Ionization Potential Research Articles

CO Oxidation Catalyzed by Perovskites: The Role of Crystallographic Distortions Highlighted by Systematic Experiments and Artificial Intelligence.

The identification of key materials' parameters correlated with the performance can accelerate the development of heterogeneous catalysts and unveil the relevant underlying physical processes. However, the analysis of correlations is often hindered by inconsistent data. Besides, nontrivial, yet unknown relationships may be important, and the intricacy of the various processes may be significant. Here, we tackle these challenges for the CO oxidation catalyzed by perovskites using a combination of rigorous experiments and artificial intelligence. A series of 13 ABO3 (A = La, Pr, Nd, Sm; B = Cr, Mn, Fe, Co) perovskites was synthesized, characterized, and tested in catalysis. To the resulting dataset, we applied the symbolic-regression SISSO approach. We identified an analytical expression correlated with the activity that contains the normalized unit-cell volume, the Pauling electronegativity of the elements A and B, and the ionization energy of the element B. Therefore, the activity is described by crystallographic distortions and by the chemical nature of A and B elements. The generalizability of the identified descriptor is confirmed by the good quality of the predictions for 3 additional ABO3 and of 16 chemically more complex AMn(1-x)B'xO3 (A = La, Pr, Nd; B' = Fe, Co Ni Cu, Zn) perovskites.

In-silico Study of Molecular Docking and Dynamics Simulations for N-Substituted Thiazolidinones Derived from (R)-Carvone Targeting PPAR-γ Protein: Synthesis and Characterization

In this article, we have selected the monoterpene (R)-carvone combined with thiazolidinone as scaffold. Moreover, this study details the synthesis, characterization, and theoretical analysis of novel (R)-Carvone-thiazolidinone-N-substituted derivatives, sourced from natural (R)-Carvone. The compounds were identified using HRMS, and 1H- and 13C-NMR spectral data. A theoretical analysis provided insights into the stability observed experimentally. The local electronic properties and topological features of two compounds 3 and d were studied using the Multiwfn tool and CrystalExplorer software. Specifically, the electron localization function, localized orbital locator and average local ionization energy were mapped to explore electron distribution, while interaction region indicator was used to analyze intermolecular interactions. An in silico docking study was conducted on the PPAR-γ protein to evaluate the binding affinity and interactions. Furthermore, a 200 ns molecular dynamics simulation was performed to confirm the stability of the compounds within the PPAR-γ protein’s binding site. The results indicated consistent stability for all three compounds under dynamic conditions. Lastly, in silico evaluations of drug-likeness and toxicity prediction showed that all compounds adhere to the criteria of both Lipinski’s Rule of Five and Jorgensen’s Rule of Three, confirming their potential as drug candidates.

Charge Carrier Dynamics at the Perovskite Interface with Self-Assembled Monolayers.

Self-assembled monolayers (SAMs) deposited on the hole-collecting electrodes of p-i-n perovskite solar cells effectively replace bulky hole transporting layers. However, the mechanism by which monolayers control the electronic processes and how they depend on the properties of the monolayer molecules remain poorly understood. In this study, we developed a simplified perovskite solar cell imitator with blocked electron extraction to investigate the photocurrent dynamics between the perovskite and the hole-collecting ITO electrode. We investigated the photoluminescence and photovoltage dynamics under short laser pulse excitation and addressed the influence of bulky and monomolecular hole transport layers. Our findings reveal that the photovoltage dynamics is significantly affected by the properties of the transport and perovskite layers, which in turn depend on the methods of sample preparation and exploration. Photocurrent dynamics is determined by several processes, including charge carrier displacement in the local electric field, hole transport to ITO, trapping of holes in interface trap states, and electron-hole recombination at the interface. We propose a model that takes into account molecular dipole moments and their ionization potentials to partially explain the different influences of different monolayers on the hole extraction and interfacial recombination rates. Additionally, the photovoltage dynamics also strongly depends on the illumination of the sample and shows memory effects that persist over minutes and hours and are attributed to the redistribution of ions.

Engineering of Interface Barrier in Hybrid MXene/GaN Heterostructures for Schottky Diode Applications.

