Computational & Theoretical Chemistry

This paper proposes a mathematical framework for analyzing coherence patterns across complex systems, from neural networks to cosmic structures. We introduce a coherence index that quantifies phase synchronization and examine its applications in three domains: neuroscience, cosmology, and quantum mechanics. Our approach builds upon established theories including Integrated Information Theory and quantum coherence principles, providing testable hypotheses for multiscale system behavior. Preliminary analysis of EEG data and cosmological observations suggests potential applications, though extensive validation remains necessary.

Computational chemistry software, developed to calculate the chemical properties of molecules, is known as dry research due to it's depend on theoretical calculations rather than lab experimental data collection. This study leverages such software to estimate chemical properties, which is particularly useful for newly synthesized or modified chemical compounds. Upon successful execution, the computational chemistry software generates a log file. The newly developed software in this study is designed to interface with density functional theory (DFT) software output files. It requires only two inputs from the user i.e the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) values. The software processes the input parameters to generate several key chemical properties, including ionization energy, electron affinity, hardness, chemical potential, electronegativity, softness, and electrophilicity index. Each of these parameters provides valuable insights into the chemical behavior of compounds. The software achieves an acceptable result with a 98.8% confidence interval. Utilizing this third party software is intended to add new features and increase the functionality of current platforms. The tool's emphasis on adaptability, readability, and user-friendliness is consistent with the fundamental ideas of simplicity and adaptability. By offering quick response, this tool HMG.A1 not only closes the gap but also presents opportunities for growth into other computational approaches, advancing studies in areas like materials science, drug discovery, and catalysis.

A new approach is presented for the development of quantitative structure–property relations (QSPR) based on the extraction of relevant molecular features with self‐organizing maps and the use of a modified fuzzy‐ARTMAP classifier for variable prediction. The present methodology is demonstrated for the development of a QSPR for the aqueous‐phase infinite dilution activity coefficient γ∞, based on a data set of 325 diverse organic compounds. The QSPR was developed using a set of 11 molecular descriptors (four connectivities vχ1–4, Coulomb self‐similarity measure, electron–nuclear attraction, dipole moment, sum of atomic numbers, number of filled levels, average polarizability, and nuclear–nuclear repulsion). The final set of molecular descriptors was selected from an initial pool of 23 topological and quantum chemical descriptors, including six molecular quantum similarity measures, by means of a topological analysis of self‐organization of the data set. Additional interpolated infor...

Via CASSCF/MRCI and RSPT2 calculations (single and double excitation with Davidson correction) the potential energy curves of 20 electronic states in the representation 2S 1 ( ) of the molecule SiO have been calculated. By fitting these potential energy curves to a polynomial around the equilibrium internuclear distance r e , the harmonic frequency ω e , the rotational constant B e , and the electronic energy with respect to the ground state T e have been calculated. For the considered electronic states the permanent dipole moment μ have been plotted versus the internuclear distance r. Based on the canonical functions approach, the eigenvalues E v , the rotational constant B v and the abscissas of the turning points r min and r max have been calculated. The comparison of these values to the experimental and theoretical results available in the literature is presented. In the present work 8 higher electronic states have been studied theoretically for the first time.

Adansonia digitata and Annona muricata are traditionally used medicinal plants with reported pharmacological properties. In this study, we aimed to elucidate the phytochemical composition, antioxidant activity, and antibacterial properties of partition fractions of Adansonia digitata and Annona muricata extracts obtained using chloroform, ethyl acetate, ethanol, and aqueous solvent systems. The plant extracts were successively partitioned using chloroform, ethyl acetate, ethanol, and aqueous solvent systems. Phytochemical analysis was performed using standard methods. Antioxidant activity was evaluated using FRAP and DPPH assays. Antibacterial activity was assessed using agar well diffusion and MIC determination. Phytochemical analysis revealed the presence of alkaloids (10.2-15.6%), flavonoids (8.5-12.1%), and phenolic acids (5.6-9.2%) in all fractions. The ethyl acetate fraction of Annona muricata exhibited the highest antioxidant activity (IC50 = 20.5 μg/mL) in the DPPH assay. In comparison, the chloroform fraction of Adansonia digitata showed significant antioxidant activity (IC50 = 35.2 μg/ mL) in the FRAP assay. The antibacterial evaluation demonstrated that the chloroform fraction of Adansonia digitata exhibited broad-spectrum antibacterial activity (MIC = 0.5-1.5 mg/mL) against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, whereas the ethyl acetate fraction of Annona muricata showed potent antibacterial activity (MIC = 0.25-1.0 mg/mL) against Gram-negative bacteria. Additionally, the ethanol fraction of Adansonia digitata displayed moderate antibacterial activity (MIC = 1.0-2.5 mg/mL) against Gram-positive bacteria, and the aqueous fraction of Annona muricata exhibited weak antibacterial activity (MIC = 2.5-5.0 mg/mL) against all tested bacterial strains. Comparison of antioxidant and antibacterial activities among fractions revealed
significant variations, indicating the importance of solvent selection in extracting bioactive compounds. The study validates the traditional use of Adansonia digitata and Annona muricata, highlighting their potential as natural antioxidants and antibacterial agents.

