Search

Here, analytical extended multi-state complete active space second-order perturbation method (XMS-CASPT2) gradients are used to rationalize the decreasing triplet quantum yield trend in 2-nitronaphthalene, 1-nitronaphthalene, and 2-methyl-1-nitronaphthalene, a series of nitro-substituted aromatic compounds. Comparison with the XMS-CASPT2//CASSCF (where CASSCF stands for complete active space self-consistent field method) results highlights the importance of dynamic correlation in geometry optimization and challenges the validity of an XMS-CASPT2//CASSCF approach: XMS-CASPT2 S1 minima leads to planar structures, while CASSCF optimizations trigger a pyramidalization of the nitro group. The XMS-CASPT2 results correlate the reported decreasing triplet quantum yield trend in these species to a decrease in S1 to T2 population transfer and an increase in S1–S0 decay, while no such correlation is observed when using XMS-CASPT2//CASSCF data. [ABSTRACT FROM AUTHOR]

The redox properties of half-sandwich rhodium complexes supported by 2,2′-bipyridyl (bpy) ligands can be readily tuned by selection of an appropriately substituted derivative of bpy, but the influences of single substituents on the properties of such complexes are not well documented, as disubstituted bpy variants are much more common. Here, the synthesis, characterization, and redox properties of two new [Cp*Rh] complexes (where Cp* is η5-1,2,3,4,5-pentamethylcyclopentadienyl) supported by the uncommon mono-substituted ligands 4-chloro-2,2′-bipyridyl (mcbpy) and 4-nitro-2,2′-bipyridyl (mnbpy) are reported. Single-crystal X-ray diffraction studies and related spectroscopic experiments confirm installation of the single substituents (–Cl and –NO2, respectively) on the bipyridyl ligands; the precursor monosubstituted ligands were prepared via a divergent route from unsubstituted bpy. Electrochemical studies reveal that each of the complexes undergoes an initial net two-electron reduction at potentials more positive than that associated with the parent unsubstituted complex of bpy, and that the complex supported by mnbpy can undergo a third, chemically reversible reduction at −1.62 V vs. ferrocenium/ferrocene. This redox behavior is consistent with inductive influences from the substituent groups on the supporting ligands, although the nitro group uniquely enables addition of a third electron. Spectrochemical studies carried out with UV-visible detection confirm the redox stoichiometry accessible to these platforms, highlighting the rich redox chemistry and tunable behavior of [Cp*Rh] complexes supported by bpy-type ligands. [ABSTRACT FROM AUTHOR]

A general and practical K2CO3-promoted [3+2] annulation between trifluoroacetaldehyde N-triftosylhydrazone (TFHZ-Tfs) and 4-nitroisoxazoles has been developed to access structurally diverse trifluoromethylpyrazolo[3,4-d]isoxazoles. Mechanistically, CF3CHN2 is formed in situ by TFHZ-Tfs decomposition and involves a formal [3+2] dearomative cycloaddition with 4-nitroisoxazoles, followed by aromatization via the elimination of the nitro group. Furthermore, this protocol is metal-free, scalable, mild, and operationally safe, with a broad substrate scope and high functional group compatibility. [ABSTRACT FROM AUTHOR]

The present article provides an overview of our work related to cyclization reactions of nitro-substituted electrophilic building blocks with various nucleophiles. As electrophiles, we used nitro-substituted benzoylacetones, 3-ethoxy-2-nitro-2-en-1-ones, 2-nitrobenzoyl chlorides, 4-chloro-3-nitrocoumarin, 2-nitromalonic aldehyde, 3-nitrochromone and 1-(2-chloro-5-nitrophenyl)prop-2-yn-1-ones. As nucleophiles, 1,3-dicarbonyl compounds, 1,3-bis(silyloxy)-1,3-butadienes, (heterocyclic) enamines, hydroxylamine, hydrazines, amines and amino esters were employed. The products include a variety of nitro-substituted carbo- and heterocycles that are not readily available by other methods. The electron-withdrawing nitro group can be easily transformed into an electron-donating amino group which is not only pharmacologically relevant, but can also act as a nucleophile in inter- and intramolecular reactions with electrophiles, such as aldehydes, and can be converted into other functional groups. The nitro group has the capacity to activate compounds for regioselective palladium-catalyzed CH-arylation reactions. Inter- and intramolecular CH arylations of nitro-substituted heterocyclic building blocks, such as 4-nitropyrazoles, 4-nitroimidazoles, 2-nitroindole and nitro-substituted purine analogues, allow for a convenient diversity-oriented approach to the corresponding arylated products. In addition, the nitro group can act as a leaving group in SN Ar reactions. Various fused benzofuro[3,2- b ]pyridines were prepared by intramolecular SN Ar reactions of 2-(hydroxyphenyl)-3-nitropyridines. 1 Introduction 2 Cyclizations of 1,3-Bis(silyloxy)-1,3-butadienes 3 Cyclizations of Heterocyclic Enamines 4 Reactions of Simple Nitro-Substituted Heterocycles 5 Hydroamination Reactions of Alkynes 6 Miscellaneous 7 Conclusions [ABSTRACT FROM AUTHOR]

Hydrazine hydrate as a hydrogen source has a good effect on nitro reduction, but overuse has environmental toxicity and is prone to over‐hydrogenation, resulting in low selectivity. Herein, we report a magnetically separable Rh/Fe3O4 (1.26 wt%) catalyst containing an optimal Rh content that can completely convert 3‐nitrostyrene to 3‐vinylaniline (> 99% selectivity) using a stoichiometric molar ratio of hydrazine hydrate (‐NO2:N2H4·H2O = 1:1.5). This is due to the synergy between Rh and Fe3O4 and the natural selectivity of N2H4·H2O for nitro. The synergy can reduce the activation energy of the reaction (36.6 kJ/mol), increasing the reduction rate of nitro group and avoiding the combination of active hydrogen species (H*) to H2 as well as the hydrogenation of N2H4 to NH3. Moreover, the active H* produced by N2H4·H2O is different from that produced by H2, and excess dose of N2H4 will inevitably yield H2 thus decline the selectivity. [ABSTRACT FROM AUTHOR]