The Fermi level position at the interface of a heterostructure is a critical factor for device functionality, strongly influenced by surface-related phenomena. In this study, contactless electroreflectance (CER) was utilized for the first time to investigate the built-in electric field in MXene/GaN structures with the goal of understanding the carrier transfer across the MXene/GaN interface. Five MXenes with high work functions were examined: Cr2C, Mo2C, V2C, V4C3, and Ti3C2. The physicochemical properties of the MXene/GaN structures were analyzed by using X-ray and UV photoelectron spectroscopies. It was shown that upon the coverage of the GaN surface by all investigated MXenes, a shift in the position of the surface Fermi level occurs, consequently raising the interface barrier. Additionally, the physicochemical stability of MXenes on the GaN surface was studied after annealing the structures at 750 °C. Our findings indicate that the annealing process increases the barrier height and the ionization energies of all studied structures. Furthermore, it has been shown that removing excess MXene material from the surface did not significantly impact the built-in electric field, emphasizing the robust physicochemical stability of the MXenes on the GaN surface. To validate the potential of engineering of MXene/GaN interface barrier, Schottky diodes with MXenes exhibiting the highest barrier height (Mo2C and V2C) were demonstrated.

Study of modulation in complex refractive indices induced by ultrafast relativistic electrons using infrared and THz probe pulses.

Objective 
Achieving ultra-precise temporal resolution in ionizing radiation detection is essential, particularly in positron emission tomography, where precise timing enhances signal-to-noise ratios and may enable reconstruction-less imaging. A promising approach involves utilizing ultrafast modulation of the complex refractive index, where sending probe pulses to the detection crystals will result in changes in picoseconds (ps), and thus a sub - 10 ps coincidence time resolution can be realized. Towards this goal, here, we aim to first measure the ps changes in probe pulses using an ionizing radiation source with high time resolution.
Approach 
We used relativistic, ultrafast electrons to induce complex refractive index and use probe pulses in the near-infrared (800 nm) and terahertz (THz, 300 µm) regimes to test the hypothesized wavelength-squared increase in absorption coefficient in the Drude free-carrier absorption model. We measured BGO, ZnSe, BaF2, ZnS, PBG, and PWO with 1 mm thickness to control the deposited energy of the 3 MeV electrons, simulating ionization energy of the 511 keV photons. 
Main results 
Both with the 800 nm and THz probe pulses, transmission decreased across most samples, indicating the free carrier absorption, with an induced signal change of 11% in BaF2, but without the predicted Drude modulation increase. To understand this discrepancy, we simulated ionization tracks and examined the geometry of the free carrier distribution, attributing the mismatch in THz modulations to the sub-wavelength diameter of trajectories, despite the lengths reaching 500 µm to 1 mm. Additionally, thin samples truncated the final segments of the ionization tracks, and the measured initial segments have larger inter-inelastic collision distances due to lower stopping power (dE/dx) for high-energy electrons, exacerbating diffraction-limited resolution. 
Significance
Our work offers insights into ultrafast radiation detection using complex refractive index modulation and highlights critical considerations in sample preparation, probe wavelength, and probe-charge carrier coupling scenarios.

DFT study of electronic and nonlinear optical properties of alkaline earth metals and superalkalis doped all-cis-1, 2, 3, 4, 5, 6-hexafluorocyclohexane as an efficient excess electron system