Key words: Adansonia digitata, Annona muricata, antibacterial properties, antioxidant activity, phytochemical analysis, solvent system

We have investigated at the atomic level amide-based rotaxanes set in motion in four different solvents, namely, ethyl ether, acetonitrile, ethanol and water. In three non-aqueous solvents, shuttling of the macrocycle between two binding sites separated by a free-energy barrier is coupled with a conformational change and rotation, driven primarily by hydrogen-bonding interactions. The mechanism that underlies the shuttling is completely altered when the non-aqueous solvent is replaced by water. In aqueous solution, hydrophobic interactions chiefly control shuttling of the rotaxane, leading to a sharp decrease of the free-energy barrier, thereby speeding up the process. The binding sites and the reaction pathway describing shuttling vary significantly in water compared with in the other three solvents. We found that the high polarity, the hydrogen-bond donor and acceptor ability, and the minimal steric hindrance of water conspire to modify the mechanism. These three physicochemical properties are also responsible for the lubrication by water. That water completely changes the mechanism underlying the shuttling of rotaxanes, is addressed for the first time in this study, and provides valuable guidelines for the de novo design of molecular machines.

Partitioning atomic and molecular charge densities in non-overlapping chemically significant regions is a challenging problem for quantum chemists. The present method aims to build a tool that enables the determination of “good boundaries” with the help of elementary statistical methods or information theory. This is done by minimizing an objective function with respect to the boundaries of the localization regions, the choice of this function being guided by a clarity requirement. With the sum of the indices of dispersion (ΣD) or the mutual information as the objective function, the method yields partitions in good agreement with the Aufbau rules for Li–Rn atoms and with Lewis’s pairing model for molecules.

To compliment experimental measurements, we have performed calculations of chemical shifts for perhalocyclohexasilane Si 6 X 12 (X = Cl, Br) coordinated with two halide anions (Y = Cl -, Br -, and I -) using density functional theory (DFT). We use the quantum chemical code to compute geometries and wave

Despite extensive studies in the past, deterioration of mechanical properties due to hydrogen environment exposure remains a serious problem for structural materials. More effective improvement of a material's resilience requires advanced computational methods to elucidate the fundamental mechanisms of the hydrogen effects. To enable accurate molecular dynamics (MD) studies of the hydrogen effects on metals, we have developed a high-fidelity analytical bond-order potential (BOP) for the copper-hydrogen binary system as a representative case. This potential is available through the publically available MD code LAMMPS. The potential parameters are optimized using an iterative process. First, the potential is fitted to static and reactive properties of a variety of elemental and binary configurations including small clusters and bulk lattices (with coordination varying from 1 to 12). Then the potential is put through a series of rigorous MD simulation tests (e.g., vapor deposition and solidification) that involve chaotic initial configurations. It is demonstrated that this Cu-H BOP not only gives structural and property trends close to those seen in experiments and quantum mechanical calculations, but also predicts the correct phase transformations and chemical reactions in direct MD simulations. The correct structural evolution from chaotic initial states strongly verifies the transferability of the potential. A highly transferable potential is the reason that a well-parameterized analytical BOP can enable MD simulations of metal-hydrogen interactions to reach a fidelity level not achieved in the past.

Annona muricata is a well-known economic and traditional plant of Nigeria. The study investigated the properties of constituents and antimicrobial activities of extracts of the leaf of  A . muricata . The extracts were tested against Escherichia coli , Pseudomonas aeuroginosa, Staphylococcus aureus and Candida albicans by the agar well diffusion method at concentration of 20 mg/mL. The methanol (AM2) and ethyl acetate (AM4) extracts were characterized using UV and IR spectroscopy. The morphological structure of the A . muricata leaf was observed at a magnification of 20,000X using SEM and then subjected to EDX analysis. The results of the phytochemical screening revealed the presence of phenolic compounds, flavonoids, tannins, alkaloids, saponins and cardiac glycosides in the extracts. Anthraquinone was found absent. The ethyl acetate extract was found highly active against gram positive bacteria, S. aureus (ZI of 42 mm; AI = 1.31) and ampicillin resistant gram negative P. aeruginos...

We present a first principles study based on density functional theory of thermodynamic and electronic properties of the most important intrinsic defects in the semiconductor alloy Cd1-xZnxTe with x < 0.13. The alloy is represented by a set of supercells with disorder on the Cd/Zn sublattice. Defect formation energies as well as electronic and optical transition levels are analyzed as a function of composition. We show that defect formation energies increase with Zn content with the exception of the neutral Te vacancy. This behavior is qualitatively similar to but quantitatively rather different from the effect of volumetric strain on defect properties in pure CdTe. Finally, the relative carrier scattering strengths of point defects, alloy disorder, and phonons are obtained. It is demonstrated that for realistic defect concentrations carrier mobilities are limited by phonon scattering for temperature above approximately 150 K.

Alkyl peroxides, trioxides, and the corresponding radicals are important in atmospheric chemistry, photochemical smog formation, and combustion processes, but accurate and widely accepted enthalpy data for these species are not available. In this work we verify enthalpy data for several compounds and derive the corresponding group values for use in the group additivity method. Isodesmic reactions and ab initio calculations (MP4SDTQ/6-31G*//MP2/6-31G* and G2) are used to determine enthalpies of formation for the following compounds (in kcal mol -1 ): CH 3 OOH (-31.8), C 2 H 5 OOH (-39.9), iPrOOH (iPr ) (CH 3 ) 2 -CH-, -49.0), (CH 3 ) 3 COOH (tBu ) (CH 3 ) 3 C-, -58.4), iPrOO• (-15.1), tBuCOO• (-25.2), CH 3 OOCH 3 (-31.0), C 2 H 5 OOC 2 H 5 (-47.2), iPrOOiPr, (-65.4), tBuOOtBu (-84.2), HOOOH (-23.0), CH 3 OOOH (-22.2), CH 3 OOOCH 3 (-21.4). Our results on isodesmic reactions indicate that group additivity is an accurate method to estimate enthalpies (∆H f °298 ) of alkyl peroxides and trioxides. Bond enthalpies are determined as follows: HOOO-H (82.6), CH 3 O 2 -H (86.6), C 2 H 5 O 2 -H (86.1), iPrO 2 -H (86.0), tBuO 2 -H (85.3), HOO-OH (35.8), CH 3 O-OCH 3 (38.8), CH 3 OO-OH (34.2), CH 3 O-OOH (29.6), CH 3 O-OOCH 3 (28.0), iPr-OO (36.6), tBu-OO (37.5). The recommended enthalpy group values of (O/C/O) and (O/O 2 ) are -5.5 and 9.6 kcal mol -1 , respectively.

