Nitro Research Articles

Iodine-Catalyzed Cyclization of o-Nitrothiophenols with Cyclohexanones to Phenothiazines.

Here, a novel iodine-catalyzed direct cyclization of o-nitrothiophenols with cyclohexanones to phenothiazines has been described without external oxidants and hydrogen acceptors. The nitro of o-nitrothiophenol works as both a hydrogen acceptor and a coupling group, and water is the only byproduct. The reaction involves the reduction of nitro groups, C-H bond thioetherification, and C-H bond dehydroaromatization. This scheme offers broad synthetic value for further elaborations, as exemplified by a 3-step total synthesis of antipsychotic chlorpromazine.

Antimicrobial Properties of Flavonoid Derivatives with Bromine, Chlorine, and Nitro Group Obtained by Chemical Synthesis and Biotransformation Studies.

The search for new substances of natural origin, such as flavonoids, is necessary in the fight against the growing number of diseases and bacterial resistance to antibiotics. In our research, we wanted to check the influence of flavonoids with chlorine or bromine atoms and a nitro group on pathogenic and probiotic bacteria. We synthesized flavonoids using Claisen-Schmidt condensation and its modifications, and through biotransformation via entomopathogenic filamentous fungi, we obtained their glycoside derivatives. Biotransformation yielded two new flavonoid glycosides: 8-amino-6-chloroflavone 4'-O-β-D-(4″-O-methyl)-glucopyranoside and 6-bromo-8-nitroflavone 4'-O-β-D-(4″-O-methyl)-glucopyranoside. Subsequently, we checked the antimicrobial properties of the aforementioned aglycon flavonoid compounds against pathogenic and probiotic bacteria and yeast. Our studies revealed that flavones have superior inhibitory effects compared to chalcones and flavanones. Notably, 6-chloro-8-nitroflavone showed potent inhibitory activity against pathogenic bacteria. Conversely, flavanones 6-chloro-8-nitroflavanone and 6-bromo-8-nitroflavanone stimulated the growth of probiotic bacteria (Lactobacillus acidophilus and Pediococcus pentosaceus). Our research has shown that the presence of chlorine, bromine, and nitro groups has a significant effect on their antimicrobial properties.

Structural investigations on the mitochondrial uncouplers niclosamide and FCCP.

There has been renewed interest in using mitochondrial uncoupler compounds such as niclosamide and carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP) for the treatment of obesity, hepatosteatosis and diseases where oxidative stress plays a role. However, both FCCP and niclosamide have undesirable effects that are not due to mitochondrial uncoupling, such as inhibition of mitochondrial oxygen consumption by FCCP and induction of DNA damage by niclosamide. Through structure-activity analysis, we identified FCCP analogues that do not inhibit mitochondrial oxygen consumption but still provided good, although less potent, uncoupling activity. We also characterized the functional role of the niclosamide 4'-nitro group, the phenolic hydroxy group and the anilide amino group in mediating uncoupling activity. Our structural investigations provide important information that will aid further drug development.

Antioxidant and Antimicrobial Potential of 1,8-Naphthyridine Based Scaffolds: Design, Synthesis and in Silico Simulation Studies within Topoisomerase II.

A series of spiro β-Lactams (4 a-c, 7 a-c) and thiazolidinones (5 a-c, 8 a-c) possessing 1,8-naphthyridine moiety were synthesized in this study. The structure of the newly synthesized compounds has been confirmed by IR, 1H-NMR, 13C NMR, mass spectra, and elemental analysis. The synthesized compounds were tested in vitro for their antibacterial and antifungal activity against various strains. The antimicrobial data showed that most of the compounds displayed good efficacy against both bacteria and fungi. The structure-activity relationship (SAR) studies suggested that the presence of electron-withdrawing chloro (3 b, 4 b, and 5 b) and nitro groups (7 b, 8 b) at the para position of the phenyl ring improved the antimicrobial activity of the compounds. The free radical scavenging assay showed that all the synthesized compounds exhibited significant antioxidant activity on DPPH. Compounds 8 b (IC50=17.68±0.76 μg/mL) and 4 c (IC50=18.53±0.52 μg/mL) showed the highest antioxidant activity compared to ascorbic acid (IC50=15.16±0.43 μg/mL). Molecular docking studies were also conducted to support the antimicrobial and SAR results.

