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The reactivity descriptors like electronegativity, hardness, and electrophilicity, formulated on conceptual density functional theory can explain chemical reactivity of various acids and bases, oxidants and reductants as well as electrophiles and nucleophiles through associated structure-stability diagrams. © 2014 Wiley Periodicals, Inc.

Host–guest interactions in a new aza crown analog with alkali and alkaline earth metal ions are studied at different levels of theory. All the compounds are optimized at B3LYP/6-311+G(d) level of theory. To build the general idea about the consequence of methods of computation on the interaction energy of metal ions with the ligand, geometry optimization of some selected planar systems are carried out at the M05-2X, PBE0, wB97XD, and B3LYP-D levels. Calculated geometrical parameters, interaction energies, nucleus-independent chemical shift values, and thermodynamic properties highlight the selectivity associated with these interactions. Further insights into the nature of the bonding in these ion-macrocyclic supramolecular units are obtained through the natural bond orbital, atoms-in-molecules, bond energy decomposition, and electron localization function analyses. © 2014 Wiley Periodicals, Inc.

Prompted by a recent Letter (Brito et al., 2013) [9], stability and dynamics of the cyclic and linear Be 3 2 - clusters are studied. CASSCF is used over coupled cluster and other single reference methods on the basis of T1 diagnostic. Ab initio molecular dynamics (ADMP) study reveals the fate of cyclic and linear Be 3 2 - clusters up to 3.25 ps. Total energy and conceptual density functional theory based reactivity descriptors, hardness and electrophilicity vary with time during simulation. Energy, hardness and electrophilicity trajectories help to understand the structural dynamics of Be 3 2 - clusters.

Electronic structure calculations on 6,6′-(1E,1′E)-1,1′-(propane-1,3-diylbis(azan-1-yl-1-ylidene))bis(ethan-1-yl-1-ylidene)bis(3-(prop-2-ynyloxy)phenol) (L1) and (E)-2-(1-(2-hydroxyethylimino)ethyl)-5-(prop-2-ynyloxy)phenol (L2) compounds are carried out at B3LYP/6-311 + G(d,p) level of theory. The enol forms are found to be more stable than the corresponding keto forms in gas phase, whereas in solvent phase the reverse is true. The computed vibrational frequencies of L1 and L2 are compared with the available experimental data. Major orbital contributions for each electronic transition are assigned with the help of time-dependent density functional theory (TD-DFT). The UV–Visible spectral data of L1 and L2 coincide with the theoretical data of keto forms, which reveal that the compounds L1 and L2 exist mostly in keto forms rather than in enol forms in solution. Potential energy curves for the intramolecular proton transfer in the ground (GSIPT) and excited (ESIPT) states are generated in gas and solution (solvent is dimethyl sulfoxide) phases. GSIPT for both L1 and L2 goes through a low activation barrier, whereas in case of ESIPT, barrierless proton transfer occurs.

A quasi-planar member of the so-called 'Wankel motor' family, B18(2-), is found. This boron cluster is an electronically stable dianion and a concentric doubly σ- and π-aromatic system. The inner B6 unit in B18(2-) undergoes quasi-free rotation inside the perimeter of the B12 ring. The absence of any localized σ-bond between the inner ring and the peripheral boron atoms makes the system fluxional.

Xe-binding ability of star-shaped C 5 Li 7 + cluster and O 2 Li 5 + super-alkali cluster is studied using the MP2 method. Both C 5 Li 7 + and O 2 Li 5 + clusters are found to bind with maximum twelve Xe atoms. We have also studied a series of Li decorated clusters for Xe-binding. All these clusters show good Xe-binding ability. Generally, monocationic clusters have greater binding ability with Xe atoms than the neutral clusters. In addition, a charged Li center binds Xe atoms with better dissociation energy and enthalpy than those with He through Kr. The electron transfer from Xe atoms to Li centers plays a crucial role in binding. The relative contribution of different interaction energy terms towards total interaction energy is analyzed via energy decomposition analysis (EDA). The stability of these Xe-loaded clusters is analyzed in terms of the dissociation energies and reaction enthalpies.

