Total Molecular Dipole Moment Research Articles

High energy storage density and efficiency achieved in dielectric films functionalized with strong electronegative asymmetric halogen-phenyl groups

Capacitor dielectric films exhibiting high energy storage density and efficiency within a wide operating temperature range are crucial for advancing electrical and electronic devices. The low energy storage density and working temperature as well as the high manufacturing costs of the state-of-the-art BOPP films limit their use as an energy storage unit for developing smart grids or the internet of things, while most of the polymer-based dielectric films reported currently are facing the issues of the rapid efficiency deterioration with the increasing of temperature. In this work, the high energy storage density and efficiency are achieved in the low-cost flexible epoxy films innovatively modified by trifluoro-phenyl group functionalization. Introducing strongly electronegative fluorinated phenyl groups greatly improves the energy storage density due to the increase of the total molecular dipole moment of the polymer film. Meanwhile, achieving the high energy storage efficiency is accomplished via gradually increasing the charge trapping site density of epoxy resins functionalized with different densities of fluorinated phenyl groups, which can be demonstrated through both thermally stimulated current (TSC) spectroscopy and the first-principles calculations results. Finally, it is experimentally demonstrated that deeper charge traps can be obtained in slightly crosslinked trifluoro-phenyl functionalized epoxy films, resulting in an energy storage density of 3.31 J/cm3 and a high energy storage efficiency of 95% at 100 °C.

AC/DC Analysis: Broad and Comprehensive Approach to Analyze Infrared Intensities at the Atomic Level.

We present a complete theoretical protocol to partition infrared intensities into terms owing to individual atoms by two different but related approaches: the atomic contributions (ACs) show how the entire molecular vibrational motion affects the electronic structure of a single atom and the total infrared intensity. On the other hand, the dynamic contributions (DCs) show how the displacement of a single atom alters the electronic structure of the entire molecule and the total intensity. The two analyses are complementary ways of partitioning the same total intensity and conserve most of the features of the total intensity itself. Combined, they are called the AC/DC analysis. These can be further partitioned following the CCTDP (or CCT) models according to the population analysis chosen by the researcher. The main conceptual features of the equations are highlighted, and representative numerical results are shown to support the interpretation of the equations. The results are invariant to rotation and translation and can readily be extended to molecules of any size, shape, or symmetry. Although the AC/DC analysis requires the choice of a charge model, all charge models that correctly reproduce the total molecular dipole moment can be used. A fully automated protocol managed by the Placzek program is made available, free of charge and with input examples.

A computational study on a series of phenanthrene and phenanthroline based potential organic photovoltaics

A series of phenanthrene and phenanthroline derivatives were considered computationally by the application of Density Functional Theory at the B3LYP/6-31++G(d,p) level to investigate their potential usage as organic solar cell components, thermally activated delayed fluorescence and nonlinear optic compounds. The structures were constructed as a D-π-A motif in order to increase the ability to achieve intramolecular charge transfer enabling them to act as organic semiconductors. The inter-frontier energy gap of all compounds was found to be in the range of semiconductors. The thermally activated delayed fluorescence (TADF) properties of the compounds were also discussed in relation to the results obtained by TD-DFT calculations. Some of them possessed very narrow triplet-singlet transition energy leading to future TADF applications. Moreover, the nonlinear optic characteristics of all compounds were investigated through calculations of the total molecular dipole moment (μtot), linear polarizability (αtot) and hyperpolarizability (βtot). The results indicate the potential nonlinear optic property of all of the systems.

Experimental and theoretical characterization of the 2-(4-bromobenzyl)-5-ethylsulphonyl-1,3-benzoxazole

