Intramolecular energy transfer and its influence on the overall quantum yields of Eu3+ and Tb3+ chelates with dimethyl(phenylsulfonyl)amidophosphate ligands.

Lanthanide chelates with dimethyl(phenylsulfonyl)amidophosphate (labeled as HSP) and Lewis base ligands (bpy = 2,2;-bipyridine and phen = 1,10-phenanthroline) of formula Na[Ln(SP)4] (1Ln), [Ln(SP)3bpy] (2Ln); [Ln(SP)3phen] (3Ln) (Ln = Eu3+, Gd3+, Tb3+ and Lu3+) were obtained and characterized by the X-ray, photoluminescence spectroscopy at 293 and 77 K as well as by intrinsic (QLnLn) and overall (QLnL) luminescence quantum yields. These phosphors manifest a very strong emission after excitation in the UV range of the molecular singlet states (S1) and two of them have very high QLnL values (Eu3+ and Tb3+ chelates of the type 2Ln and 3Ln). The dynamics of the excited states are discussed based on the intramolecular energy transfer theory, considering the dipole-dipole, the dipole-multipole and the exchange mechanisms. From the calculated energy transfer rates, a rate equation model was constructed and, thus, the theoretical QLnL can be obtained. A good correlation between the experimentally determined and theoretically calculated QLnL values was achieved, with the triplet state (T1) playing a predominant role in the energy transfer process for Eu3+ compounds, while the sensitization for Tb3+ compounds is dominated by the energy transfer rates from the singlet state (S1).

Chiral separation and spectroscopic characterization of mefloquine analogues.

Mefloquine, a widely used antimalarial agent, has spurred ongoing research into the development of derivatives with enhanced efficacy and reduced side effects. In this investigation, we synthesized two compounds containing N-allyl or N-tert-butylacetamid groups. A chiral liquid chromatography with polysaccharide chiral stationary phase was utilized to separate the enantiomers of both derivatives. We employed spectroscopic chiroptical and non-polarizable methods such as electronic and vibrational circular dichroism, infrared absorption and ultraviolet spectroscopies. Combined with density functional theory calculations, the stable conformers were found in solution and their spectra were subsequently simulated. We elucidated the three-dimensional structure of the enantiomerically pure compounds and assigned the absolute configuration of all prepared derivatives using both experimental and simulated spectra.

Degradation of bisphenol F by peroxymonosulfate activated with palladium-based catalysts.

In this study, supported Pd catalysts were prepared and used as heterogeneous catalysts for the activation of peroxymonosulfate (PMS) which successfully degrade bisphenol F (BPF). Among the supported catalysts (i.e., Pd/SiO2, Pd/CeO2, Pd/TiO2 and Pd/Al2O3), Pd/TiO2 exhibited the highest catalytic activity due to the high isoelectric point and high Pd0 content. Pd/TiO2 prepared by the deposition method leads to high Pd dispersion, which are the key factors for efficient BPF degradation. The influencing factors were investigated during the reaction process and two possible degradation pathways were proposed. Density functional theory (DFT) calculations demonstrate that stronger BPF adsorption and BPF degradation with lower reaction barrier occurs on smaller Pd particles. The catalytic activities are strongly dependent on the structural features of the catalysts. Both experiments and theoretical calculations prove that the reaction is actuated by electron transfer rather than radicals.

Modulating d-Orbital electronic configuration via metal-metal oxide interactions for boosting electrocatalytic methanol oxidation.

