Triazolo4,3-apyrimidine is one of the promising structural fragments for the development of drugs, including anticancer drugs. This work is devoted to the synthesis of a number of new 2-arylhydrazone ...derivatives of thiazolo3,2-apyrimidine, which are synthetic precursors for triazolo4,3-apyrimidines. The crystal structure of 6-acetyl-7-methyl-5-phenyl-2-(2-phenylhydrazineylidene)-5H-thiazolo3,2-apyrimidin-3(2H)-one was established by SCXRD. In the reduction reaction of the compound, the following system was used: vanadium(V) oxide, and sodium borohydride in ethanol at room temperature, which led to the formation of only one pair of diastereomers (1R*)-1-((5S*,6R*,7R*)-(1-(hydroxymethyl)-7-methyl-1,5-diphenyl-1,5,6,7-tetrahydro1,2,4triazolo4,3-apyrimidin-6-yl)ethan-1-ol.
The subject of this article is new potential hypoxia-sensitive azo-thiacalix4arenes derivatives in the 1,3-alternate configuration. Previously, it was shown that azo derivatives of calix4arene in the ...cone conformation form complexes with rhodamine dyes. The present work is devoted to the synthesis of new azo derivatives using the thiacalix4arene platform. A new highly productive method for the synthesis of thiacalixarene with four anionic sulfonate azo fragments on the lower rim (compounds 2a–b) for further complexation with the most common cationic dyes is reported. The chemical structures of the products obtained were established based on 1H and 13C NMR, IR spectroscopy, MALDI TOF mass spectrometry, and elemental analysis.
The synthesis of new calix4arenes adopting a
stereoisomeric form bearing two or four azide fragments on the upper rim and water-soluble triazolyl amphiphilic receptors with two or four polyammonium ...headgroups via copper-catalyzed azide-alkyne cycloaddition reaction has been performed for the first time. It was found that the synthesized macrocycles form stable aggregates with hydrodynamic diameters between 150-200 nm and electrokinetic potentials about +40 to +60 mV in water solutions. Critical aggregation concentration (CAC) values were measured using a micelle method with pyrene and eosin Y as dye probes. The CAC values of tetraalkyl-substituted macrocycles
,
(5 µM for both) are significantly lower than those for dialkyl-substituted macrocycles
,
(790 and 160 µM, respectively). Premicellar aggregates of macrocycles
,
and
,
with the dye eosin Y were used for nucleotides sensing through a dye replacement procedure. It is unusual that disubstituted macrocycles
,
bind more effectively a less charged adenosine 5'-diphosphate (ADP) than adenosine 5'-triphosphate (ATP). A simple colorimetric method based on polydiacetylene vesicles decorated with
was elaborated for the naked-eye detection of ADP with a detection limit of 0.5 mM.
Abstract
This paper evaluates the ecological and geochemical status of soils in the Opuksky Sanctuary, Republic of Crimea, Russia. The Sanctuary has been a nature reserve since the mid- 20th century. ...It is located on the Black Sea coast of the Kerch Peninsula, the Republic of Crimea. This is an integrated sanctuary established to preserve the unique steppe ecosystems associated with the limestone massif of Mount Opuk and Lake Koyashskoye, a salt lake which has a number of one-of-a-kind nature sites within a small area and features several rare species. The water area of the Sanctuary is a wetland protected international under the Ramsar Convention. The increasing anthropogenic pressure arising from agricultural and industrial development of the Crimean Peninsula, as well as the increasing tourist flow that must be controlled is what makes monitoring the area critical. Soil is the most sensitive natural environmental component to anthropogenic effects; as such, it was monitored over three years from 2017 through 2019 as part of St. Petersburg State University, Department of Environmental Geology’s student internship co-organized with the administration of the Sanctuary. This effort produced a map of heavy metals in the local soils. The authors described the patterns in pollutant migration; they also prove why the soil was vulnerable to contamination. The research effort was the first to collect data on the background presence of trace elements in the soils of potentially uncontaminated areas; this data could be of use for engineering and environmental surveying across the region. Such data is becoming relevant and essential as the Republic of Crimea’s heavy industry and agriculture are rising.
Three new organic tectons (2–4) based on the p-tert-butylthiacalix4arene backbone, blocked in the 1,3-alternate conformation, bearing four pyridyl coordinating moieties, have been synthesised and ...characterised in the solid state. The ligands are positional isomers and differ by the position of the N atom on the pyridyl unit (ortho for 2, meta for 3 and para for 4). Their combination with the Ag+ cation leads, reproducibly, to the formation of 2- and 3-D infinite silver coordination networks. Independent of the nature of the anion, the combination of 2 offering four (N,S) type chelates with the Ag+ cation affords an unprecedented diamond type 3D network. Both 3 and 4, behaving as tetrakis monodentate ligands, lead to the formation of 2-D architectures.
