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Chromenes and their derivatives have been considered as an important class of oxygen-containing heterocycles. There has been an increasing interest in the study of chromenes due to their biological activity. Herein, the structural, electronic, and vibrational properties of a chromene derivative, entitled 2‐amino‐5‐oxo‐4‐phenyl‐4,5‐dihydropyrano[3,2‐c]chromene‐3‐carbonitrile and abbreviated as Chrom-D, have been reported. The FT-IR, UV-vis, and 1H-NMR and 13C-NMR chemical shifts’ measurements were recorded. The molecular geometry and the vibrational frequencies are computed in the frame of density functional theory at the B3LYP/6-311++G(d,p) level of theory. The noncovalent interactions in the crystal lattice which are responsible to the 3D crystal structure of Chrom-D are investigated based on Hirshfeld surfaces and topological reduced density gradient (RDG) analysis. Molecular electrostatic potential surface, Mulliken charges, and Fukui functions are computed in order to find out the electrophilic and nucleophilic sites. The electronic properties of the title compound have been studied based on the TD-DFT calculations. Finally, Chrom-D has been evaluated as a multifunctional agent against Alzheimer’s disease (AD).

The structural and energetic proprieties for the Li

This study reports the combination of new statistical physics models and density functional theory (DFT) for the analysis and understanding of the adsorption of heavy metals on a flamboyant biomass-based adsorbent. Single and ternary isotherms of the adsorption of Pb2+, Hg2+ and Zn2+ ions on an adsorbent obtained from the pyrolysis of flamboyant biomass were determined experimentally at pH 5 and 298–313 K. Experimental studies showed that the adsorption of Hg2+ on flamboyant char was higher than those of Zn2+ and Pb2+ in both single and ternary solutions. A strong antagonistic effect for the multicomponent adsorption of Zn2+ was identified due to the presence of other competitive metal ions in the ternary solution. The endothermic adsorption mechanism involved in both mono- and multi-metallic solutions was explained via the integration of the results from the adsorbent physicochemical characterization and calculations using statistical physics models and density functional theory. Theoretical studies showed that the single-compound adsorption of heavy metals correlated with the calculated DFT binding energies of oxygen-containing functionalities of flamboyant surface. On the other hand, the electronegativity and the thermodynamic stability of the metal – active site complexes determined the adsorbent selectivity and adsorption capacities in the simultaneous removal of these heavy metals. In particular, the carboxylic functional groups of flamboyant char were the main active sites involved in the adsorption of these heavy metals in both mono- and multi-component aqueous solutions. These new findings contribute to a deeper understanding of the mechanisms involved in the multicomponent adsorption of relevant water pollutants such as heavy metals using carbon-based adsorbents.

Herein, we have investigated the key functions of the calix[4]arene, abbreviated as CX [1], and designed its several derivatives by substitution of the functional groups. Molecular geometry provides an intuitive understanding of the effect of functional groups on various physical properties. The addition of the N-beta -ketoimine (n=1-4) ligands has a direct effect on the stretching vibration of the H-bonding interaction. The results showed that all molecules possess absorption bands at 190 nm and in the range between 200 and 300 nm assigned to pi-pi* and n-pi* transitions. HOMO-LUMO energy gap of the CX[4]-N-beta -ketoimine, one with chemical hardness of 1.62 eV, has been found to be 3.24 eV calculated at B3LYP/6-31+G(d) level of theory. This finding explains the good kinetic stability of this compound. The large values of electrophilicity make the current molecules as a good electrophilic species. The atom in molecule (AIM) and the reduced density gradient (RDG) analyses showed the type and the strength of the interactions taking place between Cu2+ and the beta -ketoimine ligands. Tunisian's Ministry of high education and scientific research The authors acknowledge financial support from the Tunisian's Ministry of high education and scientific research. WOS:000608022300002 2-s2.0-85098997128 PubMed: 33409596

