Journal articles on the topic 'Ground-state atomic-charge distributions'

Among the ions classified in the Hofmeister series, the firstly ranked divalent sulfate anion has the strongest hydrating and water-structure making propensity. This unique characteristic actually makes it kosmotropic which causes water molecules to interact each other and contributes to gain structural stability of its hydrated clusters [SO42−(H2O)n]n = 1−40. In this study, few variably sized microhydrated sulfate clusters [SO42−(H2O)n]n = 1−4, 16 are considered separately, and inquired their chemical energetics and atomic charge distributions through ab initio based theoretical model. The main objective of this insight is to specify and interpret their thermodynamic stabilities, binding energies, and specific bonding and electronic interactions quantum mechanically. An in-depth analysis of their change in relative ground state electronic energy with respect to hydration number indicates stronger affinity of the sulfate ion towards water molecules while attaining structural stability in any aqueous type solutions. The mathematically determined values of their binding energy (DE) almost holds up the same with this structural stability order: [SO42−(H2O)16] > [SO42−(H2O)4] > [SO42−(H2O)3] > [SO42−(H2O)2] > [SO42−(H2O)], as reliable as experimentally and molecular dynamics simulation predicted trend. Moreover, the Mulliken derived partial atomic charges feature qualitative charge distribution in them which not only depicts electronic interactions between the specific atoms but also exemplifies the involvement of central sulfate units in hydrogen bond formation with surrounding water molecules.

In addition to the common 3-body decay of the neutron n → pe-ν̅e there should exist an effective 2-body subset with the electron and proton forming a Hydrogen bound state with well defined total momentum, total spin and magnetic quantum numbers. The atomic spectroscopic analysis of this bound system can reveal details about the underlying weak interaction as it mirrors the helicity distributions of all outgoing particles. Thus, it is unique in the information it carries, and an experiment unravelling this information is an analogue to the Goldhaber experiment performed more than 60 years ago. The proposed experiment will search for monoenergetic metastable BoB H atoms with 326 eV kinetic energy, which are generated at the center of a throughgoing beamtube of a high-flux reactor (e.g., at the PIK reactor, Gatchina). Although full spectroscopic information is needed to possibly reveal new physics our first aim is to prove the occurrence of this decay and learn about backgrounds. Key to the detection is the identification of a monoerergtic line of hydrogen atoms occurring at a rate of about 1 s−1 in the environment of many hydrogen atoms, however having a thermal distribution of about room temperature. Two scenarios for velocity (energy) filtering are discussed in this paper. The first builds on an purely electric chopper system, in which metastable hydrogen atoms are quenched to their ground state and thus remain mostly undetectable. This chopper system employs fast switchable Bradbury Nielsen gates. The second method exploits a strongly energy dependent charge exchange process of metastable hydrogen picking up an electron while traversing an argon filled gas cell, turning it into manipulable charged hydrogen. The final detection of hydrogen occurs through multichannel plate (MCP) detector. The paper describes the various methods and gives an outlook on rates and feasibility at the PIK reactor in Gatchina.

The ground state properties (bond lengths, bond orders, net atomic charge distribution) of various cis and trans isomers of retinal analogs have been studied at abinitio SCF and correlated levels. The effect of protonation on the properties of the retinal Schiff base analogs has also been studied. Convergence in various properties has been observed with increasing chain length justifying the use of smaller analogs mimicking retinal. Convergence is, however, slower for the protonated retinal Schiff base analogs. The protonated retinal Schiff base analogs show an increased conjugation reflected in the bond orders, bond lengths, and in the decrease in the HOMO–LUMO gap. The nodal characteristics of the HOMO of the protonated retinal Schiff base analog also indicate a strong conjugation in the vicinity of the protonated nitrogen. Based on the results of calculations at the correlated level, the sudden polarization charge transfer mechanism is shown to be an artifact of HF-based methods used in the calculations.

In the light of recent studies, we summarize our present theoretical understanding of insulating oxides in low dimensionality, including unsupported clusters, planar or stepped surfaces and ultrathin films. We review the various theoretical approaches, their efficiency in calculating ground and excited state properties, and their applications to the present systems. We discuss the forces at work which determine the atomic structure around under-coordinated atoms (equilibrium geometries of very small clusters, bond lengths, relaxation and rumpling at surfaces), the energetics associated with low dimensionality (surface energies and mean cohesion energy in clusters), the electronic properties, such as electron distribution, magnetic interactions and ordering, and electronic excitations (ionization potentials, electron affinity, quasiparticle spectra, d → d and charge transfer excitations).

Abstract In this study, to see pressure effects on optical, thermodynamic, structural, elastic, electronic properties, charge density, and phonon frequencies of the XAl (X:Rh, Ru) compounds in B2 structure, the first-principles methods were used. The ground-state properties of these compounds were determined and compared with experimental and theoretical data. High Young’s and shear modulus showed these compounds to be hard materials. The investigated compounds have ductile property according to the Paugh criterion and Poisson’s ratio calculated from elastic constants. The electronic band structure showed that these compounds have a metallic nature. Dynamic stability using phonon distribution curves was determined under pressure. The bond properties between Rh-Al and Ru-Al atoms were evaluated in detail by Mulliken Atomic Populations and charge density analysis. Also, the optical properties are examined in detail. We think that this theoretical work contributes greatly to engineering applications due to the electronic, thermodynamic, and optical behavior of XAl (X: Rh, Ru) compounds.

