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Herein we report a method for converting para-substituted pyridine rings into meta-dialkylamino-substituted benzene rings through sequential ring-opening and ring-closing reactions. The nitrogen atom in the pyridine rings was replaced with a methine group, and a dialkylamino substituent was introduced onto the original unsubstituted carbon atom in the pyridine rings. This process can be formally regarded as a hybrid of the skeletal editing and C-H amination of pyridine rings.

In this approach, formulae-based mnemonics by using the classification of negative charge (localized or delocalized) have been highlighted by innovative and time economic way to enhance interest of students’ who belong to paranoia zone of chemistry for the prediction of hybridization state of carbon atom containing negative charge (one or more) and aromatic, anti-aromatic, non-aromatic behavior of different organic compounds. Here, I have tried to hub three (03) time economic mnemonics by including three (03) formulae for the prediction of hybridization state of carbon atom (containing negative charge), aromatic, anti-aromatic, and non-aromatic behavior of organic compounds. Educators can use these mnemonics in their teaching style in the classroom lectures after discussing conventional methods and its limitation to make chemistry intriguing. This article encourages students to solve multiple choice type questions (MCQs) on ‘Aromaticity of negative charge containing organic compounds’ at different competitive examinations in a time economic ground.

A convenient synthetic approach to previously unknown NH-iminophosphonates bearing 2-, 3-, and 4-pyridyldifluoromethyl groups at the imine carbon atom was developed. The synthetic potential of these novel building blocks was demonstrated by their conversion into highly functionalized acyclic and heterocyclic aminophosphonates and phosphonic acids combining in their structure biorelevant aminophosphonic fragment, difluoromethyl group, and pyridyl, piperidyl, thiazolidin-4-one, or thiazidinan-4-one heterocyclic moieties in a single molecular platform.

This paper studies the classical restricted three-body problem of a carbon atom in the vicinity of two carbon 60 fullerenes ( fullerenes) at the nanoscale. The total molecular energy between the two fullerenes is determined analytically by approximating the pairwise potential energies between the carbon atoms on the fullerenes by a continuous approach. Using software MATHEMATICA, we compute the positions of the stationary points and their stability for a carbon atom at the nanosacle and it is observed that for each set of values, there exists at least one complex root with the positive real part and hence in the Lyapunov sense, the stationary points are unstable. Since only attractive Van der Waals forces contribute to the orbiting behavior, no orbiting phenomenon can be observed for , where the Van der Waals forces becomes repulsive. Although the orbital is speculative in nature and also presents exciting possibilities, there are still many practical challenges that would need to be overcome before the orbital might be realized. However, the present theoretical study is a necessary precursor to any of such developments.

Simple polycyclic aromatic hydrocarbons, substituted by strongly electron-donating (NH2) and withdrawing (NO2) groups, are studied employing density functional theory (DFT) calculations. A new approach to a description of the substituent effect, the energy of substituent, E(X), is proposed and evaluated. It is defined as E(X) = E(R-X)−E(R), where R is the unsubstituted system; X = NH2, NO2. Changes in the energy of the substituents, estimated for the benzene analog, Erel(X), allow the energy of the various substituents to be compared. The obtained values are interpreted through correlations with the geometry of the substituent and the substituted system. We show that Erel(X) is strongly dependent on the proximity of the substitution. Values of Erel(X) are also compared with a substituent descriptor based on atomic charge distribution–charge of the substituent active region, cSAR(X). It has been shown that these two descriptors correlate very well (R2 > 0.99); however, only for linear acenes with similar, “benzene-like” proximity. Moreover, relations between Erel(X) and cSAR(X), the geometry of the substituents, and angle at the ipso carbon atom can be explained by the well-established Bent–Walsh rule.

