Публикации

Pd/NHC complexes (NHCs – N-heterocyclic carbenes) with electron-withdrawing halogen groups were prepared by developing an optimized synthetic procedure to access imidazolium salts and the corresponding metal complexes. Structural X-ray analysis and computational studies have been carried out to evaluate the effect of halogen and CF3 substituents on the Pd–NHC bond and have provided insight into the possible electronic effects on the molecular structure. The introduction of electron-withdrawing substituents changes the ratio of σ-/π-contributions to the Pd–NHC bond but does not affect the Pd–NHC bond energy. Here, we report the first optimized synthetic approach to access a comprehensive range of o-, m-, and p-XC6H4-substituted NHC ligands, including incorporation into Pd complexes (X = F, Cl, Br, CF3). The catalytic activity of the obtained Pd/NHC complexes was compared in the Mizoroki–Heck reaction. For substitution with halogen atoms, the following relative trend was observed: X = Br > F > Cl, and for all halogen atoms, the catalytic activity changed in the following order: m-X, p-X > o-X. Evaluation of the relative catalytic activity showed a significant increase in the catalyst performance in the case of Br and CF3 substituents compared to the unsubstituted Pd/NHC complex.

Industrial activity results in ton-scale production of calcium carbide and generation of a significant amount of calcium carbide residue (CCR), which is often disposed of in the environment as waste. CCR is an active chemical, and rain washes away alkali from sludge, changing the pH of soils and water and damaging the environment. In this work, we explored new opportunities for the utilization of CCR in view of the coming industrial uptake of digital design and additive technologies. Amazingly, CCR can be successfully used as a filler for the modification of 3D printed materials towards the introduction of hybrid organic/inorganic frameworks. A series of commercially available plastics (PLA, ABS, Nylon, PETG, SBS) were successfully used as matrices for CCR-based composite production with high CCR contents up to 28%. Tensile analyses showed increases in tensile strength and Young's modulus of 9% and 60%, respectively. Moreover, in comparison with the pure plastics, the CCR-based materials better maintained the digitally designed shape (lower shrinkage). Importantly, CCR-filled materials are 3D printable, making them very promising components in the building sector. Considering the amount of already available CCR stored in the environment, this material is available in large quantities in the near future for hybrid materials, and anticipated opportunities exist in the additive manufacturing sector. The involvement of CCR in practical composite materials is equally important for environmental protection and reuse of already available multiple-ton wastes.

Biomass-derived C6-furanic compounds have become the cornerstone of sustainable technologies. The key feature of this field of chemistry is the involvement of the natural process only in the first step, i.e., the production of biomass by photosynthesis. Biomass-to-HMF (5-hydroxymethylfurfural) conversion and further transformations are carried out externally with the involvement of processes with poor environmental factors (E-factors) and the generation of chemical wastes. Due to widespread interest, the chemical conversion of biomass to furanic platform chemicals and related transformations are thoroughly studied and well-reviewed in the current literature. In contrast, a novel opportunity is based on an alternative approach to consider the synthesis of C6-furanics inside living cells using natural metabolism, as well as further transformations to a variety of functionalized products. In the present article, we review naturally occurring substances containing C6-furanic cores and focus on the diversity of C6-furanic derivatives, occurrence, properties and synthesis. From the practical point of view, organic synthesis involving natural metabolism is advantageous in terms of sustainability (sunlight-driven as the only energy source) and green nature (no eco-persisted chemical wastes).

