Artículos de revistas:

1

Jankowski, C. K., M. R. Van Calsteren, N. Aychet, J. F. Dozol, C. Moulin y C. Lamouroux. "Study of the nitration of di-n-octylcrown-6 calix[4]arene using LCMS, NMR, and molecular modelling". Canadian Journal of Chemistry 83, n.º 8 (1 de agosto de 2005): 1098–113. http://dx.doi.org/10.1139/v05-126.

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The selective HNO3 nitration of di-n-octylcrown-6 calix[4]arene using different conditions, studied with LCMS and NMR (1H and 13C) spectroscopic techniques, lead to the identification of most of the expected nitro derivative isomeric compounds. The formation of these isomers under acidic and radiolytic conditions is discussed with the help of molecular modelling.Key words: calix crown compounds, nitration of calixarenes, NMR of isomeric nitrocalixarenes, LC-ESI-MS.

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2

Shupeniuk, Vasyl, Tetyana Taras, Oksana Sabadakh, Eugene Luchkevich y Yurii Kornii. "Synthesis some 4-substituted 9,10-anthraquinones". French-Ukrainian Journal of Chemistry 8, n.º 1 (2020): 58–65. http://dx.doi.org/10.17721/fujcv8i1p58-65.

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New 4-substituted 9,10-anthraquinones (6 compouds) with amino derivations fragments were synthesized through the substitution of the bromaminic acid by amines using the Ullmann coupling reaction. The structures of the synthesized compounds were determined using LC-MS, 1H NMR, 13C NMR spectroscopy, and elemental analysis data.

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3

Kerschl, Susanna y Bernd Wrackmeyer. "Notizen: Versuche zur Herstellung eines Alkenyl(dimethyl)zinnhydrids: Gibt es eine intramolekulare Sn–H–B-Brücke?/ Attempts at the Synthesis of an Alkenyl(dimethyl)tin Hydride: Is there an Intramolecular Sn–H–B Bridge?" Zeitschrift für Naturforschung B 42, n.º 8 (1 de agosto de 1987): 1047–49. http://dx.doi.org/10.1515/znb-1987-0820.

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Abstract2-(E)-Dim ethyl(chloro)stannyl-3-diethylboryl-2- pentene (lc) reacts with trimethyltin hydride (3) to give the corresponding alkenyl(dim ethyl)tin hydride (2). Compound 2 has been characterized by 1H, 11B, 13C, 119Sn NMR . Neither the NMR nor the IR data are in support of an intramolecular Sn-H-B bridge.

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4

Fiadorwu, Joshua, Kiran Subedi, Daniel Todd y Mufeed M. Basti. "Multipronged Approach to Profiling Metabolites in Beta vulgaris L. Dried Pulp Extracts Using Chromatography, NMR and Other Spectroscopy Methods". Foods 12, n.º 18 (21 de septiembre de 2023): 3510. http://dx.doi.org/10.3390/foods12183510.

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Beetroot (Beta vulgaris L.) is known for being a rich source of phytochemicals, minerals and vitamins. This study aims to show how the combination of extraction/chromatography/mass spectrometry and NMR offers an efficient way to profile metabolites in the extracts of beetroot. Such combination may lead to the identification of more nutritional or medicinal compounds in natural products, and it is essential for our ongoing investigation to study the selective adsorption/desorption of these metabolites’ on/off nanoparticles. The aqueous and organic extracts underwent analyses using UV-vis spectroscopy; GC-MS; LC-MS; 1H, 13C, 31P, TOCSY, HSQC, and selective TOCSY NMR experiments. Polar Extract: The two forms of betalain pigment were identified by UV-vis and LC MS. Fourteen amino acids, sucrose, and other compounds, among which is riboflavin, were identified by LC-MS. Two-dimensional TOCSY showed the spin coupling correlations corresponding to some of these compounds. The HSQC spectrum showed 1H/13C spin correlation in sucrose, confirming its high abundance in beetroot. Organic Extract: GC-MS data enabled the identification of several compounds including six fatty acid methyl esters (FAME) with higher than, on average, 90% similarity score. Selective TOCSY NMR data showed the spin coupling pattern corresponding to oleic, linoleic, and linolenic fatty acids. 31P NMR spectra indicate that phospholipids exist in both the organic and aqueous phase.

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5

Xie, Yimin, Xudong Chen, Kai Zhang, Sheng Cui y Gongxia Zhang. "Elucidation of lignin and polysaccharide linkages in wheat straw by 2H/13C isotopic tracer". BioResources 18, n.º 1 (17 de noviembre de 2022): 550–69. http://dx.doi.org/10.15376/biores.18.1.550-569.

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To elucidate chemical linkages between lignin and polysaccharides, the aqueous mixed solutions of coniferin-[α-13C], syringin-[α-13C], D-glucose-[6-2H], and phenylalanine ammonia-lyase inhibitor were injected into a living wheat stalk. Internode tissues with high abundance of 2H-13C were collected. The milled wood lignin, lignin-carbohydrate complex (LCC), and residual LCC (R-LCC) with enrichment of 2H-13C were isolated. The 13C and 2H abundances showed that the lignin and polysaccharides of internode tissues were labeled by 13C and 2H, respectively. Analysis with carbon-13 nuclear magnetic resonance (13C-NMR) showed that ketal and benzyl ether bonds were formed between α-C of lignin and carbohydrates. The R-LCC and LCC were further treated with enzymes to obtain enzymatic degraded R-LCC (ED-R-LCC) and enzymatic degraded LCC (ED-LCC). 13C-NMR spectra of ED-LCC showed that the α-C of lignin side chain was combined with 6-C of carbohydrates by ether, ester, and ketal linkages. 1H-NMR differential spectra of ED-LCCs revealed an LC linkage of benzyl ether bond. Glucan-lignin (En-R-GL) and xylan-lignin (En-R-XL) complexes were separated from ED-R-LCC by ionic liquid. A part of lignin α-C was linked to cellulose 6-C by benzyl ether and α-ketal linkages. 13C-NMR spectra of En-R-XL showed there were α-benzyl ether and α-ketal bonds between lignin and xylan.

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6

Bhaskar, Prakash, Vasantha Kumar, Suresha Kumara Tholappanavara Hanumanthappa y Sowmya Haliwana Banakara Vijaykumar. "2-(3,4-Dimethoxyphenyl)-N-(4-methoxyphenyl)-1-propyl-1H-benzo[d]imidazole-5-carboxamide". Molbank 2019, n.º 3 (9 de septiembre de 2019): M1079. http://dx.doi.org/10.3390/m1079.

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2-(3,4-Dimethoxyphenyl)-N-(4-methoxyphenyl)-1-propyl-1H-benzo[d]imidazole-5-carboxamide was synthesized by the ‘one-pot’ reductive cyclization of N-(4-methoxyphenyl)-3-nitro-4-(propylamino)benzamide with 3,4-dimethoxybenzaldehyde, using sodium dithionite as a reductive cyclizing agent using DMSO as a solvent. The structure of newly synthesized compound was elucidated based on IR, 1H-NMR, 13C-NMR, and LC-MS data.

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7

Bouajila, J., G. Raffin, H. Waton, C. Sanglar, J. O. Païsse y M. F. Grenier-Loustalot. "Phenolic Resins – Characterizations and Kinetic Studies of Different Resols Prepared with Different Catalysts and Formaldehyde/Phenol Ratios (I)". Polymers and Polymer Composites 10, n.º 5 (julio de 2002): 341–60. http://dx.doi.org/10.1177/096739110201000502.

