S-(+)-(E)-1-(2-furfuryl)-5-substituted-1,3,5-hexahydrotriazine-2-N-nitroimines:Synthesis,Crystal Structure and DFT Calculations

A novel neonicotinoid analogue（C13H19N5O5,3a）had been synthesized,the structure was characterized by elemental analysis,IR and 1H NMR spectra,and the S-（＋）-（E）-configuration was confirmed by single-crystal X-ray diffraction.The crystal belongs to monoclinic,space group P21 with a = 8.7076（17）,b = 8.3211（17）,c = 10.642（2）,β = 92.370（3）o,V = 770.4（3）3,Z = 2,Dc = 1.402 g/cm3,μ = 0.110 mm-1,Mr = 325.33,F（000）= 344,S = 1.027,R = 0.0543 and wR = 0.1229 for 3601 unique reflections with 2919 observed ones（I 2σ（I））.Compound 3a is stabilized by intramolecular hydrogen bonds and intermolecular force.In addition,the structure of compound 3a was optimized by the B3LYP/6-31G（d,p）.DFT/B3LYP optimizations were performed based on X-ray geometries applying 6-31G（d,p）basis set.The optimized structure of compound 3a by the B3LYP/6-31G（d,p）method is more bent than in the crystal.IR spectrum of the solid compound is consistent with the X-ray structure.The HOMO-LUMO gap in 3a（5.3 eV）indicates high kinetic stabilities of compound 3a.The preliminary bioassay test showed that 3a exhibited good activities against Nilaparvata legen,Pseudaletia separate Walker and Aphis medicagini at 500 mg/L.

NLO response of derivatives of benzene, stilbene and diphenylacetylene：MP2 and DFT calculations

MP2 method and different functionals such as M06-HF, M06-2X, CAM-B3 LYP, PBE0, B3 LYP and M06 L incorporating different XC amounts were used to calculate the static first hyperpolarizabilies β(0) of eight molecules which are derivatives of benzene, stilbene and diphenylacetylene. The values were then compared to the experimental ones. The M06-2X functional was then selected for further calculations. NBO calculations were also performed to define the intramolecular charge transfer in each molecule. TD-DFT calculations were performed taking into account the solvent effect using the IEF-PCM formalism. Some parameters characterizing the vertical transitions such as the wavelength of the maximum absorption λ_(max) were compared to the experimental ones. Finally,solvation Gibbs free enthalpy ΔG_(solv) values have also been examined in order to determine which the specific solvent for a given molecule is.

Structure-activity relationships of oxime compounds as flotation collectors by DFT calculations

The relationships between the structure of oxime compounds(R^(1)R^(2)C=NOH,R^(1)/R^(2)=alkyl groups) with different substituents and their corresponding flotation performances were studied. The analyses of density functional theory(DFT) calculations illustrated that the introduced phenyl group at the R^(1) position could enhance the acidity,while the heptyl group could effectively increase the hydrophobicity and benefit van der Waals interactions. Meanwhile,the introduced amino group at the R^(2) position could provide cationic sites to interact with negatively charged surfaces of minerals, while the introduced hydroxyl group could provide additional action sites to form stable chelates with metal ions. Based on the structure-activity relationships, structural optimization was carried out to obtain three efficient collectors, which possessed superior flotation separation performances, proving the effectiveness of the structural modification to oxime compounds in this work.

