Exploring Border Conditions for Spontaneous Emergence of Chirality in Allylboration of 1,2,3-Triazolic Aldehydes.

A case of spontaneous chirality generation was observed during a synthetic project studying the allylboration of 1,2,3-triazolic aldehydes. Here, we present computational studies supported by experimental findings targeting the elucidation of border conditions required for the observation of spontaneous chirality generation in the reaction of 1-Ar-1-1,2,3-triazole-4-carbaldehydes with triallylborane. Three possible sources of symmetry breaking were found computationally.

First Examples of -Metal Complexes with Subporphyrazine and Its Phenylene-Annulated Derivatives: DFT Calculations.

Using quantum chemical calculation data obtained by the DFT method with the B3PW91/TZVP and M062X/def2TZVP theory levels, the possibility of the existence of four Be(II) coordination compounds, each of which contains in the inner coordination sphere and the double deprotonated forms of subporphyrazine (H), mono[benzo]subporphyrazine (H), di[benzo]subporphyrazine (H), and tri[benzo]subporphyrazine (subphthalocyanine) (H) with a ratio Be(II) ion/ligand = 1:1, were examined Selected geometric parameters of the molecular structures of these (666)macrotricyclic complexes with closed contours are given; it was noted that BeN3 chelate nodes have a trigonal-pyramidal structure and exhibit a very significant (almost 30°) deviation from coplanarity; however, all three 6-membered metal-chelate and three 5-membered non-chelate rings in each of these compounds are practically planar and deviate from coplanarity by no more than 2.5°. The bond angles between two nitrogen atoms and a Be atom are equal to 60° (in the [Be] and [Be]) or less by no more than 0.

Microporous Block Copolymers Modified with Cu(II)-Coordinated Polyethylene Oxide-Substituted Silicas for Analytical Sensors.

The influence of stable-to-self-condensation Cu(II)-coordinated polyoxyethylene-substituted silicas (ASiP-Cu-0.5) on the synthesis of microporous block copolymers (OBCs) whose structural feature is the existence of coplanar polyisocyanate blocks of acetal nature (O-polyisocyanates) and a flexible-chain component of amphiphilic nature was studied. The use of ASiP-Cu-0.

Molecular and Electronic Structures of Macrocyclic Compounds Formed at Template Synthesis in the M(II)-Thiocarbohydrazide-Diacetyl Triple Systems: A Quantum-Chemical Analysis by DFT Methods.

Using density functional theory (DFT) B3PW91/TZVP, M06/TZVP, and OPBE/TZVP chemistry models and the Gaussian09 program, a quantum-chemical calculation of geometric and thermodynamic parameters of Ni(II), Cu(II), and Zn(II) macrotetracyclic chelates, with (NNNN)-coordination of ligand donor centers arising during template synthesis between the indicated ions of elements, thiocarbohydrazide HN-HN-C(=S)-NH-NH and diacetyl Me-C(=O)-C(=O)-Me, in gelatin-immobilized matrix implants was performed. The key bond lengths and bond angles in these coordination compounds are provided, and it is noted that in all these complexes the MN chelate sites, the grouping of N atoms bonded to the M atom, and the five-membered and six-membered metal chelate rings are practically coplanar. NBO analysis of these compounds was carried out, on the basis of which it was shown that all these complexes, in full accordance with theoretical expectations, are low-spin complexes.

Introduction to Topic of the Special Issue "Quantum-Chemical Modeling and Design of Chelate and Macrocyclic Metal Complexes 2.0" from Guest Editor.

The concept of "macrocyclic compounds" combines very different classes of chemicals that contain nine or more atoms in the macrocycle; macroheterocyclic compounds, the macrocycle of which contains at least one heteroatom, are also distinguished among them [...

Thematic Exordium for Special Issue "Density Functional Theory Application on Chemical Calculation".

The history of quantum chemistry dates back to 1926, when the German physicist Erwin Schrödinger, in his classical works [...

Thematic Foreword from the Guest Editor to the Special Issue Entitled "The Role of Interactions in Complexes, Clusters and Crystal Structures-Theoretical Analyses and Experimental Evidences".

The world around us consists of a huge number and a wide variety of substances-both individual chemical compounds and their compositions (mixtures) [...

Heteroligand Iron(V) Complexes Containing Porphyrazine, -Di[benzo]porphyrazine or Tetra[benzo]porphyrazine, Oxo and Fluoro Ligands: DFT Quantum-Chemical Study.