A computational study is carried out to simulate methane hydrates as well as to know the effect of HF doping on their stability and structure. By using ab initio molecular dynamics simulation interaction of methane with HF doped clathrate hydrates is studied. The total energy profiles present insights into the stability and structure of methane hydrates. The HF doping increases the stability of the methane hydrates without any distortion of the cage when methane is encapsulated in 5 12 cages.

In the context of long-range density functional theory of softness kernel, the concepts of local and kernel electrophilicity are developed to obtain the local to global hierarchical criteria such as bilocal symmetry, asymptotic behavior, and integral local to global relationships. Further development into potential-density dependence is also provided while considering the local plus nonlocal specification of softness kernel and the associated atomic scales for the derived kernel; local and global electrophilicity are provided whose reliability is judged through the periodical features along the periodic table especially for the alkali metal atoms and the halogen atoms. © 2013 Wiley Periodicals, Inc.

The noble gas binding ability of CN3Be3(+) clusters was assessed both by ab intio and density functional studies. The global minimum structure of the CN3Be3(+) cluster binds with four noble-gas (NG) atoms, in which the Be atoms are acting as active centers. The electron transfer from the noble gas to the Be atom plays a key role in binding. The dissociation energy of the Be-NG bond gradually increases from He to Rn, maintaining the periodic trend. The HOMO-LUMO gap, an indicator for stability, gives additional insight into these NG-bound clusters. The temperature at which the NG-binding process is thermodynamically feasible was identified. In addition, we investigated the stability of two new neutral NG compounds, (NG)BeSe and (NG)BeTe, and found them to be suitable candidates to be detected experimentally such as (NG)BeO and (NG)BeS. The dissociation energies of the Be-NG bond in monocationic analogues of (NG)BeY (Y=O, S, Se, Te) were found to be larger than in the corresponding neutral counter-parts. Finally, the higher the positive charge on the Be atoms, the higher the dissociation energy for the Be-NG bond becomes.

A multiscale computational work is assessed to envisage the effect of HF doping on the stability, structure, and reactivity of clathrate hydrates. Interaction of molecular hydrogen with HF-doped clathrate hydrates is studied through ab initio molecular dynamics simulation with the aid of conceptual density functional theory. The viability of hydrogen encapsulation in HF-doped clathrate hydrates is justified in terms of the associated interaction energy, reaction enthalpy, hardness, and electrophilicity values. Calculated thermodynamic parameters are well-correlated with the maximum hardness principle and minimum electrophilicity principle for all cases. It is observed that HF doping significantly increases the stability of the studied clathrate hydrates and it also enhances the binding energy and reaction enthalpy for the encapsulation of hydrogen molecules.

A thorough analysis is carried out to understand how the microsolvation affects the hydrogen adsorbing capacity of metal ions in the presence as well as absence of the counter ions. Calculations are done at different levels of theory by using different functionals and basis sets and also by using the BSSE correction. The Be 2+ ion doped systems exhibit stronger interaction with the hydrogen molecule than the other metal doped systems. The extent of interaction is less affected by the method of computation. The reaction free energy values imply that adsorption on alkaline earth metal doped systems is spontaneous at room temperature. Interaction energies are favorable for hydrogen adsorption on the systems containing alkaline earth metal ions and the gravimetric density of adsorbed hydrogen molecule is more in those containing the alkali metal ions.

The quantum domain behavior of classical nonintegrable systems is well-understood by the implementation of quantum fluid dynamics and quantum theory of motion. These approaches properly explain the quantum analogs of the classical Kolmogorov–Arnold–Moser type transitions from regular to chaotic domain in different anharmonic oscillators. Field-induced tunneling and chaotic ionization in Rydberg atoms are also analyzed with the help of these theories. Quantum fluid density functional theory may be used to understand different time-dependent processes like ion-atom/molecule collisions, atom-field interactions, and so forth. Regioselectivity as well as confined atomic/molecular systems and their reactivity dynamics have also been explained. © 2013 Wiley Periodicals, Inc.