Microsolvation of a cation in helium quantum solvent is an attractive phenomenon leading generally to the formation of a strongly packed structure known as ‘Snowball’ feature. Here, the lowest energy structures and the relative stability of the solvated potassium cation K+ in helium clusters K+Hen up to the size n = 20 are investigated employing Density Functional Theory (DFT) and pairwise methods. The DFT calculations showed that M05–2X/6–311++G (3df, 2p) level of theory can reproduce properly the experimental data of K+He diatomic potential, whereas, in the pairwise method, the Basin-Hopping Monte Carlo (BHMC) algorithm was applied for the global optimization. The remarkable differences in the lowest energy structures computed in the frame of both methods are shown for K+He11 and K+He12 clusters. The BHMC optimization converged to an icosahedral geometry for n = 12, corresponding to the highest value of the binding energy per atom. For both methods, we have concluded that the first solvation shell is completed at the size n = 15, despite the maximum packing structure obtained at n = 17. Finally, the stability of the potassium doped helium cluster is discussed based on the Density Of States (DOS) curves.

The calix[4]arene molecule, abbreviated as CX[4], is known by the four phenolic groups and a hydrophobic cavity able to enclose small molecules. The interactions between CX[4] and NO3, NO2, CO2, and N2 gas molecules have been studied. These guest species are placed inside and outside the cavity of the host molecule CX[4]. The formation of H-bonding has been deeply discussed based on the infrared spectrum and the polarizability analysis. Global and local indices have been calculated for a series of gas (NO3, NO2, CO2 and N2) in interaction with the CX[4] molecule to explain the electrophilic or nucleophilic activations in endo-vs. exo-cavity interaction zone. As expected, there is a correlation between the proposed global electrophilicity and global nucleophilicity together for an explanation of the chemo-selectivity region. Finally, the topological parameter analyses of the host-guests interactions have been estimated by using DFT calculations., Physical chemistry, Theoretical chemistry, Calix[4]arene, Hydrogen bond, Electro-philic and nucleophilic sites, Polarizability, Interaction energies

Density Functional Theory (DFT) calculations was performed to highlighted the effects of Carbon nanospheres (CNSs) on the properties of Poly (N-vinylcarbazole) (PVK) as well as the charge transfer between them. This study is based on the diameter and number of CNSs as well as the distance between PVK and CNSs. First, a charge transfer between the PVK and the CNSs is observed and the properties of the obtained composites depend strongly not only on the diameter of CNSs but also on the distance between PVK and CNSs. Theoretical absorption spectra and charge transfer of modeling composites configurations have shown a decrease and a redshift whenever the number of CNSs is increased. Non covalent interaction governed by Van Der Waals interaction have making evidence by NBO, AIM and RDG analysis.

International audience; Calix[n]arenes (abbreviated as CX[n]) are the macro-molecules based on phenol groups with a hydrophobic cavity to encapsulate a gas or small molecules. They are used as molecular vehicles. For instance, these molecules are used in the activation of the solubility of monomers in the specific media and in pharmaceutical drug delivery. The limit of the development of gaseous pollutants will be a vital subject in the future. The polluting gases NO3, NO2, CO2, N2, etc., need cage molecules, such as CX[4], to be encapsulated. In this report, the red shift of the H-bonding interactions of the CX[4]-gas (by adding the gas inside or outside the cavity) is clearly explained by the vibrational analysis. The electronic spectra of the complexes of CX[4] with NO3, NO2, CO2, and N2) exhibit a blue-shift pick in comparison with the ones observed for the CX[4] molecule. The electrophilic and nucleophilic sites of the stable host-guest have been investigated. Additionally, the non-covalent interactions have been calculated based on the reduced density gradient RDG and QTAIM theory.

Calix[n]arenes (abbreviated as CX[n]) are the macro-molecules based on phenol groups with a hydrophobic cavity to encapsulate a gas or small molecules. They are used as molecular vehicles. For instance, these molecules are used in the activation of the solubility of monomers in the specific media and in pharmaceutical drug delivery. The limit of the development of gaseous pollutants will be a vital subject in the future. The polluting gases NO