Coordinating the interfacial interaction between Pt-based nanoparticles (NPs) and supports is a significant strategy for the modulation of d-orbital electronic configuration and the adsorption behaviors of intermediates, which is of critical importance for boosting electrocatalytic performance. Herein, we demonstrated a specific synergy effect between the ordered PtFe intermetallic and neighboring oxygen vacancies (Ov), which provides an "ensemble reaction pool" to balance the barriers of both the activity, stability, and CO poisoning issues for the methanol oxidation reaction (MOR). In our proposed "ensemble reaction pool", the deprotonation of methanol occurs on the Pt site to form the intermediate *CO, where the strain derived from the PtFe intermetallic could alter the d-orbital electronic configuration of Pt, intrinsically weakening the *CO adsorption energy, and Ov in CeO2 promote hydroxyl species (*OH) adsorption, which will react with *CO, facilitating the dissociative adsorption of *CO, thus cooperatively enhancing the performance of MOR. The X-ray absorption fine structure (XAFS) analyses reveal the electron transfer in CeO2 and then convert Ce4+ to Ce3+. The density functional theory (DFT) calculations revealed that introducing Fe induces strain could modify the d-band center of Pt, and thus lower the energy barrier of the potential-determining step. Meanwhile, the introduction of CeO2 can favor the *OH adsorption, speeding up the oxidation and removal of *CO blocked at the Pt site. Furthermore, the determined atomic arrangement and surface composition of PtFe intermetallic further guarantee the stability of MOR by suppressing less-noble metal into the electrolyte.

Interfacial interaction mechanism between Mn doped highly conjugated biochar and berberine hydrochloride.

MnSO4-modified biochar (Mn-BC) was synthesized to remove berberine hydrochloride (BH) from wastewater by utilizing tea waste as raw material and MnSO4 as modifier. Brunel Emmett Taylor (BET) analysis reveals that the specific surface area (SSA) and average pore size (Dave) of Mn-BC are 1.4 and 7 times higher than those of pristine biochar apart, attributing to the dissociation effect can promote the dispersion of MnSO4 in the pores of the biochar. Meanwhile, the doping of Mn not only introduces additional oxygen-containing functional groups (OCFGs), but also modulates the π electron density. Furthermore, Response surface method (RSM) analysis reveals that Mn-BC dosage has the most significant effect on BH removal, followed by BH concentration and pH value. Kinetic and isothermal studies reveal that the BH adsorption process of Mn-BC was mainly dominated by chemical and monolayer adsorption. Meanwhile, density functional theory (DFT) calculations confirm the contribution of Mn doping to the conjugation effect in the adsorption system. Originally proposed Mn-BC is one potentially propitious material to eliminate BH from wastewater, meanwhile this also provides a newfangled conception over the sustainable utilization of tea waste resources.

Mechanisms of Defect-Mediated Memristive Behavior in MoS2 Monolayer.

The switching dynamics of a Au∥VS2@MoS2 atomristor is explored by first-principles computations of the atomic-configuration energy and electron transport. It is found that external bias can reduce the energy barrier between the two (high- and low-) conduction states, to achieve nonvolatile resistive switching. We find that the force acting on the switching atom is a combination of electrostatic force (while its charge is induced both electrostatically and chemically) and also by electron-wind, whose effect may hinder the writing process at larger bias. The analysis uncovers how the writing and reading processes of the atomristor depend on several factors: (i) atomic structure details of the Au tip; (ii) the space-gap distance between the tip and MoS2 layer; and (iii) tip metal choice. The fundamental understanding of switching events provides useful guidance for memristor design and possible limitations.

Monolayer Penta-BeAs2: A Promising 2D Materials for Toxic Gas Sensor with High Selectivity.

The discovery of novel materials with high gas sensing selectivity is a key driver of gas sensor technology. Based on the recently reported two-dimensional (2D) pentagonal BeP2, we introduce penta-BeAs2 as a new member of the pentagonal family of materials for toxic gas sensors based on density functional theory (DFT). For electronic applications, a band structure calculation showed that penta-BeAs2 has indirect band gaps of 0.38 and 0.79 eV, using GGA-PBE or HSE functionals. Stability analysis confirmed that penta-BeAs2 is dynamically, mechanically, and thermally stable. The adsorption of toxic gases (CO, NO, and NO2) and nontoxic gases (H2, N2, H2O, and CO2) on the penta-BeAs2 monolayer was studied. The contrasting adsorption behavior observed between toxic and nontoxic gases on penta-BeAs2 (physisorption vs chemisorption) underscores its high selectivity for toxic gas-sensing applications. Adsorption energies for toxic gases fall within a moderate range (0.4-0.8 eV), indicating good reversibility and short recovery times at room temperature. Additionally, the quantum transport properties of penta-BeAs2 were studied using the nonequilibrium Green's function (NEGF) approach, confirming strong sensitivity and selectivity toward toxic gases.