Continual advancements are being pursued to discover innovative strategies for developing materials with remarkable nonlinear optical (NLO) response. Herein, electronic, geometric, thermodynamic and NLO properties of excess electron systems based on stacked Janus dimer, all-cis-1,2,3,4,5,6-hexafluorocyclohexane (C6H6F6)2 are thoroughly investigated. The excess electron systems are designed by doping alkaline earth metals (AEMs) on fluorine face and superalkalis on hydrogen face of Janus dimer. The higher values of vertical ionization energies (VIE) and interaction energies (Eint), confirm the electronic and thermodynamic stabilities of the designed complexes, respectively. Natural bond orbital (NBO) analysis is performed, and the excess electron character of the complexes is confirmed through frontier molecular orbital (FMO) analysis by highest occupied molecular orbital (HOMO) iso-densities. FMO shows a significant decrease in energy gaps (Egap) of the complexes (i.e., Eg = 1.80–3.12 eV), compared to the stacked Janus dimer (i.e., Eg = 9.41 eV). The transparency of the complexes to UV region is confirmed through UV–vis analyses, revealing their maximum absorption in visible and near-IR regions. The higher NLO response of the designed excess electron systems is further proved by the greater values of first hyperpolarizability (β o ) i.e., up to 1.70 × 106 au. Moreover, the time dependent-density functional theory (TD-DFT) computations and two-level model are employed to investigate the controlling factors of hyperpolarizability, illustrating the contribution of transition energy (∆E3), change in dipole moment (∆μ) and oscillator strength (f o ) in controlling the β o . Ab-initio molecular dynamics (AIMD) simulation further confirm that the designed superalkalide complexes are kinetically and thermally stable. The thorough investigation of these excess electron systems proves them an appropriate candidate for NLO applications.

AI-Guided Design of MALDI Matrices: Exploring the Electron Transfer Chemical Space for Mass Spectrometric Analysis of Low-Molecular-Weight Compounds.

The development of matrices for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI MS) has traditionally relied on experimental efforts. Here, we propose a Goal-Directed artificial intelligence generative model, fueled by computational chemistry calculated data, to construct a chemical space optimized for Electron Transfer (ET) processes in MALDI analysis. We utilized a group of 30 reported ET matrices, subjected to structural enumeration and molecular properties prediction using semiempirical and ab initio calculations, to establish a comprehensive database comprising diverse structural and property data. Subsequently, employing a protocol of structural enumeration with 68 canonical SMILES of Bemis-Murcko (BM) fragments, we expanded the structural complexity of the initial library. This process generated 82753 compounds organized into 10 scaffold levels, with a p50 index from the Cyclic System Retrieval (CSR) curve of scaffolds of 50%. From the resulting enumerated library, a diverse subset of structures was selected by using the Jarvis-Patrick clustering method. These structures, along with their associated properties measured from quantum mechanics and experimental data, were used to train a Machine Learning (ML) model to predict ionization energy (Ei) values. Subsequently, a Scoring Neural Network (SNN), coupled with our Goal-Directed generative model using a Recurrent Neural Network (RNN) with Deep Learning (DL) architectures, was trained. The generative model was guided using a prior network within a Reinforcement/Transfer Learning environment. The final AI-generative model learned that structures with high unsaturation, H/C ratios under 1, and molecular weights between 100 and 300 u are favorable for ET MALDI matrices, as well as those with few aromatic rings and zero aliphatic rings. Other molecular features were also favored. The resulting AI-generated library exhibits Ei values over 8.0 eV, akin to those of reported "good" ET MALDI matrices, indicating successful design with high synthesis accessibility scores. In conclusion, our generative model provided valuable insights into the molecular features ideal for ET MALDI compounds while generating a wide range of structurally diverse molecules within a similar molecular property space. The next critical step in this process is to synthesize a selection of these generated compounds for the experimental validation and further characterization.

Non-linear optical properties of hybrid materials of (OLi3) superalkali doped perylene diimide (PDI) derivative: comprehensively study via silico-technique