Catalytic dehydrocoupling of primary and secondary amine boranes and ammonia borane using tin(IV) and tin(II) catalysts is presented. These tin compounds have been demonstrated to dehydrocouple phosphines where catalytic activity was dependent on metal oxidation state. In contrast, the mechanism of amine borane dehydrocoupling appears to be substrate dependent. The most sterically encumbered substrate, t BuNH 2 BH 3 , appears to engage in b-hydrogen elimination based on the observation of t BuN ¼ BH 2 , whereas Me 2 NHBH 3 appears to be involved in a chain-growth process as evidenced by linear diborazane and the absence of amino borane. Though these tin catalysts are moderately active in the spectrum of amine borane dehydrocoupling catalysts, the dependence of mechanism on substrate appears to be unique.

The valence bond theory is applied here to an a6 initio calculation of the ground state of the benzene n electrons. A comparison of the rate of energy convergence of p, orbitals, nearest-neighbour optimized, and fully optimized orbitals calculations is made for benzene n electrons in the minimum basis set approximation. It is shown that making a full orbital optimization, only the covalent structures can reproduce the results of the fui1 configuration interaction limit. x 2 + X X ~/ ( ~ + g x 2 ) interaction

Both relativistic energy-consistent small-core ab initio pseudopotential and fully relativistic densityfunctional all-electron calculations have been carried out by exploiting the presently available highest computational capability for the first to fourth ionization potentials as well as the for Th-Lr͔͒ excitation energies for the whole series of actinide atoms. The calculated ionization potentials might be useful to guide future experimental measurements. ͓S1050-2947͑98͒06708-0͔

The generation of two‐component relativistic energy‐consistent small‐core ab initio pseudopotentials based on multi‐configuration all‐electron Dirac‐Hartree‐Fock reference data is briefly described for the 3d‐transition metals Sc to Ni. The one‐component scalar‐relativistic pseudopotentials generated by averaging over spin are tested in large‐scale correlated calculations for atomic excitation and ionization energies using even‐tempered uncontracted 25s20p15d10f8g6h valence basis sets. Comparision to experimental data demonstrates the accuracy of the pseudopotentials. In addition, preliminary results of a molecular calibration study for the spectroscopic constants of ScO in its 2Σ+ ground state are presented (Re = 1.666 Å, De ≈ 6.94 — 7.02 eV, ωe = 984 cm−1) and confirm the good transferability of the atom‐adjusted pseudopotentials to a molecular environment.

Results for the spectroscopic constants of the monohydrides, monoxides, and monofluorides of the lanthanide elements lanthanum and lutetium as well as the actinide elements actinium and lawrencium from all-electron and valence-only ab initio electronic structure calculations are presented. The valence-only investigations were carried out using energy-consistent pseudopotentials for the heavy atoms. Electron correlation was accounted for by means of the coupled-cluster method. Multireference averaged coupled-pair functional calculations were carried out to describe effects due to the mixing of the energetic close-lying ns 2-m (n-1)d m (0 e m e 2) configurations of the lanthanide (n ) 6) and actinide (n ) 7) cations. The counterpoise correction was applied to estimate the size of the basis set superposition errors. Nonrelativistic as well as quasirelativistic calculations were performed. The latter included also corrections for spin-orbit effects for the actinide compounds derived from limited configuration interaction calculations. The reliability of the pseudopotential approach is demonstrated by a comparison to the results of corresponding nonrelativistic and scalar-relativistic Douglas-Kroll-Hess all-electron self-consistent-field calculations performed with large basis sets. The influence of shell-structure effects, i.e. the filling of the 4f and 5f shell, and relativistic effects on the molecular properties is discussed. The values for the lanthanide and actinide contractions are found to depend strongly on the ligand and to vary from 6 to 11 pm for lanthanides and from 11 to 17 pm for actinides. Relativistic effects play a significant role; for example, their neglect even leads to a slight lanthanide/actinide expansion in the case of the monoxides.

Nonrelativistic and quasirelativistic energy-adjusted ab initio pseudopotentials are presented for element 105 (hahnium, Ha) together with corresponding energy-optimized valence basis sets. The method of energy adjustment of pseudopotentials is extended to a two-component formalism and to multiconfiguration wave functions. The accuracy of the pseudopotential scheme is demonstrated by a comparison of atomic valence-only results to corresponding all-electron data. Atomic multiconfiguration self-consistent field and multireference configuration interaction calculations for M and M+ (M = Nb, Ta, Ha) are compared with available experimental data. Corresponding molecular calculations, which included spin-orbit coupling, have been performed for the lowlying states of H a 0 and are compared to the results from corresponding calculations of the lighter homologs NbO and TaO.