The lowest energy structures and relative stabilities of pure and sodium-doped helium clusters Na+Hen have been determined using DFT calculations. Firstly, a series of DFT functionals have been tested by the calculation of the potential energy curve of the Na+–He system in order to find the most suitable and reliable method for studying the Na+Hen clusters. The calculations showed that the M05-2X functional combined with the extended polarized and diffused Pople basis set 6-311++G(d,p) reproduce correctly the experimental Na+–He potential energy curve. Hence, the most stable geometries of Na+Hen clusters up to n = 20 have been optimized at M05-2X/6-311++G(d,p) level. An icosahedral geometry is obtained for the Na+He12 ensuring the closure of the first solvation shell and forming the so-called ‘Snowballs’ feature. The relative stabilities of the Na+Hen clusters are discussed on the basis of the dependence of the binding energy, fragmentation energy and second-order difference of energy as well as the HOMO–LUMO energy gap with the size of the clusters. The clusters Na+He8, Na+He9 and Na+He12 are found to be relatively more stable than their neighbors. The snowball formation was explained through natural population analysis. The non-covalent interaction NCI analysis was performed on the basis of the reduced density gradient RDG. Finally, binding enthalpy, entropy and Gibbs free energy are calculated and showed that the formation process of Na+Hen clusters is endothermic.

In this work, the structures, quantum chemical descriptors, morphologic characterization of the azomethoxy-calix[4]arene were investigated. The analyses and interpretation of the theoretical and the experimental IR spectroscopy results for the corresponding compounds was performed. The complexation of the azo-methoxy-calix[4]arene with Zn2+, Hg2+, Cu2+, Co2+, Ni2+, Pb2+ and Cd2+ metal cations has been calculated by the dispersion corrected density functional theory (DFT-D3). The values of the interaction energies show that the specific molecule is more selective to the Cu2+ cation. The study of the reactivity parameters confirms that the azo-methoxy-calix[4]arene molecule is more reactive and sensitive to the Cu2+ cation than that Co2+ and Cd2+. In addition, the investigation of the electrophilic and nucleophilic sites has been studied by the molecular electrostatic potential (MEP) analysis. The Hirshfeld surface (HS) analysis of the azo-methoxy-calix[4]arene-Cu2+ interaction have been used to understand the Cu...hydrogen-bond donors formed between the cation and the specific compound. The Quantum Theory of Atoms in Molecules (QTAIM) via Non covalent Interaction (NCI) analysis was carried out to demonstrate the nature, the type and the strength of the interaction formed between the Cu2+ cation and the two symmetrical ligands and the cavity. Finally, the chemical sensor properties based on the Si/SiO2/Si3N4/Azo-methoxy-calix[4]arene for detection of Cu2+ cation were studied. Sensing performances are determined with a linear range from 10(-5.2) to 10(-2.2) M. The Si/SiO2/Si3N4/azo-methoxy-calix[4]arene structure is a promoter to have a good performance sensor. (C) 2021 Elsevier B.V. All rights reserved. Tunisian's Ministry of high education and scientific research The authors acknowledge financial support from the Tunisian's Ministry of high education and scientific research. We thanks to, M.E.C. and F.J.M. Laboratorio Nacional de Supercomputodel Sureste de Mexico (LNS-BUAP) of the CONACyT network of national labora-tories for the computer resources and support provided. We thank to, Dr. Arzu Karayel and Dr. Sevil ozknal for the theoretical calcu-lations of the azo-methoxy-calix [4] arene-cations complexes. WOS:000701648800003 2-s2.0-85111808860 PubMed: 34358783

By changing the synthesis method and through the pourbaix diagram, a novel 0D organic−inorganic hybrid like perovskite system was crystallized by slow evaporation in an aqueous solution of 2-(aminomethyl) pyridine (2-amp) and tin chloride. Compound with the formula (C6H10N2)[SnCl3]Cl was characterized by single-crystal X-ray diffraction, Infrared spectroscopy (IR), and UV-Visible (UV-Vis) as well as photoluminescence (PL) technique and thermal analysis. The crystals of (C6H10N2)[SnCl3]Cl belong to the orthorhombic system with the Pbca space group. The crystalline stability is ensured by a three-dimensional network of N-H…Cl hydrogen bonds. Theoretical calculations were performed using density functional theory with the B3LYP/LanL2DZ level for studying the molecular structure and vibrational spectra of the title compound. A satisfactory agreement has been found between the calculated and the experimental vibrational frequencies. UV-Vis reveals that (C6H10N2)[SnCl3]Cl undergoes two absorption bands with an energy gap estimated to 3.27 eV. The material exhibits an important broad-band white light emission with a correlated color temperature of 4989 K with chromaticity coordinates (CIE) of (0.34, 0.33) and CRI of 92. According to others s2 Tin-complexes, this emission is mainly resulting from the self-trapped exciton transitions within the inorganic framework. Our contribution of luminescent 0D organic-inorganic hybrid materials as lead-free lighting systems opens up a new paradigm in functional materials design.