A CsF-promoted synthesis of cyanopyrazolo[4,3-b]indoles via a [3+2] cycloaddition reaction of diazoacetonitrile with N-substituted 3-nitroindoles and subsequent elimination of the nitro group has been devised. This protocol delivers diverse cyano-containing pyrazole-fused indoles in good to excellent yields under mild conditions. Besides diazoacetonitrile, the Seyferth–Gilbert reagent (SGR) readily participated in this reaction to provide facile access to phosphonylated pyrazolo[4,3-b]indoles. [ABSTRACT FROM AUTHOR]

In this work, we designed and synthesized a series of novel triazolopyridine fused-ring compounds with alternating nitro and amine groups. Three compounds showed remarkable thermal stability at 256, 310, and 294 °C, respectively, and a low mechanical sensitivity [impact sensitivity (IS) = 40 J, friction sensitivity (FS) = 324 N; IS = 35 J, FS = 240 N; and IS > 40 J, FS = 324 N, respectively]. Significantly, two of these compounds exhibited a better detonation performance [detonation velocity (D) = 8200 and 8335 m s–1 , Detonation pressure (P) = 25.6 and 27.2 GPa, respectively] than the widely used heat-resistant explosive hexanitrostilbene (HNS; D = 7612 m s–1 , P = 24.3 GPa). Additionally, a nitramine derivative displayed a detonation performance (D = 8569 m s–1 , P = 31.3 GPa) similar to that of the high-energy explosive RDX. The superior properties of the materials were further confirmed by X-ray diffraction analysis and by several theoretical calculations (ESP, LOL–π, Hirshfeld surfaces, RDG, and NCI analyses). These results indicated that the three compounds might be potential candidates for use as heat-resistant energetic materials. [ABSTRACT FROM AUTHOR]

The energy and stability properties of energetic materials are often contradictory to each other (e.g., high energy vs low thermal stability). There is no doubt that it is still challenging to explore the effective balance between energetic performance and molecular stability, especially for melt-castable materials. In this study, we selected the 4-methoxy-3,5-dinitropyrazole framework and a stable nitro group to design a new energetic melt-castable compound, namely 4-methoxy-3,5-dinitro-1-(nitromethyl)-1 H -pyrazole (MDNNMP). Compared with the N -methylation product DMDNP and the nitrato-substituted derivative MC-7, MDNNMP exhibits a better balanced performance, including good thermal stability (Td : 203.7 °C), detonation velocity (Dv : 8099 m s–1) and impact sensitivity (20 J). The favorable balanced performance of MDNNMP suggests that it is a suitable candidate as a high-performance melt-castable material. Additionally, compared with the nitratomethyl group, the nitromethyl group demonstrates superior advantages in performance regulation. [ABSTRACT FROM AUTHOR]

Chagas disease is a prevalent health problem in Latin America which has received insufficient attention worldwide. Current treatments for this disease, benznidazole and nifurtimox, have limited efficacy and may cause side effects. A recent study proposed investigating a wide range of nitroindazole and indazolone derivatives as feasible treatments. Therefore, it is proposed that adding a nitro group at the 5-position of the indazole and indazolone structure could enhance trypanocidal activity by inducing oxidative stress through activation of the nitro group by NTRs (nitroreductases). The study results indicate that the nitro group advances free radical production, as confirmed by several analyses. Compound 5a (5-nitro-2-picolyl-indazolin-3-one) shows the most favorable trypanocidal activity (1.1 ± 0.3 µM in epimastigotes and 5.4 ± 1.0 µM in trypomastigotes), with a selectivity index superior to nifurtimox. Analysis of the mechanism of action indicated that the nitro group at the 5-position of the indazole ring induces the generation of reactive oxygen species (ROS), which causes apoptosis in the parasites. Computational docking studies reveal how the compounds interact with critical residues of the NTR and FMNH2 (flavin mononucleotide reduced) in the binding site, which is also present in active ligands. The lipophilicity of the studied series was shown to influence their activity, and the nitro group was found to play a crucial role in generating free radicals. Further investigations are needed of derivatives with comparable lipophilic characteristics and the location of the nitro group in different positions of the base structure. [ABSTRACT FROM AUTHOR]

N‐heterocyclic compounds have a broad range of applications and their selective synthesis is very appealing for the pharmaceutical and agrochemical industries. Herein we report the usage of the flavin‐dependent nitroreductase BaNTR1 for the photoenzymatic synthesis of various anthranils and quinolines from retro‐synthetically designed o‐nitrophenyl‐substituted carbonyl substrates, achieving high conversions (up to >99 %) and good product yields (up to 96 %). Whereas the effective production of anthranils required the inclusion of H2O2 in the reaction mixtures to accumulate the needed hydroxylamine intermediates, the formation of quinolines required the use of anaerobic or reducing conditions to efficiently generate the essential amine intermediates. Critical to our success was the high chemoselectivity of BaNTR1, performing selective reduction of the nitro group without reduction of the carbonyl moiety or the activated carbon‐carbon double bond. The results highlight the usefulness of an innocuous chlorophyll‐ and nitroreductase‐based photoenzymatic system for the tailored synthesis of diverse N‐heterocycles from simple nitro compounds. [ABSTRACT FROM AUTHOR]