Synthesis,Structure and DFT Calculations of a Novel Copper(Ⅱ)Complex Based on Tert-butyl 2-[N-(tert-butyloxycarbonylmethyl)-2-picolyamino]acetate

A novel copper（Ⅱ） complex with tert-butyl 2-[N-（tert-butyloxycarbonylmethyl）-2-picolyamino]acetate（ampy） was synthesized and structurally characterized by elemental analysis, FT-IR spectrum, electrospray ionization-mass spectrometry, UV-vis spectrum and single-crystal X-ray diffraction, respectively. A mononuclear copper（II） complex with ampy, [Cu（ampy）Cl2]（1）, was formed irrespective of the metal-to-ligand molar ratios（[Cu2＋]：[ampy] = 0.5：1, 1：1, and 2：1） as a single product. Complex 1 crystallizes in the orthorhombic system, space group Pbca with a = 12.343（2）, b = 18.928（3）, c = 20.058（4） A, V = 4686.1（14） A3, Z = 8, Dc = 1.3349（4） g/cm3, F（000） = 1920, S = 1.016, R = 0.0693 and w R = 0.1721 for 3151 observed reflections with I 〉 2σ（I）. X-ray diffraction analysis reveals that the central copper（II） ion is bound by pyridyl N, tertiary amine N and carbonyl O atoms of the quadridentate ampy as well as two Cl anions, constructing a slightly distorted octahedral geometry. Complex 1 further constructs a stable 3D supramolecular architecture by intermolecular C–H…Cl hydrogen bonds. In addition, the molecular geometry was calculated by density functional theory（DFT/B3LYP） method with the basis sets（6-31＋G（d,p） for H, C, N, O and Cl atoms, and LANL2 DZ for Cu atom, respectively）. The calculated results show that the optimized geometrical parameters are in good agreement with the experimental data. Natural bond orbital（NBO） analysis and frontier molecular orbitals（FMOs） analysis were investigated at the same level.

Structural and Vibrational Study of 2-（Quinolin-8-yloxy）-Acetic Acid based on FT-IR-Raman Spectroscopy and DFT Calculations

We have prepared the 2-（quinolin-8-yloxy）-acetic acid and characterized it by infrared and Raman spectroscopies in the solid phase. The Density Functional Theory （DFT） method, together with the 6-31G^＊ and 6-311＋＋ G^＊＊ basis sets, show that three stable molecules, for the anhydrous and monohydrated compounds were theoretically determined in the gas phase, and that probably the two more stable conformations are present in the solid phase of the monohydrated compound. The harmonic vibrational wavenumbers for the optimized geometries were calculated at B3LYP/6-31G^＊and B3LYP/6-311＋＋G^＊＊ levels. For a complete assignment of all the observed bands in the vibrational spectra the DFT calculations were combined with Pulay＇s scaled quantum mechanical force field （SQMFF） methodology in order to fit the theoretical Wavenumber values to the experimental ones. The characteristics of the electronic delocalization of all structures of both forms were performed by using natural bond orbital （NBO）, while the corresponding topological properties of electronic charge density are analysed by employing Bader＇s atoms in molecules theory （AIM）.

Theoretical Study of Benzothiazole and Its Derivatives: Molecular Structure, Spectroscopic Properties, NBO, MEP and TD-DFT Analyses

Benzothiazole (BTH) and its derivatives are organic molecules with biologic actions. Because of their many applications, they are produced on a massive scale and used in a number of environmental compartments. Their discharge into water produces environmental problems, exposing our environment to public health problems. A solution that can contribute to their deterioration is becoming a necessity. For this reason, a conceptual analysis of the reactivity of benzothiazole and four of its compounds was undertaken in order to investigate certain aspects of their biodegradability. A theoretical investigations of the compounds studied were conducted in the gas and water phases with the most widely used density functional theory method, Becke-3-Parameter-Lee-Yang-Parr (B3LYP) with 6-31G+ (d, p) basis. Reactivity study calculated global indices of reactivity revealed that 2-SCH3_BTH is the most reactive. Dipole moment values analysis reveals that 2-NH2_BTH is the most soluble in water, while the lipophilicity shows that 2-NH2_BTH is the most hydrophilic compound. Thermodynamic parameters values reflect that reactions are respectively exothermic and spontaneous. By analyzing an Electrostatic Molecular Potential (EMP) map, researchers can pinpoint reactive sites on a molecule and anticipate its reactivity. This assessment is further enhanced by incorporating global and local reactivity descriptors. Additionally, an exploration of frontier molecular orbitals offers valuable insights into the molecule’s charge transfer characteristics. Moreover, a combined examination of internal and external molecular interactions unveils hyperconjugative interactions arising from charge delocalization, as elucidated through natural bond orbital (NBO) analysis.

