Naphthalene Derivatives Research Articles

On the Savéant's Concerted/Stepwise Model. The Electroreduction of Halogenated Naphthalene Derivatives as a Case Study

AbstractThe electroreduction mechanism of 1‐Br‐2‐naphtol and 1‐I‐2‐naphtol, and of two inherently chiral BINOL derivatives ([1,1′‐Binaphthalene]‐2,2′‐diol, 6,6′‐dibromo and 1,1′‐Binaphthalene,6,6′‐dibromo‐2,2′‐dimethoxy; in the following named P1 and P2, respectively), is characterized by means of an integrated electrochemical and theoretical approach. The experimental characterization is based on cyclic voltammetry measurements. The experimental results indicate that the carbon halogen bond dissociates, following the electron uptake, with the formation of an insoluble final product (electro‐polymerization). The reduction mechanism is assessed and disassembled at a molecular level by using DFT based quantum mechanical calculations. Both steady state, equilibrium, and kinetic (molecular dynamics, MD, DRC calculations) properties are calculated. A consistent picture is obtained by the comparison between experimental and theoretical results, indicating that the carbon‐halogen bond dissociates following the first electron uptake, with a stepwise mechanism.

In-silico Molecular Docking of Coumarin and Naphthalene Derivatives from Pyrenacantha volubilis with the Pathological Mediators of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease which mainly targets synovial membrane during its disease pathogenesis. Available therapeutic drugs for the treatment of RA provide only symptomatic relief and are associated with severe side effects. Herbal plants comprise many active biological compounds that cure the disease with minimal adverse effects. Pyrenacantha volubilis is a climber and member of Icacinaceae family. Gas chromatography- mass spectrometry (GC-MS) analysis of ethanolic extracts of leaves of Pyrenacantha volubilis (EEPV) reveals the presence of 2-isopropyl-5-methylcyclohexyl 3-(1-(4- chlorophenyl)-3-oxobutyl)-coumarin-4-yl carbonate and 1-naphthalenepropanol, alpha-ethyldecahydro-5- (hydroxymethyl)-alpha,5,8A-trimethyl-2-methyl phytoconstitutents. Hence these compounds were docked with various pathological mediators of RA using Autodock 4.2. The docking results unveils that these compounds had better binding energy against inflammatory, oxidative stress and receptor for advanced glycation end products (RAGE) mediators that plays a pivotal role in the progression of RA. However, this study warrants further in- vitro and in-vivo studies to be carried out to establish the anti-inflammatory and anti-arthritic activity of selected phytoconstitutents.

Formation of Boundary Lubricant Films during Friction in Synthetic Oil Modified by Naphthalene Derivatives

Formation of Boundary Lubricant Films during Friction in Synthetic Oil Modified by Naphthalene Derivatives

Restriction of Twisted Intramolecular Charge Transfer Enables the Aggregation-Induced Emission of 1-(N,N-Dialkylamino)-naphthalene Derivatives.

Understanding the mechanisms of aggregation-induced emission (AIE) is essential for the rational design and deployment of AIEgens toward various applications. Such a deep mechanistic understanding demands a thorough investigation of the excited-state behaviors of AIEgens. However, because of considerable complexity and rapid decay, these behaviors are often not experimentally accessible and the mechanistic comprehension of many AIEgens is lacking. Herein, utilizing detailed quantum chemical calculations, we provide insights toward the AIE mechanism of 1-(N,N-dialkylamino)-naphthalene (DAN) derivatives. Our theoretical analysis, corroborated by experimental observations, leads to the discovery that modulating the formation of the twisted intramolecular charge transfer (TICT) state (caused by the rotation of the amino groups) and managing the steric hindrance to minimize solid-state intermolecular interactions provides a plausible explanation for the AIE characteristics of DAN derivatives. These results will inspire the deployment of the TICT mechanism as a useful design strategy toward AIEgen development.

Pd‐Catalyzed Cyclization of Alkynyl Norbornene Derivatives for the Synthesis of Benzofused Heteroarenes

AbstractModular approaches, which allow a systematic variation of heteroaromatic cores and substituents, are crucial for the development of heteroaromatic drug candidates and organic functional materials. A new strategy involving the cyclization of heteroarenes tethered with alkynes through a norbornene bridge was developed. The precursors were readily prepared by a three‐component coupling process of heteroaryl halides, norbornadiene, and terminal alkynes. The Pd catalytic system derived from Pd(OAc)2and 2‐(pyrazol‐1‐yl)pyridine transformed a variety of five‐membered heteroarenes to the corresponding benzofused products, including (di)benzothiophene, indazole, carbazole, indole, and benzofuran, with aryl and alkyl substituents at the C4(C7) position. During the cyclization process, the norbornene ring underwent a retro‐Diels‐Alder reaction, serving as an acetylene synthon. This approach was used to synthesize naphthalene derivatives from electron‐rich arenes, demonstrating its versatility in the annulation of (hetero)aromatic rings.magnified image

Biotransformation of Reactive Red 141 by Paenibacillus terrigena KKW2-005 and Examination of Product Toxicity.

