First Alliance of Pyrazole and Furoxan Leading to High-Performance Energetic Materials.

Nitrogen heterocyclic scaffolds retain their leading position as valuable building blocks in material science, particularly for the design of small-molecule energetic materials. However, the search for more balanced combinations of directly linked heterocyclic cores is far from being exhausted and aims to reach ideally balanced high-energy substances. Herein, we present the synthetic route to novel pyrazole-furoxan framework enriched with nitro groups and demonstrate a promising set of properties, viz., good thermal stability, acceptable mechanical sensitivity, and high detonation performance. In-depth crystal analysis showed that the isomers having lower-impact sensitivity values in both types of regioisomeric pairs are those with the exocyclic furoxan oxygen atom being closer to the pyrazole ring. Owing to the favorable combination of high crystal densities (1.83-1.93 g cm-3), positive oxygen balance to CO (up to +13.9%), and high enthalpies of formation (322-435 kJ mol-1), the synthesized compounds show high calculated detonation velocities (8.4-9.1 km s-1) and excellent metal accelerating abilities. The incorporation of the 3-nitrofuroxan moiety increases the thermal stability (by ca. 20 °C) and decreases the mechanical sensitivity of target hybrid materials in both types of regioisomeric pairs. Simultaneously, the detonation performance of 3-nitrofuroxans is almost identical to that of 4-nitrofuroxans, highlighting the potential of the regioisomeric tunability in the future design of energetic materials.

Catalytic Reduction of Aromatic Nitro Compounds to Phenylhydroxylamine and Its Derivatives.

Phenylhydroxylamine and its derivates (PHAs) are important chemical intermediates. Phenylhydroxylamines are mainly produced via the catalytic reduction of aromatic nitro compounds. However, this catalytic reduction method prefers to generate thermodynamically stable aromatic amine. Thus, designing suitable catalytic systems, especially catalysts to selectively convert aromatic nitro compounds to PHAs, has received increasing attention but remains challenging. In this review, we initially provide a brief overview of the various strategies employed for the synthesis of PHAs, focusing on reducing aromatic nitro compounds. Subsequently, an in-depth analysis is presented on the catalytic reduction process, encompassing discussions on catalysts, reductants, hydrogen sources, and a comprehensive assessment of the merits and drawbacks of various catalytic systems. Furthermore, a concise overview is provided regarding the progress made in comprehending the mechanisms involved in this process of catalytic reduction of aromatic nitro compounds. Finally, the main challenges and prospects in PHAs' production via catalytic reduction are outlined.

Recent progresses in bentonite/lignin or polysaccharide composites for sustainable water treatment.

Today, with the growth of the human population, industrial activities have also increased. Different industries such as painting, cosmetics, leather, etc. have broadly developed, and as a result, they also produce a lot of pollutants. These pollutants can enter the environment and pollute water, air, and soil. Organic dyes, nitro compounds, drug residues, pesticides and herbicides are pollutants that should be removed from the environment. Natural polymers or biopolymers are important types of organic materials that are broadly applied for different applications. Among them, polysaccharides and lignin, which are two types of biopolymers, have attracted much consideration owing to their advantages such as biocompatibility, environmental friendly, safety, availability, etc. Polysaccharides include cellulose, gum, starch, alginate (Alg), chitin, and chitosan (CS). On the other hand, bentonite is one of the types of clays, which owing to their properties like large specific surface area, adsorption performance, naturally available, etc., have drawn the interest of many researchers. As a result, the synthesis of a composite including polysaccharide/lignin and bentonite can be very efficient for different applications, especially environmental ones. In this review, we instigated the preparation of these composites as well as the removal performance of them. In fact, we reported recent advancements in the synthesis of lignin- and polysaccharide-bentonite composites for the removal of diverse kinds of contaminants like organic dyes, nitro compounds, and hazardous materials.

Supported of gold nanoparticles on carboxymethyl lignin modified magnetic nanoparticles as an efficient catalyst for reduction of nitroarenes and treatment of human melanoma.