Nanoelectrochemical experiments using detection based on tip enhanced Raman spectroscopy (TERS) show a broad distribution of single-molecule formal potentials E°′ for large π-conjugated molecules; theoretical studies are needed to understand the origins of this distribution. In this paper, we present a theoretical approach to determine E°′ for electrochemical reactions involving a single molecule interacting with an electrode represented as a metal nanocluster and apply this method to the Ag₂₀–pyridine system. The theory is based on the semiempirical INDO electronic structure approach, together with the COSMO solvation model and an approach for tuning the Fermi energy, in which the silver atomic orbital energies are varied until the ground singlet state of Ag₂₀–pyridine matches the lowest triplet energy, corresponding to electron transfer from the metal cluster to pyridine. Based on this theory, we find that the variation of E°′ with the structure of the Ag₂₀–pyridine system is only weakly correlated with changes in either the ground-state interaction energy or the charge-transfer excited-state energies at zero applied potential, which shows the importance of calculations that include an applied potential in determining the variation of formal potential with geometry. Factors which determine E°′ include wavefunction overlap for geometries when pyridine is close to the surface, and electrostatics when the molecule-cluster separation is large.

The first-, second- and third-order nonlinear optical properties of N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole in gas phase employing sum-over-states (SOS) method have been calculated for the first time. The ground state molecular structure of N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole was obtained by the geometrical optimizations based on the B3LYP/6-31[Formula: see text]G(d) level. The energy of excited states and transition dipole moments between different excited states were obtained by using the time-dependent density functional theory (TDDFT) based on the CAM-B3LYP/Sadlej POL level. Charge transfer during electron excitation was analyzed based on hole and electron distributions. Our calculations showed that the N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole has good nonlinear optical properties and its nonlinear optical properties arise from charge-transfer excitation and local excitation but charge transfer plays the leading role.

The aim of this work is to improve the modelling of ion populations in higher density, lower temperature astrophysical plasmas, of the type commonly found in lower solar and stellar atmospheres. Ion population models for these regions frequently employ the coronal approximation, which assumes conditions more suitable to the upper solar atmosphere, where high temperatures and lower densities prevail. The assumed conditions include all ions being in the ground state and steady-state equilibrium, where there is sufficient time for ionisation and recombination to take place. Using the coronal approximation for modelling the solar transition region gives theoretical lines intensities for the Li-like and Na-like isoelectronic sequences which are often factors of two to five times lower than observed. The works of Burgess & Summers (1969, ApJ, 157, 1007) and Nussbaumer & Storey (1975, A&A, 44, 321) show the important part ions in excited levels play when included in the modelling. As density increases metastable levels become populated and ionisation rates increase, whereas dielectronic recombination through highly excited levels is suppressed. Photo-ionisation is also shown by Nussbaumer & Storey to have an effect on the charge-state distribution of carbon in these regions. Their models, however, use approximations for the atomic rates to determine the ion balance. Presented here is the first stage in updating these earlier models of carbon by using rates from up-to-date atomic calculations and more recent photo-ionising radiances. Where atomic rates were not readily available, in the case of electron impact direct ionisation and excitation–auto-ionisation, new calculations were made using the Flexible Atomic Code and Autostructure, and compared to theoretical and experimental studies. The effects each atomic process has on the ion populations as density changes is illustrated, and final results from the modelling are compared to the earlier works. Lastly, the new results for ion populations were used to predict line intensities for the solar transition region in the quiet Sun. In comparison to coronal approximation modelling the new results show significantly improved agreement with observations.

Measurements of cross-sections of charge exchange between hydrogen atoms and low energy protons (down to the energy ~10 eV) revealed a noticeable discrepancy with previous theories. The experimental cross-sections were systematically slightly higher—beyond the error margins—than the theoretical predictions. In the present paper, we study whether this discrepancy can be eliminated or at least reduced by using the Second Flavor of Hydrogen Atoms (SFHA) in calculations. We show that for the SFHA, the corresponding cross-section is noticeably larger than for the usual hydrogen atoms. We demonstrate that the allowance for the SFHA does bring the theoretical cross-sections in a noticeably better agreement with the corresponding experiments within the experimental error margins. This seems to constitute yet another evidence from atomic experiments that the SFHA is present within the mixture of hydrogen atoms. In combination with the first corresponding piece of evidence from the analysis of atomic experiments (concerning the distribution of the linear momentum in the ground state of hydrogen atoms), as well as with the astrophysical evidence from two different kinds of observations (the anomalous absorption of the redshifted 21 cm radio line from the early universe and the smoother distribution of dark matter than that predicted by the standard cosmology), the results of the present paper reinforce the status of the SFHA as the candidate for dark matter, or at least for a part of it.