A total of 37 bacterial isolates were obtained from dye-contaminated soil samples at a textile processing factory in Nakhon Ratchasima Province, Thailand, and the potential of the isolates to decolorize and biotransform azo dye Reactive Red 141 (RR141) was investigated. The most potent bacterium was identified as Paenibacillus terrigena KKW2-005, which showed the ability to decolorize 96.45% of RR141 (50 mg/l) within 20 h under static conditions at pH 8.0 and a broad temperature range of 30-40°C. The biotransformation products were analyzed by using UV-Vis spectrophotometry and Fourier-transform infrared spectroscopy. Gas chromatography-mass spectroscopy analysis revealed four metabolites generated from the reductive biodegradation, namely sodium 3-diazenylnaphthalene-1,5-disulfonate (I), sodium naphthalene-2-sufonate (II), 4-chloro-1,3,5-triazin-2-amine (III) and N1-(1,3,5-triazin-2-yl) benzene-1,4-diamine (IV). Decolorization intermediates reduced phytotoxicity as compared with the untreated dye. However, they had phytotoxicity when compared with control, probably due to naphthalene and triazine derivatives. Moreover, genotoxicity testing by high annealing temperature-random amplified polymorphic DNA technique exhibited different DNA polymorphism bands in seedlings exposed to the metabolites. They compared to the bands found in seedlings subjected to the untreated dye or distilled water. The data from this study provide evidence that the biodegradation of Reactive Red 141 by P. terrigena KKW2-005 was genotoxic to the DNA seedlings.

Simultaneous Determination of the Chemical (kr ) and the Physical (kq ) Quenching Rate Constants of Singlet Oxygen in Aqueous Solution by the Chemiluminescence-quenching Method.

This work reports a novel and visual method for the simultaneous determination of the chemical (kr ) and the physical (kq ) quenching rate constants of singlet oxygen (1 O2 ,1 ∆g ) in aqueous media. It is based on the disruption, by a water-soluble substrate S, of the 1 O2 chemiluminescence (CL) generated by the H2 O2 /Na2 MoO4 catalytic system. A mathematical analysis of the CL signal at 1270 nm vs time provides separately the overall (kr + kq ) and the chemical (kr ) quenching rate constants. In ordinary water (H2 O), 1 O2 lifetime is short and the CL intensity is weak allowing solely the investigation of very reactive substrates for which (kr + kq ) > 3 × 106 m-1 s-1 while, in D2 O, 1 O2 lifetime is significantly longer lifetime and the CL signal is much stronger allowing the study of poorly reactive substrates for which (kr + kq ) > 4 × 105 m-1 s-1 . The method has been successfully tested on a series of anionic and nonionic water-soluble naphthalene derivatives commonly used as bio-compatible 1 O2 carriers. The obtained kr and kq values are in good agreement with the values determined by conventional techniques, namely, flash photolysis and competitive kinetics with a reference quencher.

Palladium‐Catalyzed C8‐Oxygenation of Naphthalene Derivatives: Direct Access to Naphtholactone Skeleton

AbstractHerein, a direct C8‐oxygenation of naphthalene derivatives is described. Different carbonyl groups were used as directing group to deliver corresponding naphthols via a palladium‐catalyzed oxidation reaction using PhI(OAc)2 in a TFA/TFAA mixture. Interestingly, when Weinreb amide was employed as the directing group, the naphtholactone skeleton was directly obtained. This methodology was applied to the synthesis of variously substituted naphtholactones.magnified image

Crystal Structure and Magnetism of Potassium-Intercalated 2,7-Dimethylnaphthalene

The rich physical properties of metal-intercalated polycyclic aromatic hydrocarbon materials have recently attracted considerable attention. Crystals of potassium-intercalated 2,7-dimethylnaphthalene were synthesized via solid phase reaction. The combination of XRD measurements and first-principles calculations indicated that each unit cell contains two potassium atoms and four organic molecules. Magnetization measurements revealed that the samples show a Curie paramagnetism. Theoretical calculations showed that the intercalated structure becomes metallic and has local magnetic moment. Raman spectroscopy confirmed the migration of electron from potassium 4s to carbon 2p orbital, which is the source of magnetism. Our research on naphthalene derivatives is helpful for expanding the range of novel organic magnetic materials and organic superconducting materials.