Van der Waals interactions between the valence electrons of the barium atom and the closed-shell cores have been studied using ab initio methods with a combination of pseudopotentials and core polarisation potential. We have reported the potential energy curves, the spectroscopic constants, the vibrational levels as well as the electric dipole moments for the ground and several excited states of Ba+Kr and BaKr complexes. Interesting behaviour has been observed in the potential energy curves, particularly for Σ+ states. This can show the strong repulsive interactions between Rydberg electrons and the Krypton atom.

In this work, a structural and electronic properties of 4-methoxybenzaldehyde (4MBA) have been presented. The density functional theory (DFT) along with B3LYP hybrid functional is employed. The optimized structure was found to be in well consistent with the X-ray diffraction geometry. The 4MBA crystal is stabilized by C-H⋯O intermolecular interactions along with π⋯π interactions. Various intermolecular interactions involved in 4MBA crystal have been analyzed deeply through topological atom-in-molecules (AIM) analysis and noncovalent interactions (NCI) method. Besides, Hirshfeld surface (HS) analysis and fingerprint plots are performed to determine the contribution of intermolecular contacts in 4MBA crystal packing. The electronic properties of the title compound have been investigated. Nonlinear optic (NLO) properties of 4MBA have been interpreted through the calculated first hyperpolarizability value. 4-substituted benzaldehydes, including 4MBA, are known with their competitive inhibitory activity on Tyrosinase, which also known as polyphenol oxidase (PPO). This enzyme is a rate limiting enzyme that controls the production of melamine and brown coloring of foods. Thus, molecular docking behaviors of 4MBA are presented in comparison with that of benzaldehyde (BA), 4-ethylBA, 4-tertbutylBA, 4-isoprophylBA, 4-propoxyBA, 4-butoxyBA, and Hexylresorcinol on four selected PPOs from sweet potato, grape, and mushroom. © 2018 Elsevier B.V.

In this work, the electronic behavior, charge transfer, non linear optical (NLO) properties, and thermal stability of the quinoline phosphate (QP) have been investigated. The experimental UV–Vis spectrum has been recorded in the range of 200–800 nm. Additionally, the absorption spectrum was reproduced by time-dependent density functional theory (TD-DFT) method with B3LYP functional and with empirical dispersion corrections D3BJ in combination with the 6–311+G(d,p) basis set. The electronic properties such as HOMO-LUMO energy gap and chemical reactivity have been calculated. The electrochemical characterization of the title compound is investigated using cyclic voltammetry and impedance spectroscopy methods. Finally, the thermal stability of the QP is discussed in term of differential scanning calorimetry (DSC) measurement, which showed that QP compound is thermally stable up to 150 °C.

Using ab-initio adiabatic calculation, we studied the electronic properties of the LiNe molecule. In our calculation, we investigate the adiabatic potential energy curves (PECs) of numerous 2Σ+, Π and Δ electronic states. Then, we derive spectroscopic constants, as well as their vibrational levels spacing. For the 2Σ+ states, we determined the permanent and transition dipole moment (PDM and TDM). Our approach is based on the full configuration interaction (FCI), an effective core potential (ECP) which describes the valence electron of the molecule, and the core polarization potential (CPP). Using a large Gaussian basis set, a full configuration interaction is easily carried out.

The crystal structure of (C9H7N) H3PO4 (QP) was determined from single crystals obtained by slow evaporation methods (space group Pī; a = 7.5508(3) A, b = 7.9705(3) A, c = 8.6849(3) A; α = 77.3725(18)°, β = 82.6225(19)°, γ = 74.9829(19)°). The crystal structure of QP is built up from infinite hydrogen bonding inorganic chains of (H3PO4)n lay parallel to the an axis, which are also connected to the quinoline rings through hydrogen bonds in a 3D arrangement. The structure was examined through atoms in molecules (AIM) topological and Hirshfeld surface (HS) analyses and its molecular structure optimized by theoretical density functional (DFT) calculations. The QP observed IR absorptions between 4000 and 400 cm −1 were assigned on the basis of the calculated theoretical vibrational modes.