Clonazolam is a designer triazolobenzodiazepine first synthesized in 1971 and is primarily used for its anxiolytic and sedative effects. It became a drug of misuse in 2012 and is known for its high potency and long duration of effect. Previous studies of nitrobenzodiazepines, such as nitrazepam, clonazepam, and flunitrazepam, as well as their metabolites, have demonstrated that bacterial species native to the gastrointestinal tract and active during postmortem (PM) decomposition are capable of affecting positivity and compound-to-metabolite ratios. Further studies have not been performed with clonazolam; however, it possesses the nitro functional group necessary for this biotransformation. To understand whether clonazolam may be similarly affected, PM cases (n  = 288) and driving under the influence of drugs (DUID, n  = 54) cases, positive for 8-aminoclonazolam reported by NMS Laboratories from 2020 to 2023, were selected for inclusion in this study. Concentrations of clonazolam and 8-aminoclonazolam were evaluated, and concurrent identification of parent drugs and their metabolites occurred less frequently in PM cases (n  = 1, 0.30% of cases) than in DUID cases (n  = 21, 38% of cases). The clonazolam concentration in one PM case was 13 ng/mL. In DUID cases, the median clonazolam concentration was 4.0 ng/mL and ranged from 2.0 to 10 ng/mL. 8-Aminoclonazolam had median concentrations of 13 and 19 ng/mL, with ranges 2.0–580 and 2.8–59 ng/mL for PM and DUID cases, respectively. Due to the ever-changing landscape of the designer benzodiazepine market, in vitro studies of PM microbial biotransformation of clonazolam are unavailable. The data reported herein provide valuable information in the absence of such studies and represent an alternative method of investigating this phenomenon as a potential cause of parent nitrobenzodiazepine to metabolite conversion. [ABSTRACT FROM AUTHOR]

The present article provides a personalized account on CH-arylation reactions employed for the synthesis of heterocycles. The presence of a nitro group allowed for direct and regioselective CH-arylations of pyrazoles, imidazoles, indoles and a variety of purine analogues. Direct CH-arylations without the presence of an activating nitro-group were employed for inter- and intramolecular reactions of purine derivatives, which allowed for the synthesis of a great variety of polycyclic systems. Domino C–N coupling / hydroamination / CH-activation reactions of diarylacetylenes with anilines allowed for the synthesis of polycondensated N -heterocycles. Products include indolo- and azaindolo[1,2- f ]phenanthridines, quinolino[3′,4′:4,5]pyrrolo[1,2- f ]phenanthridines, pyrimido[5′,4′:4,5]pyrrolo[1,2- f ]phenanthridines, and benzothieno[2′,3′:4,5]pyrrolo[1,2- f ]phenanthridines. The reaction of N -heterocycles, such as indoles, with 1,1-difluoroalkenes resulted in a twofold addition-elimination reaction to give 1,1-diaminoalkenes, which were transformed by CH-arylation into various polycondensated heterocycles, such as indoloisoquinolines, thienoindolizines, oxepines and helicenes. Pyridofluoranthenes, diindenopyrene and azadiindenopyrenes were prepared by a combination of Pd-catalyzed cross-coupling reactions with acid-mediated cycloisomerizations and Pd-catalyzed intramolecular CH-arylations. Bis(carbazoles), benzodithiazoles, benzodithiophenes and 2,5-diarylpyrroles were prepared by inter- and intramolecular CH-arylation reactions. [ABSTRACT FROM AUTHOR]

Dinitropyridines are one of the promising classes of heterocyclic compounds. They are considered as useful precursors of explosives and energetic compounds, agrochemicals, biosensors and biologically active compounds with diverse properties: antitumor, antiviral, anti‐neurodegenerative. Preliminary analysis of literature data shows that the chemistry of polynitropyridines has been actively developing over the past few decades. This is evidenced by the steadily growing annual number of publications. In this review the literature on the synthesis, reactions and practical application of isomeric dinitropyridines over a period of 2010–2024 is analyzed. [ABSTRACT FROM AUTHOR]

In this paper, three neutral heterocycle-triazolotriazine compounds featuring multiple amino groups and nitro groups were designed and synthesized. Among them, compounds 2 and 6 exhibit high detonation performance (Dv = 8180 m s−1, 8650 m s−1; P = 26.40 GPa, 31.5 GPa), low sensitivities (IS > 40 J, FS > 360 N) and high thermal stabilities (Td = 319 °C, 320 °C) suggesting their potential as alternatives to the traditional thermal-stable explosive HNS (Dv = 7612 m s−1, P = 24.3 GPa, IS = 5 J, FS = 240 N; Td = 318 °C). Meanwhile, compound 4 displays excellent properties (Dv = 8810 m s−1, IS = 15 J, FS = 240 N, Td = 215 °C, ρ = 1.84 g cm−3) which is superior to traditional explosive RDX (Dv = 8795 m s−1, IS = 7.5 J, FS = 120 N, Td = 208 °C, ρ = 1.80 g cm−3) making it a promising candidate as a novel secondary explosive. This research not only advances the field of triazolotriazine-based energetic materials but also explores their potential applications as heat-resistant or high-energy explosives. [ABSTRACT FROM AUTHOR]

Organic π‐scaffolds are being envisaged for new‐age electron‐ and ion‐responsive materials that can accumulate electrons as well as transport proton. However, such systems are extremely rare as electron‐deficient scaffolds are unstable in aqueous solution. Here we detail the synthesis of a water‐stable core‐naphthalenediimide‐nitrobenzyl‐viologen based tetra‐cation, which accumulates up to eight‐electrons within an exceptionally narrow potential window of +0.05 V and −1.12 V. The supramolecular interactions and the ensuing ionic framework are tunable based on the three anions, e. g. Cl−, Br− and PF6−, that are investigated in this work. The ionic framework is formed and supported by a range of H‐bonds, in which, the nitro benzyl groups act as pillars connecting the 1D water‐tapes and the halide anions. The water molecules are hydrogen‐bonded with the halide anions and bestow a facile pathway for the proton conduction, with proton conductivity up to 3.19×10−3 S cm−1. In contrast, the ionic assembly formed by the lipophilic PF6− anions do not host the water tapes and consequently the proton conductivity is found to be four orders of magnitude lower. This is a unique example, whereby proton conductivity is realized and is tunable within a highly electron‐deficient, eight‐electron acceptor, water‐stable ionic supramolecular system. [ABSTRACT FROM AUTHOR]