The second flavor of hydrogen atoms (SFHA) refers to the kind of hydrogen atoms that have only the states of the zero orbital angular momentum (the S-states), both in the discrete and continuous spectra. They were first discovered theoretically in one of my earlier papers, where a proof of their existence was also provided by analyzing atomic experiments concerning the high-energy tail of the linear momentum distribution in the ground state of hydrogen atoms. From a theoretical point of view, the discovery was based on the standard Dirac equation for hydrogen atoms without changing the existing physical laws. Recently, the existence of the SFHA was seemingly also confirmed by two types of astrophysical observations: the allowance for the SFHA explained the puzzling results concerning both the anomalous absorption of the redshifted 21 cm spectral line from the early Universe, and the observations by the Dark Energy Survey (DES) team where it was found that the distribution of dark matter in the Universe is noticeably smoother than predictions employing Einstein’s relativity. In the present review, we exhibit results from two recent papers where attention was brought to a visible difference in the cross-sections of the resonant charge exchange for collisions of the SFHA with incoming protons, compared to collisions of the usual hydrogen atoms with incoming protons. It was shown that, after taking into account the SFHA, there is a better agreement with the corresponding experimental cross-section. Coupled with the previous evidence of the existence of the SFHA, deduced from the analysis of the other kind of atomic experiments, and evidenced by two different kinds of astrophysical observations, this strengthens the standing of the SFHA as the most probable candidate for all or a part of dark matter.

For the excitation of the n = 2 states of hydrogen atoms due to electron impact, we compared the experimental and theoretical ratios of the cross-sections σ2s/σ2p. We found this theoretical ratio to be systematically higher than the corresponding experimental ratio by about 20%—far beyond the experimental error margins. We suggest that this discrepancy can be explained by the presence of the Second Flavor of Hydrogen Atoms (SFHA) in the experimental hydrogen gas. The explanation is based on the fact that, in the experiments, the cross-section σ2s was determined by using the quenching technique—by applying an electric field that mixed the 2s and 2p states, followed by the emission of the Lyman-alpha line from the 2p state. However, the SFHA only had the s-states, so the quenching technique would not count the excitation of the SFHA in the 2s state and, thus, lead to the underestimation of the cross-section σ2s. We estimates the share of the SFHA in the experimental hydrogen gas required for eliminating the above discrepancy and found this share to be about the same as the share of the usual hydrogen atoms. Thus, our results constitute the third proof from atomic experiments that the SFHA does exist, the first proof being related to the experimental distribution of the linear momentum in the ground state of hydrogen atoms, and the second proof being related to the experimental cross-section of charge exchange between hydrogen atoms and low-energy protons.