Synthesis, crystal structure, Fourier transform infrared spectroscopy (FT-IR) and quantum mechanical studies of the 2-(4-bromobenzyl)-5-ethylsulphonyl-1,3-benzoxazole (C16H14NO3SBr) have been reported. The molecular structure obtained from X-ray single-crystal analysis of the investigated compound in the ground state has been compared using Hartree–Fock (HF) and density functional theory (DFT) with the functional B3LYP and B1B95 using the 6-311++G(d,p) basis set. In addition to the optimized geometrical structures, atomic charges, molecular electrostatic potential (MEP), natural bond orbital (NBO), nonlinear optical (NLO) effects and thermodynamic properties of the compound have been investigated by using DFT. The potential energy surface (PES) scans about four important torsion angles are performed by using B3LYP/6-311++G(d,p) level of theoretical approximation for the compound. The experimental (FT-IR) and calculated vibrational frequencies (using DFT) of the title compound have been compared. The total molecular dipole moment (μ), linear polarisability (α), and the first-order hyperpolarisability (β) were predicted by using DFT with different basis sets 6-31G(d), 6-31+G(d,p), 6-31++G(d,p), 6-311+G(d) and 6-311++G(d,p) for investigating the effects of basis sets on the NLO properties. Our computational results yield that βtot for the title compound is greater than those of urea. The standard thermodynamic functions were obtained for the title compound with the temperature ranging from 200 to 450K.

Synthesis, structure, spectroscopic (FT-IR) and density functional modelling studies of 1-[(4-ethoxyphenylimino)methyl]napthalene-2-ol

Synthesis, crystallographic characterisation, spectroscopic (Fourier transform infrared spectroscopy [FT-IR]) and density functional modelling studies of the Schiff base 1-[(4-ethoxyphenylimino)methyl]napthalene-2-ol (C19H17NO2) have been reported. The molecular structure obtained from X-ray single-crystal analysis of the investigated compound in the ground state has been compared using Hartree–Fock and density functional theory (DFT) with the 6-311++G(d,p) basis set. In addition to the optimised geometrical structures, atomic charges, molecular electrostatic potential, natural bond orbital, non-linear optical (NLO) effects and thermodynamic properties of the compound have been investigated by using DFT. The experimental (FT-IR) and calculated vibrational frequencies (using DFT) of the title compound have been compared. The solvent effect was also investigated for obtained molecular energies and the atomic charge distributions of the compound. There exists a good correlation between experimental and theoretical data for enol-imine form of the compound. The total molecular dipole moment (µ), linear polarisability (α), and the first-order hyperpolarisability (β) were predicted by the B3LYP method with different basis sets 6-31G(d), 6-31+G(d,p), 6-31++G(d,p), 6-311+G(d) 150 and 6-311++G(d,p) for investigating the effects of basis sets on the NLO properties. Our computational results yield that βtot for the title compound is greater than those of urea.

Theoretical Study of the N-(2,5-Methylphenyl)salicylaldimine Schiff Base Ligand: Atomic Charges, Molecular Electrostatic Potential, Nonlinear Optical (NLO) Effects and Thermodynamic Properties

Optimized geometrical structure, atomic charges, molecular electrostatic potential, nonlinear optical (NLO) effects and thermodynamic properties of the title compound N-(2,5-methylphenyl)salicylaldimine (I) have been investigated by using ab initio quantum chemical computational studies. Calculated results showed that the enol form of (I) is more stable than keto form. The solvent effect was investigated for obtained molecular energies, hardneses and the atomic charge distributions of (I). Natural bond orbital and frontier molecular orbital analysis of the title compound were also performed. The total molecular dipole moment (µ), linear polarizability (α), and first-order hyperpolarizability (β) were calculated by B3LYP method with 6- 31G(d), 6-31+G(d,p), 6-31++G(d,p), 6-311+G(d) and 6-311++G(d,p) basis sets to investigate the NLO properties of the com- pound (I). The standard thermodynamic functions were obtained for the title compound with the temperature ranging from 200 to 450 K.

Quantum mechanical force field for water with explicit electronic polarization.

A quantum mechanical force field (QMFF) for water is described. Unlike traditional approaches that use quantum mechanical results and experimental data to parameterize empirical potential energy functions, the present QMFF uses a quantum mechanical framework to represent intramolecular and intermolecular interactions in an entire condensed-phase system. In particular, the internal energy terms used in molecular mechanics are replaced by a quantum mechanical formalism that naturally includes electronic polarization due to intermolecular interactions and its effects on the force constants of the intramolecular force field. As a quantum mechanical force field, both intermolecular interactions and the Hamiltonian describing the individual molecular fragments can be parameterized to strive for accuracy and computational efficiency. In this work, we introduce a polarizable molecular orbital model Hamiltonian for water and for oxygen- and hydrogen-containing compounds, whereas the electrostatic potential responsible for intermolecular interactions in the liquid and in solution is modeled by a three-point charge representation that realistically reproduces the total molecular dipole moment and the local hybridization contributions. The present QMFF for water, which is called the XP3P (explicit polarization with three-point-charge potential) model, is suitable for modeling both gas-phase clusters and liquid water. The paper demonstrates the performance of the XP3P model for water and proton clusters and the properties of the pure liquid from about 900 × 10(6) self-consistent-field calculations on a periodic system consisting of 267 water molecules. The unusual dipole derivative behavior of water, which is incorrectly modeled in molecular mechanics, is naturally reproduced as a result of an electronic structural treatment of chemical bonding by XP3P. We anticipate that the XP3P model will be useful for studying proton transport in solution and solid phases as well as across biological ion channels through membranes.