We report the synthesis of Ag nanocubes by using a sodium sulfide assisted solvothermal method. Small edge-length nanocubes (32 and 44 nm) were obtained at 145 and 155 °C reaction temperature in the synthesis process. The refractive index sensitivity of synthesized nanocubes was investigated with an aqueous solution of glucose. The refractive index sensitivity of 161 nm per RIU was found in the colloidal dispersion of nanocubes. On the LSPR chip made by immobilization of nanocubes on the (3-aminopropyl)trimethoxysilane modified glass coverslip, the obtained sensitivity was 116 nm per RIU. Detection of formaldehyde in water and milk samples was also performed with nanocubes of edge-length of 44 nm. Formaldehyde detection was performed by utilizing the interaction of the aryl amine of 4-aminothiophenol immobilized on the nanocubes and electrophilic carbon atom of the formaldehyde. In water and in diluted milk, the formaldehyde sensitivity of 0.62 and 0.29 nm μM−1 was obtained, respectively.

Hypochlorous acid (HOCl), with a low physiological concentration, plays a vital role in killing the pathogens and anti-inflammation in the human immune system. Deviation from the normal concentration is directly related to the inflammation-associated diseases and even cancer. Thus, it is necessary to sensitively detect the tiny concentration changes of HOCl. However, few of the reported probes could practically work well due to small Stokes shift, high detection of limits, and low SNR. In this study, HBT (2-(2′-Hydroxyphenyl)benzothiazole) was used as the candidate for the ESIPT-based fluorophore and connected to pyridine via “CC” bonds. The “CC” bonds are the reaction site for HOCl and are activated by the strong electron-withdrawing CN group located on the double-bond carbon atom, resulting in a high sensitivity towards HOCl. Thereby, the probe's emission shifted effectively to the red channel avoiding the interference from biological autofluorescence. The excellent response of the probe JBD towards HOCl enables it to detect endogenous hypochlorous acid in the cells and provides an ideal molecular tool for exploring the mechanism of hypochlorous acid in oxidative stress and its immune role.

The development of Cu-catalyzed coupling of vinylidene cyclopropanes with allyl or allenyl boronates is reported. The reaction forms a C-C bond at the terminal carbon atom of the allene moiety of vinylidene cyclopropanes with concurrent opening of the cyclopropane ring. In addition, the resulting Cu-enolate intermediate can be intercepted by external electrophiles.

A metal-templated synthetic route to cyclic (aryl)(ylidic) mesoionic carbenes (CArY-MICs) featuring an endocyclic P-ylide is presented. This approach, which requires metal templates with two cis-positioned open coordination sites, is based on the controlled cyclisation of a P,P′-diisopropyl-substituted 2,2′-diphosphinotolane (1) and leads to chelate complexes coordinated by a phosphine donor and the CArY-MIC carbon atom. The C–P bond formation involved in the former partial cyclisation of 1 proceeds under mild conditions and was shown to be applicable all over the d-block. In the presence of a third fac-positioned open coordination site, the P–C bond formation was found to be reversible, as shown for a series of molybdenum complexes. DFT modelling studies are in line with an interpretation of the target compounds as CArY-MICs., A metal-templated synthesis of cyclic (aryl)(ylidic)mesoionic carbene complexes (CArY-MICs) is presented. In the case of molybdenum carbonyls, the crucial P–C bond formation, which occurs during CArY-MIC formation, was found to be reversible.

The nitrogen-containing indeno[1,2-b]quinoxaline ring is a privileged structurally fused active system and has notable applications in various fields of chemistry. For the past several years, it has been recognized as an important building block in organic synthesis. This review summarizes the reactions of indeno[1,2-b]quinoxalinone as a key construction block for producing a variety of indeno[1,2-b]quinoxaline-based spiro-heterocyclic frameworks by means of a wide range of chemical reactions. Most of the reactions described here are multicomponent ones with readily available starting materials that produce complex molecular spiro architectures. Some of the synthesized spiro-indenoquinoxalines exhibit interesting biological activities and have promise for the generation of new drug candidates. Spiro compounds in which two cyclic rings are fused at a common carbon atom are promising interesting skeletal systems in drug discovery due to their unique conformational features, structural complexity and rigidity. The present review aims to highlight the reactions, synthetic strategies and pharmaceutical applications of diverse spiro-indeno[1,2-b]quinoxalines to date.

