Volume 89, Issue 8

New families of the transition metal complexes with photochromic ligands manifesting photoswitchable magnetic properties determined by the light-induced spin-crossover and configurational isomerization rearrangements are theoretically designed by means of DFT calculations of electromeric forms of the complexes.

Guanidine derivatives are widely used antidiabetic drugs. Metformin (biguanide) is the first-line therapy for the type 2 diabetes mellitus due to its multi-target and pleiotropic effects. Compounds that comprise guanidine moiety integrated in a heterocycle, i.e. cyclic guanidines, represent an increasing area of interest. We have synthesized and studied hypoglycemic effects of a range of cyclic guanidines, namely 2-aminobenzimidazoles and structurally related imidazo[1,2- a ]-, pyrimido[1,2- a ]-, pyrrolo[1,2- a ]-, triazolo[1,5- a ]benzimidazole tricyclic derivatives. We have determined the potential of these scaffolds using molecular modeling and QSAR analysis. Experimental studies have shown that N 9 -(diethylamino)ethyl-2,3-dihydro-imidazo[1,2- a ]benzimidazole (RU-254, diabenol) exhibits potent antidiabetic effects along with a low toxicity. We have found that diabenol exerts long-term glucose-lowering effects in prediabetic and diabetic animals, stimulates the first phase of insulin secretion and reduces the rate of liver glycogenolysis. Additionally, diabenol has been shown to exhibit antiplatelet, geroprotective and antitumor activities in animals. Clinical trials confirm that diabenol produces a range of antidiabetogenic effects such as improved glycemia, reduced HbA 1c , stimulation of insulin secretion, decreased thrombogenic potential of blood and ameliorated hemorheology.

This paper describes our recent results in the field of zirconocene-catalyzed α-oltfin transformations, and focuses on questions regarding the reaction mechanism, rational design of zirconocene pre-catalysts, as well as prospective uses of α-olefin products. It has been determined that a wide range of α-olefin-based products, namely vinylidene dimers, oligomers and polymers, can be prepared via catalysis by zirconocene dichlorides, activated by a minimal (10–20 eq.) amount of MAO. We assumed that in the presence of minimal quantities of MAO, various types of zirconocene catalysts form different types of catalytic particles. In the case of bis- cyclopentadienyl complexes, the reactive center is formed under the influence of R 2 AlCl, which makes the chain termination via β-hydride elimination significantly easier, with α-olefin dimers being formed as the primary product. Bis - indenyl complexes and their heteroanalogues, form stable cationic catalytic particles and effectively catalyze the polymerization. Mono-indenyl and mono-substituted bis- cyclopentadienyl- ansa complexes catalyze α-olefin oligomerization. Effective catalysts of dimerization, oligomerization and polymerization of α-olefins in the presence of minimal MAO quantities are proposed. Prospects of using α-olefin dimers, oligomers and polymers in the synthesis of branched hydrocarbon functional derivatives (dimers), high quality, low viscosity motor oils (oligomers), and thickeners and absorbents (polymers) are examined.

This paper analyses alternative routes for production of chemicals from different hydrocarbon gases by their direct, without syngas production, oxidative conversion to oxygenates or ethylene. Main of these routes are direct oxidation of methane to methanol (DMTM) and selective oxy-cracking of heavier natural or associated petroleum gas components which can be used for production of high value-added petrochemicals (in combination with carbonylation processes) and fuel gases, useful for gas piston engines. The advantages and practical capabilities of such technologies are discussed.

Nitrogen-rich porous materials have outstanding gas sorption and separation capacity. Using cage amines in the synthesis of metal–organic frameworks is a simple approach for generating the free nitrogen donor centers within the channels of porous materials without the post-synthetic modification. 1,4-Diazabicyclo[2.2.2]octane has a linear arrangement of nitrogen centers and can be used as a linear linker for the design of porous MOF materials. Urotropine has four nitrogen atoms and can act as a tetrahedral four-connected, pyramidal three-connected or bent two-connected linker. Such a diversity of coordination possibilities enriches the structural chemistry of MOFs and allows obtaining the frameworks with unique secondary building units and topology. The presence of cage amines in the structure affects the sorption characteristics of the materials. They demonstrate high selectivity to CO 2 and can participate as a heterogeneous base catalyst in the organic reactions. Besides that the cage-amine based metal–organic frameworks demonstrate photoluminescent properties and can be used as nanoreactors for photochemical transformations. These compounds are also an important object of thermodynamic studies helping us better understand the nature of host–guest interaction in the supramolecular systems.

