsorption which is important for efficient drug release. Further analyses on natural charge and non-covalent interactions show noticeable charge transfer and non-covalent interactions between the drug and the biphenylene-based nanostructures.

Isomeric dichloropyrazine of dual-function additives: Synergistic enhancement of lithium anode protection and sulfur redox kinetics in lithium–sulfur batteries

Lithium-sulfur batteries (LSBs) currently face challenges such as low sulfur utilization, inadequate cycling stability, and unstable lithium anode interfaces. In this study, dichloropyrazines (DCPs) are introduced as dual-functional additives into electrolyte and 2,5-DCP exhibits the most promising performance enhancement. This superiority can be attributed to its strong redox activity, lower molecular orbital energy gap, and more negative relative binding energy compared to the other DCP isomers. Specifically, DCPs demonstrate their dual functionality by promoting the formation of a stable organic-inorganic hybrid solid electrolyte interface (SEI) rich in LiCl on lithium anodes. This ensures uniform lithium deposition and suppresses dendrite growth. At sulfur cathodes, density functional theory (DFT) calculations confirm that DCPs facilitate lithium polysulfides (LiPSs) conversion kinetics through Li–N bond formation. LSBs with 2,5-DCP exhibit excellent stability at a 1C rate and retain 86.6 % capacity after 800 cycles. This study demonstrates DCPs' potential as effective dual-functional electrolyte additives in designing high-performance LSBs.

Exploring the twin potential of nanostructured TiO2:SeO2 as a promising visible light photocatalyst and selective fluorosensing platform

The present work describes the development of TiO2/SeO2 nanostructure as a potential candidate for visible light photocatalysis as well as selective fluorophore for the sensing of picric acid. The obtained nanostructure consists of uniform globular nanoparticles having approximate size of 170 nm and possess an optical band gap of 2.33 eV with absorption maxima at 473 nm. The photocatalyst was able to achieve 90.34% degradation efficiency for 2, 4-dichlorophenol (2,4-DCP) with rate constant of 0.0046 min−1 in the visible region. Further the nanostructure was able to serve as a selective fluorophore for sensing of Picric acid portraying more than 95% of fluorescence quenching when the concentration of PA is 10–4 M. Theoretical calculations indicate the interaction of organic pollutants with the nanostructure and reveal that both picric acid (− 66.21 kcal/mol) and 2,4-DCP (− 12.31 kcal/mol) possess more negative binding energy values demonstrating a strong interaction of both with the nanostructure, making it suitable for the degradation as well as sensing of organic pollutants. Thus this study explains the potential of prepared catalyst for waste water treatment.

Unveiling the potential of TPA-based molecules to tune the optoelectronic properties and enhance the efficiency of dye-sensitized solar cells.

The world's energy and environmental requirements are changing due to rapid population growth and industrial growth, and solar cells can be used to meet these demands. Dye-sensitized solar cells (DSSCs) are solar cells in which energy conversion occurs via a process similar to photosynthesis in plants. DSSC development is still in its infancy. DSSCs can operate under cloudy conditions and indirect sunlight and have attracted considerable attention due to their low cost and high efficiency. We designed two metal-free TPA-based dyes (Dye2 and Dye3) based on the reference dye Mg207 (Dye1) by increasing the donor strength of the molecule, as such dyes have shown enhanced efficiency in DSSCs. Moreover, the triphenylamine (TPA) moiety has been demonstrated to be a good donor that prevents charge recombination. Intramolecular charge transfer (ICT) from the donor to acceptor moiety was found in the sensitizers, and electrons were promoted to the conduction band (CB) of the TiO2 semiconductor. The negative binding energy of the dye@TiO2 clusters indicated that dye adsorption on the semiconductor surface was stable. The double donor increased the electron injection and electronic coupling constants in Dye2 and Dye3, indicating that these newly designed dyes have superior charge injection capacity. Accordingly, the efficiencies of DSSCs with Dye2 and Dye3 were 9.77% and 9.62%, respectively, and substitution with the TPA unit at the -R1 and -R2 positions in Dye1 resulted in better power conversion compared to the parent compound (9.09%). Increased donor strength improved photovoltaic performance by increasing current density and light-harvesting efficiency. This is a good molecular design approach for preparing targeted donor- -acceptor (D- -A) organic dyes with high DSSC efficiency. To predict the charge transport and optoelectronic characteristics of the TPA dyes, quantum chemical calculations were carried out using Gaussian16. The ground-state (S0) optimized geometries of the sensitizers were computed by utilizing DFT at the B3LYP/6-31G** level. The absorption spectra ( max) were computed by employing TD-DFT with various functionals (B3LYP, PBE1PBE, CAM-B3LYP, and BHandHLYP) in the gas and solvent (DCM) phases. Among the studied functionals, BHandHLYP was found to be best at successfully reproducing the experimental data. Thus, the absorption spectra of the newly designed dyes and dye@TiO2 were calculated at the BHandHLYP/6-31G** level. The dye@TiO2 cluster optimizations were carried out at the B3LYP/6-31G**(LANL2DZ) level.

