Functional Theory Method Research Articles

Salt and co-crystal formation from the reaction of fumaric acid with different N-heterocyclic compounds: Experimental and DFT study

In this work, four fumaric acid adducts with different nitrogenous bases were synthesized and characterized with FT-IR, 1H NMR, 13C NMR and UV-Vis. spectroscopies. The solid-state structures of the compounds were determined by X-ray diffraction analysis. In addition, quantum chemical calculations employing density functional theory (DFT/B3LYP) method with the 6 − 311++G(d,p) basis set were performed to study the structural and spectroscopic properties of the compounds, and the results were compared with the experimental findings. X-ray analysis suggests that the crystal structures is stabilized by O–H···O, N–H···O, O–H···N and C–H···O type hydrogen bonds and also π···π stacking interactions. The harmony between the experimental and theoretical structural and spectroscopic data is acceptable in general.

High-nitrogen nitrotetrazole substituted tetrazole 3-N-oxides as potential high energy density compounds

In this work, two series of novel high-nitrogen tetrazole 3-N-oxides substituted by different nitrotetrazoles were designed, and their structure and properties were investigated by using the density functional theory (DFT) method. The results shown that though there are only one to two energetic substituents in the structure, because of the high nitrogen content, ideal oxygen balance, and the big conjugated structure, all eight designed compounds not only have high heat of formation (655.4–845.6 kJ/mol), high density (1.83–1.93 g/cm3), and high detonation performance (detonation velocity: 9.06–9.50 km/s; detonation pressure: 36.7–41.8 GPa), but also possess reduced impact sensitivity (23–98 cm). Fully analyzing the energy and sensitivity, A1 and A4 have higher energy and lower sensitivity than one famous high energy compound 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX), and A3, B1, and B4 have comparable overall performance with HMX, showing that these five designed compounds may be considered as the potential high energy density compounds. In addition, the introduction of one extra nitro group into the tetrazole 3-N-oxide could not improve the combination property generally.

Synthesis, structural characterization, Hirshfeld surface analysis, and theoretical investigations of bis(benzene-1,2-dicarboxylato)bis(4-methylbenzohydrazide)zinc

Single crystals of bis(benzene-1,2-dicarboxylato)bis(4-methylbenzohydrazide)zinc (ZPTH), a novel Zn(II) complex of phthalic acid and hydrazide, were grown from aqueous solution by slow evaporation solution growth technique. The compound C32H30N4O10Zn crystallizes in triclinic system with centrosymmetric space group Pī. Its structure is built up from octahedral (ZnO4N2) linked to each other through the phthalate and hydrazide groups. The good crystallinity of the as-grown specimen is confirmed by the powder X-ray diffraction pattern. The band gap energy is estimated using diffuse reflectance data by the application of Kubelka–Munk algorithm. ZPTH exhibits fluorescent emission at 401 nm in the solid state at room temperature. Theoretical calculations were performed using density functional theory (DFT) method. Experimental observations are well supported by theoretical studies.GRAPHICAL ABSTRACT

Structural, theoretical, and third-order nonlinear optical investigations of N’-[(E)-(4-bromophenyl)(phenyl)methylidene]–4-methylbenzenesulfonohydrazide

Single crystals of N’-[(E)-(4-bromophenyl) (phenyl) methylidene]–4-methylbenzenesulfonohydrazide (4BBTH), having potential applications in nonlinear electro optic field. The structure is elucidated by single crystal X-ray diffraction analysis. The functional groups are identified by FT-IR analysis. The band gap energy is estimated using diffuse reflectance data by the application of Kubelka–Munk algorithm. Third-order nonlinear optical properties of the grown crystal were derived by employing a single beam Z-scan technique. Theoretical calculations were performed using density functional theory (DFT) method. Estimated large first-order molecular hyperpolarizality of 9.79 times of urea, suggests a charge transfer atmosphere facilitating micro level nonlinearity.GRAPHICAL ABSTRACT