Understanding the interactions of the cage molecules with a variety of invited molecules is getting very important. But, the hydrogen bonds can also play a crucial role in the interaction phenomenon. In this work, natural population analysis (NPA), chemical shifts, and atom in molecules (AIM) analysis have been used to identify the role of hydrogen bonds in the stability of CX[n] molecules. According to our calculation, the 13C NMR spectra are also sensitive to the nature of hydrogen bonds. We note that the DFT calculations have reproduced with a very good agreement, the experimentally observed chemical shifts of CX[4].

Understanding the interactions of the calix[n]arene molecules with a variety of invited chemicals entities is getting very important. In this context, we have studied a new host-guest such as the interaction of the calix[4]arenes with the bis (trifluoromethylsulfonyl) imide TFSI− ion. The energy gap has decreased from 3.53 eV to 2.11 eV indicating the reliability of the electrochemical evaluation of HOMO and LUMO energy levels. In a predominant number of cases, we obtain the spatial accumulation of HOMO and LUMO at the interface of phenol groups. Then, according to the QNBO charge distribution of these host-guests interactions, we have demonstrated the direction of charge transfer between the CX[4] molecule and the TFSI− ion. More importantly, the non covalent interactions (NCI) have been investigated that the endo-cavity position of the TFSI-4 is the most stable position between all these host-guests. By using DFT quantum methods, we have identified as a suitable host for TFSI− which can be used in the electronic technology., Materials Chemistry, TFSI- ion, electronic proprieties, gap energy, TD-DFT, Non covalent interactions.

The structural properties and relative stabilities of the Na+Nen clusters, with n = 1–16, have been investigated by using pairwise and density functional theory (DFT) methods. The DFT calculations have been carried out using the M06-2X functional combined with the augmented aug-cc-pVTZ basis sets. For both methods, the high stability is obtained for Na+Ne12 cluster with an icosahedral structure, and the twelve Ne atoms complete the first solvation shell around the Na+ cation. Therefore, the icosahedral Na+Ne12 structure will be considered as the core for the larger sizes. The relative stabilities have been studied in terms of the binding energies, second-order difference of energies, fragmentation energies and HOMO–LUMO energy gaps. The Na–Ne interactions within the Na+Nen clusters in relation to the relative stabilities have been discussed through topological atom-in-molecules and reduced density gradient analyses. Finally, the relative stabilities of the Na+Nen clusters have been discussed topologically.

The shape, size and diameter of the cavities are one of the main factors which control the interactions of the calix[n]arene molecules with cation, anion or neutral guests in sensor applications. In this work, vibrational spectroscopy analysis, molecular electrostatic potential (MEP) surface, atom in molecules (AIM) and thermochemical properties were used to check the reorganizations of hydrogen bonds in such cavity shape for the improvement of physical proprieties of CX[n] molecules. We have demonstrated that the hydrogen bonds O···H and the angles O–H···O of CX[n = 4, 6, 8] play the role of the moderator or modifier of the cavity. MEP topography reveals that the cavity form of CX[8] is less hydrophilic as compared to those of CX[4] cavity. The QTAIM theory showed that CX[4] and CX[8] has a more symmetric and well-organized cavity than CX[6]. It was also shown that the hydrogen bond enhanced the topographic parameters in CX[n] at the lower edge levels.