DFT Calculations for Corrosion Inhibition of Ferrous Alloys by Pyrazolopyrimidine Derivatives

The inhibition performance of 5-tolyl-2-phenylpyrazolo[1,5-c] pyrimidine-7(6H)thione (Tolyl), 5-tolyl-2-pheenylpyrazolo?[1,5-c]pyrimidine-7(6H)one (Inon) was?investigated as corrosion inhibitors using density functional theory (DFT) at the B3LYP/6-31?+?G(d,p) level of theory. The calculated quantum chemical parameters correlated to the inhibition efficiency are:?the?highest occupied molecular orbital energy(EHOMO),?the?lowest unoccupied molecular orbital energy (ELUMO), the energy gap (ΔEL-H), dipole moment (μ), ionization energy (Ι), electron affinity?(Α), absolute electronegativity (χ), absolute hardness (η), absolute softness (σ), the fraction of electron transferred (ΔN), and the total energy (Etot)?which?were calculated. The local reactivity has been analyzed through the Fukui function and local softness indices in order to compare the possible sites for nucleophilic and electrophilic attacks. The success of DFT calculations in predicting the inhibition efficiency?was?assessed.

First Oxidation Product of Vitamin C, the Dehydro-L-Ascorbic Acid Dimer： A Study Based on FTIR-Raman and DFT Calculations

We studied the first oxidation product of vitamin C, the dehydro-L-ascorbic acid dimer and characterized it by infrared and Raman spectroscopies in the solid phase. The Density functional theory was used to study its structure and vibrational properties. These calculations gave us a precise knowledge of the normal modes of vibration taking into account that the molecule comprises a system of five fused rings; non planar γ-lactone and furonose rings are attached to a central dioxan ring in the twisted boat conformation. The calculated harmonic vibrational frequencies are consistent with the experimental vibrational spectra. An assignment of the observed spectral features is proposed. The shift of the band located in the infrared spectrum of the ascorbic acid from 3409 cm^-1 to 3299 cml and the remarkable increase in the band intensity at 1784 cm^-1 evidences the acid decomposition into its first product, the dehydro-L-ascorbic acid. The theoretical vibrational calculations allowed us to obtain a set of scaled force constants. The nature of the different -γ-lactone, furanose and dioxan rings and their topological properties were investigated by means of natural bond orbital and Bader＇s atoms in the molecule theory, respectively.

Crystal Structure, DFT Calculation and Photophysical Studies of a Schiff Base

A Schiff base DSH （DSH = （4-dipropylanilino-styryl） hydrazine） has been synthe- sized and fully characterized by 1H NMR, 13C NMR, ESI-MS, elemental analysis and single-crystal X-ray diffraction analysis. It crystallizes in triclinic, space group Pi, with a = 8.447（5）, b = 10.543（5）, c = 14.540（5） A, a = 78.600（5）, β = 78.222（5）, y = 78.247（5）, V= 1225（1） A3, Z = 2, D,. -- 1.103 g/m3, F（000） = 444, Mr = 406.60, μ= 0.066 mm, the final R = 0.0414 and wR = 0.1065 for 8691 observed reflections with I 〉 2（/）. The structural analysis revealed that the molecule possesses good planar structure. The absorption spectra and one-photon fluorescence in different solvents were experimentally studied. The result indicates that the compound exhibits intense fluorescent emission bands in protic solvents, such as ethanol and methanol. Quantum chemical calculations based on time-dependent density functional theory （TD-DFT） at the level of TD-DFT/B3LYP/6-31G were performed to investigate the UV absorption spectrum, and influence of solvents on the fluorescence spectra is analyzed based on the optimized structure at the level of B3LYP/6-31G（d）.

