Alexey A. Kagilev

The manuscript discusses non-standard scientific and technological solutions for environmental monitoring, neutralization and subsequent deep processing of industrial and municipal waste. The manuscript is divided into three major sections devoted to monitoring, detoxification and processing of environmental pollutants. The following non-standard technological solutions for environmental monitoring are considered: Laser express chemical analysis; Laser remote sensing; Chemoresistive gas sensors for monitoring atmospheric conditions; Multi-beam optical analyzer for detection of microorganisms and organic pollutants. For neutralization of environmental pollutants, the following are considered: Modern catalysts for air purification from nitrogen and sulfur oxides; Adsorbents for carbon dioxide absorption; Advanced oxidation processes for purification of airport stormwater runoff; Advanced low-temperature plasma technologies; Catalysts for combustion of sewage sludge from municipal treatment facilities; Modern composite multifunctional polymer materials. Among technological solutions for deep processing of industrial and municipal waste, the following are considered: Nickel pincer complexes as electrocatalysts for molecular hydrogen evolution; Hydrogen sulfide-methane reforming for molecular hydrogen production; Technology of catalytic conversion of lignin-containing waste into adsorbents and fuel; New bacterial consortia for sewage sludge processing.

The reaction between cobalt tetrafluoroborate hexahydrate with 2,2′-bipyridine (Вpy) and diphenylphosphinic acid leads to the formation of a new binuclear cobalt(II) complex [Co(µ-OPPh)(Вpy)](BF) featuring sterically demanding bridging ligands. The synthesized complex was characterized by various physicochemical methods of analysis, the crystal structure was determined by X-ray diffraction. The analysis of the X-ray structure of the complex showed that the cobalt ions have a distorted octahedral coordination and are linked by bridges through two {µ-OPPh} fragments. The results of EPR spectroscopy and magnetochemical studies indicate the presence of a weak antiferromagnetic interaction between the cobalt ions in the molecule.

A Pt(II) complex bearing chelating tridentate bis-aryloxide tetrahydropyrimidinium-based N-heterocyclic carbene (NHC) was synthesized and characterized by using different techniques. Both cyclic voltammetry and differential pulse voltammetry were used to study the electrochemical properties of the complex, revealing two reversible one-electron oxidation processes. The chemical generation and isolation of one-electron-oxidized species were performed oxidizing the initial complex by means of AgBF₄. A combination of spectroscopic (UV-Vis/NIR- and EPR-) and theoretical (density functional theory (DFT)) studies suggests the formation of a Pt(II)-phenoxyl radical complex. The latter open-shell derivative was structurally characterized by means of X-ray diffraction analysis. Finally, the neutral platinum complex was tested as a mediator in the process of electrocatalytic oxidation of 2-(methylamino)ethanol (MEA).

A Pt(II) complex featuring chelating tridentate bis-aryloxide tetrahydropyrimidinium based N-heterocyclic carbene (NHC) was synthesized and characterized by using different techniques. The electrochemical properties of the complex were investigated by cyclic voltammetry as well as differential pulse voltammetry, which revealed two reversible one-electron oxidation processes. The chemical generation and isolation of one-electron-oxidized species were performed oxidizing the initial complex by means of AgBF4. The combined UV-Vis/NIR- and EPR-spectroscopy studies supported by density functional theory (DFT) calculations suggest the formation of Pt(II)-phenoxyl radical complex. The latter open-shell derivative was structurally characterized by means of X-ray diffraction analysis. Finally, the neutral platinum complex was tested as a mediator in the process of electrocatalytic oxidation of 2-(methylamino)ethanol (MEA).

The low-stable organonickel sigma-complex (2,2'-bipyridyl)bromo(2,4,6-tricyclopentylphenyl)nickel(II) [NiBr(Tcpp)(bpy)] was obtained by a modified procedure of preparative electrochemical synthesis and isolation. The crystal structure of the resulting organonickel complex was determined by the X-ray diffraction method. Its structure was compared with that of its more stable analogue [NiBr(Tchp)(bpy)], where Tchp is 2,4,6-tricyclohexylphenyl. It was found that a more efficient network of intermolecular interactions is formed in the [NiBr(Tchp)(bpy)] crystal, which is responsible for its higher stability, whereas [NiBr(Tcpp)(bpy)] is more likely to enter into an equilibrium Schlenk reaction, leading to its decomposition.

Current research fields of metal-organic frameworks (MOFs), which are being developed in the last 5-10 years by Russian scientific institutions and universities, are generalized. The review encompasses the design, synthesis, topological description, and prediction of MOF properties, the development of methods for their chemical engineering and modification, their investigation by modern physicochemical techniques, and the creation of functional materials based on porous frameworks (heterogeneous catalysts, highly efficient and highly selective sorbents of the new generation, conducting materials, systems for the target drug delivery).

Pincer complexes play an important role in organometallic chemistry; in particular, their use as homogeneous catalysts for organic transformations has increased dramatically in recent years. The high catalytic activity of such bis-cyclometallic complexes is associated with the easy tunability of their properties. Moreover, the phosphorus-based unsymmetrical pincers showed higher catalytic activity than the corresponding symmetrical analogues in several catalytic reactions. However, in modern literature, an increasing interest in the development of catalysts based on non-precious metals is observed. For example, nickel, which is an affordable and sustainable analogue of platinum and palladium, known for its low toxicity, has attracted increasing attention in the catalytic chemistry of transition metals in recent years. Thus, this mini-review is devoted to the recent advances in the chemistry of unsymmetrical phosphorus-based pincer nickel complexes, including the ligand design, the synthesis of nickel complexes and their catalytic applications.

By methods of cyclic voltammetry and preparative electrolysis, the electrochemical properties of sterically hindered imidazolium salt 3-(6-(1H-pyrazol-1-yl)pyridin-2-yl)-1-(2,6-diisopropylphenyl)-1H-imidazol-3-ium bromide containing the pyrazolyl-pyridyl moiety are studied and the N-heterocyclic carbene complexes of nickel(II) are electrochemically synthesized by the cathodic reduction of this salt in the presence of nickel(II) ions. The monitoring of this preparative electrosynthesis by mass spectrometric measurements demonstrates that these organonickel complexes can contain either one (when a diaphragm cell is used) or two (when the diaphragmless cell contains a soluble nickel anode) N-heterocyclic carbene ligands.