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The physicochemical and kinetic properties of resols prepared with different catalysts (NaOH, LiOH and Ba(OH)2) and variable formaldehyde/phenol ratios (2.5 £ R £ 3.5) were followed to determine their effects on the mechanisms and reaction products at a fixed pH and temperature. Kinetic monitoring and quantification of residual monomers were carried out by liquid chromatography coupled with mass spectrometry (LC/UV/MS), by 13C nuclear magnetic resonance (NMR) and by chemical assay for formaldehyde. Oligomer formation (n ≥ 2) was determined by LC/UV/MS, size exclusion chromatography (SEC) and 13C NMR. It was found that minor compounds form during syntheses (phenol methanol hemiacetals, hemiacetals of phenol and of oligomers…) and that the ratio R affects primarily the kinetics of formation of monomers and oligomers, in contrast to the catalysts that modify reaction mechanisms. The understanding of the structure of the resols was an important step for the determination of the final properties of the material.

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8

Vasilev, Aleksey A., Peter P. Grozdanov, Ivanka Nikolova, Valentin S. Lozanov y Meglena I. Kandinska. "Ultrasonic Synthesis and Preliminary Evaluation of Anticoronaviral Activity of 6,7-Dimethoxy-4-(4-(4-methoxyphenyl)piperazin-1-yl)-1-methylquinolin-1-ium Iodide". Molbank 2022, n.º 3 (4 de julio de 2022): M1400. http://dx.doi.org/10.3390/m1400.

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Quinoline scaffold is one of the most intensively utilized pharmacophores in drug design because of the variety of activities demonstrated by different quinoline-based therapeutics or drug-candidates. Herein, we describe an environmentally tolerant two-step procedure as a convenient synthetic approach to novel chloroquine and hydroxychloroquine analogues. The structures of the newly synthesized compounds are estimated by 1H NMR, 13C NMR, LC-MS spectrometry and IR spectroscopy.

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9

Wojcińska, Małgorzata, Jeffrey Williams, Tom J. Mabry, Ahmed A. Ahmed, Barry D. Davis, Gabor Tóth, Nabil H. El-Sayed, Irena Matławska y Jennifer Clevinger. "Flavonol Triglycosides from the Leaves of Silphium Albiflorum". Natural Product Communications 1, n.º 11 (noviembre de 2006): 1934578X0600101. http://dx.doi.org/10.1177/1934578x0600101105.

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In the course of chemotaxonomic studies of the genus Silphium two new and six known flavonol glycosides were isolated from the leaves of S. albiflorum. The structures of the new flavonoids were established by spectral analysis (1H NMR, 13C NMR, HMQC, HMBC, ROESY, TOCSY, MS) as isorhamnetin 3-O-α-L-rhamnosyl (1′“→6″)-O-β-D-galactopyranoside 7-O-β-D-apiofuranoside (1) and quercetin 3-O-α-L-rhamnosyl (1′“→6″)-O-β-D-galactopyranoside 7-O-β-D-apiofuranoside (2). LC-MS and LC-MSn (with post-column manganese complexation) were applied to elucidate the structures of some of the studied compounds.

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10

Diana, Rosita, Barbara Panunzi y Ugo Caruso. "Two Novel π -Conjugated Fluorophores for Dye-Doped LC On-Off Photoluminescence Switching". Letters in Organic Chemistry 17, n.º 5 (28 de abril de 2020): 340–44. http://dx.doi.org/10.2174/1570178616666191104094527.

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Among various classes of Photoluminescent (PL) compounds, soft-matter based materials in which chromophores are embedded in a Liquid-Crystal (LC) host polymer prove to be very attractive in the production of flexible panels and on-off temperature switches. Actually, the obtainment of low cost, easily synthesizable, and stable organic molecules soluble in the LC matrix is a challenge for both scholars and technologists. Here we describe the synthesis of two new emissive dyes based on a dicyanophenylenevinylene and on a bis-azobenzene core whose PL properties were investigated as neat solids, in solution, and in particular in a dye-doped LC nematic polymer often employed in PDLC applications. 1H NMR and 13C NMR spectroscopy allow the characterization of all compounds Their thermotropic liquid- crystalline (LC) properties were examined by differential scanning calorimetry and polarizing optical microscopy. Photoluminescence properties were characterized by fluorescence spectra.

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11

Canton, Marine, Jane Hubert, Stéphane Poigny, Richard Roe, Yves Brunel, Jean-Marc Nuzillard y Jean-Hugues Renault. "Dereplication of Natural Extracts Diluted in Glycerin: Physical Suppression of Glycerin by Centrifugal Partition Chromatography Combined with Presaturation of Solvent Signals in 13C-Nuclear Magnetic Resonance Spectroscopy". Molecules 25, n.º 21 (31 de octubre de 2020): 5061. http://dx.doi.org/10.3390/molecules25215061.

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For scientific, regulatory, and safety reasons, the chemical profile knowledge of natural extracts incorporated in commercial cosmetic formulations is of primary importance. Many extracts are produced or stabilized in glycerin, a practice which hampers their characterization. This article proposes a new methodology for the quick identification of metabolites present in natural extracts when diluted in glycerin. As an extension of a 13C nuclear magnetic resonance (NMR) based dereplication process, two complementary approaches are presented for the chemical profiling of natural extracts diluted in glycerin: A physical suppression by centrifugal partition chromatography (CPC) with the appropriate biphasic solvent system EtOAc/CH3CN/water 3:3:4 (v/v/v) for the crude extract fractionation, and a spectroscopic suppression by presaturation of 13C-NMR signals of glycerin applied to glycerin containing fractions. This innovative workflow was applied to a model mixture containing 23 natural metabolites. Dereplication by 13C-NMR was applied either on the dry model mixture or after dilution at 5% in glycerin, for comparison, resulting in the detection of 20 out of 23 compounds in the two model mixtures. Subsequently, a natural extract of Cedrus atlantica diluted in glycerin was characterized and resulted in the identification of 12 metabolites. The first annotations by 13C-NMR were confirmed by two-dimensional NMR and completed by LC-MS analyses for the annotation of five additional minor compounds. These results demonstrate that the application of physical suppression by CPC and presaturation of 13C-NMR solvent signals highly facilitates the quick chemical profiling of natural extracts diluted in glycerin.

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12

Kumar, Rakesh y Gursharan Singh. "Reactions of MoCl5 with 4-Methylpyridine, 2-Methylpyridine and 1-Methylimidazole in Tetrahydrofuran". Oriental Journal Of Chemistry 37, n.º 5 (30 de octubre de 2021): 1178–86. http://dx.doi.org/10.13005/ojc/370523.

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MoCl5 reactions with 4-methylpyridine/2-methylpyridine/1-methylimidazole in THF in 1:1/1:2 stoichiometric ratios, at room temperature were carried out. The following products were synthesized: MoO2Cl(C6H7N), 1;Mo2O2Cl5(C6H7N)2(C4H8O)2,2; Mo4O4Cl4(C6H7N)3(C4H8O)2, 3 and Mo2O4Cl4(C4H6N)2(C4H8O), 4. These compounds have been investigated by FT-IR (transmission mode), FT-1H NMR, FT -13C NMR, microbiological, LC-MS and elemental (C, H, N, Mo, Cl) studies. In view of the sensitivity of all the reactants and products towards oxidation/hydrolysis by air/moisture, all the reactions and products were handled using dry nitrogen atmosphere in vacuum line. LC-MS and elemental studies agree with the formulae of compounds.

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13

Gurav, M. M., R. M. Tigote y A. W. Suryawanshi. "Magnetically Recoverable Fe0.02Zn0.95-xCr0.05O Iron doped Catalyst for Synthesis of Dihydropyrimidones, Thiones and their Derivatives". Asian Journal of Chemistry 34, n.º 12 (2022): 3247–50. http://dx.doi.org/10.14233/ajchem.2022.24043.