A new fluorimetric and colorimetric dual-mode probe, 4-bromo-2-(hydrazonomethyl) phenol (BHP) has been synthesized and successfully utilized for the recognition of Cd2+/F‒ ions in DMSO/H2O (9:1, v/v) system. The probe displays dual channel of detection via fluorescence enhancement and colorimetric changes upon binding with F‒ and Cd2+ ions respectively. The Job’s plot analysis, ESI-MS studies, Density Functional Theoretical (DFT) calculations, 1H NMR and 19F NMR titration results were confirmed and highly supported the 1:1 binding stoichiometry of the probe was complexed with Cd2+/F‒ ions. Furthermore, intracellular detection of F‒ ions in HeLa cells and fluorescence imaging analysis in Zebrafish embryos results of the probe BHP might be used to reveal their potential applications in a biological living system. Introduction The quantification and detection of toxic metal ions in diverse fields have fascinated more attention in recent years due to their prominent and significant roles in clinical diagnosis and ecological system.1–6 Besides metal ions, anions also play an exclusive role in a variety of chemical and biological processes.7–12 In earlier, analytical methods for the detection of cations/anions has required highly sophisticated and expensive instruments such as atomic absorption spectrometry, inductively coupled plasma mass spectrometry, ion sensitive electrodes, and gas and ion chromatography. Amid, fluorescent techniques have more expedient in terms of rapidness, excellent sensitivity and selectivity, low cost, easy and feasible detection. In addition, optical detection mode analysis is a more appropriate method because of their potential features such as easy handling, real-time analysis and different signal output modes.13–16 Besides, colorimetric assays are more feasible and potent tool as they provide a simple visible authentication for analyte detection in the absence of instruments and tedious techniques. In this perspective, the recent research area has been mainly focused to design the novel multi-functional fluorometric and colorimetric sensors for the detection of ions in the different environments. Cadmium (Cd2+) is one of the important hazardous heavy transition metal ions17 in the environment due its carcinogenic nature. The higher accumulation of Cd2+ ion and inhalation of Cd-dust prompts more awful health issues in human like cancer, cardiovascular diseases, kidneys and liver damage.18 Furthermore, the Cd2+ ion has more advantages in several industries such as pigments in plastics, electroplating and batteries, etc. On the other hand, fluoride ions play an ample role in dental health and in the treatment of osteoporosis.19–22 The excess of fluoride ingestion prompted severe disease in human health like gastric and kidney problems.23 In some remote areas, the high level contamination of fluoride ions in drinking water triggered bone disease such as fluorosis.24–31 Thus, to develop and synthesize novel multifunctional probe for the detection and quantification of both cations and anions is a highly anticipated and imperative task. Scheme 1. Synthesis of probe BHP Herein, we have fabricated and synthesized a novel chromogenic and fluorogenic assay based on bromo substituted salicylhydrazone moiety for the colorimetric and fluorometric detection of F‒ ions and colorimetric detection of Cd2+ ions in DMSO/H2O (9:1, v/v) system. The UV-visible and fluorescence spectral analysis of BHP with Cd2+/F‒ ions exposed an outstanding ratiometric absorbance and colorimetric responses towards F‒ ions and also showed a visible colorimetric response towards Cd2+ ions. The fluorescence enhancement of BHP with F‒ ion was highly evaluated by DFT calculations. As well, the cell viability experimental results of BHP can be used for the detection of F‒ ions in both HeLa cells and Zebrafish embryos via high content analysis system. Experimental Methods 2.1 Materials All the chemicals used in the present study were in the analytical reagent grade and solvents used were of HPLC grade. Reagents were used as such received without any further purification. Metal ions such as K+, Na+, Ca2+, Mg2+, Fe2+, Fe3+, Ag+, Zn2+, Mn2+, Cu2+, Co2+, Ni2+, Cd2+, Al3+, Cr3+, Pb2+ and Hg2+ were purchased from Merck and S.D. Fine chemicals. The anions of Cl-, Br-, I-, SCN-, CN-, H2PO4-, HSO4-, NO3-, AcO- and F- were purchased as their tetrabutylammonium salts from Sigma–Aldrich Pvt. Ltd. Absorption measurements were performed on JASCO V-630 spectrophotometer in 1 cm path length quartz cuvette with a volume of 2 mL at room temperature. Fluorescence measurements were made on a JASCO and F- 4500 Hitachi Spectrofluorimeter with excitation slit set at 5.0 nm band pass and emission at 5.0 nm band pass in 1 cm ×1 cm quartz cell. 1H and 13C NMR spectra were obtained on a Bruker 300 MHz NMR instrument with TMS as internal reference using DMSO-d6 as solvent. Standard Bruker software was used throughout. 19F NMR spectra were recorded at 293K on BRUKER 400 MHz FT-NMR spectrometers using DMSO-d6 as solvent. ElectroSpray Ionisation Mass Spectrometry (ESI-MS) analysis was performed in the positive/negative ion mode on a liquid chromatography-ion trap mass spectrometer (LCQ Fleet, Thermo Fisher Instruments Limited, US). Fluorescence microscopic imaging measurements were determined using Operetta High Content Imaging System (PerkinElmer, US) 2.2. Synthesis of (E)-4-bromo-2-(hydrazonomethyl) phenol, BHP An absolute alcoholic solution (50 ml) of 5-bromosalicylaldehyde (0.5gm, 2.49 mmol) was refluxed under hydrazine hydrate (in excess) for 5 hr and the pale yellow color solid product was collected after recrystallized with ethanol and ethyl acetate mixture (yield, 95 %). 1H NMR (300 MHz, DMSO-d6) δ (ppm): 8.92 (s, 1H), 11.89 (s, 1H), 7.53 (d, J = 8.7 Hz, 1H), 6.94 (d, J = 5.8 Hz, 1H); 13C NMR (75 MHz, DMSO-d6) δ (ppm): 161.36, 158.51, 135.84, 131.82, 120.86, 119.69, 106.72. 2.3 Photophysical analysis of BHP The optical mode analysis of BHP towards various cations/anions in DMSO/H2O (9:1, v/v) system was carried out by using absorbance and fluorescence spectroscopy. UV-visible and fluorescence analysis of BHP with cations were gauged by using their corresponding acetate salts of metal ions. Tetrabutylammonium salts of competing anions were used for the anionic sensing analysis. 2.4 Computational Studies The optimized geometrical and ground state energy level calculations of BHP were obtained by Density functional theoretical (DFT) calculations were executed using Gaussian 09 program 32 with the 6-311G basis set. The optimized geometries and the fluorescence enhancement of probe BHP complexed with Cd2+/F- ions were attained by DFT-B3LYP level theory using 6-311G and LANL2DZ basis sets. 2.5 Cytotoxicity studies HeLa cell lines were procured from the National Center for Cell Science (NCCS), Pune, India. Cell lines are kept in the Dulbecco's Modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum (FBS), 1% antimycotic and antibiotic solution was used in this study. The cells were kept in an incubator at 25 °C with humidified atmosphere comprising 5% of CO2 and 95% of air. HeLa cells were loaded over the wells of 96 well-culture plates with a density of 1 x 104 cells/well. After 48 h of incubation, previous DMEM medium was exchanged with new medium and BHP (dissolved in DMSO) was added in the range of 0-200 µM to all the wells and further incubated over 3h. Cytotoxicity of BHP was measured by using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. After incubation of HeLa cells with BHP, the medium was detached. Further, 100 μl of DMSO was added and the resulting formazan crystals were dissolved in DMSO. The cell viability was determined by measuring the absorbance of each well at 540-660 nm (formation of formazan) using a microplate reader. 2.6 In vivo fluorescence analysis in Zebrafish embryos The fluorescence imaging analysis was performed in four days old embryos. The embryos were seeded over F- ion alone for 2 h in the E3 medium. The E3 medium was prepared by dissolving 5.0 mM NaCl, 0.17mM KCl, 0.33mM CaCl2, 0.33mM MgSO4 ingredients in H2O (2L) and the pH 7.2 was adjusted by adding NaOH. The embryos were thoroughly washed with E3 medium. Successively, incubated embryos were sowed over 25 mM of BHP (in DMSO) solution for 3h. Further, embryos were washed again with E3 medium and fixed in 10% methyl cellulose solution for the good oriented images. The fluorescent images of BHP-F- were logged using high content screening microscopy. (Excitation wavelength of 482 nm and emission wavelength range of 500-700 nm). Results and discussion The probe, (E)-4-bromo-2-(hydrazonomethyl) phenol (BHP) has been synthesized by one step condensation between hydrazine and 5-bromosalicylaldehyde in ethanol (yield, 95 %) as shown in Scheme 1. The structure of the probe BHP was confirmed via 1H, 13C NMR analysis (Figure S1-S2, See ESI) 3.1. UV–vis spectral analysis of cations with BHP To investigate the cation sensing events of BHP towards different cations in DMSO/H2O (9:1, v/v) system by using UV-vis and fluorescence titration experiments. Initially, free probe BHP exhibited an absorption band at 367 nm and further addition of mono, di and trivalent cations such as Li+, K+, Ag+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Fe2+, Hg2+, Na+, Mg2+, Ca2+, Pb2+, Fe3+ and Cr3+ exhibited tiny changes in absorption spectr due to their weak interaction towards BHP except Cd2+ ion as shown in Figure 1. Interestingly, upon titrated with Cd2+ ion, a new absorption band appeared at 470 nm due to the highly resonance induced charge transfer ability of bromo substituted salicyl moiety while the solution turns into dark yellow color from pale yellow. Increasing addition of Cd2+ ion results gradual reduction of both higher and lower energy bands at 367 nm and 470 nm respectively as depicted in Figure 2. Figure 1. UV-vis spectra of BHP (10 µM) with different cations (5 × 10-3 M) in DMSO/H2O (9: 1, v/v) system. Figure 2. UV-vis spectra of BHP (10 µM) with Cd2+ (0 – 100 µM) in DMSO/H2O (9: 1, v/v) system Besides, fluorescence response of probe BHP towards various cations such as Li+, K+, Ag+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Fe2+, Hg2+, Na+, Mg2+, Ca2+, Pb2+, Fe3+ and Cr3+ including Cd2+ ion have been inspected in DMSO/H2O (9:1, v/v) system. Initially, the probe BHP displayed low intensed fluorescence band in free state. Addition of other commonly coexistent metal ions including Cd2+ ions exhibited trivial changes in fluorescence spectra. From these results, it is concluded that the probe BHP could serve as an excellent colorimetric assay for the detection of Cd2+ ions. 3.2. The sensing analysis of BHP towards anions Moreover, the anion binding attraction of BHP towards anions have been investigated in DMSO/H2O (9:1, v/v) system via both UV-visible and fluorescence spectral techniques. Initially the probe BHP showed the absorption band at 367 nm. Upon titrated with other anions such as Cl‒, Br‒, I‒, NO3‒, AcO‒, HSO4‒, H2PO4‒ and CN‒ were failed to alter the absorbance of the probe BHP except F‒ ions as shown in Figure 3a. Moreover, the incremental addition of F‒ ions (0-50 µM), the higher energy band at 367 nm was decreased along with the increment in new absorption band at 482 nm results an excellent ratiometric response. The new low energy band observed at 482 nm due to the deprotonation of–OH group present in salicyl moiety initiated by hydrogen bonding [Figure 3b]. At that affair, the solution turns into orange color from pale yellow and it was simply discerned by naked eye [Figure 4]. Besides, under identical condition, the fluorescence titration experiment of BHP was carried out in the presence of different anions. Interestingly, the probe BHP displayed low intensed fluorescence band at 601 nm and the other competing anions were failed to affect the fluorescence intensity except F‒ ions as shown in [Figure 5a]. Further, the incremental addition of F‒ ions triggers the enhancement in intensity results an excellent “turn on” fluorescence response due to the deprotonation and the inhibition of charge transfer state stimulated by resonance around the moiety [Figure 5b]. 