Enhanced Gas Sensing Characteristics of a Polythiophene Gas Sensor Blended with UiO‐66 via Ligand Functionalization

AbstractConjugated polymers exhibit significant potential for use in gas sensors owing to their flexibility and straightforward preparation. However, the performance of organic gas sensors based on such materials is currently suboptimal owing to their poor charge‐transport properties and limited selectivity. To address this limitation, a novel strategy that involves blending a chemically modified metal–organic framework (MOF) material, UiO‐66, with a conjugated polymer is developed. The MOF porous material is chemically modified with polar nitrogen‐containing functional groups (amino and nitro groups) to create gas molecule adsorption sites. To evaluate the impact of these modifications on the sensing performance, experiments that combined the sensing performance with a density functional theory simulation are conducted. The findings reveal that gas sensors fabricated using an amine‐functionalized MOF blended with conjugated polymers exhibit significantly higher sensitivity than home polymer devices, the sensing performance of the UiO‐66‐NH2/P3HT blend film improved by a factor of two with a sensitivity of ≈2%/ppm and an LOD of 0.001 ppt. Additionally, these devices exhibit exclusive NO2‐sensing performance for other gases such as CO2 and SO2.

Innovative porous organic polymer incorporating ferrocene and s-triazine: An effective method for converting nitroarenes to benzimidazoles using visible light

The study introduces a novel porous organic polymer, FeII(Cp)2-POP, synthesized from ferrocene and s-triazine, and characterized through various analytical techniques such as FT-IR, Raman, XRD, XPS, UV–visible, SEM, HR-TEM, EDX, BET surface area analysis, TGA, photocurrent measurements, EIS, and CV. This photocatalyst exhibits reusability, contributing to by-products reduction and resource efficiency. The sustainable methodology adheres to green chemistry principles, promoting eco-friendly synthetic approaches. FeII(Cp)2-POP was utilized in the photocatalytic reduction of nitroarenes to anilines, essential organic chemistry precursors, using N2H4 and visible-light activation under mild conditions. The incorporation of porous organic polymers with a ferrocene framework displayed promising outcomes in enhancing the reduction of nitroarene compounds, with a focus on reducing the nitro-functional group in benzimidazole-based compound.

Synthesis, characterization and biological activities of nitrophenol-substituted phosphazene dendrimers

This study introduces the synthesis and characterization of two novel nitrophenol-substituted phosphazene dendrimers, [N3P3(OC6H5NO2)6] (III) and [N3P3(OC6H5(NO2)2)5O]ˉ.C6H16N+.H2O (IV), derived from hexachlorocyclotriphosphazene (HCCP). The structures of the compounds were determined using elemental analysis, infrared spectroscopy, and X-ray crystallography. The optical properties of the crystals were investigated by photophysical methods. The thermal properties of the compounds were measured by thermogravimetry-differential thermal analysis (TG-DTA). The antibacterial and anticancer properties of the compounds were tested based on the antibacterial tests against Gram-negative (Escherichia coli ATCC 8739 G(-)) and Gram-positive (Staphylococcus aureus ATCC 6538 G(+), Bacillus subtilis 2a ATCC 23,857 G(+)) bacteria, as well as the MTT assay test on K562 leukemia cells (ATCC: CCL-243) and MCF-7 breast cancer cells (ATCC: HTB-22). The presence of six homogeneous 2-nitrophenol substitutions in compound III reduces the fluorescence of the phosphazene ring. The results showed that compound IV has a higher fluorescence intensity and similar toxicity to MCF-7 and HDF cells. The structural differences and the number of nitro groups in the nitrophenol ligands account for these variations. Our results suggest that these cyclophosphazene derivatives have promising properties for biomedical applications and further studies are warranted to explore their mechanisms of action and therapeutic potential.