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A new technique for the impregnation of magnetic based catalyst component onto the organic molecules are widely discussed. Due to its benefits of high surface area, separation simplicity, recyclability and limited leaching of catalytic active ingredients from the catalyst, in the present work, iron-doped Fe0.02Zn0.95-xCr0.05O heterogeneous catalyst was applied in the synthesis of dihydropyrimidones, thiones and their derivatives. The synthesized compounds were elucidated by their IR, 1H NMR and 13C NMR and LC-MS analysis.

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14

Fujiwara, Tao, Ayumi Uehara, Junichi Kitajima, Tsukasa Iwashina, Sadamu Matsumoto y Yasuyuki Watano. "Genkwanin 4′-O-glucosyl-(1→2)-rhamnoside from New Chemotype of Asplenium normale in Japan". Natural Product Communications 9, n.º 9 (septiembre de 2014): 1934578X1400900. http://dx.doi.org/10.1177/1934578x1400900917.

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New flavone glycoside, genkwanin 4′- O-β-glucopyranosyl-(1→2)- O-α-rhamnopyranoside was isolated from the fronds of new chemotype of Asplenium normale D.Don, together with two known C-glycosylflavones, vicenin-2 and lucenin-2. The chemical structure of the isolated glycoside was established by UV, LC-MS, characterization of acid hydrolysates, and 1H and 13C NMR spectroscopy.

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15

Manoharan, Dhinesh kumar. "Synthesis, Characterization and Evaluation of Anti-inflammatory Activity of Novel Indoline Derivatives". JOURNAL OF ADVANCES IN CHEMISTRY 12, n.º 12 (15 de junio de 2016): 4557–63. http://dx.doi.org/10.24297/jac.v12i12.4826.

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Series of indoline derivatives were synthesized using N-(4-aminophenyl) indoline-1-carbothiamide as a precursor. The structures of synthesized compounds were confirmed by FT-IR, 1H-NMR, 13C-NMR and LC-MS. The in vitro anti-inflammatory activity of synthesized indoline derivatives were examined by standard anti-denaturation assay. The compounds 4a (IC50 = 62.2 µg/ml) and 4b (IC50 = 60.7 µg/ml) showed potent inhibition on protein denaturation. The compounds 5a (IC50 = 97.8 µg/ml) exhibits moderate inhibition on protein denaturation

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16

Krska, Rudolf, Elvira Welzig, Ralf D. Josephs, Wolfgang Kandler, Hans Pettersson, Susan MacDonald, Adrian Charlton et al. "Purity Assessment of Crystalline Zearalenone". Journal of AOAC INTERNATIONAL 86, n.º 4 (1 de julio de 2003): 722–28. http://dx.doi.org/10.1093/jaoac/86.4.722.

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Abstract Commercially available solid zearalenone (ZON) to be used as a certified liquid calibrant (BCR-699) in a project funded by the European Commission within the Standard Measurement and Testing program was characterized and its purity determined. The degree of purity of the ZON was examined by UV spectrophotometer, liquid chromatography (LC) with diode array and fluorescence detection, 1H and 13C-NMR spectrometry, LC–mass spectrometry (LC/MS/MS), ion chromatography (IC), and differential scanning calorimetry (DSC). The diagrams obtained from DSC analysis and the UV spectrum showed no detectable impurities. Likewise, no impurities were observed by LC analysis with both diode array and fluorescence detection. IC determination revealed negligible contamination of ZON with chloride of 0.020 ± 0.005% and nitrate of 0.016 ± 0.006%. Zearalanone (ZAN) was identified as one of 2 minor (0.2%) impurities by LC/MS/MS. The 1H-NMR measurements revealed an additional peak, which has not been previously reported in the literature. It could be identified as part of the ZON spectrum as the signal arising from the phenolic proton attached to C4'. The manufacturer states an additional contamination with 0.2% methylene chloride, which could be confirmed to an extent of 0.1% by 1H-NMR. Minor impurities, whose structures remain unknown, were discovered at 3.5 and <1 ppm. Total percentage of impurities based on NMR measurement was estimated not to exceed 1%. A purity of 99.5% with a tolerance of ±0.5% was finally attributed to the ZON studied in this project.

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17

Asquith, Christopher y Graham Tizzard. "6-Bromo-N-(2-methyl-2H-benzo[d][1,2,3]triazol-5-yl)quinolin-4-amine". Molbank 2019, n.º 4 (27 de octubre de 2019): M1087. http://dx.doi.org/10.3390/m1087.

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We describe a straightforward synthesis of the title compound, incorporating a relatively rare 2-methyl-2H-1,2,3-triazole heterocylic motif as a potential kinase inhibitor motif. The small molecule crystal structure has been resolved, revealing an interesting packing arrangement and overall conformation. We also performed routine characterization with 1H/13C-NMR and liquid chromatography (LC) and high-resolution mass spectra (HRMS).

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18

Moriyasu, Takako, Keiko Minowa, Miho Sakamoto, Kiyoko Kishimoto, Hideo Kadoi, Jun'ichi Nakajima, Ken'ichiro Mori, shuzo Ogino, Haruhiko Fukaya y Yasuo Shida. "Differentiation Between Sulfoaildenafil and Its Analogs". Journal of AOAC INTERNATIONAL 94, n.º 6 (1 de noviembre de 2011): 1770–77. http://dx.doi.org/10.5740/jaoacint.10-425.

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Abstract An analog of aildenafil, which is a potent and highly selective inhibitor of phosphodiesterase 5, was found in a dietary supplement marketed for enhancement of sexual function. The compound was isolated by silica gel column chromatography, and its structure was identified by means of 13C-NMR spectrometry, 1H-NMR spectrometry, high-resolution MS, and X-ray structure determination. The compound was identified to be sulfoaildenafil (other names: thioaildenafil, dimethyl sildenafil thione, and thiomethisosildenafil). Sulfoaildenafil is very similar to the compound thiohomosildenafil. As it is difficult to distinguish between them by LC-photodiode array detector analysis, ultra-performance LC (UPLC)/MS, ion trap LC/MS/MS (LC/IT-MS/MS), and GC/MS were performed. The mass spectra of thiohomosildenafil by UPLC/MS and LC/IT-MS/MS showed mass fragments of m/z 58, 72, and 355, and the mass spectrum by GC/MS showed mass fragments of m/z 56, 72, and 420. Some of these fragments had low intensities, but they were useful for distinguishing between the two compounds. The relationship between aildenafil (other names: dimethylsildenafil and methisosildenafil) and homosildenafil is similar to that between sulfoaildenafil and thiohomosildenafil. Therefore, these were also examined.

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19

Wang, Qing, Huang Chen, Hao Xing, Yuan Deng, Zhi-Wang Luo y He-Lou Xie. "Long Rod-Like Liquid Crystal Containing Azobenzene and the Applications in Phase-Transition Regulation and Orientation of Nematic Liquid Crystal". Crystals 11, n.º 4 (13 de abril de 2021): 418. http://dx.doi.org/10.3390/cryst11040418.

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Phase-transition and orientation of liquid crystal (LC) are two crucial factors for LC application. In this work, a long rod-like LC compound containing double azobenzene (M1) is successfully designed and synthesized. The combing technologies of nuclear magnetic resonance (1H NMR, 13C NMR) and Fourier transform infrared spectroscopy (FTIR) are used to identify the chemical structure of the molecule. Additionally, the polarized optical microscopy (POM), differential scanning calorimetry (DSC), and one-dimensional wide-angle X-ray diffraction (1D WAXD) experimental results show that M1 exhibits an ultrawide range of LC phases and a stable LC structure even at ultrahigh temperature, which indicates that this LC can be applied in some especial devices. Further, the compound M1 is used to tune the LC temperature range of the commercial LC 4-cyano-4′-pentylbiphenyl (5CB). A series of samples 1–7 are obtained through doping different contents of M1, which show different LC temperature ranges that are dependent on the composition ratio of M1 and 5CB. More interestingly, all resultant samples show spontaneous vertical orientation on the hydrophilic glass substrate. Meanwhile, due to the effect of azobenzene in the compound M1, a reversible transition between homeotropic to random orientation of the LC molecules is achieved when these LC cells are alternately exposed to UV irradiation and visible light, which implies that this material shows potential application in especial display and optical storage technologies.