This article represents the synthesis and characterizations of Au NPs immobilized and carboxymethyl lignin (CML) modified Fe3O4 nanoparticles (Fe3O4@CML/Au NPs) following a bio-inspired protocol without the participation of any toxic and harmful reductant or stabilizers. Following various physicochemical methodologies, such as FT-IR, FE-SEM, TEM, EDX, XRD, VSM, and ICP-OES, the textural characteristics and different structural aspects were evaluated. The Fe3O4@CML/Au NPs nanocomposite was subsequently explored towards the catalytic reduction of diverse aromatic nitro functions using green conditions. An excellent yield were achieved within very short reaction time. Nine recycling runs of the nanocatalyst were completed without a discernible loss of catalytic activity, thanks to its easy magnetic recovery. The DPPH assay was carried out to examine the antioxidant effectiveness. The Fe3O4@CML/Au NPs nanocomposite inhibited half of the DPPH in a 250 µg/mL solution. To measure the anti-human melanoma efficacy of Fe3O4@CML/Au NPs nanocomposite, MTT assay was applied on HT144, MUM2C, IPC-298 and SKMEL24 cell lines. Fe3O4@CML/Au NPs nanocomposite had high anti-human melanoma efficacy on above tumor cells. The best finding of anti-human melanoma properties of Fe3O4@CML/Au NPs nanocomposite was seen in the case of the SKMEL24 cell line. The IC50 of Fe3O4@CML/Au NPs nanocomposite was 137, 145, 185, and 125 µg/mL against HT144, MUM2C, IPC-298 and SKMEL24 cells, respectively. This research exhibited remarkable anti-human melanoma and antioxidant efficacies of Fe3O4@CML/Au NPs nanocomposite in the in vitro condition.

Mild and efficient synthesis and base-promoted rearrangement of novel isoxazolo[4,5-b]pyridines.

An efficient method for the synthesis of isoxazolo[4,5-b]pyridines has been developed on the basis of readily available 2-chloro-3-nitropyridines via the intramolecular nucleophilic substitution of the nitro group as a key step. The previously unknown base-promoted Boulton-Katritzky rearrangement of isoxazolo[4,5-b]pyridine-3-carbaldehyde arylhydrazones into 3-hydroxy-2-(2-aryl[1,2,3]triazol-4-yl)pyridines was observed.

Two metastable high hydrates of energetic material 3,3',5,5'-tetranitro-4,4'-bipyrazole.

Poly-stoichiometry of hydrated phases is relatively uncommon for organic materials and extended libraries of such species adopting different aqua-to-substrate ratios are still rare. The kinetically controlled higher hydrates could be particularly interesting for their structural relationships, which presumably may imprint some features of the substrate/substrate and aqua/substrate bonding in solutions, and provide insights into the nucleation stage. Two metastable high hydrates are prepared by crash crystallization. The crystal structures of 3,3',5,5'-tetranitro-4,4'-bipyrazole tetrahydrate, C6H2N8O8·4H2O, (1), and 3,3',5,5'-tetranitro-4,4'-bipyrazole pentahydrate, C6H2N8O8·5H2O, (2), are intrinsically related to the previously reported anhydrate and monohydrate, while displaying natural evolution of the patterns upon progressive watering. The accumulation of the water molecules causes their clustering, with the generation of one-dimensional tapes and two-dimensional layers in the genuine channel hydrates (1) and (2), respectively, versus the pocket hydrate structure of C6H2N8O8·H2O. The hydration primarily affects the pyrazole sites. It conditions the emergence of N-H...O and O-H...N hydrogen bonds, which is a destructive factor for pyrazole/pyrazole N-H...N hydrogen bonding. At the same time, extensive noncovalent interactions of the organic molecules, namely, lone pair-π-hole O...N interactions of the NO2/NO2 and NO2/pyrazole types, are more competitive to the hydrogen bonding and the motifs of mutual organic/organic stacks remain intact with the increase in hydration. These trends agree with the results of Hirshfeld surface analysis. The contributions of the contacts involving H atoms are increased in line with the growing number of water molecules, while the fraction of O...N/N...O (NO2) contacts is nearly invariant. One may postulate the significance of the lone pair-π-hole interactions to the aggregation of nitro species in solutions and their relevance for the sebsequent development of the solid-state patterns through nucleation.

Metal-Free Nitrogen-Doped Mesoporous Carbons for the Mild and Selective Synthesis of Pyrroles from Nitroarenes via Cascade Reaction.