3.3. Competitive experiments To gauge the selectivity and recognizing ability of BHP, competitive analysis was performed in the presence of varying concentration of F‒ ion (0-50 µM). Initially, the probe was treated with 5 × 10-3 M of different anions such as, CN-, I-, Br-, Cl-, NO2-, CH3COO-, H2PO4- and HSO4-. The other common competing anions were failed to bind with the probe BHP except F- ion [Figure 6 (a) and (b)]. From these observations, it is ensured that BHP could act as an excellent selective and sensitve chromogenic receptor for F- ions in real time monitoring and different biological applications. Figure 3 (a): UV-vis spectra of BHP with 5 × 10-3 M of other anions in DMSO/H2O (9: 1 v/v) system. (b) UV-visible spectra of BHP (5 µM) with F‒ (0-50 µM) in DMSO/H2O (9: 1 v/v) system. Figure 4. Naked eye detection of F‒ ions with BHP under visible light (top) and UV-lamp (bottom) and BHP with Cd2+ visible light only (bottom). Figure 5 (a): Fluorescence spectra of BHP (5µM) with 5 × 10-3 M of other anions in DMSO/H2O (9: 1, v/v) system. Excitation at 482 nm. Slit width is 5 nm. (b) Fluorescence spectra of BHP (5µM) with F‒ (0-50 µM) in DMSO/H2O (9: 1, v/v) system. Excitation at 482 nm. Slit width is 5 nm. Figure 6 (a): Selectivity analysis of F‒ ion with BHP in the presence of competing anions. Excitation at 480 nm, Slit width = 5 nm. (b) The blue bars represent the change of the fluorescence intensity of BHP with the consequent addition of other anions. The pink bars represent the addition of the competing anions to BHP. Excitation at 480 nm, Slit width = 5 nm. 3.4. Job’s plot analysis and calculation of binding constant of BHP for Cd2+/F‒ ions Furthermore, the Job’s plot [Figure 7(a) and (b)] analysis based on UV-visible and fluorescence titration experiments results confirmed the 1:1 binding stoichiometry of BHP with both Cd2+/F‒ ions respectively. To further support the binding stoichiometry of BHP with Cd2+/F‒ions, ESI-MS spectral analysis were performed. The ESI-MS spectral analysis of BHP-Cd2+/BHP-F‒ disclosed peaks at 327.45/258.28 corresponds to [BHP+Cd2++Na+]/[BHP+F‒+H++Na+] respectively (Figure S3-S4, See ESI). Furthermore, the 1:1 binding stoichiometry of BHP with F− ions was confirmed via 1H NMR titration profile (Figure 8) and 19F NMR. The deprotonation of ‒OH group present in the salicyl moiety was initiated by hydrogen bonding and the plausible binding mode of BHP with Cd2+ and F‒ ion is shown in Scheme 2. Further, the absorbance and fluorescence intensity changes of Cd2+ ions (A472 nm) and F‒ ions (A482 nm, I603 nm) were plotted against [Cd2+] and [F‒] respectively provided a good linear relationship between both BHP and Cd2+/F‒ ions (Figure S5, S6 and S7, See ESI). From absorbance and fluorescence titration profile, the binding constant values of BHP for Cd2+/F‒ ions were calculated using modified Benesi-Hildebrand method ions (Figure S8, S9 and S10, See ESI). The binding constant values of BHP with Cd2+ ions were found to be 4.26 ×10-4 M from UV-visible titration profile. Similarly, the binding constant values of BHP with F‒ ions were estimated to be 6.03 ×10-3 M / and 3.01 × 10-4 M from UV-visible and fluorescence titration profile respectively. The detection limits (LOD) of F‒ were calculated to be 0.05 nM respectively. Moreover, the LOD values of BHP signifies that the probe might be utilized for the quantitative determination of F‒ ions in environment and real system. Figure 7 (a) Job’s plot for BHP with F‒ ion. (b) Job’s plot for BHP with Cd2+ ion Scheme 2. Binding mode of BHP with Cd2+/F‒ ions 3.5. 1H NMR titrations of BHP with F- ions In addition, to confirm and highly supported the 1:1 binding stoichiometry of probe with F- ions, 1H NMR titrations was performed. Upon addition of F- ion (0.5 equiv), the proton signal corresponds to phenolic –OH group at 11.14 ppm was gradually decreased. Further, addition of 1 equiv. of F- ions to BHP showed the complete disappearance of –OH proton signal as depicted in Figure 8. Moreover, the binding stoichiometric ratio of F- ion with BHP was further supported by 19F NMR experiment. The (H2F)- signal appeared at -124.33 ppm (Figure S11-S12, See ESI) confirms the deprotonation process arose from phenolic –OH proton. Figure 8 1H NMR titration of BHP with F- (0-1equiv) in DMSO-d6 3.6. DFT calculations of BHP with Cd2+/F- ion To recognize the fluorescence enhancement of probe BHP after complexation with F-, DFT calculations were accomplished. The optimized structures of BHP, BHP-Cd2+ and BHP-F- were obtained using DFT/B3LYP-6-311G and B3LYP/LanL2DZ basis sets respectively. The frontier molecular orbital diagram obtained from optimized structure of BHP is presented in Figure 9. Upon binding with Cd2+ ion, the HOMO and LUMO are delocalized over the entire salicyl unit and their energy gap was reduced. It is noteworthy that inhibition of charge transfer in probe BHP renders the reduction of absorbance at 367 nm and 470 nm. Moreover, Complexation of F- ion to the probe BHP leads to lowering of HOMO-LUMO energy gap. In the presence of F-, HOMO and LUMO are distributed over the whole molecule of BHP. From these results, the F- ion was efficiently binded and complexed with BHP than Cd2+ ion. Figure 9. Frontier molecular orbital diagram of BHP, BHP-Cd2+and BHP-F‒ 3.7. Live cell Imaging analysis of BHP in HeLa cells / Zebrafish embryos The cell viability or cytotoxicity analysis of BHP (0–200 µM) against Human HeLa cells were performed using MTT assay. In 100 µM of BHP, cell viability was obtained as too high as 98%. (Figure S13, See ESI). Hence, the probe was sucessfully used for live cell imaging analysis of F- ions in Figure 10. Live cell fluorescence imaging analysis of BHP in HeLa cells. (a) Bright field images of HeLa cells incubated with BHP (25 µM) for 3h (b) Fluorescence merged images of HeLa cells incubated with BHP (25 µM) (c) Fluorescence image of HeLa cells incubated with BHP (25 µM) alone (d) Fluorescence image of HeLa cells incubated with BHP (25 µM) and 25 µM of F‒ ions for 1 h HeLa cells. Further, the HeLa cells were pre-treated with 25 µM of BHP alone for 3 h. Then HeLa cells were seaded with 25 µM of F- ions for 1h. In the absence of F- ions, the probe BHP exposed a weak yellow fluorescence. However, addition of F- ions to the probe BHP induced a bright orange fluorescence (Figure 10). These results endorsed that the probe BHP can be successfully utilized for the intracellular fluorescence imaging analysis of F- ions in HeLa cells. Besides, the exceptional cell viability output of BHP has been further explored in four days Zebrafish embryos. Zebrafish has positioned as a well-known vertebrate model in numerous biological applications. From this perspective, we have utilized also zebrafish embryos as a living animal model to expose the excellent imaging potential of BHP for the detection of F‒ ion in the biological environment (Figure 11) . Figure 11. Fluorescence imaging analysis of F‒ ion in 4 days old Zebrafish embryos developed with BHP and various concentrations of F‒ ion (a) bright field images of BHP (25 µM) alone, (b) fluorescence merged images of BHP and F- ion (25 µM) (c) fluorescence image of BHP (25 µM) alone (d) 25 µM of F‒ ion for 2 h continuously incubated with BHP (25 µM) for 3 h. 3.8. Evaluation of BHP with previous reports The probe BHP has valid and multi features such as single step synthesis, dual-mode recognition, turn-on fluorescence response and colorimetric change. The probe BHP displayed unique sensing property among other dual sensors. Table S1 compares the sensing performance of BHP with recently reported F‒ receptors. Amid, BHP exhibits too low limit of detection when compared with other previously reported chemoreceptors cited in table S1. Also, the limit of detection of BHP is within the range of recommended limits set by both EPA and WHO for F‒ Ions. Moreover, the fluorescence imaging experiments inferred that the probe BHP can be utilized as potential tool for mapping F‒ ion distribution in HeLa cells and Zebrafish embryos. Conclusions We have designed and synthesized a new chromogenic and fluorogenic probe based on salicylhydrazone derivative for the selective and sensitive detection of both Cd2+/F- ions by colorimetrically and fluorimetrically respectively. As per our knowledge, it is a novel simple hydrazone receptor for sensing carcinogenic heavy metal Cd2+ via colorimetric method and biologically significant F‒ ion by both colorimetric and fluorimetric methods. The binding constant value of Cd2+ ion was found to be 4.26×10-4 M by UV-visible method where as 6.03×10-3 and 3.01×10-4 M for F- ion by both UV-visible and fluorescence methods respectively. The limit of detection was found to be 0.05 nM for F- ion. The excellent biological potential of BHP has been successfully utilized for the detection of F- ions in Zebrafish embryos and human HeLa cells. Acknowledgments The authors acknowledge the financial support from the Council of Scientific and Industrial Research, Extramural Research, New Delhi, India (Grant No. 01(2901)17/EMR-II. The Department of Science and Technology, SERB, Extramural Major Research Project (Grant No. EMR/2015/000969), Department of Science and Technology, CERI, New Delhi, India (Grant No. DST/TM/CERI/C130(G) and we acknowledge the DST-FIST, DST-PURSE,DST-IRPHA, UPE programme and UGC-NRCBS, SBS, MKU for providing instrumentation facilities. References Jäkle, F. Chem. Rev. 2010, 110, 3985. 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AbstractThe paper describes a new approach to the thermodynamic formalization for calculation of molecular energy and charge distribution in ground state by means of the variational equation of DFT. In order to thermodynamically formalize the molecular calculation, the pseudo chemical potential (PCP) is conceptualized, where a molecule is broken into multi-phase(atom) one-component(electron) systems and the energy of system is represented as PCP. Calculation of the molecular energy and atomic charge by PCP is put forward, thereafter the approach is proved to be valid and its efficiency (accuracy and calculation speed) is verified.