DFT calculation on relaxation and electronic structure of sulfide minerals surfaces in presence of H_2O molecule

First-principles calculations are performed to investigate the relaxation and electronic properties of sulfide minerals surfaces(MoS2, Sb2S3, Cu2 S, ZnS, PbS and FeS2) in presence of H2 O molecule. The calculated results show that the structure and electronic properties of sulfide minerals surfaces have been influenced in presence of H2 O molecule. The adsorption of the flotation reagent at the interface of mineral-water would be different from that of mineral surface due to the changes of surface structures and electronic properties caused by H2 O molecule. Hence, the influence of H2 O molecule on the reaction of flotation reagent with sulfide mineral surface will attract more attention.

DFT and TD-DFT Study of Bis[2-(5-Amino-[1,3,4]-Oxadiazol-2-yl) Phenol](Diaqua)M(II) Complexes [M = Cu, Ni and Zn]: Electronic Structures, Properties and Analyses

Ground state geometries, spectral (IR and UV-Vis) properties, analysis of frontier molecular orbitals (FMOs), natural bond orbital (NBO) analysis and molecular electrostatic potential (MEP) surfaces of three transition metal complexes [Cu(AOYP)2(OH2)2] (A), [Ni(AOYP)2(OH2)2] (B) and [Zn-(AOYP)2(OH2)2] (C), have been studied theoretically by the Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) methods. AOYP is the oxadiazole ligand 2-(5-amino-[1,3,4]-oxadiazol-2-yl)phenol. The geometries of these complexes were initially optimized using two basis sets: LAN2DZ and a generic basis set, the latter of which was selected for subsequent analysis. The stability of the complexes arising from intramolecular interactions and electron delocalization was estimated by natural bond orbital (NBO) analysis. The NBO results showed significant charge transfer from lone pair orbitals on the AOYP donor atoms O19, O21, N15 and N36 to central metal ions in the complexes, as well as to the benzene and oxadiazole rings. The electronic spectrum of (A) showed bands at 752 and 550 nm mainly attributable to ligand-to-metal charge transfer (LMCT) transitions, and a band at 446 nm assigned to a d-d transition. The electronic spectrum of (B) consisted of bands at 540, 463 and 395 nm mainly due to d-d transitions. Calculated electronic bands for (C) occurred at 243, 238 and 235 nm, arising from intraligand charge transfer (ILCT) transitions within AOYP. A good agreement in terms of band positions was found between experimental and calculated absorption spectra of the complexes.

Dielectric constant predictions for energetic materials using quantum calculations

The dielectric constant(DC)is one of the key properties for detection of threat materials such as Improvised Explosive Devices(IEDs).In the present paper,the density functional theory(DFT)as well as ab-initio approaches are used to explore effective methods to predict dielectric constants of a series of 12 energetic materials(EMs)for which experimental data needed to experimentally determine the dielectric constant(refractive indices)are available.These include military grades energetic materials,nitro and peroxide compounds,and the widely used nitroglycerin.Ab-initio and DFT calculations are conducted.In order to calculate dielectric constant values of materials,potential DFT functional combined with basis sets are considered for testing.Accuracy of the calculations are compared to experimental data listed in the scientific literature,and time required for calculations are both evaluated and discussed.The best functional/basis set combinations among those tested are CAM-B3LYP and AUG-ccpVDZm,which provide great results,with accuracy deviations below 5%when calculated results are compared to experimental data.