An unexpected nitro group displacement during a nitro-Mannich reaction led to the one-pot formation of the octahydro-2H-pyrazino[1,2-a]pyrazine core, representing the shortest access to date to this pharmacologically relevant heterobicyclic system. A mechanistic hypothesis is suggested and supported by specific experiments and HRMS analysis of reaction mixtures. [ABSTRACT FROM AUTHOR]

Pnictogens, classified within group 15 elements, play a pivotal role in the constitution of a diverse array of drug molecules, natural products, and functional materials. Recent research has increasingly prioritized the exploration of mild conditions for synthesizing C–Pnictogen (C–N and C–P) bonds, highlighting a growing emphasis on efficient and sustainable synthetic methodologies. This Short Review explores fundamental mechanisms, addresses constraints, and assesses diverse methodologies, underscoring the potential of photocatalyst- and transition-metal-free photochemical reactions in advancing sustainability. Divided into two segments, it encompasses recent advancements in reactions facilitating C–N and C–P bond formation. 1 Introduction 2 Carbon–Nitrogen (C–N) Bond Formation 3 Carbon–Phosphorus (C–P) Bond Formation 4 Summary and Outlook [ABSTRACT FROM AUTHOR]

Indazoles are a very important group of nitrogen-containing heterocycles with a wide range of biological and medicinal applications. These properties make them highly attractive for drug development, particularly when combined with sulfonamides to enhance their medicinal potential. In this work, we synthesized an indazole-based sulfonamide, namely the 1-((2-chloro-5-methoxyphenyl)sulfonyl)-5-nitro-1H-indazole (3). The reduction of the nitro group of 5-nitroindazole (1) to its corresponding amine was also performed to yield compound (4). Both compounds' structures were elucidated using various spectroscopic techniques such as 1H NMR, 13C NMR, infrared (IR), and high-resolution mass spectrometry (HRMS). Our molecular docking studies suggest that compounds (3) and (4) have a strong affinity for MAPK1, indicating their potential as cancer treatments. [ABSTRACT FROM AUTHOR]

The pursuit of novel or modified substances based on a natural origin, like flavonoids, is essential in addressing the increasing number of diseases and bacterial resistance to antibiotics, as well as in maintaining intestinal balance and enhancing overall gut health. The primary goal of this research was to evaluate the impact of specific flavonoid compounds—chalcones, flavanones, and flavones—substituted with -Br, -Cl, -CH3, and -NO2 on both pathogenic and probiotic microorganisms. Additionally, this study aimed to understand these compounds' influence on standardized normal and pathologically altered intestinal microbiomes. 8-Bromo-6-chloroflavone 4′-O-β-D-(4″-O-methyl)-glucopyranoside and 8-bromo-6-chloroflavanone showed the most promising results as bactericidal agents. They significantly limited or inhibited the growth of pathogenic bacteria without adversely affecting the probiotic's growth. Digestion in vitro studies indicated that 6-methyl-8-nitroflavone and 8-bromo-6-chloroflavone positively modulated the gut microbiome by increasing beneficial bacteria and reducing potentially pathogenic microbes. This effect was most notable in microbiomes characteristic of older individuals and those recovering from chemotherapy or antibiotic treatments. This study underscores the therapeutic potential of flavonoid compounds, particularly those with specific halogen and nitro substitutions, in enhancing gut health. [ABSTRACT FROM AUTHOR]

A method to assemble 2‐aminobenzoxazoles via iron‐catalyzed redox condensation of amines, carbon disulfide and 2‐nitrophenols is reported. The reaction features advantages of environmentally friendly iron catalyzed conditions, readily available starting materials, and excellent atom‐, step‐ and redox‐ economy compared to known protocols. Experimental investigation suggests a mechanism encompassing iron‐catalyzed reduction of the nitro group of 2‐nitrophenols by the dithiocarbamate group from amine‐CS2 adduct. [ABSTRACT FROM AUTHOR]

Schematic of Zn2+ deposition behavior on the Zn anode and Zn@ZIF-N anode. [Display omitted] • The zeolitic imidazole framework (ZIF-N) with electron-withdrawing nitro groups exhibits zincophilicity and hydrophilicity. • The Zn@ZIF-N anode exhibits a lower polarization ratio and extended cycle life. • The full battery achieves a cycle life of 1600 cycles. Aqueous zinc-ion batteries (AZIBs) have garnered attention from researchers for their high theoretical capacity, safety, and low cost. However, the uncontrolled growth of zinc (Zn) dendrites and spontaneous corrosion reactions on the Zn anode significantly compromise the cycle life of AZIBs. This paper proposes the utilization of a novel zeolitic imidazole framework (ZIF-N) material with zincophilicity and hydrophilicity for modifying the Zn anode of AZIBs. ZIF-N incorporates numerous electron-withdrawing nitro groups at the Zn/ZIF-N interface to regulate the uneven electron distribution on the Zn anode. The modified Zn anode (Zn@ZIF-N) exhibits a lower polarization ratio (32.18 mV at 4 mA cm−2) and an extended cycle life (over 700 h at 4 mA cm−2). At a current density of 1 mA cm−2, the battery composed of a Zn@ZIF-N anode and NVO (NaV 3 O 8) achieves a cycle life of 1600 cycles. This work provides a straightforward and cost-effective strategy for modifying the Zn anode to prolong the cycle life of AZIBs. [ABSTRACT FROM AUTHOR]

The effects of planar biaxial strain on the stability, electronic structure, and magnetic properties of monolayer CrS2 systems doped with nitrogen group elements have been investigated based on first principles. Calculations of energy differences, formation energies, bond population, and binding energies indicate the relative stability of the system. Calculations of the electronic structure (energy band structure, density of states, and differential charge density distribution) and magnetic parameters (spin density profiles, single-atom magnetic moments, and total magnetic moments of the system) show that atomic doping in conjunction with strain induces several excellent electronic properties of the system, such as magnetic semiconductors and semimetals. The bandgap of the spin-down channel increases with tensile strain and decreases with compressive strain. In addition, we note that the total magnetic moments of the monolayer CrS2 system and the N atom-doped system decrease with tensile strain and show an increase with compressive strain. The above results provide a reference for further investigation of this material and its application in nanospin devices. [ABSTRACT FROM AUTHOR]