Abstract Objective: Although in heavy-ion therapy, the quantum molecular dynamics (QMD) model is one of the most fundamental physics models providing an accurate daughter-ion production yield in the final state, there are still non-negligible differences with the experimental results. The aim of this study is to improve fragment production in water phantoms by developing a more accurate QMD model in Geant4. Approach: A QMD model was developed by implementing modern Skyrme interaction parameter sets, as well as by incorporating with an ad hoc α-cluster model in the initial nuclear state. Two adjusting parameters were selected that can significantly affect the fragment productions in the QMD model: the radius to discriminate a cluster to which nucleons belong after the nucleus-nucleus reaction, denoted by R, and the squared standard deviation of the Gaussian packet, denoted by L. Squared Mahalanobis's distance of fragment yields and angular distributions with 1, 2, and the higher atomic number for the produced fragments were employed as objective functions, and multi-objective optimization (MOO), which make it possible to compare quantitatively the simulated production yields with the reference experimental data, was performed. Main results: The MOO analysis showed that the QMD model with modern Skyrme parameters coupled with the proposed α-cluster model, denoted as SkM*α, can drastically improve light fragments yields in water. In addition, the proposed model reproduced the kinetic energy distribution of the fragments accurately. The optimized L in SkM*α was confirmed to be realistic by the charge radii analysis in the ground state formation. Significance: The proposed framework using MOO was demonstrated to be very useful in judging the superiority of the proposed nuclear model. The optimized QMD model is expected to improve the accuracy of heavy-ion therapy dosimetry.