Effect of the alkali metal(Li, Na, K) substitution on the geometric,electronic and optical properties of the smallest diamondoid: First principles calculations

In this study we employed the B3LYP/6-311++G(d,p) method combined with the CIS/6-311++G(d,p) calculation to investigate the effects of the type and the number of alkali metal atoms(Li, Na, K) on the geometric, electronic, and optical properties of alkali metals substituted into adamantanes. Substituting alkali metal(Li, Na, K)atoms caused significant changes in the electronic and optical properties of adamantane. The Ad-1Li, Ad-1Na,and Ad-1K structures showed a dramatically decreased energy gap and ionization potential, while adding more alkali metal atoms slightly decreased these properties. Substituting more alkali metals led to a shift in the maximum absorption wavelength from the visible to the infrared region, depending on the type of alkali metal atom substituted. The magnitude of shift occurred in the following order: Li b Na b K. These characteristics suggest the possibility of tunable electronic structures of this material for optoelectronic device applications.

Electronic band structures and optical properties of atomically thin AuSe: first-principle calculations

As a large family of 2D materials, transition metal dichalcogenides(TMDs) have stimulated numerous works owing to their attractive properties. The replacement of constituent elements could promote the discovery and fabrication of new nanofilm in this family. Using precious metals, such as platinum and palladium, to serve as transition metals combined with chalcogen is a new approach to explore novel TMDs. Also, the proportion between transition metal and chalcogen atoms is found not only to exist in conventional form of 1 : 2. Herein, we reported a comprehensive study of a new 2D precious metal selenide, namely AuSe monolayer. Based on density functional theory, our result indicated that AuSe monolayer is a semiconductor with indirect band-gap of 2.0 eV, which possesses superior dynamic stability and thermodynamic stability with cohesive energy up to–7.87 eV/atom. Moreover, it has been confirmed that ionic bonding predominates in Au–Se bonds and absorption peaks in all directions distribute in the deep ultraviolet region. In addition, both vibration modes dominating marked Raman peaks are parallel to the 2D plane.

Synthesis and Density Functional Theory(DFT) Calculation of Haptens for PAHs

Five PAHs haptens 3 a～3 e were synthesized from naphthalene, anthracene, chrysene, pyrene and acenaphthene via two steps including Friedel-Crafts acylation and WolffKishner-Huang reduction. The sixth hapten 4-(acenaphthylen-3-yl)butanoic acid(3 f) was prepared from hapten 3 e via three steps including esterification, bromination and elimination. Their structures were confirmed by melting point, ~1H NMR and ^(13)C NMR. Their optical properties and crystal structures were also investigated. The results of density functional theory(DFT) calculation provided the supports that the size, shape(geometry) and electronic properties at the corresponding parts of 3 a～3 f did not change significantly, compared to those of PAHs. The haptens 3 a～3 f were coupled with bovine serum albumin(BSA) to make antigens. The coupling ratios were 1:20～1:38. These results show that the haptens could be used to induce specific antibodies for PAHs.

Electronic structure of O-doped SiGe calculated by DFT+U method

To more in depth understand the doping effects of oxygen on SiGe alloys, both the micro-structure and properties of O-doped SiGe （including： bulk, （001） surface, and （110） surface） are calculated by DPT ＋ U method in the present work. The calculated results are as follows. （i） The （110） surface is the main exposing surface of SiGe, in which O impurity prefers to occupy the surface vacancy sites. （ii） For O interstitial doping on SiGe （110） surface, the existences of energy states caused by 0 doping in the band gap not only enhance the infrared light absorption, but also improve the behaviors of photo-generated carriers. （iii） The finding about decreased surface work function of O-doped SiGe （110） surface can confirm previous experimental observations. （iv） In all cases, O doing mainly induces the electronic structures near the band gap to vary, but is not directly involved in these variations. Therefore, these findings in the present work not only can provide further explanation and analysis for the corresponding underlying mechanism for some of the experimental findings reported in the literature, but also conduce to the development of μc-SiGe-based solar ceils in the future.