Reaction mechanisms of chlorinated disinfection byproducts formed from nitrophenol compounds with different structures during chlor(am)ination and UV/post-chlor(am)ination

Nitrophenol compounds (NCs) have high formation potentials of disinfection byproducts (DBPs) in water disinfection processes, however, the reaction mechanisms of DBPs formed from different NCs are not elucidated clearly. Herein, nitrobenzene, phenol, and six representative NCs were used to explore the formation mechanisms of chlorinated DBPs (Cl-DBPs) during chlor(am)ination and UV/post-chlor(am)ination. Consequently, the coexistence of nitro and hydroxy groups in NCs facilitated the electrophilic substitution to produce intermediates of Cl-DBPs, and the different positions of nitro and hydroxy groups also induced different yields and formation mechanisms of Cl-DBPs during the chlorination and UV/post-chlorination processes. Besides, the amino, chlorine, and methyl groups significantly influenced the formation mechanisms of Cl-DBPs during the chlorination and UV/post-chlorination processes. Furthermore, the total Cl-DBPs yields from the six NCs followed a decreasing order of 2-chloro-3-nitrophenol, 3-nitrophenol, 2-methyl-3-nitrophenol, 2-amino-4-nitrophenol, 2-nitrophenol, and 4-nitrophenol during chlorination and UV/post-chlorination. However, the total Cl-DBPs yields from the six NCs during chloramination and UV/post-chloramination followed a quite different order, which might be caused by additional reaction mechanisms, e.g., nucleophilic substitution or addition might occur to NCs in the presence of monochloramine (NH2Cl). This work can offer deep insights into the reaction mechanisms of Cl-DBPs from NCs during the chlor(am)ination and UV/post-chlor(am)ination processes.

Exploring the Limits of the Generalized CHARMM and AMBER Force Fields through Predictions of Hydration Free Energy of Small Molecules.

Accurate force field parameters, potential energy functions, and receptor-ligand models are essential for modeling the solvation and binding of drug-like molecules to a receptor. A large and ever-growing chemical space of medicinally relevant scaffolds has also required these factors, especially force field parameters, to be highly transferable. Generalized force fields such as the CHARMM General Force Field (CGenFF) and the generalized AMBER force field (GAFF) have accomplished this feat along with other contemporaneous ones like OPLS. Here, we analyze the limits in the parametrization of drug-like small molecules by CGenFF and GAFF in terms of the various functional groups represented within them. Specifically, we link the presence of specific functional groups to the error in the absolute hydration free energy of over 600 small molecules, predicted by alchemical free energy methods implemented in the CHARMM program. Our investigation reveals that molecules with (i) a nitro group in CGenFF and GAFF are, respectively, over- or undersolubilized in aqueous medium, (ii) amine groups are undersolubilized more so in CGenFF than in GAFF, and (iii) carboxyl groups are more oversolubilized in GAFF than in CGenFF. We present our analyses of the potential factors underlying these trends. We also showcase the use of a machine-learning-based approach combined with the SHapley Additive exPlanations framework to attribute these trends to specific functional groups, which can be easily adopted to explore the limits of other general force fields.

Highly Selective Electroreduction of Nitrobenzene to Aniline by Co-Doped 1T-MoS2.

The selective electrocatalytic reduction of nitrobenzene (NB) to aniline demands a desirable cathodic catalyst to overcome the challenges of the competing hydrogen evolution reaction (HER), a higher overpotential, and a lower selectivity. Here, we deposit Co-doped 1T MoS2 on Ti mesh by the solvothermal method with different doping percentages of Co as x % Co-MoS2 (where x = 3, 5, 8, 10, and 12%). Because of the lowest overpotential, lower charge-transfer resistance, strong suppression of the competing HER, and higher electrochemical surface area, 8% Co-MoS2 achieves 94% selectivity of aniline with 54% faradaic efficiency. The reduction process follows first-order dynamics with a reaction coefficient of 0.5 h-1. Besides, 8% Co-MoS2 is highly stable and retains 81% selectivity even after 8 cycles. Mechanistic studies showed that the selective and exothermic adsorption of the nitro group at x % Co-MoS2 leads to a higher rate of NB reduction and higher selectivity of aniline. The aniline product is successfully removed from the solution by polymerization at FTO. This study signifies the impact of doping metal atoms in tuning the electronic arrangement of 1T-MoS2 for the facilitation of organic transformations.