AbstractEnergy, structure, and charge are fundamental quantities characterizing a molecule. Whereas the energy flow and structure change in chemical reactions are experimentally characterized, determining the atomic charges of a molecule in solution has been elusive, even for a triatomic molecule such as triiodide ion, I3−. Moreover, it remains to be answered how the charge distribution is coupled to the molecular geometry; which I-I bond, if two I-I bonds are unequal, dissociates depending on the electronic state. Here, femtosecond anisotropic x-ray solution scattering allows us to provide the following answers in addition to the overall rich structural dynamics. The analysis unravels that the negative charge of I3− is highly localized on the terminal iodine atom forming the longer bond with the central iodine atom, and the shorter I-I bond dissociates in the excited state, whereas the longer one in the ground state. We anticipate that this work may open a new avenue for studying the atomic charge distribution of molecules in solution and taking advantage of orientational information in anisotropic scattering data for solution-phase structural dynamics.

Abstract The ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) collaboration plans to measure the ground-state hyperfine splitting of antihydrogen in a beam at the CERN Antiproton Decelerator with initial relative precision of $$10^{-6}$$ 10 - 6 or better, to test the fundamental CPT (combination of charge conjugation, parity transformation and time reversal) symmetry between matter and antimatter. This challenging goal requires a polarised antihydrogen beam with a sufficient number of antihydrogen atoms in the ground state. The first measurement of the quantum state distribution of antihydrogen atoms in a low magnetic field environment of a few mT is described. Furthermore, the data-driven machine learning analysis to identify antihydrogen events is discussed. Graphic Abstract