The cascade synthesis of pyrroles from nitroarenes is an attractive alternative strategy. However, metal catalysts and relatively high temperatures cover the existing reported catalytic systems for this strategy. The development of nonmetallic heterogeneous catalytic systems for the one-pot synthesis of pyrrole from nitroarenes under mild conditions is both worthwhile and challenging. Herein, we describe an exceptionally efficient method for the synthesis of N-substituted pyrroles by the reductive coupling of nitroarenes and diketones over heterogeneous metal-free catalysts under mild conditions. Nonmetallic NC-X catalysts with high activity were prepared from the pyrolysis of well-defined ligands via simple sacrificing hard template methods. Hydrazine hydrate, formic acid, and molecular hydrogen can all be used as reducing agents in the hydrogenation/Paal-Knorr reaction sequence to efficiently synthesize various N-substituted pyrroles, including drugs and bioactive molecules. The catalytic system was featured with good tolerance to sensitive functional groups and no side reactions such as dehalogenation and aromatics hydrogenation. Hammett correlation studies have shown that the electron-donating substituents are beneficial for the one-pot synthesis of N-substituted pyrroles. The results established that the outstanding performance of the catalyst is mainly attributed to the contribution of graphitic N in the catalyst as well as the promotion effect of the mesoporous structure on the reaction.

New 3-amino-2-thioxothiazolidin-4-one-based inhibitors of acetyl- and butyryl-cholinesterase: synthesis and activity.

Aim: 2-Thioxothiazolidin-4-one represents a versatile scaffold in drug development. The authors used it to prepare new potent acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors that can be utilized, e.g., to treat Alzheimer's disease. Materials & methods: 3-Amino-2-thioxothiazolidin-4-one was modified at the amino group or active methylene, using substituted benzaldehydes. The derivatives were evaluated for inhibition of AChE and BChE (Ellman's method). Results & conclusion: The derivatives were obtained with yields of 52-94%. They showed dual inhibition with IC50 values from 13.15 µM; many compounds were superior to rivastigmine. The structure-activity relationship favors nitrobenzylidene and 3,5-dihalogenosalicylidene scaffolds. AChE was inhibited noncompetitively, whereas BChE was inhibited with a mixed type of inhibition. Molecular docking provided insights into molecular interactions. Each enzyme is inhibited by a different binding mode.

Characterization of an efficient N-oxygenase from Saccharothrix sp. and its application in the synthesis of azomycin.

BACKGROUND: The nitro group constitutes a significant functional moiety within numerous valuable substances, such as nitroimidazoles, a class of antimicrobial drugs exhibiting broad spectrum activity. Conventional chemical methods for synthesizing nitro compounds suffer from harsh conditions, multiple steps, and environmental issues. Biocatalysis has emerged as a promising alternative to overcome these drawbacks, with certain enzymes capable of catalyzing nitro group formation gradually being discovered in nature. Nevertheless, the practical application is hindered by the restricted diversity and low catalytic activity exhibited by the reported nitrifying enzymes. RESULTS: A novel N-oxygenase SaRohS harboring higher catalytic capability of transformation 2-aminoimidazole to azomycin was characterized from Saccharothrix sp. Phylogenetic tree analysis revealed that SaRohS belongs to the heme-oxygenase-like diiron oxygenase (HDOs) family. SaRohS exhibited optimal activity at pH 5.5 and 25 â„ƒ, respectively. The enzyme maintained relatively stable activity within the pH range of 4.5 to 6.5 and the temperature range of 20 â„ƒ to 35 â„ƒ. Following sequence alignment and structural analysis, several promising amino acid residues were meticulously chosen for catalytic performance evaluation. Site-directed mutations showed that threonine 75 was essential for the catalytic activity. The dual mutant enzyme G95A/K115T exhibited the highest catalytic efficiency, which was approximately 5.8-fold higher than that of the wild-type and 22.3-fold higher than that of the reported N-oxygenase KaRohS from Kitasatospora azatica. The underlying catalytic mechanism was investigated through molecular docking and molecular dynamics. Finally, whole-cell biocatalysis was performed and 2-aminoimidazole could be effectively converted into azomycin with a reaction conversion rate of 42% within 14 h. CONCLUSIONS: An efficient N-oxygenase that catalyzes 2-aminoimidazole to azomycin was screened form Saccharothrix sp., its phylogenetics and enzymatic properties were analyzed. Through site-directed mutation, enhancements in catalytic competence were achieved, and the molecular basis underlying the enhanced enzymatic activity of the mutants was revealed via molecular docking and dynamic simulation. Furthermore, the application potential of this enzyme was assessed through whole cell biocatalysis, demonstrating it as a promising alternative method for azomycin production.

Carbon quantum dots and chitosan-based heterogeneous silver catalyst for reduction of nitroaromatic compounds.