Waste Biomass-Derived Activated Carbon-Supported 0D, 1D, 2D, and 3D Nanostructures of Copper Oxide for Hydrogenation Reaction: A Study on the Role of Structural Properties.

Intensive attention is given to the morphology-controlled synthesis of inorganic nanomaterials because of their intrinsic shape-dependent properties. In this article, different dimensions (D) of copper oxide (CuO) nanoparticles (such as 0D-sphere, 1D-rod, 1D-belt, 2D-rolling pin sheets, 3D-octahedron, and 3D-throne) are prepared. The catalytic efficacy of these differently shaped CuO catalysts is compared for hydrogenation reactions under reducing agent-free conditions. The order of catalytic activity of the CuO catalyst is found to be belt > octahedron > rolling pin > rod > sphere > throne. The best catalyst among the different shaped CuO catalysts, namely belt shape, is supported on the functionalized groundnut shells activated carbon sheets (FGNC). Interestingly, 25 wt % CuO/FGNC catalysts exhibit the highest catalytic activity for the reduction of nitro compounds. Importantly, the highly active FGNC-supported catalyst is reused for up to 10 cycles without any noticeable loss in the catalytic activity.

Crystal structure characterization, Hirshfeld surface analysis, and DFT calculation studies of 1-(6-amino-5-nitronaphthalen-2-yl)ethanone

The title compound, C12H10N2O3, was obtained by the deacetylation reaction of 1-(6-amino-5-nitronaphthalen-2-yl)ethanone in a concentrated sulfuric acid methanol solution. The molecule comprises a naphthalene ring system bearing an acetyl group (C-3), an amino group (C-7), and a nitro group (C-8). In the crystal, the molecules are assembled into a two-dimensional network by N...H/H...N and O...H/H...O hydrogen-bonding interactions. n–π and π–π stacking interactions are the dominant interactions in the three-dimensional crystal packing. Hirshfeld surface analysis indicates that the most important contributions are from O...H/H...O (34.9%), H...H (33.7%), and C...H/H...C (11.0%) contacts. The energies of the frontier molecular orbitals were computed using density functional theory (DFT) calculations at the B3LYP-D3BJ/def2-TZVP level of theory and the LUMO–HOMO energy gap of the molecule is 3.765 eV.

Transient spectroscopic insights into nitroindole’s T1 state: Elucidating its intermediates and unique photochemical properties

Indoles are notable for their distinct photophysical and photochemical properties, making them useful indicators in biological systems and promising candidates for a variety of pharmaceutical applications. While some indoles exhibit room temperature phosphorescence, such a phenomenon has not been observed in nitroindoles. Typically, adding of a nitro group into aromatic compounds promotes ultrafast intersystem crossing and increases the formation quantum yield of the lowest excited triplet (T1). Therefore, understanding the reactivity of nitroindoles′ T1 states is imperative. This study investigated the physical properties and chemical reactivities of the T1 state of 6-nitroindole (3HN-6NO2) in both polar aprotic and protic solvents, using transient absorption spectroscopy. Our results demonstrate the basicity and acidity of 3HN-6NO2, emphasizing its potential for protonation and dissociation in mildly acidic and basic conditions, respectively. Furthermore, 3HN-6NO2 has a high oxidizing capacity, participating in electron transfer reactions and proton-coupled electron transfer to produce radicals. Interestingly, in protic solvents like alcohols, 3HN-6NO2 dissociates at the –NH group and forms N-H…O hydrogen-bonded complexes with the nitro group. By identifying transient absorption spectra of intermediates and quantifying kinetic reaction rate constants, we illuminate the unique properties of the T1 state nitroindoles, enriching our understanding of their photophysical and photochemical behaviors. The results of this study have significant implications for their potential application in both biological systems and materials science.

Hydrogen-bond stabilized π-π stacking in the solvent-induced dimerization of 4-nitro-1-naphthol: A spectroscopic and computational investigation

π-π Stacking is crucial for stabilizing molecular structures and facilitating interactions in biological systems and chemical processes. The presence of electron-withdrawing and electron-donating substituents, particularly the hydroxyl group, significantly influences the energetics and energetically favorable configurations of π-stacked complexes. In this study, we utilized UV–Vis absorption and resonance Raman spectroscopies, alongside density functional theory (DFT) calculations, to investigate the competition between dissociation and self-aggregation of 4-nitro-1-naphthol (NNH) in various polar solvents. Our results demonstrate the self-aggregation of NNH in polar solvents and identify the most likely dimer configuration, which is antiparallel π-stacked and stabilized by hydrogen bonds between hydroxyl and nitro groups. Given its broad applications in mass spectrometry, environmental remediation, and aerosol tracking, a comprehensive understanding of the molecular interactions and structural properties of NNH is essential for its effective use in various scientific fields.