The pathways and timescales of vibrational energy flow in nitromethane are investigated in both gas and condensed phases using classical molecular mechanics, with a particular focus on relaxation in liquid water. We monitor the flow of excess energy deposited in vibrational modes of nitromethane into the surrounding solvent. A marked energy flux anisotropy is found when nitromethane is immersed in liquid water, with a preferential flow to those water molecules in contact to the nitro group. The factors that permit such anisotropic energy relaxation are discussed, along with the potential implications on the molecule's non-equilibrium dynamics. In addition, the energy flux analysis allows us to identify the solvent motions responsible for the uptake of solute energy, confirming the crucial role of water librations. Finally, we also show that no anisotropic vibrational energy relaxation occurs when nitromethane is surrounded by argon gas. [ABSTRACT FROM AUTHOR]

The nitro moiety is an indispensable functional group in organic synthesis due to its facile introduction and reduction to the corresponding amines for a plethora of organic transformations. Owing to its distinct electronegative and conventional properties, it has been used for activated aromatic nucleophilic substitution (SNAr) reactions, Smiles reactions, Henry reactions, acyl anion equivalents, etc. Recently, the excellent photochemical properties of nitroarenes have been rediscovered by several groups, and their untapped potential in organic synthesis under UV or visible light irradiation has been exploited. Photoexcited nitroarenes can undergo facile reduction to amines, azo-coupling, metal-free reductive C--N coupling with boronic acids via a 1,2-boronate shift, hydrogen atom transfer (HAT), oxygen atom transfer for anaerobic oxidation of organic molecules, molecular editing via nitrene intermediates, denitrative coupling of β-nitrostyrene, radical α-alkylation of nitroalkanes, etc. They have also been used as a photolabile protecting group in medicinal chemistry and chemical biology applications. Here, we summarise the recent findings on visible-light-mediated transformations involving nitro-containing organic molecules. [ABSTRACT FROM AUTHOR]

Regioselective distal C−H functionalization of nitroarenes by overriding proximal C−H activation has remained an unsolved challenge. Herein, we present a palladium-catalyzed meta-C−H alkenylation of nitroarene substrate, achieved through leveraging the non-covalent hydrogen bonding interactions. Urea-based templates comprising an elongated biphenyl linker designed in such a way that it interacts with nitro group via strong hydrogen bonding interaction, while a cyano based directing group is attached along the template to coordinate with the palladium center, thereby facilitating the activation of the remote meta-C−H bond of nitrobenzene. Computational mechanistic investigation and the analysis of non-covalent interaction deciphers the crucial role of H-bonding in regulating the regioselectivity. Regioselective distal C-H functionalization of nitroarenes by overriding proximal C-H activation has remained an unsolved challenge. Herein, the authors present a palladium-catalyzed meta-C-H alkenylation of nitroarene substrate, achieved through leveraging the noncovalent hydrogen bonding interactions. [ABSTRACT FROM AUTHOR]

2D materials based on Group 15 elements (pnictogens) have appeared during the last ten years, with a rich surface chemistry characterized by a plethora of dangling electron pairs, ready to interact with outer molecules. These molecular interactions enable catalytic properties beyond any external electro‐ or photo‐stimulus. In analogy with carbocatalysis, defined as thermal catalytic processes over extended carbon surfaces (graphene, nanotubes, etc.), we propose here the term "pnictocatalysis", defined as thermal catalytic processes over extended pnictogen surfaces (which include phospho‐, arsene‐, antimony‐ and bismuth‐catalysis). Pnictocatalysis consitutes a new field in catalysis, with unexplored latent reactions to be encountered. In this minireview, we show the few examples found to date (not more than ten), which mark the pathway to find new pnictocatalyzed reactions, not exclusive with two‐dimensional (2D) materials but also with other pnictogen nanostructures. [ABSTRACT FROM AUTHOR]

A regiospecific synthesis of N9‐alkylated purines as novel acyclic nucleosides was developed. This approach is based on reconstructive methodology involving the construction of a target heterocyclic scaffold on a readily available 5‐aminotetrazole moiety, which is subsequently cleaved under reductive conditions due to azido‐tetrazole tautomerism. It appeared that the rate of reduction for the azide fragment in 6‐nitro‐7‐alkylaminotetrazolo[1,5‐a]pyrimidines is much greater than the rate of nitro group reduction. Treatment of these heterocycles with hydrogen over a palladium catalyst resulted in the formation of triaminopyrimidines in excellent yields through the reduction of both the azide and nitro group. Triaminopyrimidines were transformed into the desired N9‐alkylated purines, and an analog of the marketed drug penciclovir was synthesized by the developed method. [ABSTRACT FROM AUTHOR]

Metal sulfide-incorporated graphitic carbon nitride-based semiconductor catalysts have attracted considerable attention in the field of clean energy and environmental remediation because of their low cost, eco-friendliness, high efficiency, and ease of use. Herein, we demonstrate a facile one-pot synthesis of CuS nanoparticles in situ grown on the layered porous sulfur-doped graphitic carbon nitride nanosheets (CuS/S-g-C3N4), which act as a catalyst for the reduction of 4-nitrophenol. 4-Nitrophenol was reduced (converted into 4-aminophenol) by about 89.92% and 99.98% with S-g-C3N4 and CuS/S-g-C3N4 composites, respectively, within 3 min. The results demonstrate that the CuS/S-g-C3N4 nanohybrid composite showed superior catalytic performance compared to bare S-g-C3N4 due to the enhancement caused by increasing the affinity of accessible surface-active edge sites and interfacial contact allowing an effective modification of the electronic structure, high structural porosity, and richness in sulfur vacancy. Further, the fast electron transfer 4-NP reduction mechanism on CuS/S-g-C3N4 was explicated and discussed. Additionally, the CuS/S-g-C3N4 nanocomposite revealed good stability towards catalytic reduction even after repeated usage. Thus, the present study affords an in situ synthesis of CuS on the S-g-C3N4 nanocomposite for improving the catalytic conversion of the nitro group to the amine group. [ABSTRACT FROM AUTHOR]