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20

Wecksler, Aaron T., Victor Lundin, Ambrose J. Williams, Karthik Veeravalli, Dorothea E. Reilly y Sung-Hye Grieco. "Bioprocess Development and Characterization of a 13C-Labeled Hybrid Bispecific Antibody Produced in Escherichia coli". Antibodies 12, n.º 1 (14 de febrero de 2023): 16. http://dx.doi.org/10.3390/antib12010016.

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Monoclonal antibodies (mAbs) are highly efficacious therapeutics; however, due to their large, dynamic nature, structural perturbations and regional modifications are often difficult to study. Moreover, the homodimeric, symmetrical nature of mAbs makes it difficult to elucidate which heavy chain (HC)-light chain (LC) pairs are responsible for any structural changes, stability concerns, and/or site-specific modifications. Isotopic labeling is an attractive means for selectively incorporating atoms with known mass differences to enable identification/monitoring using techniques such as mass spectrometry (MS) and nuclear magnetic resonance (NMR). However, the isotopic incorporation of atoms into proteins is typically incomplete. Here we present a strategy for incorporating 13C-labeling of half antibodies using an Escherichia coli fermentation system. Unlike previous attempts to generate isotopically labeled mAbs, we provide an industry-relevant, high cell density process that yielded >99% 13C-incorporation using 13C-glucose and 13C-celtone. The isotopic incorporation was performed on a half antibody designed with knob-into-hole technology to enable assembly with its native (naturally abundant) counterpart to generate a hybrid bispecific (BsAb) molecule. This work is intended to provide a framework for producing full-length antibodies, of which half are isotopically labeled, in order to study the individual HC-LC pairs.

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21

Sowmya, P. T. y K. M. Lokanatha Rai. "Synthesis and Liquid Crystalline Properties of a New Homologous Series of 4,5-Disubstituted 2H-[1,2,3]-Triazoles via Azide-Chalcone Oxidative Cycloaddition Reaction". Australian Journal of Chemistry 70, n.º 7 (2017): 764. http://dx.doi.org/10.1071/ch16540.

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A new homologous series of 4,5-disubstituted 2H-[1,2,3]-triazole derivatives were synthesized from chalcones and sodium azide via oxidative cycloaddition reaction; CuI was used as catalyst. Flexibility in the synthesized molecules was provided by attaching straight alkoxy chains. The synthesized compounds were characterized by elemental analysis, and 1H NMR and 13C NMR and LC-MS spectroscopies . The stability and range of the mesophases increased with the length of the chain on the triazoles. The melting point, transition temperatures, and enantiotropic liquid crystal morphologies were determined by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) equipped with a hot stage.

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22

Alqudah, Enas, Malak Abbadi, Sawsan Alqadoomi, Ibtihal Abo Hameda, Sharif Arar y Kamal Sweidan. "Identification and Separation of the Degradation Products of Vildagliptin Tablets and Raw Material using LC-MS and NMR, and then Exploration of the Corresponding Degradation Pathways". Jordan Journal of Pharmaceutical Sciences 16, n.º 2 (24 de julio de 2023): 478. http://dx.doi.org/10.35516/jjps.v16i2.1535.

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A gradient high performance liquid chromatography (HPLC) method has been developed for the qualitative and quantitative analyses of vildagliptin related substances. This method is based on using of RP-C18 (250 × 4.6 mm×5µm) and gradient elution with phosphate buffer and methanol as mobile phase. Various forced degradation studies were conducted to establish an impurity profile for vildagliptin in the tablet formula. Three degradation products were produced upon exposing vildagliptin to different degradation conditions (acidic, basic, oxidative, photolytic, aqueous and thermal); their structures were characterized using LC-MS and NMR (1H NMR, 13C NMR and DEPT) techniques. Some excipient components, examined in this study, had major effect towards producing any extra new degradation products.

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23

Tisserant, Leo-Paul, Jane Hubert, Michelle Lequart, Nicolas Borie, Nicolas Maurin, Serge Pilard, Philippe Jeandet et al. "13C NMR and LC-MS Profiling of Stilbenes from Elicited Grapevine Hairy Root Cultures". Journal of Natural Products 79, n.º 11 (14 de noviembre de 2016): 2846–55. http://dx.doi.org/10.1021/acs.jnatprod.6b00608.

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24

Sakaguchi, Keisuke, Junichi Kitajima y Tsukasa Iwashina. "Kaempferol Tri- and Tetraglycosides from the Flowers of Clematis Cultivar". Natural Product Communications 7, n.º 2 (febrero de 2012): 1934578X1200700. http://dx.doi.org/10.1177/1934578x1200700210.

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A new kaempferol glycoside, kaempferol 3- O-α-rhamnopyranosyl-(1→2)-[α-rhamnopyranosyl-(1→6)-β-glucopyranoside]-7- O-β-glucopyranoside (2) was isolated from the flowers of Clematis cultivar “Jackmanii Superba”, together with a known kaempferol 3- O-α-rhamnopyranosyl-(1→6)-β-glucopyranoside-7- O-β-glucopyranoside (1). The chemical structures of the isolated glycosides were established by UV, LC-MS, characterization of acid hydrolysates, and 1H and 13C NMR spectroscopy.

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25

LeBlanc, Patricia, Nadine Merkley, Krista Thomas, Nancy I. Lewis, Khalida Békri, Susan LeBlanc Renaud, Frances R. Pick, Pearse McCarron, Christopher O. Miles y Michael A. Quilliam. "Isolation and Characterization of [D-Leu1]microcystin-LY from Microcystis aeruginosa CPCC-464". Toxins 12, n.º 2 (23 de enero de 2020): 77. http://dx.doi.org/10.3390/toxins12020077.

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[D-Leu1]MC-LY (1) ([M + H]+ m/z 1044.5673, Δ 2.0 ppm), a new microcystin, was isolated from Microcystis aeruginosa strain CPCC-464. The compound was characterized by 1H and 13C NMR spectroscopy, liquid chromatography–high resolution tandem mass spectrometry (LC–HRMS/MS) and UV spectroscopy. A calibration reference material was produced after quantitation by 1H NMR spectroscopy and LC with chemiluminescence nitrogen detection. The potency of 1 in a protein phosphatase 2A inhibition assay was essentially the same as for MC-LR (2). Related microcystins, [D-Leu1]MC-LR (3) ([M + H]+ m/z 1037.6041, Δ 1.0 ppm), [D-Leu1]MC-M(O)R (6) ([M + H]+ m/z 1071.5565, Δ 2.0 ppm) and [D-Leu1]MC-MR (7) ([M + H]+ m/z 1055.5617, Δ 2.2 ppm), were also identified in culture extracts, along with traces of [D-Leu1]MC-M(O2)R (8) ([M + H]+ m/z 1087.5510, Δ 1.6 ppm), by a combination of chemical derivatization and LC–HRMS/MS experiments. The relative abundances of 1, 3, 6, 7 and 8 in a freshly extracted culture in the positive ionization mode LC–HRMS were ca. 84, 100, 3.0, 11 and 0.05, respectively. These and other results indicate that [D-Leu1]-containing MCs may be more common in cyanobacterial blooms than is generally appreciated but are easily overlooked with standard targeted LC–MS/MS screening methods.