Deep removal of arsenic from arsenic-bearing gypsum using a seed-induced crystal control technique and its mechanisms

Arsenic-bearing gypsum (ABG), a byproduct from the lime/ferric sulfate process in the waste acid treatment of the heavy non-ferrous industry, represents a substantial hazardous arsenic (As) waste issue in China. Due to the potential arsenic leakage, the disposal of ABG poses an urgent challenge to the surrounding environment. The elevated As content and the low-value-added recycling products are the primary hurdles hindering ABG recycling. In this study, precise control over the gypsum crystal and As species in Na2SO4-H2SO4 solutions under mild conditions facilitated the deep removal of As (with a leaching efficiency of 92.45 % and a final product As concentration of 80.32 ppm) and simultaneous preparation of high-strength α-bassanite (with a compressive strength of 35.38 MPa) from the pre-treated ABG. This process occurred during the recrystallization from dihydrate gypsum (CaSO4·2H2O, DH) to α-bassanite (α-CaSO4·0.5H2O, α-HH), involving DH dissolution followed by α-HH crystallization. The encapsulated As was fully released during the dissolution process, crucial for the efficient elimination of As impurities. H2SO4 dissolved the released As, transforming it into the protonated species (H3AsO4) with a distinct structure and a less negative binding energy (ΔEB) to SO42-. This transformation prevented the chemical incorporation of the released As during the α-HH crystallization process. Additionally, the morphology and size of α-HH were controlled by seeding in the mixed solutions. The formation of large short-columnar α-HH crystals with a low specific surface area significantly reduced the surface adsorption of As, further enhancing As leaching efficiency. Importantly, the large short-columnar α-HH was identified as high-strength gypsum with high added value. This study provided innovative guidance for efficiently removing impurities from gypsum and pioneered a cost-effective approach for the clean and high-value utilization of industrial gypsum residues.

Molecular Dynamics Simulation for the Acidic Compounds Retention Mechanism Study on Octyl-Quaternary Ammonium Mixed-Mode Stationary Phase.

With the widespread application of mixed-mode chromatography in separation analysis, it is becoming increasingly important to study its retention mechanism. The retention behavior of acidic compounds on mixed-mode octyl-quaternary ammonium (Sil-C8-QA) columns was investigated by computer simulation. Firstly, the benzoic acid homologues were used as the analytes, and the simulation model was constructed by the Materials Studio. Geometric optimization, annealing and molecular dynamics (MD) simulation of these complexes resulted in optimized conformations. The binding energy, mean square displacement (MSD) and torsion angle distribution generated by MD simulation were then analyzed. The results showed that the more negative binding energy, the greater the MSD and the narrower the torsion angle distribution, indicating that the stationary phase behaves with stronger interaction and retention. The retention behavior of five acidic drugs on the Sil-C8-QA column was then successfully explained by simulation. Acidic drugs are more retentive on the mixed-mode column due to the more substantial interaction brought by the reversed-phase/ion-exchange mixed-mode mechanism compared to other single-mode columns. This simulation method is expected to provide ideas for studying the separation mechanism and predicting the retention behavior of more complex samples.

In Vitro and Molecular Docking Evaluation of the Anticholinesterase and Antidiabetic Effects of Compounds from Terminalia macroptera Guill. & Perr. (Combretaceae).