The oxidative stress is considered to be involved in the pathogenesis of many diseases. The antioxidative defense system in the living organism regulates the toxic impact of ROS and there is strong evidence that the antioxidants prevent some pathologies including cancer. The specific chemical properties of metal-based drugs impart innovative pharmacological profiles to this type of therapeutic agents, most likely in relation to novel biomolecular mechanisms. This review will focus on a novel approach to design polyfunctional metal-based physiollogically active compounds with opposed modes of action – prooxidant metal center and antioxidant 2,6-dialkylphenol group. The synthesis and anti/prooxidant activity and cytotoxicity studies of novel organometallic/coordination compounds (ferrocenes, complexes with di-(2-picolyl)amine ligand, porphyrins, pyridines, thiols, carboxylates) based on either biogenic metals (Fe, Mn, Co, Cu, Zn, Ni) or exogenic metals (Sn, Au, Rh) are presented and discussed. The results allow us to conclude that combining in one molecule a redox active metal center and cytoprotective functional organic moiety with antioxidative function is a promising way to rational metallodrug design in modern medicinal chemistry.

The new efficient and environmentally safe methods for preparation of various classes of organic and organoelement compounds, including organonickel sigma-complexes and organophosphorus compounds bearing P–C bonds have been created using the electrochemical methods. The synthetic application of the elaborated techniques towards the process of formation of new carbon-carbon, carbon-metal and carbon-phosphorus bonds are discussed. The mechanisms of the proposed processes and the nature of the formed in the overall electrochemical process intermediates are disclosed. The elaborated methods operated in the principals of “green chemistry” can be considered as an efficient alternative to some classical methods for preparation of active catalysts, biologically active molecules and new polynuclear complexes displaying practically useful properties.

Monoterpenes and their derivatives play an important role in the creation of new biologically active compounds including drugs. The review focuses on the data on various types of biological activity exhibited by monoterpenes and their derivatives, including analgesic, anti-inflammatory, anticonvulsant, antidepressant, anti-Alzheimer, anti-Parkinsonian, antiviral, and antibacterial (anti-tuberculosis) effects. Searching for novel potential drugs among monoterpene derivatives shows great promise for treating various pathologies. Special attention is paid to the effect of absolute configuration of monoterpenes and monoterpenoids on their activity.

In this review we briefly discuss some new trends in the design of single molecule magnets based on transition (3d, 4d, 5d) and rare-earth (4f) metal ions. Within this broad theme the emphasis of the present review is placed on the molecules which exhibit strong magnetic anisotropy originating from the unquenched orbital angular momenta in the ground orbitally degenerate (or quasi-degenerate) states. Along with the general concepts we consider selected examples of the systems comprising orbitally-degenerate metal ions and demonstrate how one can benefit from strong single-ion anisotropy arising from the first-order orbital angular momentum. The role of crystal fields, spin-orbit coupling and structural factors is discussed. Some observation stemming from the analysis of the isotropic exchange interactions, magnetic anisotropy and strongly anisotropic orbitally-dependent superexchange are summarized as guiding rules for the controlled design of single molecule magnets exhibiting high barriers for magnetization reversal and, consequently, high blocking temperatures.

A comparative study of nickel-tungsten sulfide catalysts for hydrodearomatization prepared in situ in a reaction medium by different methods (from a [BMPip] 2 Ni(WS 4 ) 2 precursor in a hydrocarbon or in an ionic liquid, from a suspension of nickel and tungsten salts formed from inverted emulsions in hydrocarbons, or from oil-soluble precursors) has been carried out. It has been found that the use of the oil-soluble precursors makes it possible to reach a high degree of sulfidizing of the active phase and a high degree of its promotion by nickel at a small size of the active phase particles. The resulting catalyst can be applied to the hydrogenation of both the naphthalene and substituted methylnaphthalenes (2-methylnaphthalene, 2,6-dimethylnaphthalene, 2,3-dimethylnaphthalene, and 2,3,6-trimethylnaphthalene) with the high selectivity for decalins and to the hydrodearomatization of light cycle oil with the complete removal of di- and polycyclic aromatic compounds.