PDI-Imidazole and PDI-Imidazole combined with OLi3 (OLi3@PDI-Imidazole) were the two types of materials that we examined in this study to see how light behaved in each of the complex. To explore this, we employed the three different method such as rB3LYP/6–31G(d, p) DFT, CAM-B3LYP and WB97XD. The impact of PDI-Imidazole and OLi3@PDI-Imidazole geometries, maximum absorption ( λmax ), FMO, vertical ionization energies ( EVI ), Binding Energies ( Eb ), Hyperpolarizabilities, DOS, Dipole Moments (μ), ESP, EDDM, and Global Reactivity parameters have been examined. The type of contacts as well as the vibrational frequencies of PDI-Imidazole and OLi3@PDI-Imidazole were investigated using NCl, iso-surface, Raman spectroscopy, and IR research. The electron transport characteristics of the OLi3@PDI-Imidazole surface was significantly enhanced in comparison to the PDI-Imidazole surface by lowering the bandgap energies from 1.27 eV to 1.03 eV. In contrast to the pure PDI-Imidazole surface, which had lower values for linear polarizability ( α0 ) (547.08 au) and first hyperpolarizability ( β0 )(201.133au), OLi3@PDI-Imidazole surface displayed significant enhancements in linear polarizability ( α0 = 706.472 au) and first hyperpolarizability ( β0 = 21314.360 au). It was observed by TD-DFT calculations that all the compounds had appreciable improvements in their interaction energies, HOMO–LUMO and UV–vis absorption and vertical ionization potential. Future development of nonlinear optical (NLO) devices has been discovered to benefit from the addition of OLi3 to the PDI-Imidazole surface.

Theoretical Study on the Dissociation Mechanism of Thiophene in the UV Photoabsorption, Ionization, and Electron Attachment Processes

ABSTRACTA computational study on the intricate mechanism of thiophene ring‐fragmentation (TRF) in the UV photodissociation, dissociative ionization, and dissociative electron attachment process has been performed. The complete fragmentation process is studied using high level G4 composite method for neutral, cationic, and anionic species by elucidating a detailed mechanism for various reaction channels. The study shows that for neutral thiophene, the major pathway is the migration of H atom and subsequent fragmentation through a transition state yielding acetylene (HC≡CH) and H2C=C=S. However, for the thiophene cation, the acetylene (HC≡CH)+H2C=C=S+ channel is a two‐step and barrier less process. The onset of CH3+HC=C=C=S channel has been observed in both the thiophene cation and anion which was absent in the neutral analogue. Similarly, the onset of H2S+HC≡C—C≡CH channel has been found to operate only in the thiophene cation. Others, such as HCS and HS elimination channels have been found in all the species showing similar dissociation mechanism. For the thiophene anion, the TRF process is very much similar to that of thiophene cation. However, the reaction enthalpies of the various elimination channels in the anionic species are lower as compared to that of cationic species. During the study, the ionization energies and electron affinities of various molecules/radicals produced during the fragmentation process of thiophene were also computed.

Adsorption sites and interactions of pigments in molasses-based distillery effluent on starch-based composites: Ternary competitive adsorption and theoretical calculations

The pigment present in molasses-based distillery effluent constitutes a primary factor influencing its degradation. Adsorption is an effective approach to eliminate pigment from wastewater. In this study, a cationic cassava starch (CCS) magnetic composite (CCS@Fe3O4) was prepared and used as adsorbents for the removal of undesirable pigments. The adsorption behaviors of caffeic acid (CA), gallic acid (GA), and melanoidin (ME) on CCS@Fe3O4 in the wastewater were investigated using single and ternary competitive adsorption systems. The equilibrium adsorption capacities of CA, GA, and ME on CCS@Fe3O4 were 197.04, 195.55, and 623.97 mg/g at the optimized conditions (0.3 mg/mL CCS@Fe3O4 dosage, temperature of 38 °C, and pH of 7). The adsorption kinetic model showed that chemisorption accounted for most of the adsorption of CA, GA, and ME on CCS@Fe3O4. The adsorption mechanisms of pigments on CCS@Fe3O4 were explored at the molecular level through quantum chemical calculations. The electrostatic potentials (ESP), average local ionisation energy (ALIE), and Fukui indices calculation indicated that the quaternary ammonium group in CCS@Fe3O4 was more susceptible to electrophilic reactions. The CC and benzene rings in CA and GA, and the COO- in ME, represent sites of attack for quaternary ammonium during adsorption. Furthermore, the competitive adsorption results, adsorption energy, and electron transfer data demonstrated that the adsorption capacity of CCS@Fe3O4 for pigments followed the order ME>GA>CA. Overall, the competitive adsorption mechanisms of CA, GA, and ME on CCS@Fe3O4 were unveiled, with quantum chemical calculations offering crucial insights into the adsorption process.