Understanding the Electrochemical Carbon Dioxide Reduction Reaction Mechanism of Lattice Tuning of Copper by Silver Single-Crystal Surface.

Intermolecular interactions and adsorbate coverage on a metal electrode's surface/interface play an important role in CO2 reduction reaction (CO2RR). Herein, the activity and selectivity of CO2RR on bimetallic electrode, where a full monoatomic Cu layer covers on Ag surface (CuML/Ag) are investigated by using density functional theory calculations. The surface geometric and electronic structure results indicate that there is high electrocatalytic activity for CO2RR on the CuML/Ag electrode. Specifically, the CuML/Ag surface can accelerate the H2O and CO2 adsorption and hydrogenation while lowering the reaction energy of the rate-determining step. The structure parameters of chemisorbed CO2 with and without H2O demonstrate that activated H2O not only promotes the C-O dissociation but also provides the protons required for CO2RR on the CuML/Ag electrode surface. Furthermore, the various reaction mechanism diagrams indicate that the CuML/Ag electrode has high selectivity for CO2RR, and the efficiency of products can be regulated by modulating the reaction's electric potential.

Aluminum fluorides as noncovalent Lewis acids in proteins: The case of phosphoryl transfer enzymes.

The Protein Data Bank (PDB) was scrutinized for the presence of noncovalent O···Al Triel Bonding (TrB) interactions, involving protein residues (e.g. GLU and GLN), adenosine/guanine diphosphate moieties (ADP and GDP), water molecules and two aluminum fluorides (AlF3 and AlF4-). The results were statistically analyzed, revealing a vast number of O···Al contacts in the active sites of phosphoryl transfer enzymes, with a marked directionality towards the Al σ-/π-hole. The physical nature of the TrBs studied herein was analyzed using Molecular Electrostatic Potential (MEP) maps, the Quantum Theory of Atoms in Molecules (QTAIM), the Non Covalent Interaction plot (NCIplot) visual index and Natural Bonding Orbital (NBO) studies. As far as our knowledge extends, it is the first time that O···Al TrBs are analyzed within a biological context, participating in protein trapping mechanisms related to phosphoryl transfer enzymes. Moreover, since they are involved in the stabilization of aluminum fluorides inside the protein's active site, we believe the results reported herein will be valuable for those scientists working in supramolecular chemistry, catalysis and rational drug design.

Chalcogen bonds enable efficient photoreduction of sulfur-containing heterocycles.

Chalcogen bonding interactions have attracted significant attention in a broad chemistry community, with a particular focus on their ability to stabilise the key transition states in various organic synthetic routes. In this work, we demonstrate that they can also be harnessed in selective photoredox reactions, which cannot be otherwise achieved with alternative approaches to photoreduction. We demonstrate this concept through the photoreduction of the sulfur-containing DNA nucleoside precursor thioanhydrouridine to 2'-deoxy-thiouridine, revealing the previously unrecognized role of bisulfide in this process. Based on quantum chemical simulations, we identify a stable chalcogen-bonding complex of the hydrosulfide anion and thionhydrouridine (HS-…S contacts), which enables directional photoinduced electron transfer, resulting in the formation of non-canonical DNA nucleoside. We also disprove the possibility that photoreduction of thioanhydronucleosides could be initiated by hydrated electrons generated from irradiated bisulfide anions which do not interact with the chromophore. Finally, we show that selective photoreduction mediated by chalcogen bonds can only occur for chromophores, which exhibit sufficiently long excited-state lifetimes in the locally-excited states to undergo transition to the productive charge transfer state. These findings can be further used in the design of similar photoredox reactions which can employ the potential of chalcogen bonding interactions.

Enhancing Magnesium-Ion Storage in a Bi-Sn Anode through Dual-Phase Engineering.