A combination of tetrasulfonylcalix4arene (3-4H) together with a calix4arene dicarboxylate derivative 2-4H led, in the presence of MII(NO3)2 (M = Co, Ni, Zn), to the formation of three novel ...isostructural metallomacrocycles of formula M3(DMF)2(μ3-H2O)-(2-2H)-3. The structure of the prepared coordination compounds was studied in the solid state using single crystal/powder X-ray diffraction studies. The X-ray diffraction on single crystal revealed that the structure of the obtained supramolecular complexes is composed of a trinuclear metallic cluster M3+6 held between one di-deprotonated molecule of (2-2H)2− offering two carboxylate groups for binding metal cations and one tetra-deprotonated compound 34−, where four oxygen atoms, belonging to four deprotonated phenolic moieties and three oxygen atoms coming from three SO2 groups, are coordinated with the cluster core. Thus, an example of an easily reproducible molecular recognition pattern involving two different types of calix4arene based ligands, displaying different coordination moieties, and trinuclear metallic clusters, is reported here. In addition, it has been shown that the cone moieties of the calixarene also encapsulate solvent molecules.
Spinach is an economically important vegetable crop widely cultivated and consumed worldwide. This early ripening leafy vegetable is rich in bioactive components, fiber, micro and macro elements, ...vitamins, and has high antioxidant activity. Results of numerous studies on the effects of spinach on human health confirm its beneficial effect. The species S. oleracea L. is cultivated commercially. The ancestor of cultivated spinach is S. turkestanica Iljin, which has a breeding potential for different economically valuable traits. Its biochemical composition has been studied extremely little. The present article offers a comparative evaluation of the biochemical profile and antioxidant activity of cultivated and wild spinach species. The material for the study was a representative sample of 48 collection accessions of spinach from the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR). The accessions were grown in 2019 and 2020 in the open ground of the Pushkin and Pavlovsk Laboratories of VIR. The antioxidant activity was studied spectrophotometrically by the DPPH assay of free radical scavenging at a wavelength of 515 nm. A significant similarity of the two species in most biochemical parameters was revealed, which confirms their phylogenetic relationship. Significant differences were found in the content of phenolic elements, which determine the elevated values of antioxidant and antiradical activity of S. turkestanica. The article presents correlation matrices of species biochemical composition, describes general trends, negative relationships and conjugated factors. The identified promising accessions of both cultivated and wild spinach are recommended for breeding for increased content of phenolic compounds, ascorbic acid and antioxidant activity. The result of the study helps to reveal the potential of the crop as a valuable source of bioactive components and high antioxidant activity.
For the first time amphiphilic calix4arenes bearing oxyethyl-imidazolium polar headgroups on one side and alkyl fragments on another side of the macrocyclic platform were synthesized. Critical ...aggregation concentration (CAC) value was estimated using two methods: (a) pyrene fluorescent probe; (b) fluorescein probe based on both its fluorescent and absorbance properties in micellar solution. All plots were adequately described by a sigmoidal Boltzmann type function. A comparative analysis of the CACs were detected by using two types of dyes was held. The system calixarene - fluorescein was found to different change the absorbance and colorimetric response toward various adenosines phosphates.
Display omitted
•New N-oxyethylimidazolium-modified calixarene were synthesized.•The visible absorption and emission of dyes were used as a probe molecule to determine aggregation.•CAC of surfactants were determined from the sigmoidal shaped plots or inflection points.•The system calixarene-fluorescein was used as sensor for adenosine phosphates.
Thiazolopyrimidines are attractive to medical chemists as new antitumor agents due to their high inhibiting activity towards the tumor cells replication process and easy modification of their ...structure by varying of the number and nature of substituents. The presence of asymmetric C5 carbon atoms requires the development of racemic mixture separation procedures for these heterocycles. One of the more effective ways is the crystallization of a racemic compound as a conglomerate. A prerequisite for such separation is the formation of non-centrosymmetric crystals presenting Sohncke space groups. For the construction of chiral supramolecular ensembles in a crystalline state, hydrogen bonds were chosen as supramolecular synthons. In this context, salicylic derivatives at the C2 atom of thiazolopyrimidines were synthesized. The crystal structures of the obtained compounds were established by SCXRD. The regularities of the solvent’s influence on the crystal packaging were revealed. The conditions for the preparation of crystals with the chiral space group due to intermolecular hydrogen bonds were discovered.
Combinations of tetramercaptotetrathiacalix4arene pyridyl-appended positional isomers with HgCl2 lead to the formation of neutral coordination networks with their dimensionality imposed by the ...position of the N atom on the pyridyl group.
PDF