Deconvolution of light- and heavy-hole contributions to measurements of the temperature-dependent Hall effect in zincblende copper iodide

This study presents a detailed experimental investigation of conductivity and Hall effect measurements in copper iodide (CuI), which is complemented by density-functional theory and Boltzmann-transport calculations. We have evaluated the temperature dependence of the transport data of solution-grown bulk single crystals, textured thin films grown by pulsed laser deposition, and additional data published in the literature. The density of compensating donorlike defects is determined from fits comprising ionized-impurity scattering. This is considered for determining acceptor densities and corresponding activation energies. In the course of this investigation, meticulous attention has been paid to the intricate interplay between light-hole and heavy-hole contributions, as well as the experimental values observed in zincblende CuI. This study has yielded two distinct ionization energies for acceptors in unintentionally doped CuI, with values of EI,1=95 meV and EI,2=330 meV, respectively. Published by the American Physical Society 2024

Energy Level Tuning in Conjugated Donor Polymers by Chalcogen Exchange for Low Dark Current Organic Photodetectors.

The performance of organic photodetectors (OPDs) using conjugated polymer donors and molecular acceptors has improved rapidly, but many polymers are difficult to upscale due to their complex structures. This study examines two low-complexity thiophene copolymers with substituted benzooxadiazole (FO6-BO-T) or benzothiadiazole (FO6-T). Substituting sulfur with oxygen in FO6-BO-T increased its ionization energy without affecting the optical gap. When blended with the nonfullerene acceptor IDSe, FO6-BO-T showed a significantly lower dark current density (2.06·10-9 A cm-2 at -2 V) compared to FO6-T. Grazing incidence wide-angle X-ray scattering (GIWAXS) measurements demonstrated that pristine FO6-BO-T exhibited a more ordered morphology than FO6-T. However, blending resulted in a significant disruption to the ordered domains in both cases, with a loss of orientational order, suggesting that FO6-BO-T's improved performance is largely related to its increased ionization energy. This study demonstrates the potential of chalcogen atom engineering to enhance the performance of the OPD in scalable polymers.

Modelling stellar irradiances I: the transition regions of FGKM stars

ABSTRACT We employed advanced ionization equilibrium models that we developed in Dufresne et al. (2024), which include charge transfer and density effects, to model UV stellar irradiances for a sample of stars. Our sample includes $\epsilon$ Eridani (K2 V), $\alpha$ Centauri A (G2 V), Procyon (F5 V), and Proxima Centauri (M5.5 Ve). We measured line fluxes from STIS data sets and used O iv and O v as density diagnostics to find the formation pressure of ions in the transition region (TR) and adopted a simple differential emission measure (DEM) modelling. Our findings indicate significant improvements in modelling spectral lines from anomalous ions such as Si iv, C iv, and N v of the Li- and Na-like sequences, which produce the strongest lines in the UV. For example, the Si iv lines were under-predicted by a factor of 5 and now are within 40 per cent the observed fluxes. The improved models allow us to obtain for the first time reliable estimates of some stellar chemical abundances in the TR. We compared our results with available photospheric abundances in the literature and found no evidence for the first ionization potential (FIP) effect in the TR of our stellar sample. Finally, we compared our results with the solar TR that can also be described by photospheric abundances.

Technological Features of Filler Wire Melting for Arc Welding and Surfacing with the Introduction of SF6 into Protective Gas Atmosphere

On the basis of the results of experimental studies the paper establishes important patterns of dependence of the frequency of short circuits of the arc gap and the coefficient of loss of electrode metal due to spatter from the voltage on the arc and the feed rate of the filler wire during welding and surfacing with the introduction of gaseous SF6 into the Ar + CO2 protective mixture. It is proposed to introduce fluorine-containing components of SF6 directly into the protective gas mixture of 82 % Ar + 18 % CO2 in quantities not exceeding 2 %. The technology makes it possible to reduce the amount of diffusion hydrogen in the deposited metal, which is an urgent task when welding high-strength steels and materials sensitive to hydrogen embrittlement. Previously, we resolved a number of issues related to the obstacle to increasing the concentration of S in the deposited metal, which made it possible to determine the most effective concentrations of SF6 in the protective gas environment, limited to 1.5 % by volume of the total composition (Ar + CO2) + SF6. At the same time, modification of the protective gas atmosphere with the halide compound SF6 has a significant effect on the melting characteristics of the electrode wire and temperature indicators in the arc combustion zone. This is due to the high ionization potential of fluorine as a product of the high-temperature dissociation reaction of SF6. The results obtained have made it possible to determine the most effective relationships between the values of the mode parameters, as well as to study the specifics of melting the filler wire in a protective atmosphere modified with SF6. Important regularities have been established that reveal the technological features of welding and surfacing with modification of the protective atmosphere with halide compounds.