Magnesium-ion batteries (MIBs) are a "beyond Li-ion" technology that are hampered by Mg metal reactivity, which motivates the development of anode materials such as tin (Sn) with high theoretical capacity (903 mAh g-1). However, pure Sn is inactive for Mg2+ storage. Herein, Mg alloying with Sn is enabled within dual-phase Bi-Sn anodes, where the optimal composition (Bi66.5Sn33.5) outperformed single-phase Bi and Sn electrodes to deliver high specific capacity (462 mAh g-1 at 100 mA g-1), good cycle life (84% after 200 cycles), and significantly improved rate capability (403 mAh g-1 at 1000 mA g-1). Density functional theory (DFT) calculations revealed that Mg alloys first with Bi and the subsequent formation of the Mg3Bi2//Sn interfaces is energetically more favorable compared to the individual Mg3Bi2 and Sn phases. Mg insertion into Sn is facilitated when Mg3Bi2 is present. Moreover, dealloying Mg from Mg3Bi2:Mg2Sn systems requires the creation of Mg vacancies and subsequent Mg diffusion. Mg vacancy creation is easier for Mg2Sn compared to Mg3Bi2, while the latter has slightly lower activated Mg-diffusion pathways. The computational findings point toward easier magnesiation/demagnesiation for BiSn alloys over pure Bi or pure Sn, corroborating the superior Mg storage performance of Bi-Sn electrodes over the corresponding single-phase electrodes.

Interfacial interactions between colloidal polystyrene microplastics and Cu in aqueous solution and saturated porous media: Model fitting and mechanism analysis.

Microplastic (MP) and heavy metal pollution have received much attention. Few researches have been carried out on the influence of the interaction between MPs and heavy metals on their transport in saturated porous media, which concerns their fate. Therefore, the interaction mechanisms between colloidal polystyrene microplastics (PSMPs) and Cu were first carried out by applying batch adsorption experiments. Subsequently, the transport and retention of PSMPs and Cu in saturated porous media was explored through column experiments. The interaction process between PSMPs and Cu was further investigated using density functional theory (DFT) calculations. Findings demonstrated that PSMPs had strong adsorption capacity for Cu ((60.07 ± 2.57) mg g-1 at pH 7 and ionic strength 0 M) and the adsorption process was chemically dominated, non-uniform, and endothermic. The O-containing functional groups on PSMP surfaces showed essential roles in Cu adsorption, and the adsorption process mainly contained electrostatic and complexation interactions. In column experiments, Cu could inhibit PSMP transport by the cation bridging effect and changing the electrical properties of glass beads, while PSMPs may facilitate Cu transport through the carrying effect. These findings confirmed that interfacial interactions between MPs and Cu could influence their transport in saturated porous media directly, providing great environmental significance.

XPS Binding Energy Shifts in 2D Ti3C2Tz MXene go largely Beyond Intuitive Explanations: Rationalization from DFT Simulations and Experiments.

MXenes are prototypes of surface tunable 2D materials with vast potential for properties tuning. Accurately characterizing their surface functionalization and its role in electronic structure is crucial, X-ray photoelectron spectroscopy (XPS) being among the go-to methods to do so. Despite extensive use, XPS analysis remains however intricate. Focusing on the benchmark MXene Ti3C2Tz, Density Functional Theory (DFT) calculations of core-level binding energy shifts (BE.s.) are combined with experiments in order to provide a quantitative interpretation of XPS spectra. This approach demonstrates that BE.s. are driven by the complex interplay between chemical, structural, and subtle electronic structure effects preventing analysis from intuitive arguments or comparison with reference materials. In particular, it is shown that O terminations induce the largest BE.s. at Ti 2p levels despite lower electronegativity than F. Additionally, F 1s levels show weak sensitivity to the F local environment, explaining the single contribution in the spectrum, whereas O 1s states are significantly affected by the local surface chemistry. Finally, clear indicators of surface group vacancies are given at Ti 2p and O 1s levels. These results demonstrate the combination of calculations with experiments as a method of the highest value for MXenes XPS spectra analysis, providing guidelines for otherwise complex interpretations.

Effective removal of Pb (II) from wastewater by zinc-iron bimetallic oxide-modified walnut shell biochar: A combined experimental and DFT calculation approach.

