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[en] Present article is devoted to correlation of paramagnetic resonance data and quantum chemical calculations for possible conformations of enin triols. Factors leading to formation of intramolecular hydrogen bonds with using paramagnetic resonance have been revealed. The quantum chemical calculations of obtained conformations has been conducted.
[en] It was not easy to distinguish enol-form (HPM) from the 1,2-addition adduct DPIP possessing same chemical formula. Based on the NMR spectroscopic methods including DEPT, COSY and g-HSQC, HPM's structure was confirmed and allowed to rule out the formation of DPIP. In addition, the same reactions of DPM with pyrrolidine under acid free condition gave the similar results giving keto/enol isomers of 1:4 ratio. The synthesis and characterization of new fluorophores is receiving increasing attention because of the potential applications of fluorophores as light emitting materials in LED and fluorometric probes for biomolecules. For this purpose 2-(2,6-dimethyl-pyran-4-ylidene)-malononitrile (DPM) is used as a key intermediate for synthesis of the red emission dyes viz. 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran(DCM), 4-(dimethylene-2-methyl-6-[2-(2,3,6,7-tetrahydro-1H, 5H-benzo[ij]quinolizin-8-yl)vinyl]-4H-pyran as well as in the synthesis of the symmetrical DCM derivative, 4-(dicyanomethylene)-2,6-bis(4-dimethylaminostyryl)-4H-pyran. Now a days, these materials have become attractive because of their tunable electronic properties, representing low excitation gap and are suitable for electron or hole transferring in various electronic devices
[en] We have carried out 77Se nuclear magnetic resonance (NMR) measurements in order to probe the surface state of topological insulator Bi2Se3 nanoparticles physically mixed with insulating Al2O3 nanoparticles. Two distinct peaks in the NMR spectra were separately assigned to the surface and the bulk regions in the samples with different mixing ratios, manifesting an increase in the surface effect.
[en] A number of mimetic peptides of apolipoprotein A-I, a major component for high density lipoproteins (HDL), were screened from the phase-displayed random peptide library by utilizing monoclonal antibodies (A12). A mimetic peptide for A12 epitope against apolipoprotein A-I was selected as FVLVRDTFPSSVCCP(pA2) exhibiting 45% homology with Apo A-I in the BLAST search. Solution structure determination of this mimotope was made by using 2D-NMR data and NMR-based distance geometry (DG)/molecular dynamic calculations. The resulting DG structures had low penalty value of 0.4-0.6 A2 and the total RMSD of 0.7-1.7 A. The mimotope pA2 exhibited a characteristic β-turn conformation from Val to Phe near Pro residue
[en] Two new monocyclic naphthene derivatives (1and 2) along with seven known compounds for the first time from the chloroform soluble fraction of the Tamarix indica. The structures of the isolated compounds were elucidated on the basis of modern sophisticated, EIMS, HREIMS, 1D and 2D-NMR spectroscopic techniques. The known compounds were recognized as 1- eicosanoyl (3), 6-heneicosanyl-1,2,4-trimethoxybenzene (4), 3 hydroxybenzoic acid (5), ethyl gallate (6) gallic acid (7), β-sitosterol (8) and methyl grevillate (9). (author)
[en] General, fast, and efficient stitching methods for the synthesis of dendrimers with linear PEG units at a core, as dendritic-linear-dendritic materials, were developed. The synthetic strategy involved the click reaction between an alkyne and an azide. The linear core building blocks, three dialkyne-PEG units, were chosen to serve as the alkyne functionalities for dendrimer growth via click reactions with the azide-dendrons. These three building blocks were employed together with the azide-functionalized Frechet-type dendrons in a convergent strategy to synthesize the Frechet-type dendrimers with different linear core units. Their structure of dendrimers was confirmed by 1H and 13C NMR spectroscopy, IR spectroscopy, mass spectrometry, and GPC analysis