The feasibility of having MF3 (where M = Rh, Ir, Pd, Pt, Ag, Au) supported AlN nanoflakes (AlNF) was investigated through density functional theory based calculations. The thermodynamic analysis reveals that the superhalogen MF3 molecules can bind with the host AlNF in a thermodynamically favorable way. The nature of interaction in between the metal centers and the host is of partly covalent type whereas the F centers bind with the host in a non-covalent fashion as vindicated by natural bond orbital and atoms-in a-molecule analyses. An ab initio molecular dynamics study carried out at 298 K temperature confirms the stability of the MF3@AlNF moieties in a dynamical context. The MF3 guests can reduce the HOMO-LUMO gaps of the host nanoflakes. In general, the MF3@AlNF complexes can sequestrate polar adsorbates such as CO, NO, and H2O in a thermodynamically favorable way in most of the cases. An ab initio molecular dynamics calculation illustrates that the MF3@AlNF can adsorb the chosen representative polar molecules in a more favorable way as compared to the corresponding adsorption scenario in the case of pristine AlNF.

The stability of noble gas (Ng) bound B3+ clusters is assessed via an in silico study, highlighting their structure and the nature of the Ng–B bonds. Ar to Rn atoms are found to form exceptionally strong bonds with B3+ having each Ng–B bond dissociation energy in the range of 15.1–34.8 kcal mol−1 in B3Ng3+ complexes with a gradual increase in moving from Ar to Rn. The computed thermochemical parameters like enthalpy and free energy changes for the Ng dissociation processes from B3Ng3+ also support the stability of Ar to Rn analogues for which the corresponding dissociation processes are endergonic in nature even at room temperature. The covalent nature of the Ng–B bonds is indicated by the localized natural Ng–B bond orbitals and high Wiberg bond indices (0.57–0.78) for Ng–B bonds. Electron density analysis also supports the covalency of these Ng–B bonds where the electron density is accumulated in between Ng and B centres. The orbital interaction energy is the main contributor (ca. 63.0–64.4%) of the total attraction energy in Ng–B bonds. Furthermore, the Ng–B bonding can be explained in terms of a donor–acceptor model where the Ng (HOMO) → B3Ng2+ (LUMO) σ-donation has the major contribution.

A distinctive N-substituent controlled electrophilic N-transfer of oxaziridines with donor–acceptor cyclopropanes in the presence of MgI2 is reported. Contrary to earlier reports, the oxaziridine having bulkier N-substituents can also give N-transferred product instead of the O-transferred one. Interestingly, the oxaziridines having α-H containing N-substituents lead to the pyrrolidine derivatives through [3 + 2] cycloaddition. A mechanistic reasoning for this divergent reactivity is depicted by density functional theory calculations and validated through energy decomposition analysis.

The possibility of obtaining metal cluster (M3O(+), M = Li, Na, K) supported pristine, B-doped and BN-doped graphene nanoflakes (GR, BGR and BNGR, respectively) has been investigated by carrying out density functional theory (DFT) based calculations. Thermochemical analysis reveals the good stability of M3O(+)@GR/BGR/BNGR moieties. The dynamic stability of M3O(+)@GR/BGR/BNGR moieties is confirmed through an atom-centered density matrix propagation simulation at 298 K up to 500 fs. Orbital and electrostatic interactions play pivotal roles in stabilizing the metal-cluster supported graphene nanoflakes. The metal clusters lower the Fermi levels of the host nanoflakes and enable them to exhibit reasonably good optical response properties such as polarizability and static first hyperpolarizability. In particular, Na3O(+)/K3O(+)@BGR complexes exhibit very large first hyperpolarizability values at the static field limit. All the M3O(+)@BGR/BNGR moieties demonstrate broadband optical absorption encompassing the ultraviolet, visible as well as infrared domains. The metal-cluster supported graphene nanoflakes, in general, can sequestrate polar molecules, viz. CO, NO and CH3OH, in a thermodynamically more favorable way than GR, BGR and BNGR. In the adsorbed state, the CO, NO and CH3OH molecules, in general, attain an 'active' state as compared to their free counterparts.