The modified walnut shell biochar (WBC) was prepared through zinc-iron bimetallic oxide modification (ZF@WBC) at 600 °C under oxygen-limited conditions in this study. Through adsorption experiments, characterization analyses, and density functional theory (DFT) calculations, the adsorption properties of ZF@WBC to Pb (II) were investigated and the mechanism underlying such adsorption was elucidated. Characterization results showed that the surface area (375.9709 m2/g) and total pore volume (0.205319 cm3/g) of ZF@WBC were significantly greater than those of walnut shell biochar. The maximum adsorption capacity of ZF@WBC for Pb (II) was found to be 104.26 mg/g, which is 2.57 times higher than that of WBC according to the adsorption experiments conducted. The observed adsorption behavior followed both the pseudo-second-order (PSO) kinetic model and Langmuir isothermal adsorption model, suggesting that chemisorption plays a major role in the absorption process. Based on SEM, XRD, XPS, FTIR characterizations along with DFT calculations performed in this study, it can be concluded that surface complexation, ion exchange, electrostatic attraction, physical absorption are among the main mechanisms responsible for absorption of Pb (II) by ZF@WBC. Furthermore, even in the presence of interfering ions at different concentrations, ZF@WBC exhibited a removal rate above 70% for Pb (II). Therefore, ZF@WBC has great potential as an effective absorbent for removing Pb (II) from wastewater, while also offering opportunities for biomass waste resource utilization.

High Affinity Inhibitors of the Macrophage Infectivity Potentiator Protein from Trypanosoma cruzi, Burkholderia pseudomallei, and Legionella pneumophila─A Comparison.

Since Chagas disease, melioidosis, and Legionnaires' disease are all potentially life-threatening infections, there is an urgent need for new treatment strategies. All causative agents, Trypanosoma cruzi, Burkholderia pseudomallei, and Legionella pneumophila, express a virulence factor, the macrophage infectivity potentiator (MIP) protein, emerging as a promising new therapeutic target. Inhibition of MIP proteins having a peptidyl-prolyl isomerase activity leads to reduced viability, proliferation, and cell invasion. The affinity of a series of pipecolic acid-type MIP inhibitors was evaluated against all MIPs using a fluorescence polarization assay. The analysis of structure-activity relationships led to highly active inhibitors of MIPs of all pathogens, characterized by a one-digit nanomolar affinity for the MIPs and a very effective inhibition of their peptidyl-prolyl isomerase activity. Docking studies, molecular dynamics simulations, and quantum mechanical calculations suggest an extended σ-hole of the meta-halogenated phenyl sulfonamide to be responsible for the high affinity.

Theoretical study of point defects on transport properties in metallic interconnections.

During the line width reduction, electron scattering caused by various defects in metal interconnects increases dramatically, which causes leakage or short circuit problems in the device, reducing device performance and reliability. Point defects are one of the important factors. Here, using density functional theory and non-equilibrium Green's function methods, we systematically study the effects of point defects on the transport properties of metals Al, Cu, Ag, Ir, Rh, and Ru, namely vacancy defects and interstitial doping of C atom. The results show that the conductivity of all systems decreases compared to perfect systems, because defects cause unnecessary electron scattering. Since the orbital hybridization of the C atom with the Al, Cu and Ag atoms is stronger than that metals Ir, Rh and Ru, the doping of C atom significantly reduces the conductivity of metals Al, Cu and Ag compared to vacancy defects. In contrast, vacancy defects have a greater impact than doping on the transport properties of metals Ir, Rh and Ru, which is mainly attributed to the larger charge transfer of the host atoms around the vacancies caused by lattice distortion. In addition, metal Rh exhibits excellent conductivity in all systems. Therefore, in order to optimize the transport properties of interconnect metals, our work points out that the doping of impurity atoms should be avoided for metals Al, Cu and Ag, while the presence of vacancy defects should be avoided for metals Ir, Rh and Ru, and Rh may be an excellent candidate material for future metal interconnects.

Aplospojaveedins A-C, unusual sulfur-containing alkaloids produced by the endophytic fungus Aplosporella javeedii using OSMAC strategy.