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26

Bhupatiraju, Rajesh Varma, Battula Sreenivasa Rao, Kapavarapu Maruthi Venkata Narayana Rao y Mandapati Varaprasad Reddy. "A NOVEL RIVAROXABAN DEGRADATION IMPURITY DETECTION BY RP-HPLC, EXTRACTION BY PREPARATORY CHROMATOGRAPHY, AND CHARACTERIZATION BY LCMS, NMR, AND FT-IR: ANALYSIS OF NOVEL IMPURITY IN BATCH SAMPLES AND TABLETS OF RIVAROXABAN". RASAYAN Journal of Chemistry 15, n.º 04 (2022): 2373–81. http://dx.doi.org/10.31788/rjc.2022.1547008.

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A novel rivaroxaban degradant was obtained at 0.45% w/w level during the “RP-HPLC” analysis in the acetic acidexposed rivaroxaban sample. This novel rivaroxaban degradant has a relative retention period (RRT) of approximately 0.95 min. This 0.95 RRT impurity was recognized by LC-MS and then characterized by 1H NMR, 13C NMR, NMR HSQC, NMR HMBC and NMR D2O exchange analyses, and FT-IR techniques. Employed Zorbax XDB C18 eclipse as the main column and Ghost-Guard-LC, ANP00001 as the Ghostbuster column for 0.95 RRT molecule analysis. The mobile phase, phosphate buffer, and acetonitrile mixture, with a simple gradient, were provided to a column at a flow of 1.0 ml/min rate. Samples were evaluated employing a wavelength of 250 nm and injected sample at a volume of 3.0 µL. Good sensitivity was obtained (LOD –0.02% concentration and LOQ – 0.05% concentration) with levels extremely less than allowable limits (0.15%). In the concentration ranges of 0.045% (LOQ) – 0.225% (150% of permissible limits), the technique demonstrated the best linearity for 0.95 RRT molecule analysis, with coefficients of determination of 0.9958. The recovery rate ranged from 93.2% to 105.7%. This approach is shown to be capable of determining 0.95 RRT impurity levels in three rivaroxaban batch samples and one rivaroxaban commercial tablet.

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27

SHARMA, JYOTSNA, HARDEEP SINGH TULI, MAYANK KINGER, RAM PAL, ZAHOOR ABBAS y MANOJ KUMAR. "Synthesis, Characterization and Biological Screening of Novel Imidazolylpyrazole Scaffolds". Asian Journal of Chemistry 34, n.º 3 (2022): 614–18. http://dx.doi.org/10.14233/ajchem.2022.23570.

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A novel series of 3-(4-aryl)-4-(4,5-diphenyl-1H-imidazol-2-yl)-1-phenyl-1H-pyrazole was synthesized by employing the well-known Debus-Radziszewski reaction. Structures of all the newly synthesized compounds have been characterized by various spectroscopic techniques viz. FTIR, 1H and 13C NMR, LC-MS and elemental analysis. All these compounds were also screened for antimicrobial potential against bacterial strains of S. aureus, K. pneumoniae and fungal strains of A. niger and T. rubrum.

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28

Iwashina, Tsukasa, Sadamu Matsumoto, Junichi Kitajima, Takehisa Nakamura, Goro Kokubugata, Monica Suleiman y Idoris M. Said. "Apigenin Di- and Trirhamnoside from Asplenium normale in Malaysia". Natural Product Communications 5, n.º 1 (enero de 2010): 1934578X1000500. http://dx.doi.org/10.1177/1934578x1000500110.

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Two new flavone rhamnosides, apigenin 7-O-α-L-rhamnopyranosyl-(1→4)-O-α-L-rhamnopyranoside and apigenin 7-O-α-L-rhamnopyranosyl-(1→4)-O-α-L-rhamnopyranoside-4′-O-α-L-rhamnopyranoside were isolated from the fronds of Asplenium normale D. Don, together with two known C-glycosylflavones, vicenin-2 and lucenin-2. The chemical structures of the isolated glycosides were established by UV, LC-MS, characterization of acid hydrolysates, and 1H and 13C NMR spectroscopy.

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29

Lou, Rensheng, George Rottinghaus, Andrew L. Thomas, Doug Monroe, Kevin Tran y Robert E. Smith. "Identification of Unknown Compound in Apocynum cannabinum by High Resolution Mass Spectrometry (HRMS) and 600 MHz NMR". Journal of Regulatory Science 4, n.º 3 (22 de julio de 2016): 14–19. http://dx.doi.org/10.21423/jrs-v04n03p014.

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High resolution mass spectrometry (HRMS) was able to determine that the m/z of the [M+H]+ ion formed by an unknown compound that was purified by preparative scale liquid chromatography (LC) was 137.05966. This was done rapidly and easily by direct infusion. Neither a column nor chromatography was needed. This is within 0.4 ppm of the mass calculated by ThermoFisher’s exact mass calculator for the protonated version of C8H8O2. Based on this, the compound could have been 2’-, 3’- or 4’-hydroxyacetophenone or 2’-, 3’- or 4’-methoxybenzaldehyde. However, 1H- and 13C-NMR spectra of the isolated compound showed that it was 4’-hydroxyacetophenone, without needing a standard. Neither mass spectrometry (MS) nor NMR could have identified this compound by itself. Finally, HRMS was also able to verify that another peak isolated by preparative scale LC was apocynin, or 4’-hydroxy-3’-methoxyacetophenone.https://doi.org/10.21423/jrs-v04n03p014 (DOI assigned 5/31/2019)

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30

Lee-Chang, Kim Jye, Matthew C. Taylor, Guy Drummond, Roger J. Mulder, Maged Peter Mansour, Mina Brock y Peter D. Nichols. "Docosahexaenoic Acid Is Naturally Concentrated at the sn-2 Position in Triacylglycerols of the Australian Thraustochytrid Aurantiochytrium sp. Strain TC 20". Marine Drugs 19, n.º 7 (1 de julio de 2021): 382. http://dx.doi.org/10.3390/md19070382.

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The Labyrinthulomycetes or Labyrinthulea are a class of protists that produce a network of filaments that enable the cells to glide along and absorb nutrients. One of the main two Labyrinthulea groups is the thraustochytrids, which are becoming an increasingly recognised and commercially used alternate source of long-chain (LC, ≥C20) omega-3 containing oils. This study demonstrates, to our knowledge for the first time, the regiospecificity of the triacylglycerol (TAG) fraction derived from Australian thraustochytrid Aurantiochytrium sp. strain TC 20 obtained using 13C nuclear magnetic resonance spectroscopy (13C NMR) analysis. The DHA present in the TC 20 TAG fraction was determined to be concentrated in the sn-2 position, with TAG (16:0/22:6/16:0) identified as the main species present. The sn-2 preference is similar to that found in salmon and tuna oil, and differs to seal oil containing largely sn-1,3 LC-PUFA. A higher concentration of sn-2 DHA occurred in the thraustochytrid TC 20 oil compared to that of tuna oil.

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31

Holota, Serhii, Ihor Yushyn, Andrzej Gzella y Roman Lesyk. "3-(2-Diisopropylaminoethyl)-5-(4-methoxybenzylidene)thiazolidine-2,4-dione". Molbank 2022, n.º 3 (24 de junio de 2022): M1394. http://dx.doi.org/10.3390/m1394.

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Thiazolidine-2,4-dione core is widely used in the medicinal chemistry of different types of potential drug-like small molecules. In the present work, the synthesis of a novel non-condensed thiazolidine-2,4-dione-bearing derivative is reported by the two-step cost-effective approach including alkylation and Knoevenagel condensation. The structure of the synthesized 3-(2-diisopropylaminoethyl)-5-(4-methoxybenzylidene)thiazolidine-2,4-dione was determined and characterized using 1H, 13C NMR, LC-MS spectra and the X-ray diffraction method.