AbstractWe have measured atomic pair distribution functions (PDF) of La1−xCaxMnO3 using high energy x-ray diffraction. This approach yields accurate PDFs with very high real-space resolution. It also avoids potential pitfalls from the more usual neutron measurements that magnetic scattering is present in the measurement, that the neutron scattering length of manganese is negative leading to partial cancellation of PDF peaks, and that inelasticity effects might distort the resulting PDF We have used this to address the following questions which do not have a satisfactory answer: (1) What are the amplitudes and natures of the local Jahn-Teller and polaronic distortions in the CMR region. (2) Is the ground-state of the ferromagnetic metallic phase delocalized or polaronic. (3) As one moves away from the ground-state, by raising temperature or decreasing doping, towards the metal insulator transition, how does the state of the material evolve?

Abstract The interaction between a proton and a ground state hydrogen atom is studied using a standard three-body classical trajectory Monte Carlo (CTMC) and a quasi-classical trajectory Monte Carlo (QCTMC) model where the quantum feature of the collision system is mimicking using the model potential in the Hamiltonian as was proposed by Kirschbaum and Wilets (C. L. Kirschbaun, and L. Wilet, Phys. Rev. A 21, 834 (1980)). The influence of the choice of the model potential parameters (α,ξ) on the initial radial and momentum distribution of the electron are analyzed and optimized. We found that although these distributions may not be as close to the quantum results as the distribution of standard CTMC results, we can find the combination of the (α,ξ) where the calculated cross sections are closer to the experimental data and closer to the results obtained quantum mechanically. We show that the choice of 3 < α < 5 is reasonable. To validate our observation, we present cross sections for ionization, excitation, charge exchange, and state selective charge exchange to the projectile bound state. Calculations are carried out in the projectile energy range between 10 and 1000 keV/amu.

Abstract Born effective charges Zi, β α *, dielectric tensors εα,βand the dynamic stability for AgMgF3 and KMgF3 compounds were treated based on the harmonic and quasi-harmonic theory implemented in phonopy code. The band gap for both compounds as well as the effective masses of electrons and holes are calculated at different pressures using the TB-mBJ (GGA) approximation within the framework of the density functional theory. Furthermore, absorption coefficient, refractive index, extinction coefficient, reflectivity, and optical conductivity, for both compounds were calculated. On the other hand, we studied the nature of atomic bonds by the topological distribution of the charge density as well as computing the effective charge of each atom based on the Quantum Theory of Atoms in Molecules (QTAIM) as implemented in Bader code, therefore the ionic type for bonds was explored. The mechanical stability was verified after calculating the elastic ‎behavior at the equilibrium ground-state for both compounds. Thermal properties such as heat capacity at constant volume, entropy, Debye temperature, and thermal expansion coefficient are treated depending on the quasi-harmonic model. They are examined under both pressure and temperature influences. The thermoelectric properties of the compound AgMgF3 showed a high figure of merit (ZT) reached 0.75 at a temperature of 300 K if it was doped with a concentration of 1021 cm-3 of n-type.