Phytochemical analysis and biological activities of “Cherchoomoro” (Nepeta adenophyta Hedge)

Ethnopharmacological relevanceNepeta adenophyta Hedge (Lamiaceae) is an endemic therapeutic herb from Astore, Gilgit (Pakistan). This plant species has been reported among the local communities, especially for treating abdominal pain, kidney pain, menstrual pain, headache, and controlling bleeding disorders. Therefore, the scientific basis is provided for the relief of pain as it is used in various pain management among the natives, especially as ethnogynecological herbal remedy. Aim of the studyThe present study investigates the analgesic and anti-inflammatory effects of the ethanolic extract of N. adenophyta in animal models. Furthermore, the extract was also studied to determine their valuable phytoconstituents. Material and methodsThe biological effects were determined via tail-flick, hot plate, and acetic-acid-induced abdominal writhing methods. At the same time, anti-inflammatory activity was assesed via oxidative burst and antioxidant DPPH assay. Gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-mass spectrometry (LC-MS) techniques were employed to understand the phytochemicals present in the crude ethanolic extract of Nepeta adenophyta. ResultsIn the current study, Nepeta adenophyta extract exhibited potent analgesic and anti-inflammatory effects on different pain models and indicated that the analgesic effect of N. adenophyta extract is mediated both in central and peripheral ways. Dose-dependent and significant (P < 0.05) increases were shown in pain threshold, at 45 min post-treatment, with 20 and 40 mg/kg of the extract in the tail-flick model. The effects of the extract were similar to aspirin but lower to those by morphine (2.5 mg/kg) in the same tests. The extract (20–40 mg/kg) showed dose-dependent inhibition of writhing with a significant (P < 0.001) increase protection against thermal stimuli in hot plate test as compared to control and similar to aspirin and morphine. Further, the anti-inflammatory activity of the crude in oxidative burst and DPPH assays showed significant inhibitory activity. The chemical profile analysis showed major phytochemicals, including long chain derivatives of alkane and alcohol, phenolics, naphthalene, naphthopyran, androsten phenanthrenone, nepetalactones, flavonoids etc. ConclusionsNepeta adenophyta Hedge is suggested as a natural alternative for mild pain relief. Our findings endorse the folklore use of N. adenophyta in different pain managements which can be attributed to the presence of polyphenolic compounds, naphthalene derivatives, flavanoids and nepetalactones etc.

Chemical Composition and Low-Temperature Fluidity Properties of Jet Fuels

The physicochemical properties of petroleum-derived jet fuels mainly depend on their chemical composition, which can vary from sample to sample as a result of the diversity of the crude diet processed by the refinery. Jet fuels are exposed to very low temperatures both at altitude and on the ground in places subject to extreme climates and must be able to maintain their fluidity at these low temperatures otherwise the flow of fuel to turbine engines will be reduced or even stopped. In this work, an experimental evaluation of the effect of chemical composition on low-temperature fluidity properties of jet fuels (freezing point, crystallization onset temperature and viscosity at −20 °C) was carried out. Initially, a methodology based on gas chromatography coupled to mass spectrometry (GC–MS) was adapted to determine the composition of 70 samples of Jet A1 and Jet A fuels. This methodology allowed quantifying the content, in weight percentage, of five main families of hydrocarbons: paraffinic, naphthenic, aromatic, naphthalene derivatives, and tetralin- and indane-derived compounds. Fuel components were also grouped into 11 classes depending on structural characteristics and the number of carbon atoms in the compound. The latter compositional approach allowed obtaining more precise model regressions for predicting the composition–property dependence and identifying individual components or hydrocarbon classes contributing to increased or decreased property values.