A comprehensive study about functionalization and de-functionalization of MOF-808 as a defect-engineered Zr-MOFs for selective catalytic oxidation

In metal–organic frameworks (MOFs), confined space as a chemical nanoreactor is as essential as coordinatively unsaturated metal site catalysis. The properties of MOFs can be adjusted through the incorporation of functional groups and open metal sites in frameworks that can modify the catalytic performance. In this regard, a set of defect-engineered MOFs, Ex-MOF-808(NH2, NO2, H) and Mix-MOF-808(NH2, NO2, H), were synthesized by ultrasonic-assisted linker exchange approach (Ex-MOFs) and solvothermal mixing ligand method (Mix-MOFs), respectively. Further, the relationship between the preparation method, structural properties, and catalytic efficiency of the prepared materials in the selective oxidation of methyl phenyl sulfide (MPS) has been investigated. By analyzing zeta potential, it was found that in the exchange method, the amount of defect and functional groups on the surface of MOFs are more than in the mixing method, which also affects the catalytic activity. In our contribution, mix-MOF-808(NO2) carrying nitro groups at their organic linkers, which has a well-dispersion of nitro groups at the framework exhibits selective conversion of MPS to sulfone (91 %). Furthermore, the performance of stable heterogeneous catalysts was investigated for three cycles, which demonstrated their great potential for advanced catalytic oxidation.

Development of new nitrogen-oxygen systems in the Laboratory of Chemistry of Nitro Compounds at the Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences

Development of new nitrogen-oxygen systems in the Laboratory of Chemistry of Nitro Compounds at the Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences

The chelation mechanism of neonicotinoid insecticides influencing cadmium transport and accumulation in rice at different growth stage

The combined exposure of heavy metals and organic contaminates can influence the transport and accumulation of heavy metals within the soil−rice system. However, the underlying mechanisms of this process remain largely unknown. Herein, this study investigated the influence of three neonicotinoid insecticides (NIs), including imidacloprid (IMI), clothianidin (CLO), and thiamethoxam (THI), on the Cd transport and accumulation in rice (Oryza sativa) at different growth stages. Particular focus lied on their complex interaction and key genes expression involved in Cd transport. Results showed that the interaction between Cd and NIs was the dominant factor affecting Cd transport and accumulation in rice exposed to NIs. All three NIs chelated with Cd with nitrogen (N) on the IMI and THI nitro groups, and the N on the CLO nitro guanidine group. Interestingly, this chelation behavior varied between the tillering stage and the filling/ripening stages, resulting in diverse patterns of Cd accumulation in rice tissues. During the tillering stage, all three NIs considerably inhibited Cd bioavailability and transport to the above-ground part, lowering Cd content in the stem and leaf. The inhibition was increased with stronger chelation ability in the order of IMI (−0.46 eV) > CLO (−0.41 eV) > THI (−0.11 eV), with IMI exhibiting the highest binding energy for Cd and reducing Cd transfers from root to stem by an impressive 94.49 % during the tillering stage. Conversely, during the filling/ripening stages, NIs facilitated Cd accumulation in rice roots, stems, leaves, and grains. This was mainly attributed to the generation of nitrate ions and the release of Cd2+ during the chelation between Cd and NIs under drainage condition. These findings provide theoretical basis for the treatment of combined contamination in field and deep insights into understanding the interaction of organic contaminants with heavy metals in rice culture process.