Alzheimer's disease (AD) and diabetes are non-communicable diseases with global impacts. Inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are suitable therapies for AD, while α-amylase and α-glucosidase inhibitors are employed as antidiabetic agents. Compounds were isolated from the medicinal plant Terminalia macroptera and evaluated for their AChE, BChE, α-amylase, and α-glucosidase inhibitions. From 1H and 13C NMR data, the compounds were identified as 3,3'-di-O-methyl ellagic acid (1), 3,3',4'-tri-O-methyl ellagic acid-4-O-β-D-xylopyranoside (2), 3,3',4'-tri-O-methyl ellagic acid-4-O-β-D-glucopyranoside (3), 3,3'-di-O-methyl ellagic acid-4-O-β-D-glucopyranoside (4), myricetin-3-O-rhamnoside (5), shikimic acid (6), arjungenin (7), terminolic acid (8), 24-deoxysericoside (9), arjunglucoside I (10), and chebuloside II (11). The derivatives of ellagic acid (1-4) showed moderate to good inhibition of cholinesterases, with the most potent being 3,3'-di-O-methyl ellagic acid, with IC50 values of 46.77 ± 0.90 µg/mL and 50.48 ± 1.10 µg/mL against AChE and BChE, respectively. The compounds exhibited potential inhibition of α-amylase and α-glucosidase, especially the phenolic compounds (1-5). Myricetin-3-O-rhamnoside had the highest α-amylase inhibition with an IC50 value of 65.17 ± 0.43 µg/mL compared to acarbose with an IC50 value of 32.25 ± 0.36 µg/mL. Two compounds, 3,3'-di-O-methyl ellagic acid (IC50 = 74.18 ± 0.29 µg/mL) and myricetin-3-O-rhamnoside (IC50 = 69.02 ± 0.65 µg/mL), were more active than the standard acarbose (IC50 = 87.70 ± 0.68 µg/mL) in the α-glucosidase assay. For α-glucosidase and α-amylase, the molecular docking results for 1-11 reveal that these compounds may fit well into the binding sites of the target enzymes, establishing stable complexes with negative binding energies in the range of -4.03 to -10.20 kcalmol-1. Though not all the compounds showed binding affinities with cholinesterases, some had negative binding energies, indicating that the inhibition was thermodynamically favorable.

Cyclo[16]carbon through the lens of density functional theory: Role of impurity decoration in hydrogen evolution reaction

The increasing global demand for sustainable energy sources has intensified the search for cost-effective catalysts in the hydrogen evolution reaction (HER). Single-atom catalysts (SACs) supported on suitable substrates have emerged as promising alternatives. In this study, we investigate the utilization of cyclo[16]carbon (C16 nanocluster) as a support for second-row transition metals (TMs) based SACs. The exploration focuses on analyzing the geometry, electronic properties, stability, and catalytic performance of TM@C16 SACs in the context of HER. Notably, highly negative binding energy values, structural modifications, and altered dipole moments collectively affirm the strong binding between the TMs and the C16 nanocluster. The incorporation of TMs onto the C16 nanocluster substantially enhances the conductivity of the latter. Studied SACs primarily showed H2 evolution via Volmer-Heyrovsky mechanisms. Notably, Pd@C16 and Rh@C16 displayed superior catalytic performance, with ΔGHV values of −0.007 eV and 0.05 eV, respectively. The determination of the exchange current via a volcano plot as a function of Gibbs free energy for hydrogen evolution over these designed SACs further validates their efficacy. Our findings establish Pd@C16 and Rh@C16 as highly stable and efficient SACs for the HER, underscoring their potential in advancing sustainable energy technologies.

Marine-Derived Cytosine Arabinoside (Ara-C) Inhibits Biofilm Formation by Inhibiting PEL Operon Proteins (Pel A and Pel B) of Pseudomonas aeruginosa: An In Silico Approach.

Pseudomonas aeruginosa (P. aeruginosa) is a gram-negative biofilm-forming opportunistic human pathogen whose vital mechanism is biofilm formation for better survival. PelA and PelB proteins of the PEL operon are essential for bacterial-synthesized pellicle polysaccharide (PEL), which is a vital structural component of the biofilm. It helps in adherence of biofilm on the surface and maintenance of cell-to-cell interactions and with other matrix components. Here, in-silico molecular docking and simulation studies were performed against PelA and PelB using ten natural bioactive compounds, individually [podocarpic acids, ferruginol, scopadulcic acid B, pisiferic acid, metachromin A, Cytarabine (cytosine arabinoside; Ara-C), ursolic acid, oleanolic acid, maslinic acid, and betulinic acid], those have already been established as anti-infectious compounds. The results obtained from AutoDock and Glide-Schordinger stated that a marine-derived cytosine arabinoside(Ara-C) among the ten compounds binds active sites of PelA and PelB, exhibiting strong binding affinity [Trp224 (hydrogen), Ser219 (polar), Val234 (hydrophobic) for PelA; Leu365 and Glu389 (hydrogen), Gln366 (polar) for PelB] with high negative binding energy -5.518kcal/mol and -6.056kcal/mol, respectively. The molecular dynamic and simulation studies for 100ns showed the MMGBSA binding energy scores are -16.4kcal/mol (Ara-C with PelA), and -22.25kcal/mol (Ara-C with PelB). Further, ADME/T studies indicate the IC50 values of AraC are 6.10mM for PelA and 18.78mM for PelB, which is a comparatively very low dose. The zero violation of Lipinski's Rule of Five further established that Ara-C is a good candidate for drug development. Thus, Ara-C could be considered a potent anti-biofilm compound against PEL operon-dependent biofilm formation of P. aeruginosa.