Synthesis, modeling, bioactivity, docking, binding energy analysis of new effective piperazine derivatives as effective drug candidates for treatment of Parkinson’s disease

In this study, density functional theory (DFT) calculations were initially conducted to explore the molecular structure, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), LUMO-HOMO energies, as well as the excited states of new piperazine derivatives using the CAM-B3LYP/Def2TZV level of theory. Detailed quantum molecular descriptors for the compounds, including ionization potential (IP), electron affinities (EA), hardness (η), softness (S), electronegativity (μ), electrophilic index (ω), electron-donating power (ω−), electron accepting power (ω+), and energy gap (Eg), were calculated. The chemical properties and bioactivity of these compounds, such as molecular weight, lipophilicity, number of hydrogen bond (HB) donors and acceptors, molar refractivity, polarity, solubility, flexibility and saturation, were also investigated. Subsequently, a molecular docking study was performed to identify effective compounds that could act as strong inhibitors against Parkinson’s Disease. The Michaelis-Menten constant (Km) was determined using the CAM-B3LYP/Def2TZV level of theory. The binding energy between the protein with ID:5CGJ and the organic compounds demonstrated excellent binding affinity. Therefore, the structures: 4-(4-methylpiperazin-1-yl)-4-oxo-N-(4-sulfamoylphenyl)butanamide (21), N-(4-((4-methylpiperazin-1-yl)methyl)phenyl)-4-(morpholinomethyl) benzamide (22), cаn bе usеd for potential application аgаinst Parkinson’s Disease.

Formation of Paraldehyde (C6H12O3) in Interstellar Analog Ices of Acetaldehyde Exposed to Ionizing Radiation.

Acetaldehyde (CH3CHO) plays a crucial role in the synthesis of prebiotic molecules such as amino acids, sugars, and sugar-related compounds, and in the progress of chain reaction polymerization in deep space. Here, we report the first formation of the cyclic acetaldehyde trimer - paraldehyde (C6H12O3) - in low-temperature interstellar analog ices exposed to energetic irradiation as proxies of galactic cosmic rays (GCRs). Utilizing vacuum ultraviolet photoionization reflectron time-of-flight mass spectrometry and isotopic substitution experiments, paraldehyde was identified in the gas phase during the temperature-programmed desorption of the irradiated acetaldehyde ices based on the calculated adiabatic ionization energies and isomer-specific dissociative fragmentation patterns upon photoionization. As acetaldehyde is ubiquitous throughout the interstellar medium and has been tentatively identified in interstellar ices, paraldehyde could have formed in acetaldehyde-containing ices in a cold molecular cloud and is an excellent candidate for gas-phase observation in star-forming regions via radio telescopes. The identification of paraldehyde in the gas phase from the processed acetaldehyde ices advances our understanding of how complex organic molecules can be synthesized through polymerization reactions in extraterrestrial ices exposed to GCRs.

Insight into Carrier and Phonon Transports of PbSnS2 Crystals.