A four-step synthesis of the natural product pseudane IX, starting from 3-oxododecanoic acid phenylamide and including only one chromatographic purification, was accomplished with an overall yield of 52%. The same synthetic sequence, but with a controlled partial reduction of a nitro group in the penultimate intermediate, led to the N-oxide of pseudane IX (NQNO). A shortened three-step variation of the synthesis allowed for the preparation of novel carboxamide analogs of the natural product. An agar diffusion assay against six different bacterial strains revealed significant antibacterial activity of the novel analogs against S. aureus at a concentration of 100 µg/mL. One of the novel compounds showed a remarkably broad spectrum of antibacterial activity, comparable to that of the positive control NQNO. [ABSTRACT FROM AUTHOR]

Building blocks have been identified that can be functionalised by sequential nucleophilic aromatic substitution. Some examples are reported that involve the formation of cyclic benzodioxin and phenoxathiine derivatives from 4,5-difluoro-1,2-dinitrobenzene, racemic quinoxaline thioethers, and sulfones from 2,3-dichloroquinoxaline and (2-aminophenylethane)-2,5-dithiophenyl-4-nitrobenzene from 1-(2-aminophenylethane)-2-fluoro-4,5-dinitrobenzene. Four X-ray single-crystal structure determinations are reported, two of which show short intermolecular N–O...N "π hole" contacts. [ABSTRACT FROM AUTHOR]

Nonradiative recombination at the front contact interface of kesterite solar cells hinders the extraction of photo‐generated carriers, significantly restricting the efficiency enhancement. However, identifying the recombination centers and proposing effective passivation strategies remain open questions. First‐principles calculations combining with nonadiabatic molecular dynamics (NAMD) simulations unveil that the interfacial translational symmetry breaking in elemental valence states leads to a detrimental donor‐like Cu2ZnSnS4/CdS interface with deep states originating from the interfacial Sn‐5s orbital, which serve as significant nonradiative recombination centers. Here, two mechanisms are proposed for eliminating the deep interface states: 1) directly replacing Sn‐5s with higher outer orbital levels by substituting group IIIA elements (In and Ga) for the interfacial Sn atom; 2) introducing an extra defect‐level coupling with Sn‐5s by substituting group VA elements (N, P, and As) for the S atoms bonded with the interfacial Sn atom. The representative InSn and PS acceptor defects, which are energetically favorable at the detrimental donor‐like interface, effectively passivate the deep interface states, markedly improving the carrier lifetimes by weakening nonadiabatic coupling between the band edge and the interfacial states. This study reveals the origin of the interfacial nonradiative recombination of kesterite solar cells and offers insights into interfacial passivation in semiconductor devices. [ABSTRACT FROM AUTHOR]

This paper outlines a novel strategy for the preparation of seven-membered-ring lactams from simple nitroarenes. The approach is based on a photochemical dearomative ring expansion starting with the conversion of the nitro group into a singlet nitrene. This process is mediated by blue light, occurs at room temperature and overall enables the insertion of the nitro N -atom into the benzenoid framework. This step transforms the aromatic starting material into a seven-membered ring azepine that, following hydrogenation and hydrolysis, is converted into the desired caprolactams in just three steps. [ABSTRACT FROM AUTHOR]

Synthetic route of 3,5-dichlorosalicylic acid anilide containing the carboxymethoxy group in the aniline fragment in ortho-position to amide group has been suggested. The obtained intermediate (2,4-dichloro-6-nitrophenoxy)-N,N-dimethylacetamide has been reduced into the amine and acylated with 3,5-dichloro-2-hydroxybenzoyl chloride, and then protective N,N-dimethylamide group has been selectively hydrolyzed in an alkaline medium. Without protection of the carboxyl group, the reaction with 3,5-dichloro-2-hydroxybenzoyl chloride has afforded mainly 6,8-dichloro-2H-1,4-benzoxazin-3(4H)-one. [ABSTRACT FROM AUTHOR]

A series of 61 thiazolidine-2,4-diones bearing a styryl group at position 5 was synthesized in 2–5 steps and their structure was proved by elemental and spectral analyses. The compounds obtained were evaluated in vitro against the promastigote stage of the kinetoplastid parasite Leishmania infantum and the human HepG2 cell line, to determine selectivity indices and to compare their activities with those of antileishmanial reference drugs. The study of structure–activity relationships indicated the potential of some derivatives bearing a nitro group on the phenyl ring, especially when located at the meta position. Thus, among the tested series, compound 14c appeared as a hit compound with good antileishmanial activity (EC50 = 7 µM) and low cytotoxicity against both the hepatic HepG2 and macrophage THP-1 human cell lines (CC50 = 101 and 121 µM, respectively), leading to good selectivity indices (respectively, 14 and 17), in comparison with the reference antileishmanial drug compound miltefosine (EC50 = 3.3 µM, CC50 = 85 and 30 µM, SI = 26 and 9). Regarding its mechanism of action, among several possibilities, it was demonstrated that compound 14c is a prodrug bioactivated, predominantly by L. donovani nitroreductase 1, likely leading to the formation of cytotoxic metabolites that form covalent adducts in the parasite. Finally, compound 14c is lipophilic (measured CHI LogD7.7 = 2.85) but remains soluble in water (measured PBS solubility at pH7.4 = 16 µM), highlighting the antileishmanial potential of the nitrostyrylthiazolidine-2,4-dione scaffold. [ABSTRACT FROM AUTHOR]