Recently, Benavides-Garcia and Balasubramanian (BB) reported results from calculations on several lowlying states of OsH ( I ) . At the end of their paper appeared a Note Added in Proof, which contains several erroneous statements concerning our previously published paper on the low-lying states of RuH and OsH as well as other species (2). In this comment we wish to correct their statements. First, the classification of our "WB-MRCI(SD) method" as "rather inferior" is unfounded. In our calculations on low-lying states of OsH we used the following methods: state averaged complete-active-space SCF (CASSCF) and subsequent multi-reference CI, including single and double excitations (MRCI(SD)). Our MRCI(SD) calculations included all single and double excitations from every configuration in the CASSCF, which led to up to 680 000 configurations for the low-lying quartet states and up to 170 000 configurations for the sextet states, when our own Wood-Boring-MEFIT pseudopotential ( WB-MEFIT-PP) is used with the corresponding basis set! Compared to the maximum of 3 10 416 configurations used by BB in their SOCI method, which is technically completely equivalent to our MRCI(SD), and bearing in mind that BB not only treated quartet and sextet states but also doublet states in their calculations, their treatment for the former states cannot be "more complete" than ours. Second, the hint on differences between results with our "WB-MRCI( SD) method" and "the HW-RECP method" is misleading. In our MRCI(SD) calculations we compared two relativistically corrected atomic pseudopotentials for OS and corresponding GTO basis sets: a pseudopotential of Hay and Wadt (HW-RECP) (3) and our own WB-MEFIT-PP (4), both substituting the M('-603+-tore orbit& of the 0s atom (the OS pseudopotential of Ross et al. (RP-RECP) (5), used by BB, was not yet published at the time we worked on OsH). We observed that the use ofthe HW-RECP and our WB-MEFIT-PP leads to quite different results for the low-lying states of OsH. We were able to show that these differences arise from shortcomings of the HW-RECP which already exhibits errors for the low-lying states of the OS atom. Therefore it is at least not fair by BB to compare their energy separations with results which we obtained with the HW-RECP. Third, the citation of results from our "WB-MRCI(SD) method" is incorrect. BB compare their SOCI values for the "II ground state of OsH with values reported by us for the 4X_ excited state (an R, value from MRCI( SD) and an w, value from CASSCF). Our correct MRCI( SD) values for R, and w, are 1.569 8, and 2303 cm-', respectively. Furthermore, we did not find a 42 -ground state with our WB-MEFIT-PP at the MRCI( SD) level but only at the CASSCF level. However, the CASSCF calculations were only performed to get a good reference wavefunction for the following MRCI( SD) calculations! At the MRCI( SD) level, the 411 state was found to be lowest, in our calculations. For the 4A-411 and 42--411 energy separations we found term values T, of 5045 and 1503 cm-', respectively-the corresponding SOCI values of BB are 2897 and 3008 cm-'. This discrepancy is discussed below. The single correct statement in BBS Note Added in Proof is the one concerning the neglect of spin-orbit coupling in our investigations on RuH and OsH. This effect was not included, since our main interest was a comparison of the pseudopotentials available for Ru and OS. We now performed additional calculations for OsH with the RP-RECP for OS to extend our comparison and to get an idea what might cause the discrepancies between BBS results and our former results regarding the term sequence of the low-lying quartet states as well as the bond distance of the 4A state. BB found a 411 ground state, followed by a 4A, a 4Z-, and a 4+ excited state. Their quartet states all show quite similar bond distances at the SOCI level. Our results, obtained with the WB-MEFIT-PP at the MRCI(SD) level, also yield a 411 ground state, but the following sequence is 42-, 4@, and 4A. Moreover, we found a bond distance for the 4A state which is greater by 1 I pm than the bond distances for the other quartet states. Unfortunately it was not possible for us to exactly reproduce the calculations of BB-no information is given in their paper on the hydrogen basis set. Moreover, they do not report whether they used s-basis functions on OS or not. Therefore, we assumed that they used the same (5slp)/ [3slp] hydrogen basis set and that they might have used the samef-basis function with an exponent of 0.3 as in their previous work on RuH (6). We first tested the RP-RECP and the basis set ( 7) for their behavior in calculations on the 0s atom. The excitation and ionization energies of the 0s atom, obtained in numerical Hat-tree-Fock or SCF calculations, are less than 0.2 eV off the energies which can be

A summary is given of our recently developed semiempirical pseudopotentials and their applications, and new results are presented on the K, molecule. A core-polarization potential [ 1-31 is incorporated into semiempirical pseudopotentials [46]. The pseudopotential for the atom with core A is

SCF and large scale MRCI calculations using quasi-relativistic energy-adjusted ab initio pseudopotentials for Yb treating the 4f orbitals explicitly in the valence space together with extended basis sets have been performed for low-lying electronic states of YbH and YbF in the K-coupling scheme. Spin-orbit coupling was treated by means of energy-adjusted ab initio spin-orbit operators in connection with quasi-relativistic DGCI calculations in the intermediate coupling scheme. The results for the YbH 4f'%%' *Z+ (Q= l/2) and YbF 4f'40z02~4012~+ (Q= l/2) ground states (YbH: R,=2.074 A. DO= 1.43 e%'. w,= 1276 cm-', YbF: R,=2.045 A. D,,=4.87 eV, 0~~492 cm-') are m excellent agreement with available expenmental data (YbH: R,=2.053 A, Do< 1.93 eV or < 1.55 eV, w,= 1249 cm-'; YbF: I&=2.016 A, D,,=4.80 eV or > 5.36 eV, we=502 cm-'). A combination of Inexpensive pseudopotential molecular orbital calculations includmg the 4f orbitals in the pseudopotential core and subsequent hgand field calculations for the 4f shell is proposed and shown to yield results in satisfactory agreement with those of higher level calculations.