Effects of cotton plant (Gossypium herbaceum Linn.) extracts on some vancomycin and methicillin-resistant pathogenic bacteria

Bacterial resistance to antibiotics is a serious global problem, hence attention is being turned to plants as alternative source of antimicrobial to combat the menace of antibiotic resistance among pathogenic microorganisms. This study explores the antibacterial properties of Gossypium herbaceum leaf extracts against a spectrum of antibiotic-resistant bacteria such as Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, sourced from clinical isolates at Don Bosco Catholic Laboratory and Obafemi Awolowo University Teaching Hospital in Nigeria. The research utilized cold extraction methods with methanol and n-hexane solvents to prepare the extracts, which were then analyzed for their phytochemical composition, revealing the presence of flavonoids, steroids, tannins, terpenoids, and glycosides. Antibacterial activity was assessed using the disc diffusion method, with the extracts showing varying zones of inhibition; n-hexane extracts produced zones between 21.35 mm and 4.10 mm, while methanol extracts showed zones between 18.75 mm and 5.05 mm at a concentration of 200mg/mL. Minimum inhibitory concentrations (MIC) were determined, with n-hexane extracts ranging from 25 mg/mL to 6.25 mg/mL and methanol extracts from 50 mg/mL to 6.25 mg/mL. Further analysis of the bioactive fractions was conducted through Fourier Transform Infrared Spectroscopy (FTIR), which identified six distinct bioactive compounds in the methanol extract, including alkenes, alcohols, amines, phenols, nitro compounds, and alkanes. Plasmid profiling indicated the presence of plasmids in clinically significant pathogens like P. aeruginosa and S. aureus, suggesting a potential mechanism for their antibiotic resistance. Overall, the study highlights the significant antibacterial activity of G. herbaceum extracts against resistant bacteria and suggests their potential as alternative antimicrobial agents in combating antibiotic resistance, which is a growing global health concern.

Synthesis and Characterization of Hexahydropyrimidines and Their New Derivatives

Three new hexahydropyrimidine derivatives 1a – 1c were successfully synthesized using the Mannich-type reaction. Furthermore, the synthesis of three amino bases 2a – 2c was achieved through the reduction reaction of pyrimidine compounds using hydrazine, followed by the substitution reaction of nitro groups at diverse positions. Subsequently, one of the synthesized amino base derivatives 2c underwent conversion into seven Schiff bases 3a – 3g via a condensation reaction involving the aforementioned amino base derivative and a selection of benzaldehyde derivatives. Four amide compounds 4a – 4d have been synthesized by a reaction of the secondary amine group in the pyrimidine ring with benzoyl chloride. The products were subjected to comprehensive characterization employing rigorous analytical techniques, including FT-), 1H-NMR (Proton Nuclear Magnetic Resonance Spectroscopy), and LC-MS (Liquid Chromatography–Mass Spectrometry). Additionally, the Molecular Electrostatic Potential (MEP) study was carried out to further investigate the properties of the synthesized compounds. The yields of the three methods used to synthesise new hexahydropyrimidine derivatives varied depending on the specific substituents added to the aromatic ring.

Small Copper Nanoclusters Synthesized through Solid-State Reduction inside a Ring-Shaped Polyoxometalate Nanoreactor.

Cu nanoclusters exhibit distinctive physicochemical properties and hold significant potential for multifaceted applications. Although Cu nanoclusters are synthesized by reacting Cu ions and reducing agents by covering their surfaces using organic protecting ligands or supporting them inside porous materials, the synthesis of surface-exposed Cu nanoclusters with a controlled number of Cu atoms remains challenging. This study presents a solid-state reduction method for the synthesis of Cu nanoclusters employing a ring-shaped polyoxometalate (POM) as a structurally defined and rigid molecular nanoreactor. Through the reduction of Cu2+ incorporated within the cavity of a ring-shaped POM using H2 at 140 °C, spectroscopic studies and single-crystal X-ray diffraction analysis revealed the formation of surface-exposed Cu nanoclusters with a defined number of Cu atoms within the cavities of POMs. Furthermore, the Cu nanoclusters underwent a reversible redox transformation within the cavity upon alternating the gas atmosphere (i.e., H2 or O2). These Cu nanoclusters produced active hydrogen species that can efficiently hydrogenate various functional groups such as alkenes, alkynes, carbonyls, and nitro groups using H2 as a reductant. We expect that this synthesis approach will facilitate the development of a wide variety of metal nanoclusters with high reactivity and unexplored properties.