A synthetic approach to a novel type of phosphonium and mixed phosphonium-iodonium ylides containing a conformationally fixed phosphonium fragment is developed. New representatives of these families of chemical compounds based on cyclic phenoxaphosphinine were synthesized. One compound was structurally characterized by single-crystal X-ray diffraction. Based on the 1H NMR data, one can state that phosphonium ylide exists in solution in the form of two geometric isomers even at room temperature. This is indicative of pronounced double-bond character of the bond between the ylide carbon atom and the stabilizing carbomethoxy group.

1-Aryl-3-(2-hydroxy-5-R-phenyl)prop-2-en-1-ones reacted with the Reformatsky reagent derived from methyl 1-bromocyclohexanecarboxylate to give 4-(2-aryl-2-oxoethyl)-6-R-2H,4H-spiro[[1]benzopyran-3,1′-cyclohexan]-2-ones. The products are formed as a result of intramolecular cyclization of the adduct of the organozinc reagent and substituted chalcone via nucleophilic attack of the phenoxide oxygen atom on the ester carbonyl carbon atom. No cyclization products resulting from attack of the enolate oxygen atom on the ester carbonyl carbon atom were detected.

Chemically, fat or oil is a mixture of triacylglycerol molecules, in which glycerol esterified with three fatty acids. Fatty acid is a monocarboxilic acid containing even number of carbon atom started from 4 to 22. Based on the length of fatty acid in triacylglycerol, fats and oils can be classified into two groups; medium chain triglycerides and long chain triglycerides. Coconut oil belongs to medium chain triglycerides oil because it’s fatty acids consist mostly of medium chain fatty acids (C4:0 to C12:0) and dominated by lauric acid (C12:0), hence usually called as lauric oil. In the year of 1950s, coconut oil was claimed that saturated fats, including coconut oil, could increase blood total cholesterol and hence is atherogenic, while unsaturated fats decrease total cholesterol. However, in 1990s, coconut oil was found to be different from the other saturated oils. Coconut oil composed of medium chain fatty acids with high amount of lauric acid. Coconut oil is metabolized differently from long chain triglycerides saturated oil, and therefore coconut oil has numerous beneficial nutritional values and health promotion. Consumption of food rich in medium chain fatty acids reduces the level of body fat and the decrease the risk of heart disease, diabetes, increase mother’s milk quality and active as potential antibacterial agent.

LC-MS-oriented fractionation of the sponge Aaptos suberitoides resulted in the isolation of four heptacyclic alkaloids, aaptodines A-D (1-4), which contain 9,10-dihydrofuro[2,3-f][1,3]oxazolo[5,4-h]quinolone and 7,8-dihydrocyclopenta[de][1,6]naphthyridine subunits with a spiro carbon atom. The structures were determined on the basis of NMR spectroscopic and single-crystal X-ray diffraction data analysis aided by electronic circular dichroism calculations and Mosher's method. A biosynthetic pathway for the formation of aaptodines A-D is postulated. Aaptodine D exhibits potent inhibition against osteoclast formation.

We have performed a combined structural and computational analysis of short contacts between bromine and the carbon atom of a carbonyl group. Surprisingly, 9% of such contacts are arranged in such ...

International audience; A systematic comparison of lipophilicity modulations upon fluorination of isopropyl, cyclopropyl and 3-oxetanyl substituents, at a single carbon atom, is provided using directly comparable, and easily accessible model compounds. In addition, comparison with relevant linear chain derivatives is provided, as well as lipophilicity changes occurring upon chain extension of acyclic precursors to give cyclopropyl containing compounds. For the compounds investigated, fluorination of the isopropyl substituent led to larger lipophilicity modulation compared to fluorination of the cyclopropyl substituent.

Two new derivatives of the bis(3,5-dimethylpyrazol-1-yl)methane modified by introduction of organosilyl groups on the central carbon atom, one of which bearing a chiral fragment, have been easily p...

The complexes of TrR3 (Tr = B and Al; R = H, F, Cl, and Br) with three N-bases (NH3, CH2NH, and HCN) and three O-bases (CH3OH, H2CO, and CO) are utilized to explore the hybridization effect of N and O atoms on the strength, properties, and nature of the triel bond. The sp-hybridized O and N atoms form the weakest triel bond, followed by the sp2-hybridized O atom or the sp3-hybridized N atom, and the sp3-hybridized O atom or the sp2-hybridized N atom engages in the strongest triel bond. The hybridization effect is also related to the substituent of TrR3. Most complexes are dominated by electrostatic, with increasing polarization contribution from sp to sp2 to sp3. Although the CO oxygen engages in a weaker triel bond, its carbon atom is a better electron donor and the interaction energy even amounts to -37 kcal/mol in the BH3 complex.