A variety of chemical phenomena are governed by transitions at crossing points of potential energy surfaces of electronic states with different spin multiplicities, if not directly, but indirectly in the midst of the processes. In other words, this intercrossing transition makes one of the most significant key mechanisms in chemical reactivity. Since the basic theory is now available to treat the transitions with appropriate theoretical methods and techniques, it is possible to comprehend the chemical reactivity of chemical systems, ranging from organic, inorganic, as well as realistic model systems of chemical processes in heterogeneous catalysis with the effects of transitions taken into account properly. Furthermore, it becomes feasible to control chemical reactivity by controlling the transitions at crossing points, and also to develop new molecular functions by using peculiar properties of non-adiabatic transitions. These may be realized, if we apply appropriately designed lase...

Ab initio calculations were performed on CH 3CH2OOH, CH3CHClOOH, and CH3CCl2OOH molecules using the Gaussian92 system of programs. Geometries of stable rotational conformers and transition states for internal rotation were optimized at the RHF/6-31G* and MP2/6-31G* levels of theory. Harmonic vibrational frequencies were computed at the RHF/6-31G* level of theory. Potential barriers for internal rotations were calculated at the MP2/6-31G**/HF/6-31G* level. Parameters of the Fourier expansion of the hindrance potentials have been tabulated. Standard entropies ( S°298) and heat capacities ( Cp(T)’s, 300e T/K e 1500) were calculated using the rigid-rotor -harmonic-oscillator approximation based on the information obtained from theab initio studies. Contributions from hindered rotors were calculated by summation over the energy levels obtained by direct diagonalization of the Hamiltonian matrix of hindered internal rotations. Enthalpies of formation for these three molecules were calcula...

Metal oxides have been reported as high capacity anode materials in Lithium-ion batteries (LIBs) but lack merit of commercialization due to volume-expansion during operation and poor electronic conductivity. Nanosized metal oxide could be used to circumvent these demerits. In this work, we examined the application of tin oxide nanoclusters (Sn 3 O z , z = 0, 3-7) as anode materials in LIB using ab initio density functional theory perspective. Analysis of moderately lithiated tin oxide nanoclusters (Li x Sn 3 O z , x = 1-10) indicates a tremendous reduction in volume-expansion due to high surface area of the nanoclusters by analysis of change in Sn-Li bond length with number of lithiation by process of alloying. Structural analysis also revealed the formation of Li 2 O by conversion reaction during lithiation. Stability studies by binding energy (B.E.) during lithiation showed decreased stability as lithiation increased. The role of chemical reactivity concept on the lithiation of Sn 3 O z nanoclusters were revealed by the physicochemical properties of the nanoclusters. Electrophilicity studies reveals the capability of the nanoclusters to accept electrons from the inserted Li. Sn 3 and Sn 3 O 3 nanoclusters were the most suitable anode materials amongst other nanoclusters presented with average intercalation voltage (AIV) of 0.67 and 1.12 V respectively. The adsorption energy (E ads) and dissociation energy (E dis) obtained showed that Li dimer formation can be prevented by these nanoclusters as anode. The calculations substantiate the suitability of tin oxide nanoclusters as anode material in LIBs.

An algorithm for generating novel connectivity topological descriptors, denoted SP (subgraph property), is proposed and exemplified for P being the number of vertices N, walk degree wt'e), Randić index X, and Wiener index W. SP indices based on wt'e) and x wt'e) (Razinger's extension of x index) are tested for correlation with some physico-chemical properties of octane isomers.

By using electrospray ionization mass spectrometry (ESI-MS), it was proven experimentally that the univalent cesium cation (Cs + ) forms with meso-octamethylcalix[4]pyrrole (abbrev. 1) the cationic complex species 1 . Cs + . Further, applying quantum chemical DFT calculations, four different conformations of the resulting complex 1 . Cs + were derived. It means that under the present experimental conditions, this ligand 1 can be considered as a macrocyclic receptor for the cesium cation. ___________________________________________________________________________ The development of ditopic ion-pair receptors and calix[4]pyrrole based anion receptors * Corresponding author.

a -movement of aniomel forward b -movement of bending back. ward * Optimize number of segments to achieve smooth motion * Minimize size and number of SMA wires to minimize energy needs * Control and coordination of multiple elements: maneuverability, rigidity, speed, and buoyancy * Control of temperature (heating & cooling) to maximize frequency response * Mechanical design & fabrication of skeleton, mass distribution system, & mechanism to transfer internal motive forces to external interface with water column

Formation of vacancy-interstitial Frenkel pairs, together with the properties of interstitials and vacancies in CdTe, ZnTe, and their alloys were investigated by first-principles calculations. Generation of Frenkel pairs on the cation sublattice strongly depends on the Fermi energy: the presence of excess free electrons reduces the energy barrier for the pair generation from 2.5 eV in intrinsic samples to 1.2 eV. Moreover, E F determines both the stability of Frenkel pairs with respect to recombination and their binding energy, which varies from ϳ0.2 to ϳ1 eV. A strong dependence on the Fermi energy, i.e., on the charge state, is also found for stable sites and barriers for diffusion of isolated interstitials. In particular, neutral interstitials have two ͑meta͒stable sites, corresponding to two local minima of energy, and diffuse by jumps between them. Positively charged interstitials have only one stable site and diffuse by twice longer and curvilinear jumps. For the relevant charge states, the barriers for diffusion range from 0.5 to 1 eV, which imply a high mobility of interstitials. Most of these properties are traced back to the defect-induced deep gap levels, their occupation, and their dependence on the defect's site. The important role of the ionicity of the host is pointed out. On the other hand, generation of Frenkel pairs on the anion sublattice requires energy of about 5 eV, and thus is nonefficient. The obtained results suggest that formation of Frenkel pairs is a microscopic origin of two effects recently observed in Schottky junctions based on CdZnTe and other II-VI alloys, namely, the reversible changes in conductivity by a few orders of magnitude, and the ferroelectric-like behavior of polarization.