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32

Khaniani, Yeganeh, Matthias Lipfert, Dipanjan Bhattacharyya, Rolando Perez Pineiro, Jiamin Zheng y David Wishart. "A Simple and Convenient Synthesis of Unlabeled and 13C-Labeled 3-(3-Hydroxyphenyl)-3-Hydroxypropionic Acid and Its Quantification in Human Urine Samples". Metabolites 8, n.º 4 (21 de noviembre de 2018): 80. http://dx.doi.org/10.3390/metabo8040080.

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An improved method to synthesize the highly abundant and biomedically important urinary metabolite 3-(3-hydroxyphenyl)-3-hydroxypropionic acid (HPHPA) is reported. The modified protocol is based on an indium-mediated sonochemical Reformatsky reaction. The synthesis is a simple two-step route as opposed to a complex four-step route previously reported in the literature that requires specialized equipment, flammable materials, and high-pressure reaction vessels. The described procedure also provides an expedient route to prepare a 13C isotopically labeled HPHPA that can be used as a standard for quantitative LC-MS analysis. This report also illustrates how the synthesized metabolite standard was used to detect and accurately quantify its presence in human urine samples using both NMR and LC-MS techniques.

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33

Madasu, Suri Babu, Nagaji Ambabhai Vekariya, M. N. V. D. Hari Kiran, Badarinadh Gupta, Aminul Islam, Paul S. Douglas y Korupolu Raghu Babu. "Synthesis of compounds related to the anti-migraine drug eletriptan hydrobromide". Beilstein Journal of Organic Chemistry 8 (30 de agosto de 2012): 1400–1405. http://dx.doi.org/10.3762/bjoc.8.162.

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Eletriptan hydrobromide (1) is a selective serotonin (5-HT1) agonist, used for the acute treatment of the headache phase of migraine attacks. During the manufacture of eletriptan hydrobromide the formation of various impurities were observed and identified by LC–MS. To control the formation of these impurities during the preparation of active pharmaceutical ingredients, the structure of the impurities must be known. Major impurities of the eletriptan hydrobromide synthesis were prepared and characterized by using various spectroscopic techniques, i.e., mass spectroscopy, FTIR , 1H NMR, 13C NMR/DEPT, and further confirmed by co-injection in HPLC. The present study will be of great help in the synthesis of highly pure eletriptan hydrobromide related compounds.

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34

Qin, Qiu Yan, Yi Ping Qian, Zi Yu Wang y Xiao Lin Fan. "Design and Synthesis of Fluorescent Betahistine Conjugates with Unique Imaging Property". Advanced Materials Research 557-559 (julio de 2012): 712–15. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.712.

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Labeling cardiovascular drugs probes with a fluorescent tag is an alternative method of measuring drugs activities and distributions in vivo, and further using of advanced tools to diagnose or detect cardiovascular diseases. Using this approach, a fluorescent probe (betahistine-Flu, 1) of Betahistine-based was synthesized and characterized by 1H NMR, 13C NMR and LC-MS, and its UV-Vis absorption spectral and fluorescence spectral, and fluorescence imaging in cell model were investigated. It was found that the fluorescent probe display strong green fluorescence, and have good optical effect in cell. This study reveals a good and interesting results of betahistine-directed fluorescent probe, and its may be a possible candidate for cardiovascular disease diagnosis and analysis in vivo.

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35

Venkataramana, Rupireddy, Venkata Chittireddy, Dongamanti Ashok y Kudle Rao. "Microwave-assisted synthesis of 2,8-di(alkyl/aryl)-4,6-dichloro-2H,8H-pyrano[3,2-g] chromene-3,7-dicarbaldehydes and their antimicrobial activity". Journal of the Serbian Chemical Society 84, n.º 4 (2019): 355–64. http://dx.doi.org/10.2298/jsc180127011v.

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A series of 2,8-di(alkyl/aryl)-substituted bischromanone derivatives were synthesized in one pot from 4,6-diacetylresorcinol and aliphatic/aromatic aldehydes in the presence of pyrrolidine/piperidine under conventional heating and microwave irradiation. The 2,8-di(alkyl/aryl)-substituted bischromanones were converted into a new series of 4,6-dichloro-3,7-diformyl-2,8-di(alkyl/aryl)-substituted bischromenes using the Vilsmeier?Haack reagent. The structures of the compounds were established based on elemental analysis, IR, 1H-NMR, 13C- -NMR and LC?MS spectral data. All the synthesized compounds were evaluated for their antimicrobial activity. Some of the compounds showed very good activity compared to standard drugs against all the tested pathogenic bacteria and fungi.

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36

Kovalenko, Drushlyak, Konovalova, Mariutsa, Kravchenko, Ivachtchenko y Mitkin. "Novel One-Pot Synthesis of Methyl 4-Hydroxy-2-thioxo-1,2-dihydroquinoline-3-carboxylate: Synthetic and Crystallographic Studies". Molbank 2019, n.º 4 (14 de octubre de 2019): M1085. http://dx.doi.org/10.3390/m1085.

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A new suitable method of synthesis of methyl 4-hydroxy-2-thioxo-1,2-dihydroquinoline-3-carboxylate by condensation of methyl 2-isothiocyanatobenzoate and methyl malonate is described. The structure of the compound both and by-product methyl 2(methoxycarbonothioylamino)benzoate was confirmed by means of elemental analysis, 1H NMR, 13C NMR, LC/MS and single crystal X-ray diffraction. UV/Vis and IR spectra of compounds are described. The presence of a strong intramolecular hydrogen bond between the hydroxy group and the carbonyl oxygen atom of the ester group in methyl 4-hydroxy-2-thioxo-1,2-dihydroquinoline-3-carboxylate is shown. The crystal structure of product was stabilized through intermolecular hydrogen bonds.

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37

Zarev, Yancho. "Isolation and characterization of 3- O-caffeoyloleanolic acid from Robinia pseudoacacia stem bark". Pharmacia 70, n.º 4 (24 de octubre de 2023): 1209–12. http://dx.doi.org/10.3897/pharmacia.70.e110402.

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Robinia pseudoacacia, a deciduous tree native to North America, has various medicinal properties, including antioxidant, antitumour, diuretic and antispasmodic effects. The plant contains various bioactive compounds, such as alkaloids, flavonoids, tannins, and phenols. However, caution is advised as all parts of the plant, except the flowers, are poisonous due to the phytotoxin robinin and its glycoside. The bark, on the other hand, shows resistance to rot due to the antifungal compounds dihydrorobinetin and robinetin. This study focuses on the stem bark of R. pseudoacacia from Bulgaria, a widely distributed wild species. Using advanced chromatographic techniques, we isolated and identified 3-O-caffeoyloleanolic acid, a new compound in the genus Robinia and R. pseudoacacia. Structural characterization was performed by state-of-the-art spectroscopic methods, including 1H NMR, 13C NMR and 2D NMR (COSY, HSQC, HMBC), as well as by LC-HRESI-MS analysis.

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38

Iwashina, Tsukasa, Junichi Kitajima, Takayuki Mizuno, Sergey V. Smirnov, Oyunchimeg Damdinsuren y Katsuhiko Kondo. "New Kaempferol 3,7-Diglycosides from Asplenium ruta-muraria and Asplenium altajense". Natural Product Communications 10, n.º 3 (marzo de 2015): 1934578X1501000. http://dx.doi.org/10.1177/1934578x1501000310.

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A flavonoid was isolated from the fronds of Asplenium ruta-muraria and A. altajense (Aspleniaceae) collected in the Altai Mountains and adjacent area. The compound was identified as kaempferol 3- O- β-[(6″′- E-caffeoylglucopyranosyl)-(1→3)-glucopyranoside]-7- O- β-glucopyranoside (1) by UV, 1H and 13C NMR spectroscopy, LC-MS, and acid and alkaline hydrolyses. Another flavonoid (2) was isolated from A. altajense, as a minor compound, together with 1 and identified as deacylated compound 1, i.e. kaempferol 3- O-laminaribioside-7- O-glucoside. They were found in nature for the first time.