The paper concerns application of two types of organic materials – porous aromatic frameworks (PAFs) with diamond-like structure and the ordered mesoporous phenol-formaldehyde polymers (MPFs) – as supports for metal and metal sulfide nanoparticles. The obtained hybrid materials were tested in hydrogenation of various unsaturated and aromatic compounds. Ruthenium catalyst, based on PAF (Ru-PAF-30), possessed high activity in exhaustive hydrogenation of phenol into cyclohexanol with TOF value of 2700 h −1 . Platinum catalyst, based on modified with sulfo-groups MPF (MPF-SO 3 H-Pt), was selective in semi-hydrogenation of terpenes, [α-terpinene, γ-terpinene, terpinolene, (s)-limonene]. Bimetallic Ni–W sulfide catalysts, prepared by in situ decomposition of [(n-Bu) 4 N] 2 Ni(WS 4 ) 2 within the pores of MPFs and PAFs, possessed high efficiency in hydrogenation-hydrocracking of naphthalenes as model substrates.

Alzheimer’s disease has a complex multifactorial nature; therefore, a promising approach for the development of efficient therapeutic agents is the concept of multitarget drugs, which affect several biological targets involved in the pathogenesis of the disease. We developed a synthetic algorithm for conjugating several pharmacophoric ligands acting on the key stages of pathogenesis of several neurodegenerative diseases and synthesized hybrid structures combining the γ-carboline fragment of Dimebon with carbazole and tetrahydrocarbazole moieties. Using the complex primary screening system the structures have been revealed that combine the high inhibitory activity and selectivity towards butyrylcholinesterase with the radical-scavenging activity and the ability to potentiate tubulin polymerization to microtubules with a normal structure and/or prevent mitochondrial permeability transition. The lead compound was identified for future optimization and development of new multi-target drugs against neurodegenerative diseases combining the cognitive-stimulating and neuroprotective potentials.

Development of alternative energy sources is one of the main trends of modern energy technology. Lithium-ion batteries and fuel cells are the most important among them. The increase in the energy and power density is the essential aspect which determined their future development. We provide a brief review of the state of developments in the field of nanosize electrode materials and electrolytes for lithium-ion batteries and hydrogen energy. The presence of relatively inexpensive and abundant elements, safety and low volume change during the lithium intercalation/deintercalation processes enables the application of lithium iron phosphate and lithium titanate as electrode materials for lithium-ion batteries. At the same time, they exhibit low ionic and electronic conductivity. To overcome this problem the following main approaches have been applied: use of nanosize materials, including nanocomposites, and heterovalent doping. Their impact in the property change is analyzed and discussed. Hybrid membranes containing inorganic nanoparticles enable a significant progress in the fuel cell development. Different approaches to their preparation, the reasons for ion conductivity and selectivity change, as well as the prospects for their application in low-temperature fuel cells are discussed. This review may provide some useful guidelines for development of advanced materials for lithium ion batteries and fuel cells.

Direct metal-free C–H functionalization of arenes with nucleophiles is a new chapter in the chemistry of aromatics. Comprehensive studies on nucleophilic substitution of hydrogen in arenes (the S N H reactions), including mechanisms, intermediates, mathematic and electrochemical modeling, kinetics, electron-transfer, etc. have shown that this is not the hydride ion, but C–H proton is departed, and this process is facilitated by the presence of an appropriate oxidant or an auxiliary group. The S N H reactions, as a part of the general C–H functionalization concept, change the logic of organic synthesis. They open new opportunities, avoiding incorporation of good leaving groups or other auxiliaries in an aromatic ring, as a prefunctionalization step, thus providing a better correspondence to the principles of green chemistry.

The review focuses on the synthesis and chemical properties of polyfluoroalkylated 2-ethoxymethylene-3-oxo esters. The scope and peculiarities of their use as organic reagents in reactions with various N-, C-, O-, mono- and dinucleophiles are discussed in detail. The high reactivity of such derivatives is employed in the construction of enaminoketone, arene and heterocycle frameworks. Particular attention is paid to applications of these building blocks as chemicals for fine organic synthesis, bioactive compounds and metal complexes synthesis.