The use of non–precious metals for electrocatalytic hydrogen reaction (HER) is particularly important for energy conservation and environmental protection. In this work, three new cobalt corroles containing o−, m−, and p−nitrobenzyl (1, 2, 3) at the meso 10−position of the corrole macrocycle were synthesized, and their electrocatalytic hydrogen evolution reaction in organic and neutral aqueous systems was also investigated. The results show that these three cobalt corroles have significant catalytic HER activity in both systems, and the catalytic efficiency follows 1 > 3 > 2, which indicates that the position of the nitro group can affect the catalytic property of the complexes. In the organic phase, when using trifluoroacetic acid or p−toluenesulfonic acid as the proton source, the electrocatalytic HER may undergo an EECC (E: electron transfer, C: proton coupling) pathway. In a neutral aqueous system, the HER turnover frequency value of 1 is up to 137.4 h−1 at 938 mV overpotential. [ABSTRACT FROM AUTHOR]

Dearomative Diels‐Alder cycloadditions between nitroarenes and 2‐trimethylsilyloxycyclohexadiene are carried out under high pressure at room temperature in the absence of any chemical promoter. Reactions are performed with different arenes, including the highly aromatic naphthalenes and quinolines. They lead to 3D‐scaffolds with exquisite exo‐diastereoselectivity. The exo approach is characterized by lower distortion of the substrates in a late TS and by more favorable orbital interactions presumably between the nitro group and the dienic part, explaining the stereoselectivity. [ABSTRACT FROM AUTHOR]

Bacterial nitroreductase enzymes capable of activating imaging probes and prodrugs are valuable tools for gene-directed enzyme prodrug therapies and targeted cell ablation models. We recently engineered a nitroreductase (E. coli NfsB F70A/F108Y) for the substantially enhanced reduction of the 5-nitroimidazole PET-capable probe, SN33623, which permits the theranostic imaging of vectors labeled with oxygen-insensitive bacterial nitroreductases. This mutant enzyme also shows improved activation of the DNA-alkylation prodrugs CB1954 and metronidazole. To elucidate the mechanism behind these enhancements, we resolved the crystal structure of the mutant enzyme to 1.98 Å and compared it to the wild-type enzyme. Structural analysis revealed an expanded substrate access channel and new hydrogen bonding interactions. Additionally, computational modeling of SN33623, CB1954, and metronidazole binding in the active sites of both the mutant and wild-type enzymes revealed key differences in substrate orientations and interactions, with improvements in activity being mirrored by reduced distances between the N5-H of isoalloxazine and the substrate nitro group oxygen in the mutant models. These findings deepen our understanding of nitroreductase substrate specificity and catalytic mechanisms and have potential implications for developing more effective theranostic imaging strategies in cancer treatment. [ABSTRACT FROM AUTHOR]

A series of transition metal‐pnictogenide compounds were prepared starting from [(Dipp2NacNac)MCl] (M=Cr, Mn, Fe, Zn) (Dipp2NacNac=HC{C(Me)N(Dipp)}2) and [M'E(SiMe3)2] (M'=Li, K; E=P, As, Sb) as well as [Li(Et2O)nPH2] and [Li(tmeda)AsH2]. In the course of these investigations we were able to characterize all permutations for compounds of the composition [(Dipp2NacNac)ZnE(SiMe3)2] (E=P, As, Sb) and [(Dipp2NacNac)ZnEH2] (E=P, As). Moreover, the synthesis of selected compounds of type [(Dipp2NacNac)ME(SiMe3)2] for M=Cr, Mn, Fe and E=P−Sb are described. As part of our efforts, we established a number of bonding motifs that are underexplored in the literature to date. All isolated compounds, were examined by NMR spectroscopy, IR spectroscopy, Elemental analysis and X‐Ray structure analysis. DFT calculations on the chromium compounds were performed to investigate the binding situation between chromium and the group 15 element in more detail. [ABSTRACT FROM AUTHOR]

New C–N-bonded bisazoles were obtained by cine-substitution of 1,3-dinitro-1H-pyrazole-4-carbonitrile by the action of N-azoles. Their spectral characteristics were investigated using multinuclear NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Sodium salt of 3-nitro-4-hydroxy-7-methylthio-4H-[1,2,4]triazolo[5,1-c][1,2,4]triazinide mono-hydrate (compound (1)) is one of promising compounds exhibited potential antiviral activity against the Coxsackie B3 virus. Using cyclic voltammetry, it was found that the electrochemical activity of compound 1 on a glassy carbon electrode in a Britton–Robbinson buffer solution (BRB) is due to the electroreduction of the nitro group. A method for determining compound 1 using direct cathodic square-wave voltammetry is developed. The linearity range of the calibration curve using the developed method in a BRB solution (pH 2.0 ± 0.1) is 10–300 mg/L (R2 = 0.999) with the limits of detection and determination being 1.27 and 4.11 mg/L, respectively. [ABSTRACT FROM AUTHOR]

Reaction of 4,6-dinitroresorcinol (1) and the nitrogen base 1,4-diazabicyclo[2·2·2]octane (2) affords the 1:2 salt and proton-transfer compound 1,4-diazabicyclo[2·2·2]octane-1,4-diium bis(5-hydroxy-2,4-dinitrophenolate) (3). Compound 3 crystallizes in the triclinic crystal system (space group P-1) with a = 8.3242(5) Å, b = 11.9915(7) Å, c = 12.4595(7) Å, α = 116.282(2)°, β = 100.576(3)°, γ = 101.051(2)°, 1042.30(11) Å3 and Z = 2. The dication 2- H 2 2 + forms charge assisted donating bifurcated N+−H⋅⋅⋅O− hydrogen bonds to the phenolate moieties of two monoanions of 1. The latter exhibit an intramolecular O−H⋅⋅⋅O hydrogen bond between the hydroxy group and the nitro group in ortho position. The crystal structure of 3 features pseudo B-centering of the lattice, which relates the two crystallographically distinct monoanions of 1 by a pseudo translation. The possible B-centring is broken by the ethylene groups of 2-H22+, which are related in neighbouring molecules by centres of symmetry. [ABSTRACT FROM AUTHOR]