Methane is the simplest hydrocarbon, consisting of one carbon atom and four hydrogen atoms. It is abundant in marsh gas, livestock rumination, and combustible ice. Little is known about the use of methane in human disease treatment. Current research indicates that methane is useful for treating several diseases including ischemia and reperfusion injury, and inflammatory diseases. The mechanisms underlying the protective effects of methane appear primarily to involve anti-oxidation, anti-inflammation, and anti-apoptosis. In this review, we describe the beneficial effects of methane on different diseases, summarize possible mechanisms by which methane may act in these conditions, and discuss the purpose of methane production in hypoxic conditions. Then we propose several promising directions for the future research.

Oxidation of 4-phenyl-1-pivaloylsemicarbazide leads to the formation of two structural isomers: 5-tert-butyl-5-hydroxy-4-phenyl-4,5-dihydro-3H-1,2,4-triazol-3-one and 1-tert-butyl-4-phenyl-1,2,4-triazolidine-3,5-dione. Isomerization of 5-tert-butyl-5-hydroxy-4-phenyl-4,5-dihydro-3H-1,2,4-triazol-3-one to 1-tert-butyl-4-phenyl-1,2,4-triazolidine-3,5-dione proceeds upon heating and is accompanied by the migration of the tert-butyl group from the carbon atom to the nitrogen atom.

α-Amino acids are present in two opposite configurations due to the presence of a central carbon atom which is a chiral center. While L-amino acids are present in large amount in nature, only tiny quantities of their D-enantiomers exist. For a long time, D-amino acids have been considered of bacterial origin only, but recently we realized that they are present in all living organisms: notably, D-amino acids play specific and relevant functions in the different organisms. Detection and quantification of D-amino acids are mandatory to shed light on their physiological roles, especially related to foods and human health. Chromatographic techniques are among the most commonly used analytical methods for the enantioseparation of amino acids. Here, we revised the latest improvements in chromatographic direct methodologies based on chiral selectors and aimed to improve analytical speed, sensitivity, robustness, and reproducibility. While current methods are well suited for D-amino acid analysis in foodstuffs and pharmaceuticals, further improvements seem required for their simultaneous, fast and sensitive detection in biological fluids, an emerging field since D-amino acids have been proposed as biomarkers of different and relevant human pathologic states.

The microscopic-order-macroscopic-disorder (MOMD) approach for NMR lineshape analysis has been applied to the University of Windsor Dynamic Materials (UWDM) of types 1, 2, α−3, β−3, and 5, which are metal–organic frameworks (MOFs) comprising mobile mechanically interlocked molecules (MIMs). The mobile MIM components are selectively deuterated crown ether macrocycles – 24C6, 22C6, and B24C6. Their motion is described in MOMD by an effective/collective dynamic mode characterized by a diffusion tensor, R, a restricting/ordering potential, u, expanded in the Wigner rotation matrix elements, [Formula: see text] , and features of local geometry. Experimental (2)H lineshapes are available over 220 K (on average) and in some cases 320 K. They are reproduced with axial R, u given by the terms [Formula: see text] and [Formula: see text] , and established local geometry. For UWDM of types 1, β−3, and 5, where the macrocycle resides in a relatively loose space, u is in the 1–3 kT, R(‖) in the (1.0–2.5) × 10(6) s(−1), and R(⊥) in the (0.4–2.5) × 10(4) s(−1) range; the deuterium atom is bonded to a carbon atom with tetrahedral coordination character. For UWDM of types 2 and α−3, where the macrocycle resides in a much tighter space, a substantial change in the symmetry of u and the coordination character of the (2)H-bonded carbon are detected at higher temperatures. The activation energies for R(‖) and R(⊥) are characteristic of each system. The MOMD model is general; effective/collective dynamic modes are treated. The characteristics of motion, ordering, and geometry are physically well-defined; they differ from case to case in extent and symmetry but not in essence. Physical clarity and consistency provide new insights. A previous interpretation of the same experimental data used models consisting of collections of independent simple motions. These models are specific to each case and temperature. Within their scope, generating consistent physical pictures and comparing cases are difficult; possible collective modes are neglected.

