Molar Diamagnetic Susceptibility Research Articles

“Property Prediction from Structural Differences”: II. Application to the molar diamagnetic susceptibilities of amino acids

One of the main aims of the theoretical chemists is to introduce new and useful approaches for the estimation of chemical reactivity descriptors of Conceptual Density Functional Theory (CDFT) like absolute hardness, polarizability and magnetizability. In addition to providing results close to experimental results, the methods developed for this purpose must also be easily applicable to many molecular systems and easy to learn. “Property Prediction from Structural Differences” method proposed by one of the authors of this article is based on the idea that various properties of molecules can be easily calculated by taking the sum of the functional group contributions in the structure of the molecule. The most important thing in the applying of the method is the reliable determination of functional group contributions. In the present paper, using “Property Prediction from Structural Differences” method, we predicted the molar diamagnetic susceptibilities of amino acids with reasonably good accuracy. The computed values are in good agreement with experimental data and the results of previously introduced theoretical models. The reason why amino acids were especially preferred in the study is the lack of the molar diamagnetic susceptibility data of some amino acids in the literature. Additionally, to test whether a molar diamagnetic susceptibility based scale can be proposed for the calculation of any CDFT based reactivity descriptor, DFT computations were also performed for amino acid molecules. The relationships between parameters were evaluated in terms of the electronic structure rules like Maximum Hardness, Minimum Polarizability, Minimum Magnetizability and Minimum Electrophilicity Principles.

Property prediction from structural differences: I. Molar diamagnetic susceptibilities of organic chemical systems

In the present paper, a new and simple method to predict the molar diamagnetic susceptibilities of organic compounds, including complex organic structures like cholesterol and cholic acid is introduced. By courtesy of the method, magnetic susceptibilities of large chemical systems are predicted as so close to experimental values without any complex calculation. The method can be easily applied to compute the magnetic susceptibilities of the organic systems that their magnetic susceptibilities are not reported in the literature. This is one of the paper series regarding to the method called as “Property Prediction from Structural Differences.”

Can van der Waals constants be used in the chemical reactivity analysis? A new approach as a support to minimum magnetizability principle

AbstractOne of the most important purposes of theoretical chemists is to derive new, useful, and reliable equations to compute the well‐known parameters like hardness, polarizability, magnetizability, and electrophilicity providing enough hints for the reactivity analysis of the chemical systems. In the derivation of such equations, our research team widely considers the popular electronic structure rules like electronegativity equalization, maximum hardness, minimum polarizability, minimum magnetizability, and minimum electrophilicity principles. Recently, in the light of maximum entropy and minimum magnetizability principles, Kaya and Chattaraj (2021) presented a simple way to calculate their standard absolute entropies (S0298) based on molar diamagnetic susceptibilities (χm) of inorganic ionic systems. In the present paper, a new and useful molar diamagnetic susceptibility calculation method including the use of van der Waals constants (a and b) is introduced. Here, we named this method as Kaya–Şimşek approach. Through the relations between molar diamagnetic susceptibility and van der Waals constants, we can easily predict the magnetic susceptibility of molecules that their magnetic susceptibilities are unknown. The results of the equations derived are quite close to experimentally reported data. The analyses made proved that van der Waals constants can be considered as chemical reactivity descriptors. We propose that in stable states, van der Waals constants are minimized. The validity of minimum magnetizability principle is supported with solid evidences.

Two empirical formulae for estimating standard entropy of inorganic ionic solids and a possible connection between two associated electronic structure principles

Two empirical formulae for estimating the standard entropies of some inorganic ionic solids are proposed. Linear relations are suggested between the standard entropy and the cube root of the formula unit volume as well as the cube root of the diamagnetic susceptibility, building a bridge between conceptual density functional theory and solid state chemistry. It is noted that the stabilities of inorganic ionic crystals are closely related to their molar diamagnetic susceptibilities. The suggested correlation provides a connection between the maximum entropy and minimum magnetizability principles.

QSPR study of molar diamagnetic susceptibility of diverse organic compounds using multiple linear regression analysis

QSPR study of molar diamagnetic susceptibility of diverse organic compounds using multiple linear regression analysis

Improved QSPR Study of Diamagnetic Susceptibilities for Organic Compounds Using Two Novel Molecular Connectivity Indexes