DFT-based calculations reveal that the global minimum of IrB12- is a C3v symmetric bowl-like structure in which the Ir atom is located on the concave side of the bowl similar to its lighter congeners, CoB12- and RhB12-.

Concepts and Methods in Modern Theoretical Chemistry: Statistical Mechanics, the second book in a two-volume set, focuses on the dynamics of systems and phenomena. A new addition to the series Atoms, Molecules, and Clusters, this book offers chapters written by experts in their fields. It enables readers to learn how concepts from ab initio quantum

The potential for gas storage (C2H2, C2H4, C2H6, CO2, CO, H2, N2, NO2, NO) molecules and rare gas (Rg) atoms (He n –Xe n , where n = 1, 2) within the recently synthesized octa acid (OA) moiety is assessed through density functional theory-based computations. It is shown that C2H2, C2H4, C2H6, N2, Kr, and Xe atoms/molecules bind with octa acid in a thermodynamically favorable way. Wiberg bond indices, non-covalent interaction indices, and energy decomposition analyses are used to explore the nature of the interaction between guest atoms and octa acid. The nature of the interaction in between either two guest atoms (in the cases of Rg atoms) or guest and cage atoms is mostly of non-covalent type in nature. An ab initio molecular dynamics simulation carried out at 50 and 298 K temperatures reveal that many of the studied systems particularly concerning polar and π electron cloud containing guest molecules show good dynamical stability at both temperature regimes. Except for the case of Ne-encapsulated octa acid, all other rare gases tend to get liberated from the host at room temperature although they remain inside the host at low temperature, thereby showing good dynamical stability of the Rg-encapsulated octa acid complexes up to 500 fs. In order to reaffirm the dynamical stability, Ne2@OA and CO@OA are studied at 50 and 298 K up to 600 fs as test cases.

The efficacy of different conceptual density functional theory based reactivity descriptors and nucleus independent chemical shift in analyzing the hydrogen trapping potential of a wide variety of systems is reviewed in this chapter. The influence of aromaticity on the stability/reactivity of hydrogen storage material as well as structural and bonding aspects of those materials are explored. Charges on the different active sites in a molecule play a crucial role in their hydrogen-trapping ability. Temperature−pressure diagrams highlighting the ΔG

A molecular dynamics simulation is carried out to explore the possibility of using sI clathrate hydrate as hydrogen storage material. Metastable hydrogen hydrate structures are generated using the LAMMPS software. Different binding energies and radial distribution functions provide important insights into the behavior of the various types of hydrogen and oxygen atoms present in the system. Clathrate hydrate cages become more stable in the presence of guest molecules like hydrogen.

The geometries of 8 dienes and 18 dienophiles are optimized at the B3LYP/6-311 + G (d) level. The ionization potential (I), electron affinity (A), electronegativity (χ), hardness (η), chemical potential (μ), global electrophilicity (ω), electron accepting power (ω+) and electron donating power (ω−) values are computed employing ΔSCF method. The net reactivity index (Δ), electrophilicity difference of the reactants (Δω), the fractional number of electrons transferred (ΔN), energy change (ΔE) and electrophilicity-based charge transfer descriptor (ECT) for the Diels-Alder (DA) reactions are computed. Charge-based descriptors like ΔN, ΔE and ECT exhibit good quadratic / linear correlation with of the diene to dienophile electron flow (DDpF) type of DA reactions. Δω has also reasonably good quadratic / linear correlation with ΔN, ΔE ECT and. Charge-based descriptors like ΔN, ΔE and ECT have relatively worse correlation (quadratic / linear) with of the dienophile to diene electron flow (DpDF) type of DA reactions. Δω has also similar poor correlation (quadratic / linear) with ΔN, ΔE, ECT and for these types of reactions. It can be concluded that charge-based Density Functional Theory (DFT) descriptors can illustrate the DDpF type of DA reactions properly. A possible reason for not so good correlation in the case of DpDF-type reactions is provided. The charges of the reactive sites of the dienes and dienophiles are also computed with the Mulliken population analysis and natural population analysis schemes at the same level of theory. Copyright © 2012 John Wiley & Sons, Ltd.