The simultaneous optimization of n-type and p-type thermoelectric materials is advantageous to the practical application of the device. As an emerging thermoelectric material, PbSnS2 exhibits highly competitive thermoelectric properties due to its unique carrier and phonon transport characteristics. To promote the utilization of this low-cost thermoelectric material, p-type PbSnS2 crystals are synthesized and optimized through Na doping and Se alloying. The resulting thermoelectric transport properties differ significantly from those reported for n-type crystals, prompting us to compare and analyze both n-type (Cl-doped) and p-type (Na-doped) PbSnS2 crystals from various perspectives. Cl doping is subject to weaker "Fermi pinning" and lower impurity ionization energy compared with Na doping, leading to higher doping efficiency. The different optimal performance directions in n-type and p-type crystals can be attributed to the distinct charge density distributions near the conduction band minimum (CBM) and the valence band maximum (VBM). Additionally, both n-type and p-type crystals exhibit ultralow lattice thermal conductivity due to the low symmetry of their twisted NaCl structure combined with the strong anharmonicity. This comprehensive analysis of PbSnS2 crystals provides a solid foundation for further performance optimization and device assembly, while also sheds light on the investigation of layered thermoelectric materials.

A Critical Evaluation of the Hybrid KS DFT Functionals Based on the KS Exchange-Correlation Potentials.

We have developed a critical methodology for the evaluation of the quality of hybrid exchange-correlation (XC) density functional approximations (DFAs) based on very fundamental quantities, i.e., Kohn-Sham (KS) XC potentials, self-consistent electron densities, first ionization potentials (IPs), and total energies. Since the XC potentials, the primary objects in the current study, are not directly accessible for the hybrids, we calculate them by inverting the KS electron densities. Utilizing this methodology, we tested 155 hybrid DFAs available in the LIBXC library using FCI and CCSD(T) methods as a reference. We have found that a group of functionals produces very decent XC potentials, mainly those with a large mixture of Hartree-Fock exchange. Moreover, the value of IP strongly depends on the XC potential quality. On the other hand, we show that the XC energy is dominated by functional-driven error, which in some cases leads to substantial errors in electronic densities. The study shows new directions for constructing more accurate XC functionals within the KS-DFT framework.

Development of new sustainable pyridinium ionic liquids: From reactivity studies to mechanism-based activity predictions.

This study addresses the development of sustainable pyridinium ionic liquids (ILs) because of their potential applications in agriculture and pharmaceuticals. Pyridinium-based ILs are known for their low melting points, high thermal stability, and moderate solvation properties. We synthesized three novel pyridinium-based ILs: 1-(2-(isopentyloxy)-2-oxoethyl)pyridin-1-ium chloride, 1-(2-(hexyloxy)-2-oxoethyl)pyridin-1-ium chloride, and 1-(2-(benzyloxy)-2-oxoethyl)pyridin-1-ium chloride. The biological activities of these compounds were evaluated through plant growth promotion, herbicidal, and insecticidal assays. Our results show that the benzyloxy derivative significantly enhances wheat and cucumber growth, whereas the isopentyloxy compound has potent herbicidal effects. Computational methods, including DFT calculations and molecular docking, were applied to understand the structure‒activity relationships (SARs) and mechanisms of action. The computational techniques involved dispersion-corrected density functional theory (DFT) with the B3LYP functional and the 6-311G** basis set. Grimme's D3 corrections were included to account for dispersion interactions. The calculations were performed via GAMESS-US software. Quantum descriptors of reactivity, such as ionization potential, electron affinity, chemical potential, and electrophilicity index, were derived from the HOMO and LUMO energies. Molecular docking studies were conducted via the CB-Dock server via AutoDock Vina software to predict binding affinities to cancer-related proteins. Petra/Osiris/Molinspiration (POM) analysis was used to predict the drug likeness and other pharmaceutical properties of the synthesized ILs.

Core and valence photoelectron spectroscopy of a series of substituted disulfides.

The valence and core photoelectron spectra of three substituted disulfide systems, α-lipoic acid, trans-4,5-dihydroxy-1,2-dithiane, and di-Boc-cystamine, are presented alongside detailed theoretical analysis based on equation-of-motion coupled-cluster singles doubles for ionization potentials and the nuclear ensemble approach. A comparison of the linear and five- and six-membered ring cyclic structures reveals that the energetic separation of the non-bonding sulfur orbitals can be used to calculate a reliable estimate of the C-S-S-C dihedral angle, even for substituted disulfides, and that the sulfur 2p, oxygen 1s, and valence band photoelectron spectra are a useful site-specific probe of hydrogen bonding.