Structural, spectroscopic properties and theoretical studies of (E)-1-(4-Bromophenyl)-3-(2,3,4-trimethoxyphenyl)prop-2-en-1-one as a potential anti-oxidant agent

ABSTRACTThe new chalcone compound namely (E)-1-(4-Bromophenyl)-3-(2,3,4-trimethoxyphenyl)prop-2-en-1-one (C18H17BrO4) is crystallized in the monoclinic crystal system of P21/c space group. The unit cell dimensions are: a = 8.0753 (10) Å, b = 21.873 (3) Å, c = 9.3362 (12) Å, α = 90°, β = 99.369 (2), γ = 90° and Z = 4. The single crystal was grown using slow evaporation solution growth technique. The newly synthesized compound was characterized by using IR, 1H- and 13C-NMR, UV-Vis and single crystal X-ray diffraction analyses. Quantum chemical method of Density Functional Theory (DFT) with B3LYP/6-311++G(d,p) has been employed to study the structural and spectral properties of the compound. The electronic absorption spectrum was calculated using the time dependent functional theory (TDDFT) method. The most stable conformer of the title chalcone is identified from the computational results. Hirshfeld surface analysis with fingerprint plots has been used as a graphical tool for visualization and understanding of intermolecular interactions. Intermolecular C‒H····O interaction observed stabilize the crystal structure, forming an infinite one dimensional column. The effect of this intermolecular interaction in the solid state can be seen in the difference between the experimental and the theoretically optimized geometrical parameters. The crystal is transparent in the entire visible region and absorptive in the UV region. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron potential (MEP). The other molecular properties like charge transfer are explain using Mulliken population analysis. The antioxidant test indicated that the 2,3,4-trimethoxy substitution on the bromide chalcone to be one of the favorable modification to enhance its metal chelating activity.

Exact Solution of the Two-Dimensional Problem on an Impact Ideal-Liquid Jet

The two-dimensional problem on the collision of a potential ideal-liquid jet, outflowing from a reservoir through a nozzle, with an infinite plane obstacle was considered for the case where the distance between the nozzle exit section and the obstacle is finite. An exact solution of this problem has been found using methods of the complex-variable function theory. Simple analytical expressions for the complex velocity of the liquid, its flow rate, and the force of action of the jet on the obstacle have been obtained. The velocity distributions of the liquid at the nozzle exit section, in the region of spreading of the jet, and at the obstacle have been constructed for different distances between the nozzle exit section and the obstacle. Analytical expressions for the thickness of the boundary layer and the Nusselt number at the point of stagnation of the jet have been obtained. A number of distributions of the local friction coefficient and the Nusselt number of the indicated jet are presented.

Elaborating a new excited state intramolecular proton transfer (ESPT) mechanism for a new π-conjugated dye 2, 2′-((5-(2-(4-methoxyphenyl)ethenyl)-benzene-1,1-diyl)-bis-(nitrilomethylylidene)-diphenol)

In this work, the excited state dynamical behavior of a novel π-conjugated dye 2,2′-((5-(2-(4-methoxyphenyl)ethenyl)-benzene-1,1-diyl)-bis-(nitrilomethylylidene)-diphenol) (C1) has been investigated. Two intramolecular hydrogen bonds of C1 are tested to pre-existing in the ground state via AIM and reduced density gradient. Using a time-dependent density functional theory (TDDFT) method, it has been substantiated that the intramolecular hydrogen bonds of C1 should be strengthened in the S1 state via analyzing fundamental bond length, bond angles, and corresponding infrared vibrational modes. The most obvious variation of these two hydrogen bonds is the O4–H5···N6 bond, which might play important roles in excited state behavior for the C1 system. Furthermore, based on electronic excitation, charge transfer could occur. Just due to this kind of charge re-distribution, two hydrogen bonds should be tighter in the first excited state, which is consistent with the variation of hydrogen bond lengths. Thus, the phenomenon of charge transfer is reasonable evidence for confirming the occurrence of the excited state proton transfer (ESPT) process in the S1 state. Our theoretically constructed potential energy surfaces of C1 show that excited state single proton transfer should occur along with the O4–H5···N6 hydrogen bond rather than the O1–H2···N3 bond. We not only clarify the ESIPT mechanism for C1 but put forward new affiliation and explain a previous experiment successfully.