[Display omitted] 2 ' -Hydroxychalcones of 2-cinnamoyl-4-nitro-1-naphthol series were obtained by the condensation between 2-acetyl- 4-nitro-1-naphthol and benzaldehydes. The presence of the 4-positioned nitro group in the 1-hydroxy-2-naphthyl fragment contributes to the excited state intramolecular proton transfer (ESIPT) fluorescence of these 2 ' -hydroxy- chalcones in the solid state. Compound with dimethyl- amino substituent, 2-(4-dimethylaminocinnamoyl)-4-nitro- 1-naphthol, also demonstrates ESIPT in solution. [ABSTRACT FROM AUTHOR]

An efficient and versatile synthesis of alcohols via transfer hydrogenation from ketones with isopropanol, utilizing [Ni(6,6′‐(OH)2‐2,2′‐bpy)][Br2] under alkaline conditions, has been documented. It was noteworthy that many readily reducible or labile functional groups such as nitro, cyano, and halide, within the same molecular framework, did not undergo any change under the standard reaction conditions. Furthermore, the gram scale transfer hydrogenation reaction was successfully carried out with good yield using a common route with only a single purification by column chromatography. [ABSTRACT FROM AUTHOR]

Two 3D coordination polymers based on dinuclear dianionic helicates, K2[MII2(L)3] M = MnII (1) and NiII (2), were obtained by slow liquid–liquid diffusion of solutions of 2-hydroxy-5-nitrobenzaldehyde, 4,4′-methylenedianiline, KOtBu and the metal salt at room temperature. The resulting dianionic triply stranded helicates self-assemble into novel 3D coordination polymers, in which the helicate units act as connectors. The assembly is promoted by the phenolate bridging ability and the coordination of the pre-organized NO2 groups to K–(O–N–O)4–K nodes, resulting in robust paramagnetic materials. SC-XRD shows that the metal centers are located 11.257(2) and 11.264(1) Å apart. The Mn–L bond lengths correspond to the high-spin (HS, S = 5/2) state for 1. The magnetic behavior for both complexes shows weak magnetic exchange, as expected due to the spin carrier separation, and the confirmation of the HS-sate for the MnII centers. For complex 1, an antiferromagnetic exchange is detected, whereas for complex 2, a mixture of intramolecular antiferromagnetic and intermolecular ferromagnetic exchanges are detected. Thus, we demonstrated that nitro groups can be used for the stabilization of anionic complexes because coordination to K+ results in stable intricate architectures. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We investigated the inhibition of thermal runaway of styrene polymerization by DNPB. DNBP is an inhibitor in styrene polymerization reaction. Polymerization is one of eighteen hazardous processes. Styrene polymerization reaction is characterized by high heat production and fast reaction rate. Firstly, differential scanning calorimetry (DSC) and adiabatic calorimetry (ARC) were chosen to study the effect of different mass of DNBP on thermal behavior in non-isothermal and adiabatic environments. Secondly, exploring the inhibitory effect of DNBP at different runaway temperatures using an oil bath reactor. The results showed that when DNBP was at 0.80%, effective inhibition was obtained at different runaway temperatures. Finally, GC/MS and Gauss16 were used to infer the mechanism of inhibition in terms of macroscopic products and microscopic instabilities. The results showed that the products of the oil bath reactor experiments were related to the mass of DNBP, and when DNBP was 0.80%, the products increased and the main reaction was inhibited. Finally, it was deduced that the nitro group undergoes a possible path of direct addition reaction with the styrene radical before bond breaking. [ABSTRACT FROM AUTHOR]

Density Functional Theory is used to unravel the mechanism of the nitrobenzene to aniline reduction, catalyzed by dioxomolybdenum (VI) dichloride. The use of pinacol as an oxoaccepting reagent and the production of only acetone and water as byproducts, signals a novel and environmentally friendly way to add value to the oxygen‐rich biomass‐derived polyols. The reaction proceeds through three consecutive cycles, each one responsible for one of the three reductive steps needed to yield aniline from nitrobenzene, with nitrosobenzene and hydroxylamine as intermediates. Each cycle regenerates the catalyst and releases one water and two acetone molecules. The mechanism involves singlet/triplet state crossings, a crucial feature in polyoxomolibdate catalyzed processes. The role of the Mo‐coordinated water as the provider of the mysterious protons needed to reduce the nitro group, was revealed. The disclosure of this challenging mechanism and its rate limiting step can contribute to the design of more effective Mo(VI) catalysts. [ABSTRACT FROM AUTHOR]

Heterocycles that pair main group elements and nitrogen are extremely important within the π‐conjugated heterocycles research community. Compared to the vast number of boron‐nitrogen heterocycles, those that include phosphorus are less common. Furthermore, the use of phosphorus‐nitrogen triple bonds of any type to prepare such compounds is unprecedented. Here, we pair pyridyl hydrazonide ligands with phosphadiazonium cations and demonstrate that the chelated Mes*NP group is directly implicated in the photophysical and redox properties observed for the resulting heterocycles. In doing so, we introduce a novel building block for the production of phosphorus‐containing heterocycles that could find use in small molecule activation and catalysis or as the functional component of emerging organic electronics. [ABSTRACT FROM AUTHOR]

New promising energetic materials comprised of 1,2,4-triazole and furoxan rings and bearing explosophoric nitro group were rationally designed and synthesized. All newly prepared compounds were thoroughly characterized and their physicochemical properties were estimated. In the newly synthesized series, (1,2,4-triazolyl)furoxan 4 is completely insensitive to impact and friction and possesses good detonation performance (D = 8.4 km s-1; P = 33 GPa) enabling its further exploration as a promising high-energy material. [ABSTRACT FROM AUTHOR]