In this research work, our central focus is upon a novel organic-inorganic hybrid material with an efficient broadband green light emission based on a tin halide (C6H10N2)[SnCl6] of the general formula AMX6 (A= Organic cation; M= Metal other than lead and X= Halogen). This compound was grown by slow evaporation technique in an aqueous solution and was characterized by X-ray diffraction, infrared spectroscopy (IR), UV-Visible (UV–Vis), photoluminescence technique and thermal analysis. X-ray investigation demonstrates that this compound crystallizes in the monoclinic system with the space group P21/c. The optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the title compound were theoretically carried out using density functional theory (DFT) with the Becke three parameter, Lee Yang Parr (B3LYP) and Los Alamos National Laboratory 2 Double-Z (LanL2DZ) (B3LYP/LanL2DZ) level. Calculated and experimental results go in good correlation. The optical study on (C6H10N2)[SnCl6] revealed two absorption bands with an energy gap equal to 3.56 eV. Photoluminescence measurements exhibited a strong emission at 530 nm at room temperature.

A general quantum theoretical approach of the υX-H IR lineshape of cyclic dimers of moderately H-bonded species in the crystalline phase is proposed. In this model, the adiabatic approximation is performed for each separate H-bond bridge species of the dimer, a strong non-adiabatic correction is introduced into the model via the resonant exchange between the fast mode excited states of the two moieties, the intrinsic anharmonicity of the low-frequency mode through a Morse potential, direct and indirect damping, and a selection rule breaking mechanism for forbidden transitions in IR. The present model reduces satisfactorily to many models in the literature dealing with more special situation. It has been applied to the cyclic dimers of 2-thiopheneacetic acid (2-TAA) and his deuterated derivative in the crystalline phase. It correctly fit the experimental line shape of the hydrogenated compound and predicts satisfactorily the evolution in the line shapes with isotopic substitution. Numerical calculations show that mixing of all these effects allows one to reproduce satisfactorily the main features of the experimental IR line shapes of hydrogenated and deuterated 2-TAA crystals and is expected to confirm the importance of the Fermi resonances and Davydov coupling in reproducing the experimental spectra, Moroccan Journal of Chemistry, Vol 5, No 3 (2017)

In the present work, we reported a structural investigation of liquid ethylene glycol (EG) at 298 K and atmospheric pressure via neutron scattering and DFT calculation. Original scattering data at large scattering wave vectors were analyzed to deduce the structure factor SM(q), the molecular form factor F1(q) and the intermolecular pair correlation function gL(r). A large variety of hydrogen-bonded dimers and trimers has been considered in order to describe the intermolecular arrangement of the liquid EG. Natural bond orbital (NBO) and atoms-in-molecules (AIM) analyses have been performed to get insight about the nature of hydrogen bond between EG molecules. Complete vibrational assignments and analysis of fundamental modes of the more probable clusters were performed on the basis of potential energy distribution (PED) calculations and the available experimental infrared and Raman spectra in the liquid phase.

The adsorption of the methylene blue on the biomass obtained from brazilian berries seeds was studied. Experimental adsorption data and results of the physicochemical characterization of the adsorbent besides theoretical physics-based calculations were utilized to understand the dye adsorption mechanism. A monolayer adsorption model was proposed to simulate the dye adsorption assuming an interaction adsorbent + adsorbate via two different functional groups on biomass surface. This statistical physics model calculated the number of bonded MB dye molecules and the saturated adsorption capacity for both functional groups at different temperatures. For instance, the values of n1 and n2 were 0.34 and 0.51 at 298 K thus indicating that MB molecules interacted via a horizontal adsorption orientation with two and three functional groups of biomass surface. Calculations based on statistical physics and density functional theory characterized the role and relevance of proposed functional groups on dye adsorption including its thermodynamic parameters. Results demonstrated that the hydrogen and oxygen functionalities of biomass surface were the main responsible functional groups for dye adsorption. Therefore, this paper reports new findings to understand the adsorption mechanism of dye molecules on lignocellulosic biomasses.

Structural study and relative stabilities of Li+-doped helium clusters Li+Hen (n = 1–18) has been reported in this work using two theoretical protocols. The first one is based on the basin-hopping optimization technique, where the total energy of each cluster is described by an additive model describing Li+-He and He–He interactions. The second one is the DFT calculations, in which the initial structures are generated by ABCluster algorithm and CALYPSO software. The CSA shape was found where the first solvation shell is completed at n = 10. The relative stabilities of Li+Hen (n = 1–18) clusters have been discussed based on the variation of the binding energy, second-order difference in energy, fragmentation energy and HOMO-LUMO energy gap as a function of the cluster size. The results showed that Li+He10 is the most stable cluster. The dipole moment is calculated and showed the polar character of the Li+Hen clusters. Finally, the interatomic interactions have been examined topologically by the means of AIM and non-covalent reduced density gradient (NC-RDG) analyses.