Cytochrome ba3 is a proton-pumping heme-copper oxygen reductase from the extreme thermophile Thermus thermophilus. Despite the fact that the enzyme&#39;s active site is buried deep within the protein, the apparent second order rate constant for the initial binding of O2 to the active-site heme has been experimentally found to be 10(9) M(-1) s(-1) at 298 K, at or near the diffusion limit, and 2 orders of magnitude faster than for O2 binding to myoglobin. To provide quantitative and microscopic descriptions of the O2 delivery pathway and mechanism in cytochrome ba3, extensive molecular dynamics simulations of the enzyme in its membrane-embedded form have been performed, including different protocols of explicit ligand sampling (flooding) simulations with O2, implicit ligand sampling analysis, and in silico mutagenesis. The results show that O2 diffuses to the active site exclusively via a Y-shaped hydrophobic tunnel with two 25-Å long membrane-accessible branches that coincide with th...

Present-day theoretical computation methods are quite effective at anticipating how corrosion inhibitors would behave on metal surfaces, conserving time and resources on laboratory testing. The present study aims to predict the inhibitory effectiveness of certain furan derivatives on surfaces of Fe (110) and Sn (111) in acidic media. To compare their fundamental attributes against corrosion as well as their behavior on iron (Fe) and tin (Sn) surfaces in an acid medium, six urea derivatives have been chosen for this purpose: Imidazolidin-2-one (Cpd A), 4-methylimidazolidine-2-one (Cpd B), Tetrahyropyrimidin-2(1H)-one (Cpd C), 1,3-dimethylimidazolidin-2-one (Cpd D), 1,1-diethylurea (Cpd E), 1,3-dimethylurea (Cpd F). The anti-corrosive characteristics of Cpds A - F were generally explored using Density Functional Theory and Monte Carlo simulations. The results indicate that the compounds had low energy gaps, the highest occupied molecular orbital energy, global hardness, as well as ionization energy and high Electron affinity, ELUMO, global softness, and number of transferred electrons, which explained their corrosion inhibition potentials. Electrostatic potential (ESP) and Fukui indices identified the reactive sites with the ability to accept and donate electrons via back-donation to the metal's d-orbital. The Monte Carlo simulation demonstrated a favorable contact between the Fe (110) and Sn (111) surfaces and inhibitory molecules in the acidic medium. In the industrial sectors, these compounds may be secured as corrosion protectors.

Photochemistry deals with chemical reactions taking place in the presence of light. Immense amount of solar energy received from sun can be utilized for these reactions. The computational investigation of realistic models of organic compounds is becoming a standard practice nowadays. Computer programs can mimic the process of photochemical reactions and predict the outcome of such reactions and thereby, eliminate the need of some lab testing. Current review describes the photochemical reaction from absorption of energy to formation of photoproduct, using computational techniques such as Gaussian 94, MOLCAS, CAS-SCF/MP2 etc. available in standard quantum chemistry packages. This makes computer an important and inseparable tool for chemists and many industrial processes.

Schistosoma mansoni flatworm pathogen, we report further structure activity relationships (SAR) of 19 N-phenylbenzamide analogs. Our previous SAR studies, designed by selecting representative substituents from the Craig plot, identified 9 and 11 which possessed electron-withdrawing groups that benefited potency. This study sought to enhance the potency of this chemotype by incorporating other electron-withdrawing functionalities not studied previously and to overcome the potential pharmacokinetic liabilities associated with the high lipophilicity of frontrunner compounds. Compared to the most potent compound, 9 (EC 50 = 80 nM), from our previous work, the most potent compounds in the current study (32 (EC 50 = 1.17 µM), 34 (EC 50 = 1.64 µM) and 38 (EC 50 = 1.16 µM)) were less active although they retained single digit micromolar potency. Furthermore, compound 38 generated a CC 50 value of > 20 µM in counter toxicity screens using HEK 293 cells, translating to a wide selectivity index of > 17.

Density functional at the B3LYP levels of theory using the Pople's 6-311+G(3df) basis sets and the Dunning's aug-cc-pVTZ correlation consistent basis sets have been employed to determine the enthalpy of formation (∆H f 0 (298)) of CF 3 OOC(O)F at 298 K, using the isodesmic reaction CF 3 OOCF 3 + FC(O)OOC(O)F → 2 CF 3 OOC(O)F. Thus, the B3LYP/6-311+G(3df) and B3LYP/aug-cc-pVTZ methods yield ∆H f 0 (298) values of-273.3 and-273.2 kcal mol-1 , respectively. From the reported ∆H f 0 (298) for CF 3 O• and FC(O)O• radicals, bond energy dissociation (D O-O) values of 38.3 and 38.2 kcal mol-1 are deduced for CF 3 OOC(O)F, which are in agreement with the reported value for related peroxides. Also, calculations for the enthalpy change in the peroxide bond excision reaction were performed at the B3LYP and B3PW91 using several basis sets. The corresponding D O-O values obtained using these enthalpy changes are too low independently of both basis sets and method of calculation used for the calculation.

