Terpyridines are well-known ligands in coordination chemistry, are valued for their conformational flexibility and strong metal-binding properties, and are also of interest as fluorophores. This study focused on the synthesis and comprehensive investigation of a new class of bis-oxazolo[5,4-b]pyridine derivatives, designed based on their structural similarity to terpyridines. Four novel compounds, 4a-d, were synthesized by cyclization of amide derivatives of 3-aminopyridin-2(1H)-ones using pyridine-2,6-dicarboxylic acid and its dichloride as key acidic components. Their structures and purity were confirmed by melting point analysis, high-resolution mass spectrometry, and 1H, 13C NMR spectroscopy. Compounds 4a-c exhibit UV absorption at 323-357 nm and intense blue to deep-blue fluorescence (357-474 nm, & tscy;i approximate to 0.32-0.84) in chloroform, dichloromethane, and acetonitrile, attributed to p-p* transitions within the conjugated ring system. These findings suggest their potential as phosphors for organic electronics. Computational modeling of 4a-c molecules provided insight into their electronic structures, conformational stability, and predicted optical behavior. The most stable conformers (4a-II, 4b-II, 4c-II ') exhibited a progressive decrease in the HOMO-LUMO gap from 4a to 4c, correlated with the enhancement of photoactivity. Among them, compound 4a stands out as the most promising luminophore, displaying the most intense and narrow luminescence band, owing to its high molecular symmetry and stable emission characteristics. Overall, this study lays the foundation for future studies of bis(oxazolo[5,4-b]pyridine) derivatives in coordination chemistry and optoelectronic materials development.
The diversity and structure of fungal communities in the Entic Podzol (Turbic) under variously disturbed reindeer pastures on the Yamal Peninsula were examined by the cultural method and DNA metabarcoding. We isolated 29 species from 16 genera of fungi assigned to the phyla Ascomycota and Mucoromycota by plating method and 434 OTUs of seven phyla (Ascomycota, Basidiomycota, Glomeromycota, Mortierellomycota, Mucoromycota, Olpidiomycota, and Rozellomycota) by DNA metabarcoding (251 OTUs were identified at the species level). In total, 276 species from 214 genera were discovered in this soil. Only four species were found by both methods, and this again indicated the need to use fundamentally different approaches to assess fungal diversity. The OTUs of fungi were classified by the FungalTraits database into 15 ecological-trophic groups. Microbiota of the Entic Podzol (Turbic) under pastures was dominated by soil and litter saprotrophs and by ectomycorrhizal and lichenized species, which were followed by plant and animal pathogens and then by xylotrophic saprotrophs and lichen pathogens, and coprophilous fungi comprised a smaller proportion. Both methods demonstrated that as pastures degraded, species diversity in the soil decreased, the taxonomic and trophic structure of the fungal biota significantly changed, and a smaller number of species dominated. This was especially pronounced, when the soils under slightly and strongly disturbed pastures were compared. The significance of these changes was confirmed by statistical analysis of the data. Changes of trophic and taxonomic groups of fungi in the Podzol Turbic during the degradation of reindeer pastures are discussed.
Relevance. One of the major challenges for any gas field located in permafrost conditions is the formation of hydrate plugs within field pipelines. The procurement and delivery of the required amount of hydrate inhibitor to the gas site can result in significant operational costs. Therefore, a compact unit for methanol production from synthesis gas via autothermal conver-sion has been considered and modeled. Aim. Using Aspen Hysys software, to model a unit for synthesis gas production through autothermal conversion, as well as a methanol production unit with a capacity of 50 tons per day. Objects. Synthesis gas, metha-nol, autothermal conversion of methane, mathematical model of methanol production. Methods. Modeling of a static model using Aspen Hysys software, employing "heterogeneous catalytic reactors" to accurately predict the degree of natural gas conversion into synthesis gas. Results and conclusions. The authors have modeled a methanol synthesis unit with a capacity of 50 tons per day. It was established that autothermal methane conversion is the most preferable method for the second stage of the reactor, due to the lowest methane consumption for heating within this technology. It was determined that carbon dioxide methane con-version is unsuitable because it requires significantly higher methane consumption for reactor heating, as well as necessitating an additional membrane unit for carbon dioxide separation before the reaction. Single-reactor configurations proved ineffective under gas field conditions due to their high water consumption compared to other methods and low methanol productivity. Ad-ditionally, the mandatory implementation of distillation columns is required to separate synthesis gas from excess water.
The subgenus Steneotarsonemus (Steneotarsonemoides) Mitrofanov & Sharonov of Russia is reviewed. Females of Steneotarsonemus (Steneotarsonemoides) azureus Mitrofanov & Sharonov, S. (S.) cerinus Mitrofanov & Sharonov, and S. (S.) porrectus Livshits et al. are redescribed based on type materials. The female, male and larva of S. (S.) rugosus sp. nov., collected from Calamagrostis arundinacea (Poaceae) in Western Siberia, and female of S. (S.) fuscus sp. nov., collected from Spodiopogon sibiricus (Poaceae) in Primorski Krai, Russia, are described. A key to species of the subgenus Steneotarsonemus (Steneotarsonemoides) is provided. Two species, namely, S. amlisoae Karmakar et al., 2021 and S. indianensis Karmakar & Mondal, 2021, previously described in the subgenus Steneotarsonemoides, moved to the nominative subgenus Steneotarsonemus s. str.
The genus Ptilodontella Kiriakoff, 1967 (the type species Bombyx cucullina Denis & Schiffermüller, 1775) has been separated from the synonymy with the genus Ptilodon Hübner, 1822 (the type species Phalaena camelina Linnaeus, 1758) and reinstated as a distinct genus (stat. rev.) based on differences in male and female genitalia. Additionally, a new species, Ptilodontella albertisp. n., has been described from the Greater and Lesser Caucasus and the Pontic Mountains spanning northern Turkey, with the type locality in the Republic of South Ossetia. This new species differs from its close relatives Ptilodontella cucullina (Denis & Schiffermüller, 1775) comb. rev. and Ptilodontella saerdabensis (Daniel, 1938) comb. n. in the shape of antennal rami and the genitalia of both sexes. Variability in wing patterns among species is demonstrated and is regarded as an unreliable feature for distinguishing the three species. The distribution boundary between the new species and P. cucullina lies between the lowland Pontic steppe and the foothills of the Greater Caucasus, while the boundary between the new species and P. saerdabensis is situated between the Lesser Caucasus and the Alborz Mountains. None of these species are found to fly sympatrically.