Summary The different modes of stabilization for carbenes are briefly discussed in the context of the discovery of their first stable representatives. Largely because a diversity of stable carbenes are available today, their use has spanned across the chemical sciences, including medicinal and material applications. Much less is known about the isolobal group 15 cousins of carbenes, namely nitrenes and phosphinidenes, given that only one example of each has been isolated. The difficulties associated with their applications are discussed, and possible solutions are presented. As for group 13 element carbenoids, two types are considered: (1) mono(Lewis base)-stabilized borylenes that have been recently isolated and (2) borylenes, the only carbenoids discussed in this article that have eluded the synthetic skills of investigators. This Perspective describes potentially attainable targets, such as monocoordinated aminocarbanions, aminocarbynes, and aminocarbocations, which feature a carbon atom with six, five, and four valence electrons, respectively.

The Suzuki–Miyaura coupling of cyclopropyl boronic derivatives with (het)aryl halides was evaluated as a method for parallel synthesis of sp3-enriched compound libraries. The scope and limitation of the procedure were established. It was shown that the method was applicable to a wide range of cyclopropyl trifluoroborates and (het)aryl bromides. Limitations of the method included trifluoroborates bearing bulky substituents at the α position, as well as (het)aryl bromides with ester moieties. A 96-member library was prepared to illustrate the concept with 68% success rate and 30% average yield. Calculated physico-chemical properties of the products obtained (in particular, sp3-hybrid carbon atom fraction Fsp3 = 0.16-0.83 range, 0.52 on average), as well as neglectable “LogP drift” effect, observed experimentally (0.02 units) showed that the method is well-compatible with lead-oriented synthesis criteria.

Herein, we report the synthesis, characterization, and reactivity of the N-(isocyanoimine)triphenylphosphine (CNNPPh3) and bis(diisopropylamino)cyclopropenylidene (BAC) adducts of [Ce(NR2)3] (R = S...

Herein we report a novel and straightforward protocol for the construction of valuable gem-BPs by means of proton-coupled electron-transfer (PCET)-triggered enamido C(sp2 )-H diphosphorylation. This reaction represents a rare example of realizing the challenging double C-P bond formation at a single carbon atom, thus providing facile access to a broad variety of structurally diverse bisphosphonates from simple enamides under silver-mediated conditions. Initial mechanistic studies demonstrated that the diphosphorylation involves two rounds of PCET-initiated radical relay process.

The evolution of structural and electronic properties of neutral and charged iron clusters doped with a single carbon atom, FenC0,±1 (n = 1-13) series, is studied in this work; which has been carri...

The crystal structure of 4-chloro-1H-pyrazole has been determined at 170 K, showing a hydrogen-bonded trimeric mol­ecular assembly that is isostructural to its bromo analogue, 4-bromo-1H-pyrazole., The structure of 4-chloro-1H-pyrazole, C3H3ClN2, at 170 K has ortho­rhom­bic (Pnma) symmetry and is isostructural to its bromo analogue. Data were collected at low temperature since 4-chloro-1H-pyrazole sublimes when subjected to the localized heat produced by X-rays. The structure displays inter­molecular N—H⋯N hydrogen bonding and the packing features a trimeric mol­ecular assembly bis­ected by a mirror plane (m normal to b) running through one chlorine atom, one carbon atom and one N—N bond. The asymmetric unit therefore consists of one and one-half 4-chloro-1H-pyrazole mol­ecules. Thus, the N—H proton is crystallographically disordered over two positions of 50% occupancy each.

Fatty acids are long-chain hydrocarbons. They are called unsaturated fatty acids when they lack the maximum possible number of hydrogen atoms attached to every carbon atom. For example, if stearic acid, which has 18 carbon atoms and frequently occurs in animal and plant fats, is missing 2 hydrogen atoms, then a double bond is present and the resulting acid is oleic acid.