Influence of H-Content on Thermo-Mechanical Properties of NiAl Alloys

The effect of Hydrogen on thermo-mechanical properties and performance of metals and alloys are of critical importance. In recent years, the relevance of H-metal interactions has been broadened into functional metallic compounds and alloys as they find use in energy and medical applications. Here, we aim to assess the influence of H-content on thermal, physical, chemical, and mechanical properties on Nickel-Aluminum alloys using Molecular Dynamics (MD) and Density Functional Theory (DFT) methods. We report studies on Ni3Al, Al3Ni, AlNi with H-content ranging from 1% to 10% at elevated temperatures for different structures such as B1, B2, L10, A4 and random and ordered in L12 to establish enthalpy-temperature-concentration, volume-temperature concentration, volume-pressure-concentration relationships. From these relationships we derive thermodynamic and mechanical properties such as thermal expansion, bulk modulus and Young modulus.

Electronic and Spectroscopic Properties of La2@C112 Isomers

Among the 3352 isolated pentagon rule(IPR) isomers and 129073 non-IPR isomers satisfying adjacent pentagon pairs(APPs)≤2 of fullerene C112, the lowest-energy IPR and non-IPR isomers of C112 and C1126- have been fully screened by the density functional tight-binding(DFTB) and density functional theory(DFT) methods for studying the electronic and spectroscopic properties of La2@C112. The structural features and infrared and absorption spectra of those isomers were analyzed in detail, and the characteristic fingerprint absorption peaks were assigned. To clarify the relative stabilities of La2@C112 isomers at high temperature, entropy contributions were determined at the B3LYP level. IPR isomer La2@C112(C2:860136) is not the lowest-energy isomer but is one of the most important isomers. This is the first work that considers non-IPR C112 isomers when exploring the structure and properties of La2@C112.

Theoretical Approach Towards Rational Design and Characterization of Benzo[1,2-b:5-B’]dithiophene (BDT)-Based (A-D-A) Small Molecules of Relevance for High Performance Solar Cells

Benzo[1,2-b:5-B’]dithiophene (BDT)–based small molecules with acceptor-donor-acceptor (A-D-A) structure were designed based on the experimental system BDTT-S-TR (1) for use as potential donor materials for organic photovoltaic (OPV) devices. Their geometry structures, electronic properties and other key parameters related to OPVs such as absorption spectra, energetic driving forces ΔE L-L, power conversion efficiencies (PCEs) and intramolecular charge transfer properties have been investigated by means of density functional theory (DFT) and time dependent density functional theory (TDDFT) methods. These have been exploited as donor materials for a heterojunction with [6,6] phenyl-C71-butyric acid methyl ester (PC70BM) as acceptor material. Based on Marks model, an excellent agreement between the experimental and predicted PCE was obtained for the reported system 1/PC70BM and a significant improvement in PCEs of BHJ devices based on 2-4/PC70BM was manifested. The charge transfer rates of the interfacial charge transfer Kint er−CT and recombination Kint er −CR in 1-4/PC70BM heterojunctions have been calculated using Marcus-Levich-Jortner rate equation. The calculations show that the ratios Kint er-CT / kint er-CR for the 2-4/PC70BM heterojunctions are ~104 times higher than that of the 1/PC70BM. From these predictions, we reached our purpose to provide rational design of three novel molecules that will be more promising candidates for high-efficiency SMs OPVs materials.