First-principles calculations of structural, electronic, and thermodynamic properties of ZnO_(1-x)S_x alloys

In this study the pseudo-potential method is used to investigate the structural, electronic, and thermodynamic proper- ties of ZnOl_xSx semiconductor materials. The results show that the electronic properties are found to be improved when calculated by using LDA ~ U functional as compared with local density approximation （LDA）. At various concentrations the ground-state properties are determined for bulk materials ZnO, ZnS, and their tertiary alloys in cubic zinc-blende phase. From the results, a minor difference is observed between the lattice parameters from Vegard＇s law and other calculated results, which may be due to the large mismatch between lattice parameters of binary compounds ZnO and ZnS. A small deviation in the bulk modulus from linear concentration dependence is also observed for each of these alloys. The ther- modynamic properties, including the phonon contribution to Helmholtz free energy △F, phonon contribution to internal energy △E, and specific iheat at constant-volume Cv, are calculated within quasi-harmonic approximation based on the calculated phonon dispersion relations.

Structure and Stability of P_lO_m Cages and Their Highly Charged Protonated Clusters P_lO_mH_n^(n+):Insight from Density Functional Calculations

Density functional calculations are used to determine structural and electronic properties of P4,P4O6,P4O10,P20O30 and P20O50 clusters and their protonated derivatives.These oxygen-rich phosphorus oxides are predicted to have relatively high stabilities with respect to their components P4 and O2,and their unsaturated P and end-on O atoms as the proton acceptor can accommodate multiple protons to generate highly positively charged cationic clusters,such as P20O30H1010＋.Calculations indicate that P4O6 and P20O30 have higher reactivity toward the proton capture than the P4,P4O10 and P20O50 clusters,and the most stable protonated clusters among these different series of cationic clusters are P4H2……2＋,P4O6H2^2＋,P4O10H3^3＋,P20O30H4^4＋ and P20O50H4^4＋,respectively.The cage skeleton of the phosphorus oxide clusters shows high stability for the consecutive protonation,and the unsymmetrical stretching of the skeletal P-O bond and the wagging mode of P-H coupled with the P-O bond stretching have strong adsorptions.These computational findings are useful for further experimental and theoretical studies of novel phosphorus oxide clusters and their highly positively charged derivatives.

New ternary superconducting compound LaRu2As2： Physical properties from density functional theory calculations

In this paper, we perform the density functional theory （DFT） -based calculations by the first-principles pseudopo- tential method to investigate the physical properties of the newly discovered superconductor LaRu2As2 for the first time. The optimized structural parameters are in good agreement with the experimental results. The calculated independent elas- tic constants ensure the mechanical stability of the compound. The calculated Cauchy pressure, Pugh＇s ratio as well as Poisson＇s ratio indicate that LaRu2As2 should behave as a ductile material. Due to low Debye temperature, LaRu2As2 may be used as a thermal barrier coating （TBC） material. The new compound should exhibit metallic nature as its valence bands overlap considerably with the conduction bands. LaRu2As2 is expected to be a soft material and easily machinable because of its low hardness value of 6.8 GPa. The multi-band nature is observed in the calculated Fermi surface. A highly anisotropic combination of ionic, covalent and metallic interactions is expected to be in accordance with charge density calculation.

Pseudo-Bonding Interaction between Boron-doped Heterofullerene and Zinc Porphine Predicted by DFT Calculation

Theoretical study on the supramolecular complexes formed between boron-doped het- erofullerene （C59B） and zinc porphine （ZnF）, namely C59B-ZnP and its anion species C59B-ZnP, was performed by density functional theory calculation at wB97XD/6-31G（d） level. Strong interaction between porphyrin and heterofullerene moiety was predicted for these complexes based on geometry and electronic structure analysis. Especially, pseudobonding interaction occurring between the B atom of fullerene and the N atom of porphyrin was predicted to occur in C59B-ZnP complex, but be broken in C59B-ZnP complex. Time-dependent density functional theory calculation manifests the redshift of electron absorption for ZnP upon the interaction with heterofullerene.