This study has focused on the recovery of grape bagasse biomass to prepare new adsorbents for the removal of mercury from aqueous solutions.

The structures and relative stabilities of the Ca2+Xen (n = 1–18) clusters have been carried out using two methods: the pairwise/Monte Carlo Basin-Hopping and density functional theory methods. The lowest energy structures have been determined using classical energy minimization method where the total interactions have been obtained as a sum of pairwise potentials. The DFT calculations have been performed using the dispersion-corrected functional B97D3. For both methods the stable structures are characterized by the Ca2+ being coated by a shell of xenon atoms. For the smallest sizes n

In this work, electronic properties of alkali atoms interacting with helium rare gas (CsHe and RbHe) are studied through a full configuration interaction calculation, in cooperation with a pseudopotential approach and core polarization potential. The adiabatic potential energy curves for the ground state and numerous excited states of CsHe and RbHe systems are investigated. The corresponding spectroscopic constants such as equilibrium distance Re, well depth De, vibrational constant ωe, anharmonic constant, rotational constant Be, and transition energy Te as well as the vibrational levels of all electronic states are computed. Finally, permanent and transition dipole moment curves for the sigma states are determined and analyzed.

Density functional theory (DFT) calculations are performed to study the conformations, hydrogen-bonding network, and the stabilities of all possible molecular associations, urea–(H 2 O) n , ( n = 1–5) in aqueous solutions of urea. The B3LYP functional and the basis set 6-311++G(d, p) are used through the calculations. Natural bond orbital (NBO) theory and atoms in molecule (AIM) analysis are applied to quantify the relative strength of hydrogen bond interactions and to account their effect on the stabilities of molecular arrangements. The charge transferred from lone pair of the hydrogen bond acceptor to antibonding orbital of the donor provides the substantial stabilizing component of the hydrogen bond. The energy analyses prove that O H⋯O interactions between water molecules give more stability of the clusters. The hydrogen bonded structure is found to be slightly influenced by the presence of urea molecules.

This study is interested in the illustration of ab initio potential energy curves for Ba+Arn (n = 1–4) clusters. The electronic structures of these molecules are calculated using [Ba2+] and [Ar] non-empirical core pseudo-potentials complemented by the core polarisation operators for both atoms, which allow the consideration of core valence correlation effects. The structure and stabilities of Ba+Arn (n = 1–4) clusters are investigated. These molecules are treated as one-electron active system. Spectroscopic constants and vibrational energy levels have been derived from their potentials. The analysis of the geometric forms, basing on the potential energy curves and the spectroscopic constants, clearly shows the importance of rare gas induced dipole. We also show that the dipolar interactions can influence the coupling between atoms.

In this work, the molecular structures and vibrational spectral analyses of 3-(2-Theinyl)acrylic acid (3-2TAA) monomer and dimer structures have been reported by using density functional theory calculations at B3LYP/6-311++G(d,p) level of theory. The complete assignments of the fundamental vibrational modes were obtained using potential energy distribution. Intermolecular interactions were analyzed by orbital NBO and topological AIM approaches. The electronic properties have been carried out using TD-DFT approach. Great agreements between experimental and theoretical values were achieved throughout the analysis of structural parameters and spectroscopic features. Inhibitor characteristics on human monoamine oxidase B (MAOB) enzyme of two determined stable conformers of 3-2TAA (β and γ) along with four selective inhibitors, namely safinamide, a coumarin analogue, farnesol, and phenyethylhydrazine were investigated via molecular docking. Moreover, molecular electrostatic potential (MEP) and temperature dependency of thermodynamic functions have been reported. © 2016 Elsevier B.V.