Molecular Geometry, Vibrational Assignments, HOMO-LUMO, Mulliken's charge analysis and DFT Calculations of 2-(2-Phenylaminothiazole-5-oyl)1-methyl-6-methylbenzimidazole

The vibrational wave numbers of 2-(2-phenylaminothiazol-5-oyl)-1-methyl-6-methylbenzimidazole were calculated using B3LYP/6–31G basis set and calculations are used to assign vibrational bands obtained experimentally. The B3LYP method is able to predict vibrational frequencies and structural parameters. The optimized molecular geometry, bond lengths, bond angles, dihedral angles and harmonic vibrational wave numbers of the titled Compound have been investigated by Density Functional Theory (DFT) method. The geometries obtained from DFT method is found to be in good agreement with experimental data. The Mulliken population analysis on atomic charges has been computed using DFT calculations. Energetics of the Highest Occupied Molecular Orbital (HOMO) and Lowest unoccupied Molecular (LUMO) of the molecule were calculated using the Gaussian 09 software package.

Molecular Structure, Electronic Structure, Properties and Analyses of Five Azopyridine Ruthenium Complexes α-Cl, β-Cl, γ-Cl, δ-Cl and ε-Cl of RuCl<sub>2</sub>(4,6-Dimethyl-Phenylazopyridine)<sub>2</sub> as Potential Cancer Drugs: DFT and TD-DFT Investigations

Ground state geometries, natural bond orbital (NBO), analysis of frontier molecular orbitals (FMOs), analysis and spectral (RMN and UV-Visible) properties of five azopyridine ruthenium (II) complexes α-Cl, β-Cl, γ-Cl, δ-Cl and e-Cl of RuCl2(Dazpy)2 have been theoretically studied by the Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) methods using two basis sets: Lanl2DZ and a generic basis set in gas or in chloroform solvent. Dazpy stands for 4,6-dimethyl-phenylazopyridine. Optimized geometry shows that, except β-Cl, all the other four isomers α-Cl, γ-Cl, δ-Cl and e-Cl are C2 symmetrical. Otherwise, a good agreement was found between experimental and the calculated geometry and NMR data. Moreover, Lanl2DZ effective core potential basis set provides good chemical shifts and geometric properties. Furthermore, the prediction of the frontier orbitals (Highest Occupied Molecular Orbital or HOMO and Lowest Unoc-cupied Molecular Orbital or LUMO) shows that the most active isomer suita-ble for electronic reactions is admitted to be δ-Cl. Besides, the NBO analysis indicates that the Ru-N is formed by the electron delocalization of lone pair atomic orbital of N2 and Npy to Ru. Also, the strongest interactions between LP(N) with LP*(Ru) and LP(Cl) with LP*(Ru) stabilize the molecular struc-ture. In addition, NBO shows that the five d orbitals of Ru in the complex are organized so that there is no order of priority from one complex to another. Therefore, the transition LP(Ru) → π*(N1 = N2) corresponding to Metal to Li-gand Charge Transfer (MLCT) is in reality no more than d → π*. Besides, TDDFT prediction in chloroform solvent reveals that all the five isomerics complexes absorb in the visible region as well as efficient photosensitizers. What’s more, δ-RuCl2(dazpy)2 can potentially act as the excellent sensitizer with a large band of absorption in visible region and a small excited energy. This study can help design and find out the ability or properties of the com-plex to behave as sensitizer or potential cancer drugs.

7-(2-Ethyltiophenyl) Theophylline as Copper Corrosion Inhibitor in 1M HNO<sub>3</sub>

7-(2-ethyltiophenyl) theophylline was used as copper corrosion inhibitor in 1M HNO3 solution. The study was performed using mass loss, scanning electron microscopy (SEM) and Density Functional Theory (DFT) methods. The results show that the inhibition efficiency increases up to 91.29% with increase of the inhibitor concentration (from 0.05 to 5 mM) but decreases with raising temperature of the solution. Copper dissolution was found to be temperature and 7-(2-ethyltiophenyl) theophylline concentration dependent. The thermodynamic functions related to the adsorption of the molecule on the copper surface and that of the metal dissolution were determined. The results point out a spontaneous adsorption and an endothermic dissolution processes. Adsorption models including Langmuir, El-Awady and Flory-Huggins isotherms were examined. The results also suggest spontaneous and predominant physical adsorption of 7-(2-ethyltiophenyl) theophylline on the metal surface which obeys Langmuir isotherm model. Further investigation on the morphology using scanning electron microscopy (SEM) has confirmed the existence of a protective film of inhibitor molecules on copper surface. Furthermore, the global and local reactivity parameters of the studied molecule were analyzed. Experimental and theoretical results were found to be in good agreement.