Three-dimensional quantitative structure activity relationship (3D-QSAR) study has been carried out on the Escherichia coli DHFR inhibitors 2,4-diamino-5-(substituted-benzyl)pyrimidine derivatives to understand the structural features responsible for the improved potency. To construct highly predictive 3D-QSAR models, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) methods were used. The predicted models show statistically significant cross-validated and non-cross-validated correlation coefficient of r2 CV and r2 nCV, respectively. The final 3D-QSAR models were validated using structurally diverse test set compounds. Analysis of the contour maps generated from CoMFA and CoMSIA methods reveals that the substitution of electronegative groups at the first and second position along with electropositive group at the third position of R2 substitution significantly increases the potency of the derivatives. The results obtained from the CoMFA and CoMSIA study delineate the substituents on the trimethoprim analogues responsible for the enhanced potency and also provide valuable directions for the design of new trimethoprim analogues with improved affinity.

Temperature-pressure phase diagrams are generated through the study of hydrogen adsorption on the (N(4)C(3)H)(6)Li(6) cluster at the B3LYP/6-31+G(d) level of theory. The possibility of hydrogen storage in an associated 3D functional material is also explored. Electronic structure calculations are performed to generate temperature-pressure phase diagrams so that the temperature-pressure zones are identified where the Gibbs free energy change associated with the hydrogen adsorption process on (N(4)C(3)H)(6)Li(6) cluster becomes negative and hence thermodynamically favorable. Both adsorption and desorption processes are likely to be kinetically feasible as well.

The σ-aromaticity of M3(+) (M = Cu, Ag, Au) is analyzed and compared with that of Li3(+) and a prototype σ-aromatic system, H3(+). Ligands (L) like dimethyl imidazol-2-ylidene, pyridine, isoxazole and furan are employed to stabilize these monocationic M3(+) clusters. They all bind M3(+) with favorable interaction energy. Dimethyl imidazol-2-ylidene forms the strongest bond with M3(+) followed by pyridine, isoxazole and furan. Electrostatic contribution is considerably more than that of orbital contribution in these M-L bonds. The orbital interaction arises from both L → M σ donation and L ← M back donation. M3(+) clusters also bind noble gas atoms and carbon monoxide effectively. In general, among the studied systems Au3(+) binds a given L most strongly followed by Cu3(+) and Ag3(+). Computation of the nucleus-independent chemical shift (NICS) and its different extensions like the NICS-rate and NICS in-plane component vs. NICS out-of-plane component shows that the σ-aromaticity in L bound M3(+) increases compared to that of bare clusters. The aromaticity in pyridine, isoxazole and furan bound Au3(+) complexes is quite comparable with that in the recently synthesized Zn3(C5(CH3)5)3(+). The energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital also increases upon binding with L. The blue-shift and red-shift in the C-O stretching frequency of M3(CO)3(+) and M3(OC)3(+), respectively, are analyzed through reverse polarization of the σ- and π-orbitals of CO as well as the relative amount of OC → M σ donation and M → CO π back donation. The electron density analysis is also performed to gain further insight into the nature of interaction.

The fundamental principles of pericyclic reactions are governed by the Woodward-Hoffmann rules, which state that these reactions can only take place if the symmetries of the reactants' molecular orbitals and the products' molecular orbitals are the same. As such, these rules rely on the nodal structure of either the wave function or the frontier molecular orbitals, so it is unclear how these rules can be recovered in the density functional reactivity theory (or "conceptual DFT"), where the basic quantity is the strictly positive electron density. A third, nonsymmetry based approach to predict the outcome of pericyclic reactions is due to Zimmerman which uses the concept of the aromatic transition states: allowed reactions possess aromatic transition states, while forbidden reactions possess antiaromatic transition states. Based on our recent work on cycloadditions, we investigate the initial response of the chemical hardness, a central DFT based reactivity index, along the reaction profiles of a series of electrocyclizations. For a number of cases, we also compute complete initial reaction coordinate (IRC) paths and hardness profiles. We find that the hardness response is always higher for the allowed modes than for the forbidden modes. This suggests that the initial hardness response along the IRC is the key for casting the Woodward-Hoffmann rules into conceptual DFT.