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39

Murai, Yoshinori, Ryoji Takahashi, Junichi Kitajima y Tsukasa Iwashina. "New Quercetin Triglycoside from the Leaves of Soybean Cultivar ‘Clark’". Natural Product Communications 14, n.º 5 (mayo de 2019): 1934578X1984361. http://dx.doi.org/10.1177/1934578x19843614.

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A new flavonol triglycoside, Quercetin 3- O-α-rhamnopyranosyl-(1→4)-[α-rhamnopyranosyl-(1→6)-β-galactopyranoside], was isolated from the leaves of soybean ( Glycine max) cultivar “Clark” and identified by UV spectra, LC-ESI-MS, acid hydrolysis, and 1H and 13C NMR. The compound was found together with 7 known flavonol glycosides, quercetin 3- O-robinobioside, quercetin 3- O-rutinoside, kaempferol 3- O-rhamnosyl-(1→4)-[rhamnosyl-(1→6)-galactoside], kaempferol 3- O-robinobioside, kaempferol 3- O-rutinoside, isorhamnetin 3- O-robinobioside, and isorhamnetin 3- O-rutinoside.

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40

Bouajila, J., G. Raffin, H. Waton, C. Sanglar, J. O. Païsse y M. F. Grenier-Loustalot. "Phenolic Resins (II) – Influence of the Chemical Structure of High Molecular Weight Molecules on the Mechanisms of Cross-linking and on the Final Structure of the Resins". Polymers and Polymer Composites 11, n.º 4 (mayo de 2003): 233–62. http://dx.doi.org/10.1177/096739110301100401.

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The physicochemical characterization of the structures of the oligomers (n < 4) in resols has been carried out by fragmenting monomers in LC/UV/MS and LC/UV/MS/MS. Fragmentation mechanisms are related to the numbers and positions of substituents on the aromatic ring and to the types of oligomer junctions. It was more difficult to determine the structures of phenol hemiacetals and dimer hemiacetals because of the large number of position isomers. The resols were prepared with differing molar ratios R = Formaldehyde/Phenol and catalysts. They were cross-linked using two industrially recommended heat cycles. The progression of resin cross-linking was determined by solid state 13C NMR (CP/MAS). The residual percentage of monomers and oligomers at n < 4 was determined in leachates (water and methanol) and characterized by LC/UV/MS. The results for cross-linking advancement were correlated with the various synthesis parameters (ratio R, type of catalyst and heat cycle).

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41

Sato, Moriyuki, Seiji Ujiie, Yuji Tada y Takashi Kato. "Semirigid Homo- and Copoly(Imide-Carbonate)s Based on 3,4,3″,4″ -p-Terphenyltetracarboxdiimide". High Performance Polymers 10, n.º 1 (marzo de 1998): 155–62. http://dx.doi.org/10.1088/0954-0083/10/1/017.

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Novel thermotropic liquid crystalline (LC) semirigid homo- and copoly(imidecarbonate)s composed of a 3, 4, 3″, 4″- p-terphenyltetracarboxdiimide ring and aliphatic chains were prepared by melt polycondensation of a dihexanol derivative of 3, 4, 3″, 4″- p-terphenyltetracarboxdiimide and/or a dioxydihexanol of biphenyl taken in a definite molar ratio with hexamethylene diphenyl dicarbonate in the presence of zinc acetate, and their thermal and mesogenic properties were evaluated. The assigned structures of polymers were characterized by FT-IR and 13C NMR spectroscopy, and elemental analyses. DSC and TG-DTA measurements, polarizing microscope observations of textures and temperature-dependent x-ray analyses demonstrated that the polymers have wider LC temperature ranges (nematic phase) than analogous semirigid poly(ester-imide)s and are thermally stable up to 300 °C in air.

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42

Cebeci, Yıldız Uygun y Şengül Alpay Karaoğlu. "Design and microwave-assisted synthesis of a novel Mannich base and conazole derivatives and their biological assessment". Heterocyclic Communications 27, n.º 1 (1 de enero de 2021): 100–111. http://dx.doi.org/10.1515/hc-2020-0126.

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Abstract 4-Amino-5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one (1) was converted to the corresponding Schiff base (2) by treatment with salicylaldehyde. 1,2,4-Triazoles were then converted to the corresponding Mannich bases containing fluroquinolone core using a one-pot three-component procedure. Moreover, the synthesis of six compounds, which can be considered as conazole analogues, was performed starting from 1,2,4-triazole-3-one compounds via three steps by either conventional or microwave-mediated conditions. All the newly synthesized compounds were screened for their antimicrobial activities. Most exhibited good to moderate antibacterial and/or antifungal activity. The structural assignments of the new compounds were based on elemental analysis and spectral (IR, 1H NMR, 13C NMR, and LC-MS) data.

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43

Veeranki, Krishna Chaitanya, Jalapathi Pochampally, Ravi Chander Maroju, Vishnu Thumma y Lakshmi Satya Boddu. "1,2,3-Triazoles containing Thiazole-Piperazine Moieties: Synthesis, Biological Assessment and Molecular Docking". Asian Journal of Chemistry 35, n.º 1 (27 de diciembre de 2022): 125–34. http://dx.doi.org/10.14233/ajchem.2023.26904.

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A novel series of thiazole-triazole-piperazine multi hybrids was designed for antimicrobial activity and the synthetic method for this series has been developed by copper catalyzed 1,3-dipolar cycloaddition of thiazole-based azide with Boc-piperidine based alkyne in the presence of CuSO4 and sodium ascorbate. Boc deprotection followed by alkylation of piperidine moiety in hybrid derivatives was also carried out. All the target compounds were confirmed using FTIR, 1H NMR, 13C NMR and LC-MS spectral techniques. These compounds were screened for the antimicrobial activity against bacteria and fungi. The antimicrobial activities are also comparable to standard drugs ampicillin and clotrimazole. All the molecules showed good to moderate activity and supported by molecular docking studies and ADME prediction.

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44

Abadie, Cyril y Guillaume Tcherkez. "13C Isotope Labelling to Follow the Flux of Photorespiratory Intermediates". Plants 10, n.º 3 (24 de febrero de 2021): 427. http://dx.doi.org/10.3390/plants10030427.

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Measuring the carbon flux through metabolic pathways in intact illuminated leaves remains challenging because of, e.g., isotopic dilution by endogenous metabolites, the impossibility to reach isotopic steady state, and the occurrence of multiple pools. In the case of photorespiratory intermediates, our knowledge of the partitioning between photorespiratory recycling, storage, and utilization by other pathways is thus rather limited. There has been some controversy as to whether photorespiratory glycine and serine may not be recycled, thus changing the apparent stoichiometric coefficient between photorespiratory O2 fixation and CO2 release. We describe here an isotopic method to trace the fates of glycine, serine and glycerate, taking advantage of positional 13C content with NMR and isotopic analyses by LC–MS. This technique is well-adapted to show that the proportion of glycerate, serine and glycine molecules escaping photorespiratory recycling is very small.

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45

Hryhoriv, Halyna, Illia Mariutsa, Sergiy M. Kovalenko, Victoriya Georgiyants, Lina Perekhoda, Nataliia Filimonova, Olga Geyderikh y Lyudmila Sidorenko. "The Search for New Antibacterial Agents among 1,2,3-Triazole Functionalized Ciprofloxacin and Norfloxacin Hybrids: Synthesis, Docking Studies, and Biological Activity Evaluation". Scientia Pharmaceutica 90, n.º 1 (22 de diciembre de 2021): 2. http://dx.doi.org/10.3390/scipharm90010002.