Theoretical Study of 1,3-Dipolar Cycloadditions Regioselectivity of Benzyl Azide with Glycosyl-O Acetylene Using Density Functional Theory (DFT)

A theoretical study of 1,3-cycloaddition has been carried out using density functional theory (DFT) methods at the B3LYP/6-31G* level. The regioselectivity of the reaction have been clarified through different theoretical approaches: Case of a Two-Center Process (Domingo approach), HSAB principle (Gazquez and Mendez approach), and the activation energy calculations. The analysis of results shows that the reaction takes place along concerted asynchronous mechanism and the isomer meta is favored, in agreement with the experiment results. DOI: http://dx.doi.org/10.17807/orbital.v9i5.1017

The DNA-binding behavior and DFT calculation of ruthenium(II) complexes [Ru(phen)2L](ClO4)2 (L = HMOPIP and MOHPIP)

Two ruthenium(II) complexes, [Ru(phen)2HMPIP]2+ (1) and [Ru(phen)2MHPIP]2+ (2), have been synthesized and characterized by elemental analysis, ESI-MS, and 1H NMR spectroscopy. The DNA-binding properties of 1 and 2 have been investigated by electronic and emission spectra and viscosity experiments. The results show that both 1 and 2 can bind to DNA in intercalating mode, with 1 exhibiting stronger binding affinity. These were confirmed by the strong hypochromism at IL and MLCT absorption bands in both complexes when DNA was added into solution, and the increase in relative viscosity of CT-DNA in the presence of both complexes. Moreover, the calculated intrinsic binding constant for 1 and 2 from the decay of electronic spectra is 3.82 × 105 and 2.06 × 105 M−1, respectively. Finally, the effects of the substituent groups on the DNA-binding behavior of ruthenium(II) complexes have also been rationally discussed by computer calculation of density functional theory (DFT) methods.

Theoretical investigation on ESIPT mechanism for a novel Sal-3,4-benzophen system

In this work, we theoretically investigate the properties of excited state process for a novel salicylidene sal-3,4-benzophen (Sal-3,4-B) system, which contains two intramolecular hydrogen bonds (O1-H2[Formula: see text]N3 and O4-H5[Formula: see text]N6). Based on the density functional theory (DFT) and time-dependent DFT (TDDFT) methods, we find these two hydrogen bonds should be strengthened in the S1 state, while the O4-H5[Formula: see text]N6 one could be largely affected upon the excitation process. Analyses about infrared (IR) vibrational spectra about hydrogen bond moieties also confirm this viewpoint. Frontier molecular orbitals (MOs) depict the nature of electronic excited state and support the excited state intramolecular proton transfer (ESIPT) reaction.Two kinds of stepwise potential energy curves of Sal-3,4-B in the S1 state demonstrate that only one proton could be transferred. Also based on constructing potential energy curves, the synergetic situation could be eliminated. Due to the specific ESIPT mechanism for Sal-3,4-B, we successfully explain the previous experiment and provide a reasonable attribution to the second emission peak of experiment.

