“Solvent-in-Salt” Systems for Design of New Materials in Chemistry, Biology and Energy Research

Azov V. A., Egorova K. S., Seitkalieva M. M., Kashin A. S., Ananikov V. P., Chem. Soc. Rev., 2018, 47, 1250-1284 .
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Inorganic and organic "solvent-in-salt" (SIS) systems have been known for decades but have attracted significant attention only recently. Molten salt hydrates/solvates have been successfully employed as non-flammable, benign electrolytes in rechargeable lithium-ion batteries leading to a revolution in battery development and design. SIS with organic components (for example, ionic liquids containing small amounts of water) demonstrate remarkable thermal stability and tunability, and present a class of admittedly safer electrolytes, in comparison with traditional organic solvents. Water molecules tend to form nano- and microstructures (droplets and channel networks) in ionic media impacting their heterogeneity. Such microscale domains can be employed as microreactors for chemical and enzymatic synthesis. In this review, we address known SIS systems and discuss their composition, structure, properties and dynamics. Special attention is paid to the current and potential applications of inorganic and organic SIS systems in energy research, chemistry and biochemistry. A separate section of this review is dedicated to experimental methods of SIS investigation, which is crucial for the development of this field.

Green and Sustainable Route to Carbohydrate Vinyl Ethers for Accessing Bio-Inspired Materials with a Unique Microspherical Morphology

Rodygin K. S., Werner I., Ananikov V. P., ChemSusChem, 2018, 11, 292–298.
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Synthesizing chemicals and materials based on renewable sources is one of the main tasks of modern science. Carbohydrates represent excellent renewable natural raw materials, that are eco-friendly, inexpensive and biologically compatible. Herein, we developed a green vinylation procedure for carbohydrates using readily available calcium carbide. Various carbohydrates were utilized as starting materials resulting in mono-, di- and tetra-vinyl ethers in high to excellent yields (81-92 %). The synthesized bio-based vinyl ethers were utilized as monomers in free radical and cationic polymerizations. A unique combination of smooth surface and intrinsic microcompartments was achieved in the synthesized materials. Two types of bio-based materials were prepared involving microspheres and "Swiss cheese" polymers. Scanning electron microscopy with built-in ion beam cutting was applied to reveal the spatial hierarchical structures in three-dimensional space.

Fast and Slow Release of Catalytically Active Species in Metal/NHC Systems Induced by Aliphatic Amines

Khazipov O.V., Shevchenko M.A., Chernenko A.Yu., Astakhov A.V., Pasyukov D.V., Eremin D.B., Zubavichus Y.V., Khrustalev V.N., Chernyshev V.M., Ananikov V.P., Organometallics, 2018, ASAP.
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The behavior of ubiquitously used nickel, palladium, and platinum complexes containing N-heterocyclic carbene ligands was studied in solution in the presence of aliphatic amines. Transformation of M(NHC)X2L complexes readily occurred according to the following reactions: (i) release of the NHC ligand in the form of azolium salt and formation of metal clusters or nanoparticles and (ii) isomerization of mono-NHC complexes M(NHC)X2L to bis-NHC derivatives M(NHC)2X2. Facile cleavage of the M–NHC bond was observed and provided the possibility for fast release of catalytically active NHC-free metal species. Bis-NHC metal complexes M(NHC)2X2were found to be significantly more stable and represented a molecular reservoir of catalytically active species. Slow decomposition of the bis-NHC complexes by removal of the NHC ligands (also in the form of azolium salts) occurred, generating metal clusters or nanoparticles. The observed combination of dual fast- and slow-release channels is an intrinsic latent opportunity of M/NHC complexes, which balances the activity and durability of a catalytic system. The fast release of catalytically active species from M(NHC)X2L complexes can rapidly initiate catalytic transformation, while the slow release of catalytically active species from M(NHC)2X2 complexes can compensate for degradation of catalytically active species and help to maintain a reliable amount of catalyst. The study clearly shows an outstanding potential of dynamic catalytic systems, where the key roles are played by the lability of the M–NHC framework rather than its stability.

Influence of R–NHC Coupling on the Outcome of R–X Oxidative Addition to Pd/NHC Complexes (R = Me, Ph, Vinyl, Ethynyl)

Gordeev E.G., Eremin D.B., Chernyshev V.M., Ananikov V.P., Organometallics, 2018, 37, 787-796.
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Oxidative addition of organic halides (R–X) to (NHC)Pd 0L complexes is involved in numerous metal-catalyzed reactions, and this step is expected to afford (NHC)PdII(R)(X)L intermediate complexes. However, these complexes may undergo further transformation via R–NHC coupling, which removes the NHC ligands from the metal and results in the generation of "bare" NHC-free metal species. The comparative theoretical study carried out in the present work revealed that the kinetic and thermodynamic stability of the (NHC)PdII(R)(X)L oxidative addition intermediates depends strongly on the nature of the organic group R. The predicted reactivity in the R–NHC coupling process decreases in the following order: R = Vinyl > Ethynyl > Ph > Me. Accordingly, for R = Me, a classical (NHC)PdII(R)(X)L intermediate can be expected as a product of the oxidative addition step, whereas for R = Ph, the outcome of the oxidative addition may already contain the NHC-free palladium complex. For R = Ethynyl, comparable amounts of both complexes should be formed, while for R = Vinyl, the NHC-free palladium complex can be the major product of the oxidative addition process. Unusual thermodynamic and kinetic instability of the (NHC)Pd(vinyl)(X)L complex and the tendency to vinyl–NHC coupling predicted by the computational modeling has been confirmed by experimental measurements with online mass spectrometric reaction monitoring. Thus, the outcome of the oxidative addition strongly depends on the type of organic group R and the R–NHC coupling process greatly influences the activity and stability of metal catalysts.