Mechanisms for the separation of Li+ and Mg2+ from salt lake brines using TBP and TOP systems

The tributyl phosphate (TBP)/FeCl3 system has been widely used for lithium extraction from high‑magnesium salt lakes. However, at high TBP concentrations, the Li/Mg selectivity is significantly lower. This study revealed that at high TBP concentrations, TBP alone extracted Mg2+ to form MgCl2·6TBP as the main product, thus affecting the extraction efficiency of Li+. On this basis, a neutral phosphate with long carbon chains, trioctyl phosphate (TOP), was used to replace TBP. The separation capacity and extraction mechanism of the TOP/FeCl3 system were studied, and density functional theory (DFT) calculations were employed to model the cationic complexes of the TOP and TBP systems. The results showed that in the presence of FeCl3, the extraction efficiency of Li+ (ELi) reached 91 %, and the Li/Mg separation factor (βLi/Mg) was 5688. In contrast, in the TBP/FeCl3 system with the same concentration, the ELi and βLi/Mg values were much lower at 74 % and 239, respectively. Furthermore, the TOP complex of Li+ had shorter Li − O bond lengths and a more negative binding energy, while that formed with Mg2+ had longer Mg − O bond lengths and the smallest HOMO–LUMO gap, indicating that TOP bonded more stably with Li+ and was less prone to Mg2+ extraction than TBP.

Biexcitons and quadrons in self-assembled quantum dots

We theoretically study biexcitons and quadrons in quantum dots with parabolic confinement and give a complete comparison between the two excitations. The calculation of quadron and biexciton binding energies as functions of electron-to-hole confinement potentials and mass ratios, using the unrestricted Hartree–Fock method, shows the essential differences between biexcitons and quadrons. The crossover between the negative and positive binding energies is indicated. The effect of an external magnetic field on the quadron and biexciton binding energies has also been investigated. In addition, the crossover between anti-binding and binding of both excited quadron and biexciton states in a certain range of the electron-to-hole oscillator length ratios has been found.

The hydrophilicity mechanism of anatase and rutile (110) TiO2 films based on donor-acceptor complexes

When the surface of TiO2 is exposed to ultraviolet (UV) light, its hydrophilicity increases initially and then contact angle relaxation progresses over time. We investigated the source mechanism and working principles of long-lasting hydrophilicity in an ambient environment. Previously, we reported that the amount of donor-acceptor complexes (DACs) generated by polarizable OH groups with strong charge polarity is critical for maintaining long-lasting hydrophilicity (>90 days) on an anatase surface. In less reactive TiO2 films with low surface energy, a fast relaxation occurs due to the loss of polarizable OH groups. In this research, quantitative four-peak X-ray photoelectron spectroscopy analysis with TiO2 O 1 s spectra surface analysis was used to determine the relative amount of DACs and the binding energy shifting of water adsorbates on single crystal rutile (110) and polycrystalline anatase after UV exposure or plasma treatment. Films treated with oxygen or argon plasma and/or UV were analyzed and compared to suggested mechanisms that can occur on the surface of the TiO2 phase. All treated rutile (110) films except those treated with an Ar plasma exhibited rapid contact angle relaxation during the first 3 days, and the angle increased gradually to >50° over 14 days. In contrast, all anatase films retained long-lasting hydrophilicity, demonstrating a <∼10° contact angle over 56 days. At the first measurement, the binding energies were shifted for rutile (110) treated with O2 plasma and O2 plasma+UV films, demonstrating Ti–OH and DAC values of +0.15 eV each. However, the Ti–OH and DACs of all anatase films were located in the negative binding energy position, indicating that the DACs of rutile (110) were unstable due to a relatively weak bonding. In addition, the IOH/Ibulk intensity ratio of Ti–OH for rutile (110) treated with an O2 plasma increased significantly from 20 % to 37 %. However, the intensity ratio for O2 plasma+UV increased only from 20 % to 23.8 %. This result in combination with the binding energy shifting tendency indicates that relaxed OH groups increased rapidly without UV treatment. When rutile (110) was irradiated with UV, the effect of photoinduced electron-hole pairs shown with Ti 2p spectra was much shorter than that of anatase. Differences in relaxation occurred in both phases due to the charge polarity effect between rutile (110) and anatase, the unstable DACs related to weak OH groups, and the difference in surface characteristics. Using single crystal rutile (110) with a well-defined surface, these experiments validated further the DAC mechanism and theory presented by our group. Specifically, we confirmed that both the amount of DACs and the binding energy position shifting are important for long-term hydrophilicity.