Chitosan plays a crucial role in catalysis, environmental remediation, and sustainable chemistry as a renewable and cationic polysaccharide. Chitosan-based metal catalysts are used in a broad range of chemical transformations. In the study, carbon quantum dots (CQDs) were derived from Momordica charantia fruits by microwave irradiation following a green chemistry approach. Three catalysts were designed: Ag(0)-chitosan, Ag(0)-chitosan-M. charantia fruit powder, and Ag(0)-chitosan-CQDs. The catalyst supports were prepared by stabilizing CQDs or M. charantia powder within the polymeric matrix of chitosan beads. Metallic silver particles were anchored onto glutaraldehyde cross-linked chitosan beads from the aqueous solution of silver nitrate. The heterogeneous silver catalysts were used to reduce toxic nitroaromatics (4-nitrophenol, 2-nitroaniline, 1,2-diamino-4-nitrobenzene, 2,4-dinitrophenol). The regeneration of catalysts was also covered. The reused catalysts retained their catalytic activities after ten cycles. The study suggested that presence of CQDs or M. charantia powder could improve the efficiency of the chitosan-based metallic silver catalysts.

Prediction of control temperature and emergency temperature of monadic/binary aromatic nitro compounds by quantitative structure-property relationship: correlation study of self-accelerating decomposition temperature in thermal hazard assessment.

CONTEXT: The thermal hazard of reactions caused by the structural instability of aromatic nitro compounds is a major concern in the field of chemical process safety and one of the main causes of major thermal runaway (TR) accidents such as fire and explosion. Among them, the self-accelerating decomposition temperature (SADT), as an important parameter, has been widely used to evaluate the thermal hazards of aromatic nitro compounds in actual storage and transportation processes. However, the control temperature (CT) and emergency temperature (ET), which depend on and are associated with SADT, have been rarely reported in previous studies. In this work, multiple linear regression (MLR) and artificial neural network (ANN) models for CT and ET were constructed based on the molecular descriptors corresponding to the stable structures of 27 monadic/binary aromatic nitro compounds, combined with advanced adiabatic accelerating calorimetric experiments and quantitative structure-property relationship (QSPR). The optimal subset of descriptors with significant contributions was screened out while the fit, predictive ability, and robustness of the four types of models were evaluated with internal and external validation parameters, and finally, two types of parameters (R2 and ARE) were selected as the main indicators for a comprehensive comparative analysis. The results show that the four models fit the experimental data well. During this period, the accuracy of ANN models is slightly higher than that of MLR models, and the QSPR models under the two modes (linear and nonlinear) are more inclined toward ET in prediction ability. Based on simplifying the calculation process and realizing rapid parameter prediction, this study is expected to provide technical support for engineering applications such as safe operation, safe storage and transportation of substances, and emergency response in the chemical industry. METHODS: In this work, we tested and calculated the thermal safety parameters of 27 monadic/binary aromatic nitro compounds by ARC and AKTS and further used the PubChem database and Gaussian 09 software program to obtain and optimize their corresponding molecular structures. The geometric optimization process adopts DFT on the B3LYP level and the 6-31 + G(d, p) basis set, while the same functional and basis set was used for vibration analysis. The OpenBabel toolbox and ChemDES platform were used for transformation coding and descriptor calculation. Finally, IBM SPSS Statistics 24 and MATLAB software were used to construct MLR models and ANN models, respectively.

Highly Functionalized SWCNTs with a Dopamine Derivative as a Support for Pd Nanoparticles: A Recyclable Catalyst for the Reduction of Nitro Compounds and the Heck Reaction.

Single-walled carbon nanotubes (SWCNTs) were functionalized with a dopamine derivative in which the amine group was converted to azide (dopamine azide). The direct reaction of SWCNTs and dopamine azide in o-dichlorobenzene at high temperature (160 °C) led to very highly functionalized CNTs (≈60 wt.%). Surprisingly, despite this high degree of functionalization, Raman spectroscopy detected a low disruption of the π-network of the carbonaceous support. This finding was justified by the rehybridization from sp3 to sp2 of the sidewall carbon atoms of CNTs involved in the functionalization process. Further characterization by means of different techniques such as X-ray photoelectron spectroscopy (XPS) analysis and transmission electron microscopy (TEM) allowed to shed some light on the chemical composition and morphology of the obtained material. Moreover, the estimation of the total content of phenolic units and their reducing potential after CNTs functionalization was also assessed using Folin and Ciocalteu and 2,2-diphenyl-1-picryl hydrazide (DPPH) assays. The functionalization of CNTs was exploited to immobilize palladium(II) species that were subsequently reduced with NaBH4 leading to the formation of Pd nanoparticles (NPs). The so obtained hybrid material was used as a recyclable heterogeneous catalyst for the reduction of nitro compounds and the Heck reaction.