An exhaustive exploration of the potential energy surfaces of ferrocene, ruthenocene and osmocene dimers has been performed. Our computations involving dispersion show that only four different isomers are present in each metallocene dimer. The collective action of small interaction energies of dispersive nature leads to a dissociation energy of 7.5 kcal mol(-1) for the ferrocene dimer. Dispersion has strong effects on the geometrical parameters, reducing the M···M distances by almost 1 Å. Our results also reveal that inclusion of entropic factors modifies the relative stability of the complexes. The nature of bonding is examined using the energy decomposition analysis and the non-covalent interaction index. Both analyses indicate that dispersion is the major contributing factor in stabilizing a metallocene dimer.

Experimental and theoretical studies of a new class of novel annulated imidazolium scffords 2a, 2b, 2c and their Hg(II)–NHC complexes 3a, 3b and 3c have been synthesized and characterized by different spectroscopic techniques. Molecular structures of 3a and 3b have been determined by single crystal X-ray diffraction studies. Virtual linear geometry [Ccarbene–Hg–Ccarbene 176.56(17)°] around Hg of the complex 3b is observed where as in 3a and 3c its deviate a more. DFT calculations provide geometrical parameters in conformity with the experimental values in case of 3a. The molecules prefer syn configuration over the anti due to lower energy supported by theoretical studies. Attention has given paid for theoretical calculations and comparison of 3a and 3c to observe the steric effect of –CH3 group in the scaffords where as in case of 3b the –CH3 group remain innocent.

We introduce the concepts of hard–soft acid–base (HSAB) interactions and derive parameters to characterise a magma that consists either of a solid rock, a melt or its exsolved gaseous phase. Those parameters are the electronegativity, i.e. the chemical potential changed of sign, hardness, electrophilicity and polarisability. They determine the chemical reactivity of each individual element, or its equivalence in the case of a complex system of elements or compounds. The parameter values result from equalisation methods for complex systems, i.e. the equalisation of the respective chemical potentials, or from direct computation through density functional theory (DFT). They help in characterising magma by a single value. They also provide insights into the reactivity of the melt or its fluid phase when in contact with another magma, or when considering the affinity of elements for each phase. The description leads to a better understanding on the mechanisms that control sequestration and transport of metals within the different phases during igneous activity. The presence of halogens tends to reinforce hardness, making the fluid phase attractive for hard metals such as Sn or W. Conversely, the presence of S decreases hardness of the fluid phase that becomes attractive for soft metals such as Au, Ag and Cu. Theoretical principles of maximum hardness and minimum electrophilicity can be used to identify the poles toward which the reactions should naturally evolve. The trends observed during magma evolution are also observed using these parameters, indicating two different trends toward a pole of greater stability. One pole consists in increasing the hardness at constant electrophilicity as observed for felsic magmas toward a silica-rich pole. Conversely mantle-derived magmas evolve at a constant hardness and decreasing electrophilicity in between the two poles of iron-rich and alkali-rich minerals. They respectively correspond to the Bowen and Fenner trends, though the experimental and field evidences have now some chemical explanation.

Theoretical investigation on planar N 6 4 - and N 4 2 - rings has been performed. The aromaticity of the rings has been analyzed through their nucleus independent chemical shift (NICS) values as well as the σ- and π-contribution of the Z-component of the induced magnetic field. Counter to a previously reported result [Chem. Phys. Lett. 432 (2006) 331], the N 6 4 - ring is found to be a local minimum and aromatic with planar D6h symmetry. The N 4 2 - ring exhibits conflicting aromaticity like Al 4 4 - . Both the N 6 4 - and N 4 2 - rings can be stabilized in presence of suitable counter cations and systems like N6Ca2 and N4Li2 can trap molecular hydrogen.

