Russian Chemical Bulletin最新文献

The Boger reaction with 1-morpholinocyclopentene was found to involve the nucleophilic substitution of hydrogen at the C(6) position of 5-(2-furyl)-1,2,4-triazines containing the pyridin-2-yl moiety or some its analogs at the C3 position. The structure of the unexpected Boger product, β-morpholine-substituted pyridine, was confirmed by X-ray diffraction analysis. The mechanism for this process was proposed. The photophysical properties of the resulting compounds were studied, demonstrating that in most cases, the introduction of morpholin-4-yl improved the performance.

This work presents results on the design of machine learning models trained using a large set of experimental kinetic data for the catalytic Suzuki—Miyaura reaction (approximately 5000 measurements from kinetic experiments). The training was performed on different types of datasets describing the rate and selectivity of the product formation and the product yield. The incorporation of kinetic parameters (rate and differential selectivity) significantly enhances the predictive capability of the models across a wide range of process conditions.

A new synthetic approach was developed to prepare α-methylpyridines and their cyclopentene-fused analogs via the condensation of 2-bromopropiophenones with carboxylic acid hydrazides to form 1,2,4-triazines followed by their transformation by the Boger reaction. The synthesis can be accomplished by a one-pot procedure. It was demonstrated that the α-methyl group in the pyridine moiety can be further modified.

The reaction of tris(2,6-dimethoxyphenyl)bismuth with benzoyl peroxide in benzene affords tris(2,6-dimethoxyphenyl)bismuth dibenzoate Ar₃Bi[OC(O)Ph]₂, where Ar = 2,6-(MeO)₂C₆H₃, which further reacts with AgNO₃ and AgClO₄ in chloroform to give Ar₃Bi(NO₃)₂ and Ar₃Bi(ClO₄)₂, respectively. The reduction of Ar₃Bi[OC(O)Ph]₂ with magnesium produces tris(2,6-dimethoxyphenyl)bismuth. The compounds were characterized by X-ray diffraction analysis, NMR and IR spectroscopy. The bismuth atoms in Ar₃Bi[OC(O)Ph]₂ (1) and Ar₃Bi (3) have a distorted trigonal-bipyramidal coordination (C—Bi—C angles, 117.07(14)—125.49(14)°) and a trigonal-pyramidal coordination (C—Bi—C angles, 95.97(10)—100.90(12)°), respectively. The methoxy oxygen atoms are involved in non-covalent C_Me—O⋯Bi interactions with the bismuth atoms (2.962(3)—3.290(3) Å (1), 2.994(2)—3.402(3) Å (3)).

The present work describes a method for fabrication of novel luminescent polymer composites based on non-isocyanate polysiloxane urethanes containing phenyleuropiumsiloxanes of various structures as luminescent molecular fillers. A series of filled polymers was obtained and characterized, and the physicochemical, mechanical, optical, and thermal properties of film materials based on them were studied. It was found as a result of the investigations that the novel composite materials exhibit intense luminescence characteristic of Eu³⁺ ions, the excitation of which occurs mainly due to energy transfer from the β-diketone ligand. They are also characterized by high thermooxidative stability (T_d^5% = 230–270 °C). Analysis of thermal and mechanical properties of polymer composites made it possible to establish the main factors determinining the properties of novel composite UV-sensitive coatings.

The palladium-catalyzed heteroarylation of tris(2-aminoethyl)amine (TREN) and tris(3-aminopropyl)amine (TRPN) with isomeric bromoquinolines was studied. The yields of the target N,N′,N″-tri(quinolinyl) derivatives were shown to strongly depend on both the structure of branched polyamines and the position of the bromine atom in quinolines. The best results (over 70% product yields) were achieved in the reactions of 6- and 8-bromoquinolines with TRPN, with further optimization increasing the yield of the 6-quinolinyl derivative up to 96%. Also, using the reactions of TREN and TRPN with 6-bromoquinoline, the successful application of catalysis by non-immobilized nanoparticles and the copper-containing coordination polymer HKUST-1 was demonstrated, with the formation of the target N,N′,N″-tri(quinolin-6-yl) derivatives in yields over 90%. The possibility of obtaining macrocycles was exemplified by the reaction of 3,3′-dibromobiphenyl with TRPN and its monodansylated derivative under Pd⁰ catalysis; more complex macrocycles containing TRPN and oxadiamine moieties along with a fluorophore group (quinoline or dansyl) were synthesized. The absorption and fluorescence spectra of the obtained compounds were studied in the presence of metal salts and the observed characteristic changes of these spectra in the presence of Zn^II and Cu^II ions suggest macrocyclic TRPN derivatives to be promising optical sensors for these cations.

The solvatochromic properties of 2-{5-[4-(diphenylamino)phenyl]thiophen-2-yl}-quinazolin-4(3H)-one and its (9H-carbazol-9-yl)phenyl analogue were studied. The difference between the dipole moments of the ground and excited states was calculated both theoretically (using density functional theory (DFT)) and experimentally (using the Lippert—Mataga, Bilot—Kawski polarity functions and the empirical solvent polarity parameter). The high values of these parameters indicate a considerable redistribution of electron density in the molecule upon photoexcitation and the formation of a more polar excited state. The effect of medium viscosity on photophysical properties was analyzed. A linear dependence of fluorescence quantum yield on medium viscosity was revealed for 2-[5-(4-diphenylaminophenyl)thiophen-2-yl]quinazolin-4(3H)-one, which is of interest for analytical studies.

The structure and thermal properties of the mesogenic luminophore 4-hexyloxy-4′-hexylsalicylideneaniline (1) were studied by X-ray diffraction and thermal analysis methods (differential scanning calorimetry combined with polarized light thermal microscopy). The asymmetric unit cell of the crystal of 1 contains two crystallographically independent molecules with significantly different conformations. Both molecules have a benzoid configuration of the bonds in the salicylidene moiety; the active proton was unambiguously located at the oxygen atom. On heating, compound 1 undergoes three crystal—smectic—nematic—isotropic phase transitions. Under UV irradiation, compound 1 exhibits photochromism and yellow luminescence, which is observed only in the mesophase. On cooling of the mesophase to the solid state transition temperature and below, the luminescence disappears. A comparative ability of representatives of the homologous series of 4-alkyloxy-4′-alkylsalicylideneanilines to show luminescence and its relationship with photochromism are discussed.

A metal-free oxidation of 1-benzyl-3,4-dihydroisoquinolines to 1-benzoyl-3,4-di-hydroisoquinolines was accomplished using dioxygen as an oxidant. This protocol provides a facile route for the efficient synthesis of isoquinoline alkaloids. Mechanistic investigation suggested that ionic pathway is the major route in the reaction and 1-[hydroxyperoxy(phenyl)-methyl]-6,7-dimethoxy-3,4-dihydroisoquinoline may be the key intermediate for the formation of the products.

A series of shielded o-benzoquinones combining the redox-active coordination center and photoswitchable aryldiazenyl moiety was synthesized. The stability of paramagnetic reduced forms of the synthesized o-quinones was confirmed by cyclic voltammetry. The electron density distribution in the corresponding radical anions was studied by EPR spectroscopy. The aryldiazenyl moiety of the functionalized ligands was shown to retain the ability for photoinduced reversible isomerization under visible and UV irradiation without destruction of the o-quinone fragment both in an organic solvent and solid polymer matrix.