Molecular hybrids based on 1,2,3-triazole and 1,3,4-thiadiazole cores: Synthesis, characterization, anticancer activity and in silico study

One sets of 1,3,4-thiadiazole analogs 14a-c and 15a-c were synthesized by the incorporation of two heterocyclic nuclei (1,2,3-triazole & 1,3,4-thiadiazoles) in objective of developing multifunctional molecules for anticancer disease. (R)-Carvone was used as precursors for the synthesis of new heterocycles. The 1,2,3-triazole-1,3,4-thiadiazoles 14a-c and 15a-c were synthesized in good yields from the precursors using simple procedures. The chemical structures of all the newly synthesized hybrids were established using (1H and 13C) NMR and HRMS analysis. The in vitro assessment of the activity of the resultant 1,2,3-triazole-1,3,4-thiadiazoles against human cancer cells, namely fibrosarcoma (HT-1080), lung carcinoma (A-549) and breast carcinoma (MCF-7 and MDA-MB-231) was performed using viability testing (MTT). Compound 14a was the most active heterocycle, and its cytotoxic activity was three times less actives comparable to that obtained for Doxorubicin (6 µM) as a reference. The 1,3,4-thiadiazoles 15a-c showed moderate cytotoxic activities with IC50 values ranging from 25.56 ± 1.13 to 61.81 ± 2.21 μM. Molecular docking studies were conducted against two antiapoptotic proteins namely Bcl-2, and Bcl-XL to elucidate the potential mechanisms of action. The results indicate that compounds interact favorably (binding energy = −7.6 to −9.8 kcal/mol) with the target proteins through hydrophobic, electrostatic interactions, and hydrogen bonding. The negative binding energy indicate the spontaneous nature of the interaction. Further, molecular dynamics simulation parameters such as root mean square deviation, root mean square fluctuation, radius of gyration, and solvent accessible surface area provided insights into the stability and dynamics of the protein-ligand complexes.

Design, Synthesis, Molecular Docking, and Anti‐Inflammatory Potential of Amide Coupling Carboxylate Derivatives

AbstractEight new amide‐based carboxylate derivatives were synthesized and evaluated for anti‐inflammatory potentials using in‐vitro, in‐vivo and in silico studies. In cyclooxygenase‐2 assay, maximum percent antagonist potential was exhibited by sodium 4‐((4‐fluorophenyl) amino)‐4‐oxobutanoate (93.91 %), bis ((4‐((4‐methoxy‐2‐nitrophenyl)amino)‐4‐oxobutanoyl)oxy) zinc (93.04 %), and bis ((4‐((4‐bromo‐2‐fluorophenyl) amino)‐4‐oxobutanoyl)oxy)zincio (2‐bromopyridine) (92.64 %) with IC50 values of 1.65, 2.08, and 0.288 μM/ml respectively. Celecoxib demonstrated 98.60 % effect with an IC50 value of 0.041 μM/ml. In LOX assay, 4‐((4‐methoxy‐2‐nitrophenyl)amino)‐4‐oxobutanoic acid (97.03 %), bis ((4‐((4‐methoxy‐2‐nitrophenyl)amino)‐4‐oxobutanoyl)oxy)zinc (95.45 %), and (92.53 %) demonstrated maximum percent effect with IC50 values 3.48, 0.45, and 0.83 μM/ml respectively. The standard 5‐lipoxygenase inhibitor (montelukast) resulted from a 98.39 % inhibitory effect with an IC50 value of 0.194 μM/ml. In in‐vivo analysis, the potent tested compounds (5, 10, and, 20 mg/kg) significantly (p&lt;0.001) reversed the induced edema by carrageenan. The standard drug aspirin displayed significant results (74–83 %). The standard drugs in these phlogestic agents displayed excellent results like cetirizine (67.9 %), celecoxib (81.61 %), icatibant (82.22 %) and nemesulide (87.17 %) at 5th h. The compounds displayed the inhibitory potential against targeted proteins. 4‐((4‐methoxy‐2‐nitrophenyl)amino)‐4‐oxobutanoic acid, 4‐((4‐fluorophenyl)amino)‐4‐oxobutanoic acid and sodium 4‐((4‐bromo‐2‐fluorophenyl)amino)‐4‐oxobutanoate shown excellent behavior by giving negative binding energies close of standard drugs montelukast (5F1A: −7.9 kcal/mol) and diclofenac (3O8Y: −8.5 Kcal/mol). The tested compounds were proven significant anti‐inflammatory potentials.