The ability of neutral and cationic BxLiy (x = 2–6; y = 1, 2) systems as effective hydrogen-trapping materials are investigated at the MP2 level of theory using the 6-311+G(d, p) basis set. The different conceptual DFT-based global and local reactivity descriptors and the associated electronic structure principles provide invaluable insights toward assessing the utility of the boron–lithium clusters in trapping molecular hydrogen. A consistent thermodynamic spontaneity of the allied H2-binding reactions along with a favorable decrease in the average dissociative chemisorption energies invokes the plausible usage of these cluster motifs for hydrogen loading in practice. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

Hydrogen trapping ability of various metal–ethylene complexes has been studied at the B3LYP and MP2 levels of theory using the 6-311+G(d,p) basis set. Different global and local reactivity descriptors and the associated electronic structure principles provide important insights into the associated interactions. There exist two distinct classes of bonding patterns, viz., a Kubas type interaction between the metal and the H2 molecule behaving as a η2-ligand and an electrostatic interaction between the metal and the atomic hydrogens.

In this paper, quantitative–structure–toxicity–relationship (QSTR) models are developed for predicting the toxicity of halogen, sulfur and chlorinated aromatic compounds. Two sets of compounds, containing mainly halogen and sulfur inorganic compounds in the first set and chlorinated aromatic compounds in the second, are investigated for their toxicity level with the aid of the conceptual Density Functional Theory (DFT) method. Both sets are tested with the conventional density functional descriptors and with a newly proposed net electrophilicity descriptor. Associated R2, R2CV and R2adj values reveal that in the first set, the proposed net electrophilicity descriptor (??±) provides the best result, whereas in the second set, electrophilicity index (?) and a newly proposed descriptor, net electrophilicity index (??±) provide a comparable performance. The potential of net electrophilicity index to act as descriptor in development of QSAR model is also discussed.

A bimetallic 3D network containing 1D chains of Li(6) unit rings has been synthesized by using a molybdenum containing metalloligand and the DFT calculations reveal that the rings are aromatic in behavior and resemble the corresponding hydrocarbon analogues.

Geometries of different isomers of various neutral sulfur clusters, S n (n=3–8) are optimized at the B3LYP/6-311+G* level of theory. Their stability and aromaticity behavior are analyzed in terms of the conceptual density functional theory-based reactivity descriptors and the associated electronic structure principles. The nucleus-independent chemical shift lends additional support. Possibility of bond-stretch isomerism in these clusters is explored.

In the classical rhodium–diphosphine complexes-catalyzed asymmetric hydrogenation of enamide substrates, examination on the role of catalyst electronic polarizability in the origin of enantioselectivity reveals its linear free energy relationship with the product enantiomeric ratio that is much more pronounced than analogous correlation with steric effect in the same systems. From a conceptually novel scenario, this work suggests that the often-overlooked chiral catalyst local polarizability property may function as a controlling force in enantioselection thus has important implication in rational catalyst design.

Quantum chemical parameters such as LUMO energy, HOMO energy, ionization energy (I), electron affinity (A), chemical potential (μ), hardness (η) electronegativity (χ), philicity (ωα), and electrophilicity (ω) of a series of aliphatic compounds are calculated at the B3LYP/6-31G(d) level of theory. Quantitative structure-activity relationship (QSAR) models are developed for predicting the toxicity (pIGC50) of 13 classes of aliphatic compounds, including 171 electron acceptors and 81 electron donors, towardsTetrahymena pyriformis. The multiple linear regression modeling of toxicity of these compounds is performed by using the molecular descriptor log P(1-octanol/water partition coefficient) in conjunction with two other quantum chemical descriptors, electrophilicity (ω) and energy of the lowest unoccupied molecular orbital (ELUMO). A comparison is made towards the toxicity predicting the ability of electrophilicity (ω) versusELUMOas a global chemical reactivity descriptor in addition to log P. The former works marginally better in most cases. There is a slight improvement in the quality of regression by changing the unit ofIGC50from mg/L to molarity and by removing the racemates and the diastereoisomers from the data set.