Three sulfur-containing alkaloids aplospojaveedins A-C (1-3) with a hitherto undescribed carbon skeleton comprising octahy-dronaphthalene, α, ß-unsaturated lactam and glycine-cysteine moieties were isolated from Aplosporella javeedii. Their structures were elucidated by 1D and 2D NMR spectroscopy, HR-MS, X-ray diffraction analysis, DFT-NMR and TDDFT-ECD calculations. A plausible biosynthetic pathway and putative targets are described. The blind docking suggested that 1-3 may have functional effects on several putative targets such as the GPCR cannabinoid receptor 2 or the integrin α5ß1 complex.

A DFT study of the effect of hydrostatic pressure on the structure and electronic properties of sarcosine crystal.

CONTEXT: We perform density functional theory calculations to study the dependence of the structural and electronic properties of the amino acid sarcosine crystal structure on hydrostatic pressure application. The results are analyzed and compared with the available experimental data. Our findings indicate that the crystal structure and properties of sarcosine calculated using the Grimme dispersion-corrected PBE functional (PBE-D3) best agree with the available experimental results under hydrostatic pressure of up to 3.7 GPa. Critical structural rearrangements, such as unit cell compression, head-to-tail compression, and molecular rotations, are investigated and elucidated in the context of experimental findings. Band gap energy tuning and density of state shifts indicative of band dispersion are presented concerning the structural changes arising from the elevated pressure. The calculated properties indicate that sarcosine holds great promise for application in electronic devices that involve pressure-induced structural changes. METHODS: Three widely used generalized gradient approximation functionals-PBE, PBEsol, and revPBE-are employed with Grimme's D3 dispersion correction. The non-local van der Waals density functional vdW-DF is also evaluated. The calculations are performed using the projector-augmented wave method in the Quantum Espresso software suite. The geometry optimization results are visualized using VMD. The Multiwfn and NCIPlot programs are used for wavefunction and intermolecular interaction analyses.

Factors Determining the Selectivity of NO Reduction Catalyzed by Copper-Vanadium Oxide Cluster Anions Cu2VO3‒5.

Catalytic NO reduction by CO is imperative to satisfy the increasingly rigorous emission regulations. Identifying the structural characteristic of crucial intermediate that governs the selectivity of NO reduction is pivotal to having a fundamental understanding on real-life catalysis. Herein, benefiting from the state-of-the-art mass spectrometry, we demonstrated experimentally that the Cu2VO3-5- clusters can mediate the catalysis of NO reduction by CO, and two competitive channels to generate N2O and N2 can co-exist. Quantum-chemical calculations were performed to rationalize this selectivity. The formation of the ONNO unit on the Cu2 dimer was demonstrated to be a precursor from which two pathways of NO reduction start to emerge. In the pathway of N2O generation, only the Cu2 dimer was oxidized and the VO3 moiety  functions as a "support", while both moieties have to contribute to anchor oxygen atoms from the ONNO unit and then N2 can be generated. This finding displays a clear picture to elucidate how and why the involvement of VO3 "support" can regulate the selectivity of NO reduction.

Affecting Charges and Structures of {Bi6} Architectures by 12-Electron Transition Metal Fragments.

Molecules based on polyatomic bismuth substructures are currently attracting a lot of attention owing to this heavy and essentially non-toxic element's uncommon chemical and physical properties, which include unprecedented bonding properties. Hexaatomic {Bi6} substructures that underly more complex cluster structures were recently reported to adopt different structures or exhibit different structural details as a consequence of the charge of the {Bi6} unit. This leads to either crown-shaped cycles for a nominal Bi66- or differently distorted trigonal prisms for compositions close to Bi62-. It was predicted by quantum chemistry that Bi64- should adopt a distinctly distorted boat-like shape, yet a corresponding compound has remained elusive. Here, we report a proof of this assumption by the synthesis and isolation of [K(crypt-222)]2[Bi6{Zn(hmds)}2]∙1.5THF (1), comprising a bimetallic [Bi6{Zn(hmds)}2]2- cluster that fulfils the prediction for the geometric and electronic structure of the missing link (crypt-222 = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo-[8.8.8]hexa-cosane, hmds = hexamethyldisilazanid). A detailed quantum chemical study shows how the nature of Lewis-acidic transition metal complexes - in particular, 12-electron fragments - control and fine-tune the resulting {Bi6} architectures in accordance with the degree of electron-withdrawal from the polybismuthide core.