Formation of boundary lubricating films during friction in synthetic oil modified with naphthalene derivatives

The influence of additives of naphthalene derivatives on the formation of boundary lubricating layers during friction in a dioctyl sebacate synthetic oil is considered. It is determined, that the activity of the additives is determined by the presence of acidic groups in their molecules and the ability to form complex compounds with metals. Keywords: boundary film, dioctyl sebacate, naphthalene derivatives, complex formation, lubricating properties alekc_sap@mail.ru

Optimization of 1,4-bis(arylsulfonamido)naphthalene-N,N'-diacetic acids as inhibitors of Keap1-Nrf2 protein-protein interaction to suppress neuroinflammation

The protein–protein interaction (PPI) between kelch-like ECH-associated protein 1 (Keap1) and nuclear factor erythroid 2-related factor 2 (Nrf2) is recognized as a promising target for the prevention and treatment of oxidative stress-related inflammatory diseases. Herein, a series of novel 1,4-bis(arylsulfonamido)naphthalene-N,N'-diacetic acid analogs (7p-t and 8c) were designed to further explore the structure–activity relationships of the series. Their activities were measured first with a fluorescence polarization (FP) assay and more potent compounds were further evaluated using a more sensitive time-resolved fluorescence energy transfer (TR-FRET) assay, demonstrating IC50 values between 7.2 and 31.3 nM. In cytotoxicity studies, the naphthalene derivatives did not show noticeable toxicity to human HepG2-C8 and mouse brain BV-2 microglia cells. Among them, compound 7q bearing oxygen-containing fused rings was shown to significantly stimulate the cellular Nrf2 signaling pathway, including activation of antioxidant response element (ARE)-controlled expression of Nrf2 target genes and proteins. More importantly, 7q suppressed up-regulation of several pro-inflammatory cytokines in lipopolysaccharide (LPS)-challenged BV-2 microglial cells, representing a potential therapeutic application for controlling neuroinflammatory disorders.

An efficient synthetic approach for the transition metal-free preparation of 2-bromo-3-(bromomethyl)naphthalene from naphthalene

In this paper, a new efficient method for the synthesis of 2-bromo-3-(bromomethyl)naphthalene is reported. The synthesis is based on (1) preparation of 1,4-dihydronaphthalene via Birch reduction with mild conditions from the reaction of naphthalene, and (2) the reaction between 1,4-dihydronaphthalene and dichlorocarbene generated in situ from chloroform and t-BuOK, and (3) access to the key intermediate 1H-cyclopropa[b]naphthalene from the reaction of 1,1-dichloro-1a,2,7,7a-tetrahydro-1H-cyclopropa[b]naphthalene with t-BuOK, followed by ring-opening of the three-membered cyclopropane by bromination with molecular bromine (Br2). This synthetic sequence allows simple preparation of 2-bromo-3-(bromomethyl)naphthalene in higher yields compared to the two previously reported syntheses. The synthetic approach is modular, low cost, and rapid, and can be utilized to synthesize building blocks of naphthalene derivatives.

Relationship between Volatile Composition and Bioactive Potential of Vegetables and Fruits of Regular Consumption-An Integrative Approach.

In recent years, there has been a growing interest in studying and exploring the potential health benefits of foods, mainly from vegetables and fruits from regular intake. The presence of secondary metabolites, namely polyphenols, carotenoids and terpenes, in certain food matrices seems to contribute to their functional properties, expressed through an increased prevention in the development of certain chronic diseases, namely coronary heart diseases, neurodegenerative diseases, cancer and diabetes. However, some foods’ volatile secondary metabolites also present important bioactive properties, although this is a poorly scientifically explored field. In this context, and in order to explore the potential bioactivity of volatile metabolites in different vegetables and fruits from regular consumption, the volatile composition was established using a green extraction technique, solid phase microextraction in headspace mode (HS-SPME), combined with gas chromatography tandem mass spectrometry (GC-MS). A total of 320 volatile metabolites, comprising 51 terpenic compounds, 45 organosulfur compounds, 31 aldehydes, 37 esters, 29 ketones, 28 alcohols, 23 furanic compounds, 22 hydrocarbons, 19 benzene compounds, 13 nitrogenous compounds, 9 carboxylic acids, 7 ethers, 4 halogenated compounds and 3 naphthalene derivatives, were positively identified. Each investigated fruit and vegetable showed a specific volatile metabolomic profile. The obtained results revealed that terpenic compounds, to which are associated antimicrobial, antioxidant, and anticancer activities, are the most predominant chemical family in beetroot (61%), orange carrot (58%) and white carrot (61%), while organosulfur compounds (antiviral activity) are dominant in onion, garlic and watercress. Broccoli and spinach are essentially constituted by alcohols and aldehydes (enzyme-inhibition and antimicrobial properties), while fruits from the Solanaceae family are characterized by esters in tamarillo and aldehydes in tomato.