The aim of this research work is to develop a method to provide a reasonable "prior" electron density that can be used in the so-called "Maximum Entropy Method" (MEM) refinement of Xray diffraction (XRD) data in order to reconstruct experimental electron density at a resolution allowing its accurate topological analysis. A program was developed which build electron density on a regular grid in the "Independent Atom Model" (IAM) approach, more precisely from the knowledge of individual "spherical" atomic scattering factors of the atoms constituting the unit cell of the studied compounds. IAM X-ray structure factors of bismuth and its prior density on a grid has been generated to be tested with the MEM "Enigma" software. Preliminary accuracy and performances have been compared when such reasonable "prior" density is used instead of starting with "flat" density.

The conformational characteristics of calix[4]crown-4 ether have been studied using different quantum mechanical methods. The structures optimized by the HF/6-31G(d), B3LYP/6-31G(d)/ 6-311G(d), MPW1B95/6-31G(d), MPW1PW91/6-31G(d) and M062X methods. The relative stability of different conformers follow the order: cone &gt; partial-cone &gt; 1,3-alternate. Short O-Hπ and intramolecular hydrogen bonds are observed in different conformers of calix[4]crown-4 ether. The relative stability of different conformers is dependent on the number and strength of intramolecular non-covalent interactions.

According to reports, the bioactive thiourea derivative was prepared from the ethanol solutions of thiourea and chloro acetic acid in a 1:1 M ratio. DFT calculations of 2-Imino-4-oxo-1,3-thiazolidine hydrochloride (IOTH) were performed with the use of B3LYP and the 6-311+G(2d,p) basis set. Frontier molecular orbitals, mapped electrostatic potential (MEP) map, and nonlinear optical (NLO) properties of the

The homogeneous phase reaction of [Ru(η 2-RL)(PPh 3) 2 (CO)(Cl)] (1) [η 2-RL is C 6 H 2 O-2-CHNHC 6 H 4 R(p)-3-Me-5 and R is OMe, Cl] with the sodium salts of p-nitrobenzoic acid [NaPNB] and m-nitrobenzoic acid [NaMNB] afforded the complexes of the type [Ru(η 1-RL)(PPh 3) 2 (CO)(PNB)] (2(R)) and [Ru(η 1-RL)(PPh 3) 2 (CO)(MNB)] (3(R)) respectively in excellent yield [η 1-RL is C 6 H 2 OH-2-CHNC 6 H 4 R(p)-3-Me-5]. When 1 was reacted with the nitrobenzoic acid instead of their sodium salt, the Ru─C(aryl) bond cleavage products [Ru(PPh 3) 2 (CO)(Cl)(PNB)] (4) and [Ru(PPh 3) 2 (CO)(Cl)(MNB)] (5) were obtained. The spectral (UV-vis, IR, NMR) and electrochemical data of the complexes are reported. In dichloromethane solution the type 2(R) and 3(R) complexes display two successive quasi-reversible one electron oxidation processes whereas the complexes 4 and 5 display only one oxidation process. The crystal structures of [Ru(η 1-ClL)(PPh 3) 2 (CO)(MNB)] (3(Cl)) and [Ru(PPh 3) 2 (CO)(Cl)(MNB)] (5) are reported, which revealed a distorted octahedral RuP 2 C 2 O 2 coordination sphere for 3(Cl) and RuP 2 CO 2 Cl coordination sphere for 5. The electronic structure and absorption spectra of the complexes are scrutinized by DFT and TD-DFT analyses. The complex 3(Cl) was tested for its ability to exhibit DNA-binding activity.

A new approximation formalism is applied to study the bound states of the Hellmann potential, which represents the superposition of the attractive Coulomb potential −a/r and the Yukawa potential b exp(−δr)/r of arbitrary strength b and screening parameter δ. Although the analytic expressions for the energy eigenvalues E n,l yield quite accurate results for a wide range of n, ℓ in the limit of very weak screening, the results become gradually worse as the strength b and the screening coefficient δ increase. This is because that the expansion parameter is not sufficiently small enough to guarantee the convergence of the expansion series for the energy levels.

In this account, the energy properties (total electronic energy, zero point energy correction, thermal energy correction, the change in DH f 0 on going from 0 to 298 K, atomization energy, and frontier orbital energies), dipole polarizability, and several important bands in the UV spectra (p, a, and b bands) of linear and zigzag BN-acenes and their corresponding cyclic structures have been calculated at several levels of theory. Various correlations have been reported among these properties for BN-acenes and cyclo BNacenes versus the total number of electrons and the number of rings as well. It has been demonstrated that all studied molecular properties of these series, change linearly with the number of ring as well as the number of electrons, except for frontier molecular orbital energies and excitation energies between them (UV bands). The linear changes of these properties with the number of rings and the total number of electrons were used to generate fit equations. Extracting these equations makes it possible to estimate aforementioned properties for large homologues of the series which satisfy chemical accuracy, yet requiring much less computational work. Also, it has been found that, the quality of the linear equations (values of linear correlation coefficients) with respect to either the number of electrons or rings is insensitive to the combination of methods and basis sets employed to derive the mentioned molecular electronic properties.

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In an attempt to synthesize potent blockers of the influenza A M2 S31N proton channel with modifications of amantadine, we used MD simulations and MM-PBSA calculations to project binding modes of compounds 2-5, which are analogues of 1, a dual blocker. Blocking both the S31N mutant and the wild type (WT) M2, 1 is composed of amantadine linked to an aryl head group, (4-methoxy-2-hydroxy)-benzyl. Compound 6, used as control, has an 3-(thiophenyl)isoxazolyl aryl head group, and selectively blocks M2 S31N (but not WT) in an aryl head group “out” (i.e. N-ward) binding orientation. We then tested 1-6 as anti-virals in cell culture and for M2 binding efficacy with electrophysiology (EP). The new molecules 2-5 have a linker between the adamantane and amino group which can be as small as a CMe2 in rimantadine derivative 2, or longer like phenyl in 3. Alternatively, we explored the impact of expanding the diameter of adamantane with diamantyl or triamantyl in 4 and 5, respectively. Antiviral ...