Synthesis, structure and photoresponsive properties of 4-(3-fluorobenzylideneamino)antipyrine

Organic compounds are attracting greater attention largely in the recent years owing to their potential applications in the functional materials. Herein we reported the structural and photophysical properties of 4-(3-fluorobenzylideneamino)antipyrine. The studied molecule adopts a trans configuration about the imine bond, and forms a non-planar molecular device consisted of two effectively conjugated π-electron moieties. The stronger vibrational and nonlinear optical activities are tightly related to the molecular structural characteristics revealed by the analysis on vibrational modes and frontier molecular orbitals. The intramolecular electrons can be separated by the electron-transporting with specified photon-absorbing theoretically. The total molecular dipole moment, mean linear polarizability and first-order hyperpolarizability calculated at B3LYP/6-31G(d) level are 1.5390Debye, 35.6075Å3 and 1.5391×10−29cm5/esu, respectively. The reported results indicate that the compound is a promising candidate of photoresponsive materials.

ChemInform Abstract: Aminimides as Peptidomimetics

Highly selective and specific protein-protein and peptide-protein interactions are elicited by a large number of natural specific biological responses. The mimicry of these natural interactions has been an important and useful strategy for the development of metabolically stable drugs capable of being administered orally (1-4). We report here on the use of a novel type of peptidomimetic based on the aminimide linkage. Aminimides are chemically described as hydrazinium hydroxide inner salts or as ammonium-imines. (Fig. 1) This unusual class of compounds possesses a zwitterionic nature that provides solubility in polar media (water, methanol, ethanol, acetonitrile, DMF, DMSO) as well as in nonpolar solvents such as benzene, when substituents are chosen to reduce the total molecular dipole moment. The aminimide bond has two resonance forms as shown in Fig. 1. ThepKa of the protonated form is generally less than 4. The predominant resonance form will place the formal negative charge on the more electronegative oxygen atom, although we typically use diagrams in which the formal charges reside on the two nitrogens to stress the absence of the hydrogen-bond-donating ability of the aminimide as compared the amide bond in peptides. The aminimide bond is extremely stable under both acidic and basic conditions and is highly resistant to proteolytic cleavage. Fig. 1. Resonance forms for trimethylammoniacetamidate.

Experimental and density functional studies on 4-(4-cyanobenzylideneamino)antipyrine

4-(4-cyanobenzylideneamino)antipyrine (CBAP) has been synthesized and characterized by elemental analysis, FT-IR, UV-VIS and X-ray single crystal diffraction techniques. Crystallographic study reveals that the compound adopts trans configuration about the Schiff base imine double bond. The substituted p-cyanophenyl ring indirectly linked to the pyrazoline ring by the C=N double bond is almost coplanar with the pyrazole ring, whereas the phenyl ring directly attached to the pyrazoline ring forms an effective dihedral angle. Density functional calculations have been carried out to optimize and to characterize the title compound by using B3LYP method at 6-31G(d) basis set. The calculated results show that the optimized geometry can well reproduce the crystal structural parameters and the theoretical vibrational frequencies show good agreement with experimental values. On the basis of theoretical vibrational analyses, the thermodynamic properties (standard heat capacities, standard entropies, and standard enthalpy changes) of the title compound at different temperatures have been calculated, revealing the correlations between , , and temperatures. The total molecular dipole moment, mean linear polarizability and mean first hyperpolarizability obtained by calculation are 3.4724 Debye, 40.154 Å3 and 4.5424 × 10−29 cm5/esu, respectively. Three absorption bands in UV-VIS are mainly derived from the contribution of bands π → π* and electrons transfer from HOMO to LUMO, LUMO + 1, LUMO + 2, respectively.

