Toward the synthesis, fluorination and application of N-graphyne.

The discovery of properties and applications of unknown materials is one of the hottest research areas in materials science. In this work, we navigate a route towards these goals by the development of a new type of graphyne nanostructure. It is synthesised by a Sonogashira cross-coupling reaction of 1,3,5-triethynylbenzene with cyanuric chloride resulting in an extended carbon-based material called TCC.

Pt as the limit of high oxidation states in oxide-nitride species.

A series of pentaatomic species has been investigated theoretically with relativistic DFT using the M06-L functional with both ZORA scalar relativistic correction, and including spin-orbit coupling effects. The distorted quasi-octahedral local minima for PtNO, PtNO and PtNO corresponding to decavalent Pt were found to be unstable with respect to the elimination of O, NO or N. However, barriers surrounding these minima suggest that these species could be achieved under low-temperature conditions, similar to what was predicted for PtO dications.

The high covalence of metal-ligand bonds as stability limiting factor: the case of Rh(IX)O and Rh(IX)NO.

Rhodium, a 4d transition metal and a lighter analogue of iridium, is known to exhibit its highest VIth oxidation state in RhF molecule. In this report, the stability and decomposition pathways of two species containing rhodium at a potentially formal +IX oxidation state, [RhO] and RhNO, have been investigated theoretically within the framework of the relativistic two-component Hamiltonian calculations. Possible rearrangement into isomers featuring lower formal oxidation numbers has been explored.

Atomic/Ionic Radius as Mathematical Limit of System Energy Evolution.

The classical, in its nature, concept of atomic or ionic radii, although profitable in many fields, is represented by an ambiguous choice of formulations. In this work, we propose a definition of atomic and ionic radii rooted in chemical principles and conceptual density functional theories. The estimation based on electron density fundamental response functions has been successfully tested.

Ferromagnetic ground state for a hypothetical iron-based extended metal atom chain.

Theoretical calculations for the first tri-iron-based extended metal atom chain (EMAC) molecule are reported. The studied triple-high-spin (S = 6) complex exhibits ferromagnetic ordering (according to Ising and spin-projection approximations), which renders it unique among all previously prepared and theoretically calculated EMAC compounds. This ordering originates from the prevailing ferromagnetic nearest-neighbor interactions, while the magnetic superexchange between terminal Fe(2+) sites is weaker and antiferromagnetic.

Noble gas monoxides stabilized in a dipolar cavity: a theoretical study.

Encouraged by our previous theoretical results that indicated the stabilization of the HeO unit inside the ferroelectric cavity composed of two parallel LiF dipoles, we have now undertaken the theoretical study for the related noble gas systems, (NgO)(MF)2, Ng = Ar, Kr, Xe, M = Li, Na, K. The computational results indicate that all such molecules constitute local minima, which are protected by sizable energy barriers especially for M = Li, Na, and thus these systems might constitute interesting synthetic targets at low temperatures.

Most probable distance between the nucleus and HOMO electron: the latent meaning of atomic radius from the product of chemical hardness and polarizability.

The simple relationship between size of an atom, the Pearson hardness, and electronic polarizability is described. The estimated atomic radius correlates well with experimental as well as theoretical covalent radii reported in the literature. Furthermore, the direct connection of atomic radius to HOMO electron density and important notions of conceptual DFT (such as frontier molecular orbitals and Fukui function) has been shown and interpreted.

Reactivity patterns of imidazole, oxazole, and thiazole as reflected by the polarization justified Fukui functions.

The concept of the polarization justified Fukui functions has been tested for the set of model molecules: imidazole, oxazole, and thiazole. Calculations of the Fukui functions have been based on the molecular polarizability analysis, which makes them a potentially more sensitive analytical tool as compared to the classical density functional theory proposals, typically built on electron density only. Three selected molecules show distinct differences in their reactivity patterns, despite very close geometry and electronic structure.

Polarization justified Fukui functions: the theory and applications for molecules.

The Fukui functions based on the computable local polarizability vector have been presented for a group of simple molecules. The necessary approximation for the density functional theory softness kernel has been supported by a theoretical analysis unifying and generalizing early concepts produced by the several authors. The exact relation between local polarizability vector and the derivative of the nonlocal part of the electronic potential over the electric field has been demonstrated.

Modeling the electron density kernels.

Existing approximation to the softness kernel, successfully explored in earlier work, has been extended; the normal Gauss distribution function has been used instead of the Dirac delta. The softness kernel becomes continuous functions in space and may be used to calculate the linear response function of the electron density. Three-dimensional visualization of the softness kernel and the linear response function are presented for a nitrogen atom as a working example.

Polarization justified Fukui functions.

New Fukui functions have been derived within the conceptual density functional theory by the analysis of the polarization effect of a system in static electric field. Resulting Fukui functions accurately reproduce the global softness and electronic dipolar polarizability; they meet the condition integral[f(r)/r]dr = -(partial differential mu/partial differential Z)(N) and lead to very reasonable values of the global hardness for atoms for the group of 29 main group elements. Computational clarity makes the new Fukui functions a promising tool in studies of molecular reactivity.

On reversible bonding of hydrogen molecules on platinum clusters.

The local reactivity of hydrogenated platinum clusters (Pt clusters) has been studied using the regional density functional theory method. We observed that antibond orbitals constitute the preferable binding site for hydrogen molecules H(2). Those sites are characterized by lowered electronic chemical potential and strong directionality and exhibit electrophilic nature.

Electronic stress tensor description of chemical bonds using nonclassical bond order concept.

The stress tensors are used widely for description of internal forces of matter. For some time it is also applied in quantum theory in studies of molecular properties in chemical systems. Electronic stress tensors measure effects caused by internal forces acting on electrons in molecules and particularly those between bonded atoms.

Physical nature of intermolecular interactions within cAMP-dependent protein kinase active site: differential transition state stabilization in phosphoryl transfer reaction.

The origin of enzyme catalytic activity may be effectively explored within the nonempirical theory of intermolecular interactions. The knowledge of electrostatic, exchange, delocalization, and correlation components of the transition state and substrates stabilization energy arising from each enzyme active site residue allows to examine the most essential physical effects involved in enzymatic catalysis. Consequently, one can build approximate models of the catalytic activity in a systematic and legitimate manner.

The field theoretical study of chemical interaction in terms of the Rigged QED: new reactivity indices.

How the mode of bonding affects stability and reactivity of molecule on the frame of nonrelativistic limit of the rigged quantum electrodynamics using new indices for description of bond properties related to bond orders have been characterized here. These indices are in close relation with tensorial interpretation of bond that among others allows discriminating covalent bonds using spindle structure concept. The real three-dimensional space representation of new interaction energy density utilized in this study contribute to better understanding of interaction phenomena between atoms and molecules.