This paper presents an application of the reaction class transition state theory (RC-TST) to predict thermal rate constants for hydrogen abstraction reactions of the type C 2 H 3 + alkane f C 2 H 4 + alkyl radical. The linear energy relationship (LER) was proven to hold for both noncyclic and cyclic hydrocarbons. We have derived all parameters for the RC-TST method from rate constants of 19 representative reactions, coupling with LER and the barrier height grouping (BHG) approach. Both the RC-TST/LER, where only reaction energy is needed, and the RC-TST/BHG, where no other information is needed, can predict rate constants for any reaction in this reaction class with satisfactory accuracy for combustion modeling. Our analysis indicates that less than 90% systematic errors on the average exist in the predicted rate constants using the RC-TST/ LER or RC-TST/BHG method, while in comparison to explicit rate calculations, the differences are within a factor of 2 on the average.

This work was made using the density functional theory (DFT) computational method, applying it to a graphene-doped theoretical structure with iron atoms, studied as an isolated molecular system in aqueous medium, using the functional GGA PW91, under Material Studio computational platform, to get the chemical reactivity properties of graphene doped with iron (called Fe-G) that can provide knowledge of binding of biomolecules such as peptides, enzymes, and lipids. We present some electrochemistry properties such electron affinity (EA) and ionization potential (IP). The chemical reactivity was characterized by global indicators such as, chemical potential, chemical hardness, and chemical electrophilicity index. In order to find the zones most prone to nucleophilic, electrophilic, and radical attacks, the calculation of the HOMO-LUMO boundary orbital was carried out, and the corresponding energies were obtained. Local reactivity was studied by using local selectivity descriptors such as Fukui indices.

A series of oligofluorenes bearing 3,6-dipyrenylcarbazoles as the terminal substituents showed strong blue emission with good solubility, and thermally stable amorphous and excellent film-forming properties. OLEDs using these materials exhibited excellent device performance.

To evaluate the potency of two pyridine chalcone derivatives, CHA and CHB, against breast cancer, their inhibitory activities were assessed on four different cancer cell lines (6CZ2, 6CZ3, 6CZ4, and 5TWU) using the docking and scoring method. The binding energies of CHA on the four receptors were found to be-8.0,-8.5,-8.6, and-8.3 kcal/mol, respectively, and for the CHB ligand, they were-7.9,-8.3,-8.0, and 8.1 kcal/mol. A standard breast cancer drug, exemestane, was also docked with these cancer cell lines, yielding binding energies of-8.1,-8.9, 8.9, and-8.4 kcal/mol, respectively. Both ligands demonstrated good conformity with the standard drug, with CHA exhibiting higher binding energy than CHB. Additionally, both compounds adhere strictly to the Rule of Five (Lipinski's rule), suggesting that these drug-like compounds may be suitable for oral administration.

Phenothiazine sensitized solar cells: Effect of number of cyanocinnamic acid anchoring groups on DSSC performance Shivaraj Yellappa, [a,b] Whitney A. Webre, [a] Habtom B. Gobeze, [a] Anna Middleton, [a] Chandra B. KC, [a] and Francis D'Souza *[a] Dye-sensitized solar cells (DSSCs) were built to probe the effect of number of cyanocinnamic acid anchoring groups on the ring periphery of phenothiazine dyes. Two kinds of dyes, one having substitution on the N-terminal (1) and the other at the C-3 aromatic ring (2-5) have been synthesized for this purpose. Additionally the number of cyanocinnamic acid groups have been increased to two in the case of compound 6. The N-terminal in the case of compounds 2-6 was functionalized to carry either a methyl, 2-hydroxyethane, tris(ethylene oxide) and hexyl group. Evidence for charge injection from the excited singlet state of phenothiazine to TiO2 was secured from femtosecond transient absorption spectral studies wherein ultrafast charge injection process (kCI ~ 10 10-10 11 s-1) was witnessed. The DSSCs were built on nanocrystalline TiO2 using the traditional two-electrode method. Cell performance was found to be better for Cfunctionalized phenothiazine dyes compared to N-functionalized ones, and having the second cyanocinnamic group increased the efficiency to 5.8 %.

Dye‐sensitized solar cells (DSSCs) were built to probe the effect of the number of cyanocinnamic acid anchoring groups on the ring periphery of phenothiazine dyes. Two kinds of dyes, one with substitution on the N‐terminal (1) and the other at the C‐3 aromatic ring (2–5), have been synthesized for this purpose. Additionally, the number of cyanocinnamic acid groups have been increased to two in the case of compound 6. In the case of compounds 2–6, the N terminus was functionalized to carry methyl, 2‐hydroxyethane, tris(ethylene oxide), or hexyl groups. Evidence for charge injection from the excited singlet state of phenothiazine to TiO2 was secured from femtosecond transient absorption spectral studies, wherein an ultrafast charge injection process (kCI≈1010–1011 s−1) was witnessed. The DSSCs were built on nanocrystalline TiO2 by using the traditional two‐electrode method. Cell performance was better for carbon‐functionalized phenothiazine dyes compared with that of nitrogen‐function...