Electric dipole moment of sulfuric acid from Fourier transform microwave spectroscopy

The electric dipole moment of H 2SO 4 in the gas phase has been measured using pulsed-nozzle Fourier transform microwave spectroscopy. Ninety one Stark-shifted frequencies at a series of electric field strengths have been recorded for the 1 10 ← 0 00 transition. The total molecular dipole moment ( μ tot = μ c) was determined to be 2.9643(67) D. This is approximately 0.24 D greater than the previous literature value obtained from similar measurements on the 6 43 ← 5 33 transition. Both ab initio and DFT calculations using Dunning’s aug-cc-pVnZ (n = D, T, Q, Q+d) basis sets concur with the present result.

Ab initio calculation of molecular structure and dipole moment for selected divinyl and diepoxy molecules

The ab initio quantum-chemical calculations were used to obtain the components of the dipole moment of four molecules composed of a rigid central segment and two symmetric flexible endings. The recently synthesized molecules are of interest due to their liquid-crystalline properties. Two different central segments and two kinds of endings (vinyl and epoxy) were studied. As a first step of calculations the geometry of each individual segment was optimized in order to obtain the structure of the lowest energy. The optimization of one of the central segments revealed two conformations with similar energy. Due to several possibilities of joining the endings with the central segment a series of possible conformers may be created for each of the molecules. The lowest-energy conformer was finally optimized for each structure. The relation of the total molecular dipole moment to the value and relative orientation of the dipole moments of individual segments is discussed. For the molecules in which nematic mesophase was detected it was found that replacing vinyl endings with epoxy endings results in doubling of the dipole moment. The direction of the dipole moment also strongly depends on the type of ending. The polarizability contribution to the total dipole moment is negligible for the fields lower than 10 6 V/m.

Further studies on the rotational barriers of Carbamates. An NMR and DFT analysis of the solvent effect for Cyclohexyl N, N-dimethylcarbamate

The solvent effect on the Gibbs energy of activation for rotation around the (CO)–N bond in cyclohexyl N, N-dimethylcarbamate was investigated by dynamic NMR spectroscopy and density-functional theory at the B3LYP/6-311+G ∗∗ level. The experimental barriers were about 15 kcal mol −1 with no appreciable variation when the solvent polarity was changed. A reaction field model was applied to theoretically mediate the solvent effect and the results were comparable to the experimental data. An analysis, based on the Onsager solvation theory, showed that the solvent effect on rotational barriers can be understood employing the total molecular dipole moment, the difference between the dipole moments of the ground and the transition state structures, or both, as appropriate.

The total molecular dipole moment for liquid water

For the water molecule, the dipole is the first nonzero multipole moment; it represents the polarity of the molecule and has been widely used in describing solvation behavior. A rather wide range of theoretically determined values for the total molecular dipole moment of water in condensed phases has been reported in the literature. This paper describes a means by which the average total dipole moment for the water molecule in the liquid state can be linked to experimental refractive index data. Three components comprise the mean-field approach that is employed. A formal framework is developed that relates the temperature dependence of the effective molecular polarizability to the average local electric field experienced by a liquid water molecule over a chosen temperature range. A characterization of the distributions of local fields and field gradients is also necessary, and this has been determined from the computer simulations of liquid water samples at several different temperatures for two standard water potentials. The final component, the electric response properties of the water molecule (including nonlinear contributions up to fourth order), were determined from ab initio calculations for gas- and liquid-phase molecules, and are reported elsewhere [A. V. Gubskaya and P. G. Kusalik, Mol. Phys. 99, 1107 (2001)]. By combining these three components, the temperature dependence of the average local electric field, and consequently the average total dipole moment, are extracted from data for the refractive index of liquid water. An almost 10% variation in the dipole moment with temperature is observed over the range 273 to 373 K. The value obtained for the molecular dipole moment at 300 K, 2.95±0.2 D, is in excellent agreement with a recently reported result extracted from x-ray scattering data, as well as with some recent theoretical predictions.