[en] A number of per-6-substituted-6-deoxy-β-cyclodextrin derivatives have been synthesized for many years, of them, per-6-deoxy-6-iodo-β-cyclodextrin is of great importance in supramolecular chemistry. By reviewing all published papers related to synthesis of per-6-deoxy-6-iodo-β-cyclodextrin and combining with our experimental verification, this work has reported an improved method of synthesis of per-6-deoxy-6-iodo-β-cyclodextrin. The approach mainly uses adding a certain amount of methanol instead of removing DMF before adjusting pH. We think this project is simple, efficient, high repeatable and suitable for large-scale preparation, superior even to all the previously reported methods. The synthesis of bromo, chloro substituted -per-6-β-CD may also refer to this improved method. At the same time, the detailed introduction of operation process and precautions will serve as a reference and guidance to the beginner who will engage in the study on the chemical synthesis reaction of sugar and cyclodextrin. (author)
[en] (20R,24R)-epoxy-dammar-3 beta,6 alpha,12 beta,25-tetraol (1) and (20R,24S)-epoxy-dammar-3 beta, 6 alpha,12 beta,25-tetraol(2) have been synthesized from 20(R)-protopanaxatriol with same polarity. In order to obtain optically pure 1and 2, (20R,24R)-3,6-diacetyl-20,24-epoxydammar-3 beta,6 alpha,12 beta,25-tetraol (3) and (20R,24S)-3,6-diacetyl-20,24-epoxydammar-3 beta,6 alpha,12 beta, 25-tetraol (4) were designed and prepared to enhance the polarity difference of C24 epimers. Two suitable crystals of 3 and 4 were obtained and their structures were determined by 1H NMR, 13C NMR, HR-MS and X-ray single-crystal diffraction. The results indicated that the C-24 configuration of 3 and 4 are R-form and S-form, respectively. 3 has two intramolecular hydrogen bond. While there is only one in 4 and the crystal stacking displays that it generates a right-handed helically chiral channel viewing from the crystallographic b axis via classical O-H O intermolecular hydrogen bond. (author)
[en] Present article is devoted to structure and reaction ability of 2- substituted 4.6-dioxo-4 H.5 H.6 H-trihydro-1.3-thiazine. 2- substituted 4.6-dioxo-4 H.5 H.6 H-trihydro-1.3-thiazine has been used as initials for the synthesis of several series of substituted products containing biologically active groups. In order to identify the tautomers the ultraviolet, infrared and paramagnetic resonance spectres have been detailed studied.
[en] We report here the synthesis of a series of N-aryl-2,3-dihydrobenzo[1,4]dioxine-6-sulfonamide and its N-substituted derivatives with benzyl chloride and ethyl iodide. Initially, 2,3- dihydrobenzo[1,4]dioxine-6-sulfonyl chloride (1) was subjected to react with various aryl amines (2a-e) to afford parent compounds N-aryl-2,3-dihydrobenzo[1,4]dioxine-6-sulfonamide (3a-e). At second step, these parent compounds were reacted with benzyl chloride (4) and ethyl iodide (5) as to synthesize N-benzyl-N-aryl-2,3-dihydrobenzo[1,4]dioxine-6-sulfonamide (6a-e) and N-ethyl-Naryl- 2,3-dihydrobenzo[1,4]dioxine-6-sulfonamide (7a-e) in the presence of lithium hydride and N,N'-dimethylformamide respectively. FT-IR, Nuclear Magnetic Resonance (1H-NMR) and Mass Spectrometry (MS) techniques were used to investigate the structures of these synthesized compounds. A fingerprinted study was conducted against some enzymes like butyrylcholinesterase (BChE), acetylcholinesterase (AChE) and lipoxygenase (LOX). This study revealed that most of them demonstrated a moderate activity against butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) however promisingly a good activity against lipoxygenase enzyme was observed. Finally, an antimicrobial and hemolytic activities of these sulfonamides were probed which confirmed that the parent sulfonamides 3b have the proficient antimicrobial activities, while the derivatives 6a, 7a, 7b and 7c explored a good activity against the selected panel of bacterial and fungal species. All the compounds were further computationally docked against (LOX), (BChE) and (AChE) enzymes and these interaction highlighted the importance of sulfonamides in the inhibition of the target enzymes. (author)