Abstract For predicting the molar diamagnetic susceptibilities of organic compounds, a variable molecular connectivity index mχ' and its converse index mχ'' based on adjacency matrix of molecular graphs and the variable atomic valence connectivity index δi' were proposed. The optimal values of parameters x, a, and y included in definition of δi', mχ' and mχ'' can be found by an optimization method. When x2.9, a1.10, and y0.36, a good five‐parameter model for the molar diamagnetic susceptibilities can be constructed from 0χ', 1χ', 2χ', 1χ'' and 2χ'' by using the best subset regression analysis method. The correlation coefficient r, standard error s, and average absolute deviation of the multilinear regression (MLR) model are 0.9930, 4.96 cgs, and 3.74 cgs, respectively, for the 721 organic compounds (training set). The cross‐validation by using the leave‐one‐out method demonstrates that the MLR model is highly reliable from the point of view of statistics. The average absolute deviation of predicted values of the molar diamagnetic susceptibility of another 360 organic compounds (test set) is 4.37 cgs for the MLR model. The results show that the current method is more effective than literature methods for estimating the molar diamagnetic susceptibility of an organic compound. The MLR method can provide an acceptable model for the prediction of the molar diamagnetic susceptibilities of organic compounds.

Variable Molecular Connectivity Indices for Predicting the Diamagnetic Susceptibilities of Organic Compounds

For predicting the molar diamagnetic susceptibilities of organic compounds, a variable molecular connectivity index mχ′ and its converse index mχ′′ based on the adjacency matrix of molecular graphs and the variable atomic valence connectivity index δi′ were proposed. The optimal values of parameters a, b, and y included in definition of δi′, mχ′ and mχ′′ can be found by optimization methods. When a = 1.10, b = 2.8, and y = 0.36, a good five-parameter model can be constructed from mχ′ and mχ′′ by using the best subsets regression analysis method for the molar diamagnetic susceptibilities of organic compounds. The correlation coefficient r, standard error s, and average absolute deviation (AAD) of the multivariate linear regression (MLR) model are 0.9930, 4.99, and 3.72 cgs, respectively, for the 720 organic compounds (training set). The AAD of predicted values of the molar diamagnetic susceptibility of another 361 organic compounds (test set) is 4.37 cgs for the MLR model. The results show that the current...

Modeling Diamagnetic Susceptibilities of Organic Compounds with a Novel Connectivity Index

A novel molecular connectivity index, denoted as mχ‘ and based on the adjacency matrix of molecular graphs and novel atomic valence connectivities () is proposed. The index is successfully applied to predict the molar diamagnetic susceptibilities of organic compounds. A good quantitative structure−property relationship (QSPR) model for molar diamagnetic susceptibilities can be constructed from 0χ‘, 1χ‘, and 2χ‘, using a multivariate linear regression (MLR). The correlation coefficient (r), standard error, and average absolute deviation (AAD) of the MLR model are 0.9917, 5.42 cgs, and 4.14 cgs, respectively, for 720 organic compounds. Cross-validation through the use of the leave-one-out method demonstrates that the MLR model is highly reliable. Using the MLR model, the AAD of the predicted values of molar diamagnetic susceptibilities of another 361 organic compounds (test set) is 4.69 cgs. The result shows that the current method is more accurate than literature methods for estimating the molar diamagneti...

Topological research on diamagnetic susceptibilities of organic compounds

A novel molecular connectivity index, (m)chi('), based on the adjacency matrix of molecular graphs and novel atomic valence connectivities, delta(i)(') for predicting the molar diamagnetic susceptibilities of organic compounds is proposed. The delta(i)(') is defined as: delta(i)(') = delta(i)(nu) x Ei=12:625, where delta(i)(nu) and E(i) are the atomic valence connectivity and the valence orbital energy of atom i, respectively. A good QSPR model for molar diamagnetic susceptibilities can be constructed from (0)chi('), (1)chi('), (2)chi(') and (4)chi(p)(') using multivariate linear regression (MLR). The correlation coefficient r, standard error, and average absolute deviation of the MLR model are 0.9918, 5.56 cgs, and 4.26 cgs, respectively, for the 721 organic compounds tested (training set). Cross-validation using the leave-one-out method demonstrates that the MLR model is highly reliable statistically. Using the MLR model, the average absolute deviations of the predicted values of molar diamagnetic susceptibility of another 360 organic compounds (test set) is 4.34 cgs. The results show that the current method is more effective than literature methods for estimating the molar diamagnetic susceptibility of an organic compound. The MLR method thus provides an acceptable model for the prediction of molar diamagnetic susceptibilities of organic compounds.