A common assumption that dimeric metal complexes in many catalytic systems represent a resting state and are not directly involved in catalytic processes was revised in a combined experimental and theoretical study. On-cycle participation of dimeric metal complexes, rather than typically assumed off-cycle involvement, was revealed, and advantageous performance in terms of improved selectivity was observed. The conceptual rationalization for the participation of dimeric species in the catalytic cycle was developed. The Pd-catalyzed hydrothiolation process (where strong Pd–S binding is well established and a persistent opinion for the inactive/poisoning role of dimeric species is presumed) was evaluated as a challenging system to test the concept. Activation of an (NHC)Pd(Cl)(acac) precatalyst (NHC─N-heterocyclic carbene and acac─acetylacetonate) under the reaction conditions produced monomeric (NHC)Pd(SPh) ₂ or dimeric (NHC)₂Pd₂(SPh)₄ species depending on the steric bulkiness of the NHC ligand. Dimeric complexes possessed higher selectivity and tolerated disulfide impurities in contrast to monomeric complexes. Quantum chemical modeling suggested that dimeric catalysis proceeds through the opening of only one (μ-SPh)–Pd bridging bond with retention of the dimeric structure. The second bridging bond is maintained, which prevents the monomerization of the complex. Catalytically active species were detected in a hydrothiolation reaction by high-resolution mass spectrometry and NMR spectroscopy. Proving the opportunity for productive homogeneous catalysis via strongly coordinated dimeric metal species opens new opportunities for catalyst design in the increased nuclearity dimension.

Electron microscopy (EM) is one of the most important methods for characterizing various systems, and it is traditionally applied to static solid structures. Remarkable recent developments have opened multiple possibilities for in situ observation of different phenomena, including liquid phase processes. In contrast to routine solid-state EM measurements with static images, electron microscopy in liquids often deals with ubiquitous dynamics, which can be recorded as video streams. Providing much information about the sample, real-time EM increases the complexity of data analysis, challenging researchers to develop new, highly efficient systems for data processing. The present work proposes a framework for data anal- ysis in real-time electron microscopy. Multiple algorithm choices are compared, and efficient solutions are described. Using the best algorithm, combining classical computer vision methods and deep learning-based denoising, the unique anisotropic effect of the electron beam in microstructured ionic liquid-based systems was discovered. The developed method provides an efficient approach for studying the structure and transformation of soft micro-scale domains in molecular liquids. The corresponding software was made publicly available, and detailed instructions to reapply it to other problems were provided.

Water-soluble Pt complexes are the key components in medicinal chemistry and catalysis. The well-known cisplatin family of anticancer drugs and industrial hydrosylilation catalysts are two leading examples. On the molecular level, the activity mechanisms of such complexes mostly involve changes in the Pt coordination sphere. Using 195Pt NMR spectroscopy for operando monitoring would be a valuable tool for uncovering the activity mechanisms; however, reliable approaches for the rapid correlation of Pt complex structure with 195Pt chemical shifts are very challenging and not available for everyday research practice. While NMR shielding is a response property, molecular 3D structure determines NMR spectra, as widely known, which allows us to build up 3D structure to 195Pt chemical shift correlations. Accordingly, we present a new workflow for the determination of lowest-energy configurational/conformational isomers based on the GFN2-xTB semiempirical method and prediction of corresponding chemical shifts with a Machine Learning (ML) model tuned for Pt complexes. The workflow was designed for the prediction of 195Pt chemical shifts of water-soluble Pt(II) and Pt(IV) anionic, neutral, and cationic complexes with halide, NO2−, (di)amino, and (di)carboxylate ligands with chemical shift values ranging from −6293 to 7090 ppm. The model offered an accuracy (normalized root-mean-square deviation / RMSD) of 0.98 % / 131.25 ppm on the held-out test set.

Sustainable development of mankind urgently recalls for decreasing the cost of energy storage. Continuous massive consumption of dedicated carbon electrode materials with complex internal molecular architecture calls for re-thinking both the source of materials and the process of their production. Finding an efficient sustainable solution is focused on the reuse and development of waste processing into corresponding high-value-added carbon materials. The processing of solid wastes into solid value-added carbon materials ("solid-to-solid") is relatively well developed but can be a two-stage process involving carbon architecture rearrangement and heteroatom doping. Processing liquid wastes into high-value-added solid material ("liquid-to-solid") is typically much more challenging with the need for different production equipment. In the present study, a new approach is developed to bypass the difficulty in the "liquid-to-solid" conversion and simultaneously built in the ability for heteroatom doping within one production stage. Polycondensation of liquid humins waste with melamine (as a nitrogen-containing cross-linking component) results in solidification with preferential C and N atomic arrangements. For subsequent thermochemical conversion of the obtained solidified wastes, complicated equipment is no longer required, and under simple process conditions, carbon materials for energy storage with superior characteristics were obtained. A complete sequence is reported in the present study, including liquid waste processing, nitrogen incorporation, carbon material production, structural study of the obtained materials, detailed electrochemical evaluation and real supercapacitor device manufacture and testing.