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Among all modern antibiotics, fluoroquinolones are well known for their broad spectrums of activity and efficiency toward microorganisms and viruses. However, antibiotic resistance is still a problem, which has encouraged medicinal chemists to modify the initial structures in order to combat resistant strains. Our current work is aimed at synthesizing novel hybrid derivatives of ciprofloxacin and norfloxacin and applying docking studies and biological activity evaluations in order to find active promising molecules. We succeeded in the development of a synthetic method towards 1,2,3-triazole-substituted ciprofloxacin and norfloxacin derivatives. The structure and purity of the obtained compounds were confirmed by 1H NMR, 13C NMR, 19F NMR, LC/MS, UV-, IR- spectroscopy. Docking studies, together with in vitro research against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa ATCC 27853, Candida albicans NCTC 885-653 revealed compounds in which activity exceeded the initial molecules.

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46

S Dharmaraj Santhosam, P Selvam y Abhinandan Danodia. "Isolation and characterization of three isolates of Abrus precatorius seeds by LC-MS, 1HNMR, And 13CNMR". International Journal of Science and Research Archive 8, n.º 1 (30 de enero de 2023): 404–20. http://dx.doi.org/10.30574/ijsra.2023.8.1.0056.

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The three isolates were isolated from the methanolic extract of Abrus precatorius seeds by column chromatography using silica gel 60-120 mesh as the adsorbent and methanol as the mobile phase. The isolated compounds are further purified by TLC. The compounds that have the same RF value are combined. The crude extract was named CMME. The isolated compounds named CMME I, CMME II, and CMME III are first-eluted, second, eluted, and third-eluted compounds respectively. The isolated compounds were characterized by LC-MS, 1H NMR, and 13C NMR. The compound I was found to be (4,6-O-Benzylidene) methyl-alpha D-glucopyranoside, m/z282.3923, molecular formula C14H18O6. The compound II was found to be Isoflavone base + 20, O-Malonyl Hex, m/z 502.42801, molecular formula C24H22O12. The compound III was found to be 3-Carboxy-1-methyl pyridinium chloride, m/z 173.6, molecular formula C7H8ClNO2.

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47

Hajalsiddig, Tawassl Tajelsir Hassan y Ahmed Elsadig Mohammed Saeed. "Synthesis of new 6-substituent 2-phenyl and 2-(furan-2-yl)-3-phenyl-quinoline-4-carboxylic acid derivatives". European Journal of Chemistry 10, n.º 1 (31 de marzo de 2019): 57–63. http://dx.doi.org/10.5155/eurjchem.10.1.57-63.1816.

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A synthesis of substituted quinolines has been achieved by the Doebner reaction which is a three component coupling of arylaldehyde, p-amino-acetophenone and phenyl pyruvic acid. The products of 2,3-diary-6-acetyl-quinoline-4-carboxylic acids were obtained by Claisen Schmidt condensation reaction with aldehydes in the presence of sodium hydroxide in order to give the corresponding α,β-unsaturated carbonyls. The substituted α,β-unsaturated carbonyls were condensed with urea, thiourea, hydrazine, phenyl hydrazine, semicarbazide hydrochloride and ethanolamine to synthesized 2-pyrimidinone, 2-pyrimidinethion, pyrazoline-1-phenyl, pyrazoline, pyrazoline-1-carboxamide and 1,4-oxazepines derivatives, respectively, with good yields. The purity and identities of products were elucidated through thin layer chromatography (TLC), melting point and spectroscopic data (IR, 1H NMR, 13C NMR and LC-Mass).

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48

Kumar, C. H. Praveen, S. Katagi Manjunatha y B. P. Nandeshwarappa. "Synthesis of novel pyrazolic analogues of chalcones as potential antibacterial and antifungal agents". Current Chemistry Letters 12, n.º 3 (2023): 613–22. http://dx.doi.org/10.5267/j.ccl.2023.2.001.

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The present includes the synthesis of pyrazoline derivatives using chalcones and phenyl hydrazine in the presence of ethanol. It also reveals that 2-pyrazoline complexes are physiologically active and may be used in a variety of therapeutic functions. FT-IR, 1H-NMR, 13C-NMR, LC-MS, and elemental analyses were used to characterise newly synthesised phenyl-pyrazoline derivatives. The antimicrobial activity of the synthesised compounds was assessed using the agar well diffusion assay and the Minimum Inhibition Concentration (MIC). Compounds 4b, 4f, and 4h have exhibited remarkable antibiotic action against bacterial strains such as Staphylococcus aureus, Bacillus subtilis, Salmonella. Typhi, and Shigella sp. On the other hand, compound 4h had significant antifungal activity against Candida albicans and Aspergillus fusarium and was a highly promising agent when compared to standard nystatin.

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49

Park, Jong-Won, Lee-Woon Jang, Erik C. Jensen, Amanda Stockton y Jungkyu Kim. "Sensing Techniques for Organochlorides through Intermolecular Interaction with Bicyclic Amidines". Biosensors 11, n.º 11 (23 de octubre de 2021): 413. http://dx.doi.org/10.3390/bios11110413.

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Toxic organochloride molecules are widely used in industry for various purposes. With their high volatility, the direct detection of organochlorides in environmental samples is challenging. Here, a new organochloride detection mechanism using 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) is introduced to simplify a sensing method with higher detection sensitivity. Three types of organochloride compounds-trichloroethylene (TCE), dichloromethane (DCM), and dichlorodiphenyltrichloroethane (DDT)—were targeted to understand DCM conjugation chemistry by using nuclear magnetic resonance (NMR) and liquid chromatography with a mass spectrometer (LC-MS). 13C-NMR spectra and LC-MS data indicated that DBN can be labeled on these organochloride compounds by chlorine–nitrogen interaction. Furthermore, to demonstrate the organochloride sensing capability, the labeling yield and limit of detection were determined by a colorimetric assay as well as micellar electrokinetic chromatography (MEKC). The interaction with DBN was most appreciable for TCE, among other organochlorides. TCE was detected at picomolar levels, which is two orders of magnitude lower than the maximum contaminant level set by the United States Environmental Protection Agency. MEKC, in conjunction with this DBN-labeling method, enables us to develop a field-deployable sensing platform for detecting toxic organochlorides with high sensitivity.

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50

Pannakal, Steve Thomas, Joan Eilstein, Jane Hubert, Alexis Kotland, Arpita Prasad, Amelie Gueguiniat-Prevot, Franck Juchaux et al. "Rapid Chemical Profiling of Filipendula ulmaria Using CPC Fractionation, 2-D Mapping of 13C NMR Data, and High-Resolution LC–MS". Molecules 28, n.º 17 (30 de agosto de 2023): 6349. http://dx.doi.org/10.3390/molecules28176349.

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Filipendula ulmaria, commonly known as meadowsweet, is a wild herbaceous flowering plant that is widely distributed in Europe. A range of salicylic acid derivatives and flavonol glycosides have been previously associated with the antirheumatic and diuretic properties of F. ulmaria. In the present work, a hydroalcoholic extract from F. ulmaria aerial parts was extensively profiled using an efficient NMR-based dereplication strategy. The approach involves the fractionation of the crude extract by centrifugal partition chromatography (CPC), 13C NMR analysis of the fractions, 2D-cluster mapping of the entire NMR dataset, and, finally, structure elucidation using a natural metabolite database, validated by 2D NMR data interpretation and liquid chromatography coupled with mass spectrometry. The chemodiversity of the aerial parts was extensive, with 28 compounds unambiguously identified, spanning various biosynthetic classes. The F. ulmaria extract and CPC fractions were screened for their potential to enhance skin epidermal barrier function and skin renewal properties using in vitro assays performed on Normal Human Epidermal Keratinocytes. Fractions containing quercetin, kaempferol glycosides, ursolic acid, pomolic acid, naringenin, β-sitosterol, and Tellimagrandins I and II were found to upregulate genes related to skin barrier function, epidermal renewal, and stress responses. This research is significant as it could provide a natural solution for improving hydration and skin renewal properties.

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