An analogy study on ESIPT reaction for 3BHC sensor between polar DMF and nonpolar toluene

A comparison about excited state intramolecular proton transfer (ESIPT) mechanism of a new sensor 3-(1,3-benzothiazol-2-yl)-2-hydroxynaphthalene-1-carbaldehyde (3BHC) in polar solvent dimethylformamide (DMF) and nonpolar solvent toluene have been investigated within the framework of the time-dependent density functional theory (TD-DFT) method. The reproduced previous experimental absorption and emission spectra via our calculations reveals the reasonability of the DFT and TD-DFT theoretical level. The staple bond lengths, bond angles, and corresponding infrared vibrational spectra demonstrate that the intramolecular hydrogen bond of 3BHC should be strengthened in both polar DMF and nonpolar toluene. Two kinds of ESIPT mechanisms for different solvents have been put forward; there is a low potential barrier in the ESIPT process in the DMF solvent, whereas there is almost a nonbarrier for the ESIPT process in the toluene solvent. Hence, we could conclude that the ESIPT process of 3BHC sensor is more likely to occur in the nonpolar solvent upon the photoexcitation, based on which, the excited state behavior of 3BHC could be controlled.

Modeling the Sensing Activity of Carbon Nanotubes Functionalized with the Carboxyl, Amino, or Nitro Group Toward Alkali Metals

The sensing activity of carbon nanotubes (CNTs) functionalized with the carboxyl, amino, or nitro group toward the atoms and ions of different metals are modeled using the semiempirical modified neglect of the diatomic overlap (MNDO) and density functional theory (DFT) methods. We discuss the mechanism by which the functional groups attach to the open end of a zig-zag type CNT to form a probe for chemical sensing. The interaction of the CNT-based probe with the potassium, sodium, and lithium atoms and ions is considered in detail. By comparing the results of the modeled sensing activity of the nanoprobes toward the elements of interest, we determine the optimal functional group for the CNT modification to produce a sensor suitable for identifying the potassium, lithium, and sodium atoms and ions, including those that occur in salts and alkali salts.

Probing the electronic structure and aromaticity in W3F3+/−, W3F3X (X = Li, Na, K), AND W3F3Y+ (Y = Be, Mg, Ca) clusters

The equilibrium geometries, electronic properties, and aromaticity of tungsten low-fluoride W3F 3 +/− clusters and their half-sandwich-type W3F3X (X = Li, Na, K) and W3F3Y+ (Y = Be, Mg, Ca) complexes are investigated by density functional theory (DFT) methods. The calculations reveal three types of the d bonding interaction existing in the planar regular hexagonal W3F3+ (D3h, 1A′1) cation, W3F3− (D3h, 3A′1) anion, and W3F3X (C s , 3A″) (X = Li, Na, K), W3F3Y+ (C s , 3A″) (Y = Be, Mg, Ca) complexes. The δ aromaticity is revealed in the W3F3+ (D3h, 1A′1) cation, while the W3F3− (D3h, 3A″1) anion possesses partial δ aromaticity. They have two delocalized δ electrons, satisfying the (4n+2) Huckel electron counting rule.

Opto-Electronic Investigation of Rubidium Based Fluoro-Perovskite for Low Birefringent Lens Materials

In this communication, systematic first principles calculation has been scrutinize to evaluate bonding nature, structural, electronic, and optical properties of RbHgF3. The findings are based on total energy calculations where Khon Sham (KS) equation is solved by means of density functional theory (FP-LAPW) method. Optimization of structural parameters is done with variety of approximations, which corroborates through comparison with available experimental data. Assessment of band profile through GGA plus Trans-Blaha modified Becke–Johnson (TB-mBJ) potential highlights underestimation of bandgap with traditional Generalized Gradient approximations. Specific contribution of particular states on electronic properties is investigated by means of total and partial density of states while contour maps of electron density are used to sightsee bonding character and it is evaluated that emphasized compound is (M-Γ) indirect bandgap material with mixed ionic and covalent bonding character. Additionally attention is paid to absorption and reflection spectra of RbHgF3fluoroperovskite by reconnoitering optical properties, which shows extensive absorption and reflection in high frequency regions. Expectantly, current study would benchmark various quantum mechanical effects, which must be taken into account to understand and utilize RbHgF3 in fabricating practical devices.