C-Amino-1,2,4-triazoles are challenging polynitrogen substrates for metal-catalyzed arylation due to their multidentate character, enhanced coordinating ability and decreased nucleophilicity of the amino group. In the present study, the Buchwald–Hartwig cross-coupling of diverse 3(5)-amino-1,2,4-triazoles with aryl chlorides and bromides delivering (hetero)arylamino-1,2,4-triazoles in good-to-excellent yields under Pd/NHC catalysis was developed. The use of Pd complexes with bulky NHC ligands such as IPr*OMe and TPEDO (1,1,2,2-tetraphenylethane-1,2-diol) as an in situ Pd(II) to Pd(0) reductant enabled the selective arylation of the NH2 group even in acidic NH unprotected substrates and deactivated 1-substituted 5-amino- and 4-substituted 3-amino-1,2,4-triazoles. The reaction mechanism and structure–activity relationships were studied with DFT calculations. A significant effect of the position of the N-substituent in the 1,2,4-triazole ring on the favorable reaction pathways was revealed.

For the first time, the transformation of biobased 5-HMF derivatives succeeded in a 2 × [4 + 2] cascade cycloaddition reaction, leading to a drastic (3–5-fold) increase in molecular complexity as a result of one synthetic step. A new approach to the use of plant biomass in organic synthesis using a cascade Diels–Alder reaction of 5-HMF dimer derivatives with alkynes has been developed. This reaction proceeds under thermodynamic control, diastereoselectively and regioselectively, providing rapid access to compounds of high molecular complexity with the same synthetic availability as previously obtained regular cycloadducts. As a concept illustration, under conditions of kinetic control, cycloadditions of two molecules of dienophiles are realized, and the resulting products, when heated, rearrange into thermodynamically more favorable cascade products. Reaction pathways were studied in detail using quantum chemical calculations to reveal major factors influencing the selectivity of the process. Discovery of a new sustainability pathway should be noted – to date, oligomeric derivatives are considered a waste of 5-HMF degradation, while the present study highlights them as a valuable material for the synthesis of nonplanar scaffolds.

Stable and easily detectable isotopic labels provide advanced opportunities in a wide range of chemical applications. Highly specific information can be retrieved upon analysis of isotopic label movement from one position to another. The incorporation of isotopic labels into organic molecules is in high demand; however, it may often be rather challenging. The introduction of D and 13C labels is of particular interest due to authentic signals in NMR spectra and the reliable identification of isotopic label positions in target molecules. In this work, a convenient methodology for the introduction of D and 13C labels was developed using calcium carbide as a source of D- and 13C-labeled acetylene and phosphine oxides as substrates. As a result, d4- and 13C2-1,2-bis(phosphine oxide)ethanes were isolated in yields and isotopic purities up to 99%. The resulting phosphine oxides were reduced to the corresponding phosphines, which were used as ligands for the preparation of D-labeled Ni and Pd complexes in 80–96% yields with further characterization by NMR spectroscopy, X-ray and HRMS. The incorporation of D and 13C labels using calcium carbide and acetylene is of key importance since atom-economical addition reactions can be involved with intrinsic opportunity for saving valuable isotopic labels.

The transfer of waste materials from the chemical industry to the building sector is an emerging area of sustainable development. Leftovers, by-products, tails and sludge from chemical processes may be valuable components of building mixtures. Feeding the construction industry by chemical wastes is a profitable chain for both sectors. In fact, calcium carbide residue (CCR) can be considered a link between the chemical industry and construction materials. Carbide sludge is the main waste product of acetylene gas production from calcium carbide. The released acetylene is actively used in the modern chemical industry. An alternative method of acetylene production — the cracking of oil and gas — is beyond sustainability; thus, the carbide route is more promising in the hydrocarbon-free future. However, the carbide route is accompanied by a significant amount of the side-product carbide sludge, which is currently used as a CO ₂ capture agent, binder, building material, in inorganic synthesis, etc. In this review, the potential of carbide sludge in the construction industry and other areas is highlighted.