Ionic Liquids As Tunable Toxicity Storage Media for Sustainable Chemical Waste Management

Seitkalieva M. M., Kashin A. S., Egorova K. S., Ananikov V. P., ACS Sustainable Chem. Eng., 2018, 6, 719–726.
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Storage and handling of toxic wastes is a top-priority challenge for sustainable development and public health. In recent years, the risk of irreversible environmental pollution has been increasing gradually, necessitating the development of new concepts in this highly demanding area. Here, we report a flexible approach to address the problem using tunable ionic liquids as a carrier and storage medium for chemicals. Encapsulation in microscale tunable media surrounded by an inert ionic liquid facilitates the efficient capture of chemicals. The adaptive character of the designed microscale compartments opens new possibilities for the waste management of chemicals of a diverse nature. Real-time field-emission scanning electron microscopy was used to visualize the formation of microscale compartments upon the sequestration of chemicals in ionic liquids. Ionic liquids captured the chemicals better than traditional organic solvents or water; moreover, the chemicals subsequently could be effectively extracted for destruction or utilization. Our work presents a new model for the sustainable management of chemical wastes; the concept was evaluated for a number of multiton chemicals currently affecting our environment.

Micro-Scale Processes Occurring in Ionic Liquid–Water Phases During Extraction

Seitkalieva M. M., Kashin A. S., Egorova K. S., Ananikov V. P., Sep. Purif. Technol., 2018, 196, 318-326.
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For the first time, extraction process in ionic liquids was visualized by direct electron microscopy observation. Microscopy images revealed the micro-heterogeneous nature of the studied extraction systems. Depending on the nature of ionic liquids and studied compounds, four main micro-scale areas were observed: a) uniform homogeneous phase; b) microcompartments in the liquid phase; c) solid microinclusions on the phase boundary; and d) solid microinclusions inside the separated microphases. The microscopic monitoring showed stepwise sequence of the extraction process, and the retention ability of the ionic liquid–water system decreased in the following order: homogeneous phase > microcompartments > solid microinclusions.

[3 + 2]-Cycloaddition of in Situ Generated Nitrile Imines and Acetylene for Assembling of 1,3-Disubstituted Pyrazoles with Quantitative Deuterium Labeling

Voronin V.V., Ledovskaya M.S., Gordeev E.G., Rodygin K.S., Ananikov V.P., J. Org. Chem., 2018, 83, 3819–3828.
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A novel synthetic methodology for the preparation of 1,3-disubstituted pyrazoles from in situgenerated nitrile imines and acetylene is reported. The reactions are performed in a simple two-chamber reactor. One part of the reactor is loaded with hydrazonoyl chloride precursors of active nitrile imine species and a base. The other part is used to generate acetylene from CaC2 and water. Partitioning of the reactants improves the yields of desired pyrazoles up to 99% and simplifies their isolation to a simple procedure of solvent evaporation. The approach requires no complex equipment and utilizes inexpensive, safe, and easy to handle calcium carbide as a starting material. A model deuterium incorporation is carried out according to the developed methodology, producing a series of novel 4,5-dideuteropyrazoles with excellent deuterium enrichment. Theoretical calculations on reaction mechanism and characterization of possible intermediate structures were performed.

Calcium-Mediated One-Pot Preparation of Isoxazoles with Deuterium Incorporation

Ledovskaya M., Rodygin K.S., Ananikov V.P., Org. Chem. Front., 2018, 5, 226–231.
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In this work, a novel synthetic methodology for the one-pot preparation of isoxazoles directly from the reaction of calcium carbide with aldoximes is reported. Calcium carbide acts as a safe and inexpensive acetylene source and, in addition, as a source of the Ca(OH)2 base to enable the generation of nitrile oxide. Various 3-substituted isoxazoles were synthesized from the corresponding aldoximes in good yields (up to 95%) and a series of new deuterated 4,5-dideuteroisoxazoles were prepared.

Vinylation of a Secondary Amine Core with Calcium Carbide for Efficient Post-Modification and Access to Polymeric Materials

Rodygin K.S., Bogachenkov A.S., Ananikov V.P., Molecules, 2018, 23, 648.
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We developed a simple and efficient strategy to access N-vinyl secondary amines of various naturally occurring materials using readily available solid acetylene reagents (calcium carbide, KF, and KOH). Pyrrole, pyrazole, indoles, carbazoles, and diarylamines were successfully vinylated in good yields. Cross-linked and linear polymers were synthesized from N-vinyl carbazoles through free radical and cationic polymerization. Post-modification of olanzapine (an antipsychotic drug substance) was successfully performed.