Quantitative Structure Property Relations (QSPR) for Predicting Molar Diamagnetic Susceptibilities, χm, of Inorganic Compounds

AbstractFor predicting the molar diamagnetic susceptibilities of inorganic compounds, a novel connectivity index mG based on adjacency matrix of molecular graphs and ionic parameter gi was proposed. The gi is defined as gi=(ni0.5−0.91)4·xi0.5/Zi0.5, where Zi, ni, xi are the valence, the outer electronic shell primary quantum number, and the electronegativity of atom i respectively. The good QSPR models for the molar diamagnetic susceptibilities can be constructed from 0G and 1G by using multivariate linear regression (MLR) method and artificial neural network (NN) method. The correlation coefficient r, standard error, and average absolute deviation of the MLR model and NN model are 0.9868, 5.47 cgs, 4.33 cgs, 0.9885, 5.09 cgs and 4.06 cgs, respectively, for the 144 inorganic compounds. The cross‐validation by using the leave‐one‐out method demonstrates that the MLR model is highly reliable from the point of view of statistics. The average absolute deviations of predicted values of the molar diamagnetic susceptibility of other 62 inorganic compounds (test set) are 4.72 cgs and 4.06 cgs for the MLR model and NN model. The results show that the current method is more effective than literature methods for estimating the molar diamagnetic susceptibility of an inorganic compound. Both MLR and NN methods can provide acceptable models for the prediction of the molar diamagnetic susceptibilities. The NN model for the molar diamagnetic susceptibilities appears more reliable than the MLR model.

リン酸エステル類，Ｎ‐アルキルピリジニウム塩類および各種補酵素の反磁性磁化率

The diamagnetic susceptibilities of alkyl phosphates, N-alkylpyridinium compounds and various coenzymes were determined by Gouy's method. The susceptibility for phosphate group ( · PO4-· ) was found to be 40.5 x 10-6 cm3 mol-1. The molar diamagnetic susceptibility of dipalmitylphosphatidylcholine was obtained to be 512 x 10-6 cm3 mol-1. The result was almost in accord with the estimated value, 505 x 10-6 cm3 mol-1, obtained by Pascal's additive law. The molar diamagnetic susceptibilities of various coenzymes, NAD+, NADH, NADP+, FAD were determined to be 342, 341, 370, 416 x 10-6 cm3 mol-1, respectively.

Calculations on the 2S ground state of Be II.

Extensive variational calculations on the $^{2}\mathrm{S}$ ground state of ${\mathrm{Be}}^{+}$ are reported. Using a 401-term expansion of Hylleraas-type functions, the nonrelativistic ground-state energy is determined to be -14.324 760 a.u., which is the lowest upper bound to the ground-state energy reported to date for this system. The Fermi contact interaction is determined to be 12.4980 a.u., which is in very close agreement with the experimental value of 12.503 88 a.u. The nuclear-magnetic shielding factor and the molar diamagnetic susceptibility are evaluated to be \ensuremath{\sigma}=1.415401 \ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}4}$ a.u. and \ensuremath{\chi}=-5.154 43\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$ ${\mathrm{cm}}^{3}$ ${\mathrm{mol}}^{\mathrm{\ensuremath{-}}1}$, respectively. The electron density at the nucleus, the moments 〈${r}_{i}^{n}$〉, n=-1, 1, 2, and 3, and 〈${r}_{\mathrm{ij}}^{n}$〉, n=-1, 1, and 2, are also reported. The specific mass shift (mass polarization contribution) is determined to be 2.758\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}5}$ a.u. The rate of convergence of the calculation is discussed. The role of one versus two spin eigenfunctions in the basis set is discussed with respect to its bearing on the calculation of the Fermi contact interaction.

Excess thermodynamic properties and vapor-liquid equilibrium data for then-butylamine+p-dioxane system at 25�C

Excess values of molar volumes, viscosities, molar enthalpies, Gibbs molar energies, surface tensions and molar diamagnetic susceptibilities were calculated at 25°C for then-butylamine+p-dioxane system. The observed deviations from the ideality were explained on the basis of intermolecular interactions. Van Laar's equations were the best in predicting activity coefficients for this system.

Reduced first order density matrix for the Be ground state

AbstractA reduced first order density matrix for the Be ground state is computed from an extensive configuration interaction (CI) wave function. A sequence of increasingly accurate CI wave functions Φq converging towards the exact Ψ is used to assess the quality of the results which include approximate bounds for the overlaps 〈Φq|Ψ〉, electron–nuclear coalescence cusp data, Weinhold's overlap between density matrices, virial ratios, occupation number spectra, and some expectation values. The nuclear magnetic shielding constant and the molar diamagnetic susceptibility are determined with 2.0 and 1.5% of uncertainty, respectively.

United-Atom Approximation Applied to Argonlike Molecules. III. HCl and SiH4

The united-atom approximation has been used to obtain molecular wavefunctions for HCl and SiH4 in the gaseous state. Theoretical values were determined, in each instance, for the molecular energy, bond length, force constant, molar diamagnetic susceptibility, and the coherent x-ray scattering factor. Where possible, the results were compared with the corresponding experimental data. For SiH4, a comparison of the present results was made with the earlier work of Carter and also of Albasiny and Cooper. These workers used, respectively, a numerical Hartree self-consistent-field approach and a numerical Hartree—Fock scheme, the latter study being performed within a spherical and a nonspherical approximation. For the HCl molecule, some comparison is made with the two-center SCF—LCAO—MO calculation performed by Nesbet. In each case, the united-atom treatment gave a molecular energy which was 98.9% of the experimental value. Other physical properties for HCl and SiH4 derived from the present model compare favorably with similar quantities obtained from the more elaborate calculations and also with the corresponding available experimental data.