Dipole Moments of Partially Bound Lewis Acid−Base Adducts

Stark effect measurements have been performed on six Lewis acid−base complexes containing 32SO3 and 11BF3. The following dipole moments have been obtained: HC14N−SO3 (4.4172 ± 0.0031 D); CH3C14N−SO3 (6.065 ± 0.018 D); HC15N−BF3 (4.1350 ± 0.0073 D); H315N−BF3 (5.9027 ± 0.0093 D (A state), 5.917 ± 0.010 (E state)); (CH3)315N−BF3 (6.0157 ± 0.0076 D); and (CH3)315N−B(CH3)3 (4.5591 ± 0.0097 D). Across a series of complexes with a common acid, the induced dipole moment increases sharply as the dative bond shortens. Contributions to the total molecular dipole moment arising from distortion, polarization, and charge transfer have been estimated for these and a number of related complexes, using the block-localized wave function energy decomposition analysis of Mo, Gao, and Peyerimhoff. Mulliken and natural population analyses are presented, as are electron density difference maps for HCN−SO3, (CH3)3N−BF3, and (CH3)3N−SO3. Theoretical values for the degree of charge transfer are compared with experimental estimates based on nuclear hyperfine parameters, and the validity of a simple chemical model involving charge transfer and bond moments is examined. Ab initio calculations of the induced dipole moment of HCN−SO3 and H3N−SO3 are given as a function of N−S bond length and compared with the experimentally observed values for a series of SO3 complexes. The results suggest that the induced moments of the series collectively approximate the induced dipole moment function for individual members of the series. Similar results are obtained using previously published dipole moment functions for HCN−BF3 and H3N−BF3.

Quantum simulations and a b i n i t i o electronic structure studies of (H2O)−2

The energetics of the negatively charged water dimer (H2O)−2, is studied using quantum-simulation techniques and ab initio electronic structure calculations. Using the RWK2-M potentials for water and a pseudopotential for the interaction of an electron with a water molecule in the ground state, consisting of Coulomb, adiabatic polarization, exclusion, and exchange contributions, it was found via the quantum path-integral molecular dynamics and the coupled quantum-classical time-dependent self-consistent field methods that while the minimum energy of (H2O)−2 corresponds to a nuclear configuration similar to that found for the neutral (H2O)2 cluster, other nuclear configurations are also exhibited at finite temperature, characterized by a higher total molecular cluster dipole moment and a larger magnitude of the excess electron binding energy. Quantitative agreement is found between the results obtained by the quantum simulations, employing the excess electron–molecule pseudopotential, and those derived, for selected nuclear configurations, via ab initio calculations, employing the Gaussian 86 code with the basis set for the water molecules supplemented by a large diffuse set located at the midpoint of the two oxygens and in addition by a diffuse set for the excess electron.

Infrared intensities. an mo study of the transferability of bond polar parameters

CNDO MO calculations have been carried out in order to analyse the transferability of bond polar parameters associated with infrared band intensities of methyl vibrations in the series of C 1C 5 normal paraffins and their 1-fluoro and 1-nitro derivatives. The influence of highly polar substituents on the transferability of CH parameters is assessed. It is found that the magnitude of individual parameters is independent of the total molecular dipole moment value.

Transferability of bond polar parameters: interpretation of infrared intensities in acetylene, propyne and 3-butyne

The infrared band intensities of acetylene, propyne and 2-butyne are interpreted in terms of bond polar parameters. The intensity parameters are defined as derivatives of the total molecular dipole moment with respect to linear and angular coordinates, associated with individual bond vibrational distortions. The values and the transferability of the bond polar parameters in the molecules examined are discussed.

Bond polar parameters from integrated infrared intensities

Abstract Bond polar parameters have been defined as derivatives of the total molecular dipole moment with respect to linear and angular coordinates associated with individual bond vibrational distortions, and obtained via transformation of the experimental dipole moment derivatives. In the present paper further advances in theoretical approach were presented. New type of angular bond coordinates are introduced and the number of intensity parameters reduced.

Electronic factors in the structure-activity relationship of some 1,4-benzodiazepin-2-ones.

Some significant correlations are observed between the CNS activities of a series of 59 benzodiazepines and some calculated electronic indices. The parameters concerned are the net charge on the carbonyl oxygen atom of the lactam ring and the total molecular dipole moment, correlations with the latter index being superior. The utility of the observed relationships is discussed.