Quinolone analogues of benzothiazinone: Synthesis, antitubercular structure-activity relationship and ADME profiling.

Mycobacterium tuberculosis (Mtb) has an impermeable cell wall which gives it an inherent ability to resist many antibiotics. DprE1, an essential enzyme in Mtb cell wall synthesis, has been validated as a target for several TB drug candidates. The most potent and developmentally advanced DprE1 inhibitor, PBTZ169, is still undergoing clinical development. With high attrition rate, there is need to populate the development pipeline. Using a scaffold hopping strategy, we imprinted the benzenoid ring of PBTZ169 onto a quinolone nucleus. Twenty-two compounds were synthesised and screened for activity against Mtb, with six compounds exhibiting sub micromolar activity of MIC90 <0.244 µM. Compound 25 further demonstrated sub-micromolar activity when evaluated against wild-type and fluoroquinolone-resistant Mtb strains. This compound maintained its sub-micromolar activity against a DprE1 P116S mutant strain but showed a significant reduction in activity when tested against the DprE1 C387S mutant.

Progresses in lignin, cellulose, starch, chitosan, chitin, alginate, and gum/carbon nanotube (nano)composites for environmental applications: A review.

Water sources are becoming increasingly scarce, and they are contaminated by industrial, residential, and agricultural waste-derived organic and inorganic contaminants. These contaminants may pollute the air, water, and soil and invade the ecosystem. Because carbon nanotubes (CNTs) can undergo surface modification, they can combine with other substances to create nanocomposites (NCs), including biopolymers, metal nanoparticles, proteins, and metal oxides. Furthermore, biopolymers are significant classes of organic materials that are widely used for various applications. They have drawn attention due to their benefits, such as environmental friendliness, availability, biocompatibility, safety, etc. As a result, the synthesis of a composite made of CNT and biopolymers can be very effective for various applications, especially those involving the environment. In this review, we reported environmental applications (including removal of dyes, nitro compounds, hazardous materials, toxic ions, etc.) of composites made of CNT and biopolymers such as lignin, cellulose, starch, chitosan, chitin, alginate, and gum. Also, the effect of different factors such as the medium pH, the pollutant concentration, temperature, and contact time on the adsorption capacity (AC) and the catalytic activity of the composite in the reduction or degradation of various pollutants has been systematically explained.

Straightforward and Efficient Protocol for the Synthesis of Pyrazolo [4,3-b]pyridines and Indazoles.

An efficient method for the synthesis of pyrazolo [4,3-b]pyridines has been developed on the basis of readily available 2-chloro-3-nitropyridines via a sequence of SNAr and modified Japp-Klingemann reactions. The method offers a number of advantages including utilization of stable arenediazonium tosylates, operational simplicity as well as combining the azo-coupling, deacylation and pyrazole ring annulation steps in a one-pot manner. An unusual rearrangement (C-N-migration of the acetyl group) was observed and a plausible mechanism was proposed based on the isolated intermediates and NMR experiments. In addition, the developed protocol was successfully applied to the synthesis of 1-arylindazoles combining the Japp-Klingemann reaction and cyclization of the resulting hydrazone as a one-pot procedure.

Interrupted Nef and Meyer Reactions: A Growing Point for Diversity-Oriented Synthesis Based on Nitro Compounds.

The Nef reaction (nitro to carbonyl group conversion) and related Meyer reaction are among the key transformations of aliphatic nitro compounds. The interrupted versions of these reactions in which the normal pathway is redirected to a different end product by an external nucleophile are much less common, albeit these processes substantially increase the synthetic potential of nitro compounds. In this review, examples of interrupted Nef and Meyer reactions are summarized, and the prospects of this methodology in diversity-oriented organic synthesis are analyzed. The bibliography contains 90 references.

Decorated Au NPs on lignin coated magnetic nanoparticles: Investigation of its catalytic application in the reduction of aromatic nitro compounds and its performance against human lung cancer.