Ionic radii and the method of the undetermined parameter

The basis on which values may be assigned to the radii of ions in crystals is examined. A set of radii in terms of one undetermined parameter (Li+, 2.581–δ; Na+, 2.851–δ; K+, 3.162–δ; Rb+, 3.302–δ; F–,δ–0.520; Cl–, δ–0.020; Br–, δ+0.141; I–, δ+0.399) is obtained for the alkali metal halides, which best satisfies the additivity criterion. The value assigned to the undetermined parameter δ in no way affects the accuracy of the additivity of the radii. Methods of finding δ based on the Landé assumptions, on screening constant calculations, on absolute molar refractions of the ions, and on absolute molar diamagnetic susceptibilities of the ions are in good agreement, but values of δ from measurements of electron density in crystals are at variance with them.

United-Atom Approximation Applied to Argonlike Molecules. II. PH2−, PH3, and PH4+

The united-atom treatment has been applied to the systems PH2−, PH3, and PH4+. For PH3 and PH4+, satisfactory values are obtained for the total molecular energy and ``breathing'' force constants when compared with experiment. The model gives theoretical bond lengths which are in good agreement with the observed values. Coherent x-ray scattering factors are presented for PH3 and PH4+ along with a discussion of the molar diamagnetic susceptibilities. The value of the proton affinity derived here for PH3 is found to be in general agreement with the experimental results. Except for the considerable improvement in the proton-affinity calculation, the results obtained here are in keeping with the conclusions derived from our earlier work concerning the united-atom study of H2S.

Comparison of Some Calculations on H2O and H2S

For the H2O and H2S molecules, a comparison is made of the values of the molecular energy, molar diamagnetic susceptibility, coherent x-ray scattering factor, dipole moment, 〈1/r〉 and 〈1/r2〉 as calculated by different approximate treatments. The results of a united-atom (UA) calculation, the LCAO—MO—SCF extended one-center expansion (OCE) approach of Moccia, and the LCAO—MO—SCF minimal multicenter expansion (MCE) treatment of Ellison and Shull are compared for H2O. For H2S, UA and OCE calculations are compared. All theoretical values are compared with experiment where possible, and the relative merits of the different approximate treatments are discussed. We also discuss results which might be obtained for H2S from a minimal LCAO—MO—SCF—MCE calculation. Also for H2S, we report the results of modifications in our earlier UA approach. Although the conclusions drawn in our earlier work remain unchanged by the modifications, we note a pleasing improvement on our earlier values for the force constant, molar diamagnetic susceptibility, and molecular energy.

United-Atom Approximation Applied to Argonlike Molecules. I. Hydrogen Sulfide

The united-atom approximation was applied to H2S and also to the systems HS— and S——. The wavefunction obtained for H2S was used to calculate the molar diamagnetic susceptibility and the coherent x-ray scattering factor for the gaseous form of the molecule. Values are also reported for the ``breathing'' force constant for H2S and for the theoretical bond length for both H2S and HS—. Within the present approximation a calculation was made of the bond energy for H2S dissociating into HS and S. The proton affinities for HS— and S—— were also determined. Where possible, a comparison was made with experiment. In general, except for the proton affinities and bond-energy calculation, the united-atom model applied to H2S was reasonably successful. A comparison was also made between the present radial density and the density of electrons for H2S provided by the model of ``floating'' hydrogen densities. This comparison helps to substantiate the claim made earlier, namely, that the model of ``floating'' hydrogen densities will provide a very reasonable radial distribution of electrons within molecules of the form XHn.

Radial Distribution of Electrons in the Ammonia and Hydrogen Sulfide Molecules

The model of ``floating'' hydrogen electron densities has been applied in detail to the molecules NH3 and H2S, both of the form XHn. In this way it has been shown that a reasonable radial distribution of electrons within these molecules may be obtained fairly easily from a knowledge of the molecular rotational magnetic moment which, in turn, is based on molecular beam or Zeeman effect microwave observations. Some measure of the accuracy of these molecular electron densities has been obtained by calculating the coherent x-ray scattering factor and comparing it with the corresponding experimental values. Included in the present calculations for H2S is a determination of the paramagnetic contribution to the molar diamagnetic susceptibility. In addition, values of the molar diamagnetic susceptibility have been found for NH3 and H2S which are in good agreement with the experimental results.