By using quantum chemical calculation data obtained by the DFT method with the B3PW91/TZVP and OPBE/TZVP levels, the possibility of the existence of three Fe(V) complexes, each of which contains in the inner coordination sphere porphyrazine/-di[benzo]porphyrazine/tetra[benzo]porphyrazine (phthalocyanine), oxygen (O) and fluorine (F) ions, was shown. Key geometric parameters of the molecular structure of these heteroligand complexes are given; it is noted that FeN4 chelate nodes, and all metal-chelate and non-chelate cycles in each of these compounds, are practically planar with the deviation from coplanarity, as a rule, by no more than 0.5°.

DFT Method Used for Prediction of Molecular and Electronic Structures of Mn(VI) Macrocyclic Complexes with Porhyrazine/Phthalocyanine and Two Oxo Ligands.

By using the data of the DFT quantum chemical calculation in the OPBE/TZVP and B3PW91/TZVP levels, the possibility of the existence of a manganese(VI) heteroligand complex containing porphyrazine or its tetra[benzo] derivative (phthalocyanine) and two oxygen (O) ligands, which is still unknown for this element, is shown. The parameters of the molecular structure, multiplicity of the ground state, NBO analysis data and standard thermodynamic parameters (enthalpy Δ, entropy and Gibbs's energy Δ of formation) of each of these metal macrocyclic compounds are presented. Additionally, it is noted that, based on the totality of structural data obtained by the above versions of the DFT method, the existence of a similar complex of manganese with di[benzo] derivative of porhyrazine and two oxygen (O) ligands seems doubtful.

Quantum-Chemical Prediction of Molecular and Electronic Structure of Carbon-Nitrogen Chemical Compound with Unusual Ratio Atoms: C(N).

Using various versions of quantum-chemical calculation, namely four versions of density functional theory (DFT), (DFT B3PW91/TZVP, DFT M06/TZVP, DFT B3PW91/Def2TZVP, and DFT M06/Def2TZVP) and two versions of the MP method (MP2/TZVP and MP3/TZVP), the existence possibility of the carbon-nitrogen-containing compound having an unusual M: nitrogen ratio of 1:20, unknown for these elements at present, was shown. Structural parameters data are presented; it was noted that, as may be expected, CN grouping has practically a tetrahedral structure, and the chemical bond lengths formed by nitrogen atoms and a carbon atom in the frameworks of each of the calculation methods indicated above are equal to each other. Thermodynamical parameters, NBO analysis data, and HOMO/LUMO images for this compound are also presented.

Introduction to the Topic of the Special Issue "Study on Synthesis and Properties of Metal-Containing Matrix Polymer Composites" from the Guest Editor.

As is known, one of the key objects of modern Materials Science is composite materials, or simply composites, which are used in various fields of science and technology-from the food industry to aviation, from medicine to the construction of various buildings, from agriculture to radio electronics [...

Gelatin as It Is: History and Modernity.

The data concerning the synthesis and physicochemical characteristics of one of the practically important proteins-gelatin, as well as the possibilities of its practical application, are systematized and discussed. When considering the latter, emphasis is placed on the use of gelatin in those areas of science and technology that are associated with the specifics of the spatial/molecular structure of this high-molecular compound, namely, as a binder for the silver halide photographic process, immobilized matrix systems with a nano-level organization of an immobilized substance, matrices for creating pharmaceutical/dosage forms and protein-based nanosystems. It was concluded that the use of this protein is promising in the future.

Gelatin Matrix as Functional Biomaterial for Immobilization of Nanoparticles of Metal-Containing Compounds.

The data concerning the synthesis and physicochemical characteristics of specific functional biomaterials-biopolymer-immobilized matrix systems based on gelatin as an array and chemical compounds, which include atoms of various metal elements-are systematized and discussed. The features of this biopolymer which determine the specific properties of the immobilized matrix systems formed by it and their reactivity, are noted. Data on gelatin-immobilized systems in which immobilized substances are elemental metals and coordination compounds formed as a result of redox processes, nucleophilic/electrophilic substitution reactions, and self-assembly (template synthesis), are presented.

Introduction from Guest Editors to Special Issue "Magnetism in Chemistry".

Magnetism in a chemical compound is the macroscopic result of the couplings of the spins of electrons within in it [...

Introduction to Problematics of the Special Issue "Green Biosynthesis of Nanomaterials for Biomedical Applications".

The concept of "green biosynthesis", as well as the similar and more general concept of "green synthesis", is collective and includes very diverse synthetic methods, using products vital for activity from various living organisms-of both plant and animal origin-for chemical compound production [...

Introduction from Guest Editors to Special Issue "Multi-Metallic Systems: From Strong Cooperative Bonds to Weak M-M Interactions".

As is known, the chemical elements called metals make up the majority of all the chemical elements included in the periodic table of D [...

Template Synthesis (Self-Assembly) of Macrocycles: Theory and Practice.

