Andrei V. Churakov

Using new complexes of Group 4 metals with saligenin (2‐hydroxymethylphenol) ligands, it was shown that only titanium compounds activated by Al/Mg cocatalysts (Et ₂ AlCl or Et ₃ Al ₂ Cl ₃ + Bu ₂ Mg) exhibit catalytic activity in ethylene polymerization. The authors attribute the lack of activity of the Zr and Hf complexes to differences in the redox potentials of these metals, based on the assumption that the catalytically active particle contains reduced Ti(III). Traditional activators—alkylaluminoxanes, tetrakisperfluorophenylborates, and simple organoaluminum compounds (OAC)—are unable to activate these complexes. A prerequisite for catalytic activity is the presence of Mg compounds, indicating the heterometallic (Ti‐Mg) nature of the active particle. Titanium complexes catalyze the synthesis of UHMWPE with a productivity of up to 3940 kg of PE mol ⁻¹ h ⁻¹ atm ⁻¹ . UHMWPE films obtained by solventless processing with subsequent uniaxial orientation drawing have a tensile modulus up to 120 GPa and tensile strength up to 2.3 GPa, which indirectly proves the low degree of macromolecule's entanglements. Titanium complexes, stabilized with dichlorosaligenin ligand, are also capable of catalyzing the synthesis of high molecular weight ethylene‐propylene‐5‐ethylidene‐norbornene terpolymers (EPDM).

Two-component crystals composed of potentially unstable species, namely, zwitterionic diazonium salts and hydrogen peroxide, were obtained and structurally characterized. Very unusual intermolecular bonds were observed, with the highlight being oxygen from the peroxide (often not a strong donor) interacting with the diazonium cation. Similar intramolecular interactions were also observed in the crystals of unsolvated diazonium salts. The existence of these bonds (interactions) was confirmed by the presence of the bond’s critical points (3,-1), found by means of Bader analysis of the calculated crystalline electron density. At the shortest contact, the O···N distance reaches ∼2.68 Å, and the energy is ∼15 kJ/mol. Such specific properties allow us to define these interactions as non-covalent O: →+N2−Ar interactions.

Reactions of (2E)-3-aryl-2-(4-arylthiazol-2-yl)acrylonitriles, malononitrile, and sodium methoxide or 2-[4-(4-bromophenyl)thiazol-2-yl]acetonitrile, 4-methoxybenzylidenemalononitrile, and potassium hydroxide in methanol proceed to give 6-amino-4-aryl-5-(4-arylthiazol-2-yl)-2-methoxynicotinonitriles in 38–47% yields.

Developing near-infrared (NIR) photothermal materials for solar energy harvesting and biomedical technologies is highly desirable, yet achieving both outstanding conversion efficiency and long-term stability remains a critical challenge for small-molecule systems. Here, we report a homochiral binuclear iridium(III) complex featuring an electron-deficient 1,2,4,5-tetrazine, which narrows the HOMO-LUMO gap, inducing strong and exceptionally broad NIR absorption extending up to 1200 nm in solution and 1500 nm in the solid state. The intrinsic flexibility of the tetrazine bridge enables pronounced internal butterfly-like conformational dynamics of the complex in solution. These molecular vibrations couple with low-energy charge-transfer transitions, driving highly efficient non-radiative decay of the photoexcited state. In the solid phase, the competitive interplay between anion···π and lone pair···π interactions targeting the tetrazine core serves as a structural switch, locking or unlocking the "butterfly" vibrations across different crystalline solvatomorphs. This local arrangement directly dictates the macroscopic photothermal performance and operational photostability of the material. The complex achieves a record-high photothermal conversion efficiency of up to 94.9% in powder, 93.3% on cellulose paper (808 nm laser), and 68.3% (980 nm laser) in solution, alongside superior operational photostability demonstrated by FTIR, UV-Vis-NIR spectroscopy and X-ray diffraction. When applied to solar-driven water evaporation, the system delivers an impressive efficiency of 86.6% (water evaporation rate of 1.275 kg m ⁻² h ⁻¹ ). Overall, this work establishes bridging 1,2,4,5-tetrazines and crystal engineering as powerful tools for designing high-performance organometallic photothermal materials.

This study investigates the thermal stability and gas-phase synthesis of the [PABA + iNAM] (1 : 1) and (2 : 1) cocrystals, including the first report of the 1 : 1 crystal structure.

Two novel cocrystals of zwitterionic trimethylglycine (TMG) with 2,6-dichlorophenol [TMG•2,6-dichlorophenol] (1:1) and 2,6-dibromophenol [TMG•2,6-dibromophenol] (1:2) are synthesized and structurally characterized using single crystal X-ray diffraction. To estimate the energy of various intermolecular interactions, periodic DFT calculations were performed followed by Bader analysis of the crystalline electron density. TMG molecules form dimers in [TMG•2,6-dichlorophenol] (1:1). Its supramolecular structure is governed by the primary charge-assisted H-bonds (~60 kJ/mol) and supported by C–H∙∙∙O contacts (~12 kJ/mol). Cl/Br substitution introduces a more potent halogen-bonding donor. The Br∙∙∙O⁻ interaction (~10 kJ/mol) is strong enough to reorganize the packing into a catemeric motif. As a result, TMG molecules form infinite chains in [TMG•2,6-dibromophenol] (1:2). This illustrates that “fine tuning” is not merely about changing distances, but about shifting the entire energy hierarchy of the crystal. Two-dimensional fingerprint diagrams (2D diagrams) obtained from the Hirshfeld surface and Bader’s analysis of the crystalline electron density give significantly different values of the contributions of the H∙∙∙H contacts, 28% vs. 5% respectively. The main reason for this discrepancy is the large number of relatively short intermolecular H∙∙∙H contacts without a critical bond point in trimethylglycine cocrystals.

The multicomponent reaction of cyclohexanone, cyanothioacetamide, ethyl cyanoacetate or 3,5-di­methyl-1-(cyanoacetyl)-1H-pyrazole, and allyl bromide in ethanol or acetone in the presence of N-methyl­morpholine at 25°C afforded 2-(allylsulfanyl)-4-oxo-3-azaspiro[5.5]undec-1-ene-1,5-dicarbonitrile, whereas 1-allyl-4-oxo-2-sulfanylidene-3-azaspiro[5.5]undec-1-ene-1,5-dicarbonitrile was obtained under reflux condi­tions. The product structure was studied by spectral methods and X-ray analysis.