In this work, theoretical studies on the structure, molecular properties, hydrogen bonding, and vibrational spectra of the N-methylformamide–water (NMF···3H2O) complex will be presented. The molecular geometry was optimised by using Hartree–Fock (HF), second Moller–Plesset (MP2), and density functional theory methods with different basis sets. The harmonic vibrational frequencies are computed by using the B3LYP method with 6-311++G(d,p) as a basis set and then scaled with a suitable scale factor to yield good coherence with the observed values. The temperature dependence of various thermodynamic functions (heat capacity, entropy, and enthalpy changes) was also studied. A detailed analysis of the nature of the hydrogen bonding, using natural bond orbital (NBO) and topological atoms in molecules theory, has been reported.

The structural and vibrational properties of cyclic dimer of 2-furoic acid (2FA) were predicted by combining the available experimental infrared and Raman spectra in the solid phase and ab initio calculations based on density functional theory (DFT) with Pople's basis sets. The calculations show that there are two cyclic dimers for the title molecule that have been theoretically determined in the gas phase, and that only one of them, cis conformer, is present in the solid phase. The complete assignment of the 66 normal vibrational modes for the cis cyclic dimer was performed using the Pulay's Scaled Quantum Mechanics Force Field (SQMFF) methodology. Four strong bands in the infrared spectrum at 1583, 1427, 1126 and 887 cm(-1) and the group of bands in the Raman spectrum at 1464, 1452, 1147, 1030, 885, 873, 848, 715 and 590 cm(-1) are characteristic of the dimeric form of 2FA in the solid phase. In this work, the calculated structural and vibrational properties of both dimeric species were analyzed and compared between them. In addition, three types of atomic charges, bond orders, possible charge transfer, topological properties of the furan rings, Natural Bond Orbital (NBO) and Atoms in Molecules (AIM) theory calculations were employed to study the stabilities and intermolecular interactions of the both dimers of 2FA.

In the present work, we reported a combined experimental and theoretical study on molecular structure and vibrational spectra of 2-furanacrylic acid (abbreviated as 2FAA). The FT-IR and FT-Raman spectra of 2FAA have been recorded in the regions 4000–400 and 4000–100 cm −1 . The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The monomer and dimer structures of the title molecule have been obtained from Hartree–Fock (HF) and density functional theory (DFT) B3LYP methods with 6-311++G(d,p) as basis set calculations. The vibrational frequencies were calculated by DFT method and compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. Intermolecular O H⋯O hydrogen bonds are discussed in dimer structure of the molecule. The infrared and Raman spectra were also predicted from the calculated intensities. The polarizability and first order hyperpolarizabilty of the title molecule were calculated and interpreted. A study on the electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, are performed by time-dependent DFT (TD-DFT) approach. In addition, Milliken atomic charges, possible charge transfer, natural bond orbital (NBO) and AIM topological analysis were performed. Moreover, molecular electrostatic potential (MEP) and the thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at different temperatures were calculated in gas phase.

Single crystals of a new organic-inorganic material (C6H10(NH3)2) CdCl4·H2O, were grown through a slow evaporation at room temperature and were characterized using X-ray diffraction, FT–IR, FT–Raman, UV–Vis and impedance spectroscopy analyses. This compound crystallizes in the monoclinic system (P21/c space group). The [CdCl4]2- anions form an infinite sheet of octahedrons and diprotonated (C6H10(NH3)2)2+ cations that are arranged in an opposite way. The crystal pattern is stabilized by 2D network via non-covalent N–H⋯Cl, N–H⋯O and O–H⋯Cl interactions. The density functional theory DFT was applied to investigate molecular structure and vibrational modes. The calculations were performed by using B3LYP functional method combined with LanL2DZ basis set. The optimized structure and the vibrational spectra are in good agreement with the experimental measurements. The topological atom-in-molecules (AIM) and the Hirshfeld Surface (HS) analyses were carried out to investigate quantitatively the intermolecular contacts in crystal packing in a visual manner. The optical properties were investigated by optical absorption explains the eventual charge transfer interactions that take place within the molecules. Finally the electrical and the dielectric properties of this compound were investigated by means of impedance spectroscopy measurements over a wide range of frequencies and temperatures, 209 Hz–5 MHz and 300–393 K, respectively. Nyquist plots reveal a non-Debye type relaxation process and confirmed that the complex impedance curves of the title compound obeyed the Cole–Cole formalism. Furthermore, The AC conductivity behavior of the compound has been analyzed by the Jonscher's universal power law.