For more than 60 years, in coordination chemistry (and since the beginning of the 21st century, in molecular nanotechnology, too), there has been very significant interest in template synthesis reactions, in which the design of coordination compounds (metal complexes) with complex ligands is carried out not according to the classical scheme [metal ion + ligand → complex], but according to scheme [metal ion + "building blocks" of the future ligand (the so-called ligand synthons or ligsons) → complex] [...

Twelve-Nitrogen-Atom Cyclic Structure Stabilized by 3-Element Atoms: Quantum Chemical Modeling.

Using various versions of density functional theory (DFT), DFT M06/TZVP, DFT B3PW91/TZVP, DFT OPBE/TZVP, and, partially, the MP2 method, the possibility of the existence of 3-element (M) compounds with nitrogen having unusual M: nitrogen ratio 1:12, unknown for these elements at the present, was shown. Structural parameter data were presented. It was shown that all MN4 groupings have tetragonal-pyramidal structure.

A new chemical compound with an unusual ratio of number of carbon and nitrogen atoms - C(N): quantum-chemical modelling.

Based on the results of a quantum chemical calculation using the DFT B3PW91/TZVP, MP2/TZVP and MP3/TZVP levels, the possibility of the existence of carbon-nitrogen compounds having the unusual carbon : nitrogen ratio 1 : 12, which is unknown for these elements at present, was shown. Data on the structural parameters are presented; it was shown that all CN groupings are strictly planar. In addition, the bond lengths formed by nitrogen atoms and a C atom are equal to each other, and the bond angles formed by nitrogen atoms and a C atom are equal to 90.

Molecular and Electronic Structures of Neutral Polynitrogens: Review on the Theory and Experiment in 21st Century.

The data on the existence and physicochemical characteristics of uncharged single element chemical compounds formed by nitrogen atoms and containing more than two nuclides of this element (from N to N, oligomeric and polymeric polynitrogens) have been systematized and generalized. It has been noticed that these data have a predominantly predictive character and were obtained mainly using quantum chemical calculations of various levels (HF, DFT, MP, CCSD etc.).

The Physical Chemistry and Chemical Physics (PCCP) Section of the in Its Publications: The First 300 Thematic Articles in the First 3 Years.

The Physical Chemistry and Chemical Physics Section (PCCP Section) is one of the youngest among the sections of the ()-the year 2021 will only mark three years since its inception [...

Quantum-Chemical Consideration of AlM Tetranuclear Metal Clusters (M-3-Element): Molecular/Electronic Structures and Thermodynamics.

Quantum-chemical calculation of most important parameters of molecular and electronic structures of tetra-nuclear () metal clusters having AlM composition, where M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, or Zn (bond lengths, bond and torsion angles), and HOMO and LUMO of these compounds by means of DFT OPBE/QZVP method, have been carried out. It has been found that, for each of these metal clusters, an existence of rather large amount of structural isomers different substantially in their total energy, occurs. It has been noticed that molecular structures of metal clusters of the given type differ significantly between them in terms of geometric parameters, as well as in geometric form, wherein the most stable modifications of metal clusters considered are similar between themselves in geometric form.

Cubic Octa-Carbon: Quantum-Chemical Design of Molecular Structure and Potential Way of Its Synthesis from Cubane.

Quantum-chemical calculation of most important parameters of molecular and electronic structures of octa-carbon C having cubic form (bond lengths, bond and torsion angles) using CCSD(T)/QZVP and DFT B3PW91/QZVP methods, has been carried out. NBO analysis data and HOMO/LUMO images for this compound are presented, too. Good agreement was found between the structural data obtained using the above two quantum-chemical methods and, also, with corresponding experimental data.

Models of Molecular Structures of Hexa-Nuclear AlFe Metal Clusters (n + m = 6): DFT Quantum-Chemical Design.

By using the density functional theory (DFT) method at the OPBE/QZVP level, key parameters of molecular structures of six-atomic (heterobi)nuclear metal clusters with an AlFe composition (n + m = 6) (bond lengths, bond angles, and torsion (dihedral) angles) were calculated. It was found that each of these clusters exists in a large number of structural isomers that differ substantially in terms of their total energy. Furthermore, the molecular structures of these structural isomers significantly differ regarding the geometric parameters and geometric form.

Foreword from the Editor of Special Issue "Advanced Metal Chelate Complexes: Quantum-Chemical Consideration".

The objects of the given Special Issue of -coordination compounds or complexes, represent a kind of "boundary zone" between two main classes of chemical substances, inorganic and organic, and therefore differ in a significantly greater variety of their structural and physicochemical characteristics in comparison with both inorganic and organic compounds [...