Survey of airborne organic compounds in residential communities near a natural gas compressor station: Response to community concern

IntroductionNatural gas compressor stations are located throughout the country and are used to maintain gas flow and ensure continuous distribution through the pipeline network. Compressor stations emit many air contaminants including volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs). While the serious health effects associated with the inhalation of elevated pollutant levels are clear, the relationship between proximity to natural gas compressor stations and residential health effects is not well understood. Community members living near a natural gas compressor station in Eastern Ohio expressed concerns regarding their air quality; therefore, the objective of this study was to assess exposure to airborne organics in residential air near the compressor station. MethodsOur team conducted a 24-hour air sampling campaign to assess outdoor and indoor air contaminant levels at 4 homes near the Williams Salem Compressor Station in Jefferson County, Ohio. Air quality was assessed using two techniques: 1) summa canisters to quantify VOC concentrations and 2) passive air samplers to evaluate a broader panel of VOCs and SVOCs. ResultsAmong the three homes situated < 2 km from the compressor station, indoor benzene levels were 2-17 times greater than the Ohio Environmental Protection Agency (EPA) indoor standard due to vapor intrusion. Multiple other VOCs, including ethylbenzene, 1,2,4-trimethylbenzene, 1,2 dichloroethane, 1,3 butadiene, chloroform, and naphthalene also exceeded state standards for indoor concentrations. Several SVOCs were also detected inside and outside participants’ homes, including benzene and naphthalene derivatives. ConclusionOur results validate the community members’ concerns and necessitate a more comprehensive epidemiological investigation into the exposures associated with natural gas compressor stations and methods to mitigate elevated exposures.Alarming levels of VOCS were detected inside of homes. Further research is needed to determine the source of VOC exposure and potential health effects.

Dearomative spirocyclization via visible-light-induced reductive hydroarylation of non-activated arenes

A visible-light-induced spirocyclizative hydroarylation via reductive dearomatization of a series of non-activated arenes including 2-phenyl indoles and naphthalene derivatives under mild conditions is described. An intriguing chemoselective dearomative hydroarylation of 2-phenyl indoles is presented. This dearomative hydroarylation protocol rapidly delivers valuable spirocycles with carbon−carbon double bonds from readily accessible aromatic precursors in a single step.

Solvent-controlled intramolecular excimer emission from organosilicon derivatives of naphthalene

New mono-, bis- and tetra-fluorophoric organosilicon naphthalene derivatives, that are able to form intramolecular excimers have been synthesized and characterized. The synthesized compounds show only monomeric fluorescence in dilute solutions of common organic solvents, but exhibit relatively strong excimer-like emission in DMSO-water and THF-water mixtures. In all cases, the intensity of excimer fluorescence increases with increasing water content and decreases with increasing temperature. Fully and partially overlapping excimer conformations have been modeled by DFT-based calculations. Properties of different intramolecular excimers in an ensemble of four naphthalene molecules linked to a cyclotetrasiloxane ring in an all-cis arrangement are considered.

Spirocyclizative Remote Arylcarboxylation of Nonactivated Arenes with CO 2 via Visible-Light-Induced Reductive Dearomatization

Spirocyclizative Remote Arylcarboxylation of Nonactivated Arenes with CO ₂ via Visible-Light-Induced Reductive Dearomatization

Analysis of the tautomeric equilibrium of two red monoazo dyes by UV–Visible, Raman and SERS spectroscopies

Acid Red 26 and Acid Red 18 are two early synthetic dyes belonging to the monazo dye class. The molecular structure of this class of dyes is characterized by the chromophoric azo group (NN) generally attached to benzene or naphthalene derivatives containing electron withdrawing and/or donating groups as substituents. As both red dyes have an OH group in ortho- position respect to the azo group, they undergo an azo-hydrazone tautomerism. In this work, UV–Vis, Raman and SERS spectroscopic analysis of the red dye solutions were carried out at different pH conditions, in order to evaluate the preponderance of one tautomer over the other as a function of the pH. Different experimental conditions were tested in order to find the best ones for the detection of both dyes. Thus, Raman spectra of the powder and aqueous solutions of AR26 and AR18 were obtained at the natural pH of the solutions, and above and below that value. The SERS analysis of the dye solutions were carried out at various pH values between 2 and 10, and with excitation at 442, 532 and 633 nm. The molecular structure and the theoretical Raman spectra of the two tautomers of both red dyes were calculated by DFT methods. The obtained results were used for the assignment of the Acid Red 26 and Acid Red 18 vibrational modes. Finally, a textile sample dyed with AR18 was analyzed by SERS.