In the recent years, bio-functionalized noble metal doped advanced magnetics nanocomposite materials has been materialized as potential featured catalysts in diverse applications. In this connection, we report herein a novel biogenic lignin driven Au nanoparticle supported Fe3O4 composite material. The procedure is free from any harsh reducing or stabilizing agent. Morphology and structural features were assessed following different physicochemical methodologies like FT-IR, FE-SEM, TEM, EDS, XRD, VSM and ICP-OES techniques. Thereafter, the [Fe3O4/Lignin/Au] material was successfully employed in the efficient reduction of different nitroarenes in aqueous medium. The process was monitored over UV-Vis spectroscopic study. Excellent yields were achieved with a range of diverse functionalized nitroarenes within 10-45 min of reaction. The nanocatalyst was recycled 10 times without any significant loss of catalytic activity. Distinctiveness of the material's activity was validated by comparing the results in the reduction of 4-nitrophenol. Furthermore, the prepared [Fe3O4/Lignin/Au] nanocomposite system exhibited outstanding antioxidant and anticancer effects against five lung cancer cell lines, such as, BICR 3, BICR 78, CALU 1, ChaGo-K-1, and A549. Cytotoxicity assay was determined in terms of % cell viability following MTT protocol. The corresponding IC50 values were obtained as 47, 31, 19, 25, and 31 µg/mL respectively.

Integrating a Luminescent Porous Aromatic Framework into Indicator Papers for Facile, Rapid, and Selective Detection of Nitro Compounds.

Porous aromatic framework materials with high stability, sensitivity, and selectivity have great potential to provide new sensors for optoelectronic/fluorescent probe devices. In this work, a luminescent porous aromatic framework material (LNU-23) was synthesized via the palladium-catalyzed Suzuki cross-coupling reaction of tetrabromopyrene and 1,2-bisphenyldiborate pinacol ester. The resulting PAF solid exhibited strong fluorescence emission with a quantum yield of 18.31%, showing excellent light and heat stability. Because the lowest unoccupied molecular orbital (LUMO) of LNU-23 was higher than that of the nitro compounds, there was an energy transfer from the excited LNU-23 to the analyte, leading to the selective fluorescence quenching with a limit of detection (LOD) ≈ 1.47 × 10-5 M. After integrating the luminescent PAF powder on the paper by a simple dipping method, the indicator papers revealed a fast fluorescence response to gaseous nitrobenzene within 10 s, which shows great potential in outdoor fluorescence detection of nitro compounds.

The Combined Effect of Ambient Conditions and Diluting Salt on the Degradation of Picric Acid: An In Situ DRIFT Study.

An unexpected promoting effect of KBr, used as a diluting salt, on the degradation of picric acid (PA) was observed during in situ diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy experiments performed here under accelerated ageing conditions-at 80 °C and under an inert or oxidative atmosphere. While the formation of potassium picrate was excluded, this promoting effect-which is undesired as it masks the possible effects of test conditions on the ageing process of the material-was assumed to favor a first step of the decomposition mechanism of PA, which involves the inter- or intramolecular transfer of hydrogen to the nitro group, and possibly proceeds up to the formation of an amino group. An alternative diluting salt, ZnSe, which is much less commonly used in infrared spectroscopy than KBr, was then proposed in order to avoid misleading interpretation of the results. ZnSe was found to act as a truly inert diluting salt, preventing the promoting effect of KBr. The much more chemically inert nature (towards PA) of ZnSe compared to KBr was also confirmed, at much higher temperatures than DRIFT experiments, by dynamic differential scanning calorimetry (DSC) runs carried out on pure PA (i.e., PA without salt) and PA/salt (ZnSe or KBr) solid mixtures.

CK2 Inhibition and Antitumor Activity of 4,7-Dihydro-6-nitroazolo[1,5-a]pyrimidines.

Today, cancer is one of the most widespread and dangerous human diseases with a high mortality rate. Nevertheless, the search and application of new low-toxic and effective drugs, combined with the timely diagnosis of diseases, makes it possible to cure most types of tumors at an early stage. In this work, the range of new polysubstituted 4,7-dihydro-6-nitroazolo[1,5-a]pyrimidines was extended. The structure of all the obtained compounds was confirmed by the data of 1H, 13C NMR spectroscopy, IR spectroscopy, and elemental analysis. These compounds were evaluated against human recombinant CK2 using the ADP-GloTM assay. In addition, the IC50 parameters were calculated based on the results of the MTT test against glioblastoma (A-172), embryonic rhabdomyosarcoma (Rd), osteosarcoma (Hos), and human embryonic kidney (Hek-293) cells. Compounds 5f, 5h, and 5k showed a CK2 inhibitory activity close to the reference molecule (staurosporine). The most potential compound in the MTT test was 5m with an IC50 from 13 to 27 µM. Thus, our results demonstrate that 4,7-dihydro-6-nitroazolo[1,5-a]pyrimidines are promising for further investigation of their antitumor properties.