Determined by1H NMR Research Articles

Synthesis and Photoluminescence Behavior of π-Conjugated 3-Substituted Isoquinoline Derivatives

In this work, a series of π-conjugated isoquinoline derivatives, bearing diverse aryl groups at the 3-position, were synthesized in a facile and straightforward manner. A Pdcatalyzed protocol, the Suzuki-Miyaura coupling of 3-bromoisoquinoline and different aryl boronic acids, was applied, and the structures of the resulting target compounds were determined by 1H-NMR, 13C-NMR, and HRMS. Furthermore, the photophysical properties of these compounds were investigated. Distinct halochromic properties were revealed for them, which exhibited UV emissions in ethanol but visible emissions in an acidic solution.

Synthesis and Biological Activities of N-(2-(Cyano(4,6-dimethoxypyrimidin-2-yl)methyl)phenyl) Substitued Amide Derivatives

以2-（2-硝基苯基）乙腈及4，6-二甲氧基-2-甲磺酰基嘧啶为起始原料，分别经缩合、还原及酰胺化反应合成了6个未见文献报道的Ⅳ-（2-（腈基（4，6-二甲氧基嘧啶-2-基）甲基）苯基）酰胺类衍生物，其结构经^1HNMR、MS和元素分析进行了确证。在150g／hm^2的用量条件下，合成化合物未显示出除草活性。在200mg／L浓度下，部分化合物对黄瓜灰霉病及水稻纹枯病表现出一定的抑菌作用，其中化合物4d对水稻纹枯病的抑制率为72．33％。

Microwave Assisted Synthesis of Thiol Modified Polymethacrylic acid and Its Cross‐Linking with Allyl Modified Polymethacrylic acid via Thiol‐ene “Click” Reaction

AbstractIn this paper, we describe the thiol‐ene “click” reaction with modified poly methacrylic acid in water. The thiol group was implemented by a polymer analogous condensation reaction of polymethacrylic acid (1) and cysteamine (2), which was carried out in bulk by use of microwave. The allyl modified polymethacrylic acid (5) was obtained by DCC‐coupling of the allyl amine onto the polymethacrylic acid backbone. By combination of cysteamine (3) and allyl modified polymethacrylic acid (5) the thiol‐ene click reaction could be started with a redox initiator in aqueous solution at room temperature. The kinetics of this reaction were determined by1H NMR spectroscopy and the resulting hydrogels were analyzed by rheological measurements and differential scanning calorimetry (DSC).magnified image

Pharmacometabonomic identification of a significant host-microbiome metabolic interaction affecting human drug metabolism

We provide a demonstration in humans of the principle of pharmacometabonomics by showing a clear connection between an individual's metabolic phenotype, in the form of a predose urinary metabolite profile, and the metabolic fate of a standard dose of the widely used analgesic acetaminophen. Predose and postdose urinary metabolite profiles were determined by (1)H NMR spectroscopy. The predose spectra were statistically analyzed in relation to drug metabolite excretion to detect predose biomarkers of drug fate and a human-gut microbiome cometabolite predictor was identified. Thus, we found that individuals having high predose urinary levels of p-cresol sulfate had low postdose urinary ratios of acetaminophen sulfate to acetaminophen glucuronide. We conclude that, in individuals with high bacterially mediated p-cresol generation, competitive O-sulfonation of p-cresol reduces the effective systemic capacity to sulfonate acetaminophen. Given that acetaminophen is such a widely used and seemingly well-understood drug, this finding provides a clear demonstration of the immense potential and power of the pharmacometabonomic approach. However, we expect many other sulfonation reactions to be similarly affected by competition with p-cresol and our finding also has important implications for certain diseases as well as for the variable responses induced by many different drugs and xenobiotics. We propose that assessing the effects of microbiome activity should be an integral part of pharmaceutical development and of personalized health care. Furthermore, we envisage that gut bacterial populations might be deliberately manipulated to improve drug efficacy and to reduce adverse drug reactions.

Design, Synthesis and Inclusion Properties of Butterfly-shaped Hosts

Two kinds of “butterfly-shaped” host compounds, 2,5-bis(triphenylmethyl)hydroquinone (1) and 2,5-bis(diphenylmethyl)hydroquinone (2) were designed and synthesized. 1 and 2 can form inclusion complexes with various small organic molecules. These inclusion complexes were determined by1H NMR spectroscopy, and the results were as follows: 1·DMF (1:2), 1·DMSO (1:2), 1·pyridine (1:2), 1·cyclopentanone (2:3); 2·DMF (1:2), 2·THF (1:1), 2·benzaldehyde (1:2), 2·2,5-hexanedione (1:1), 2·N-methyl-2-pyrrolidone (1:3). The complex structure of 2 with benzaldehyde was determined by single crystal X-ray diffraction analysis and the crystal structure is stabilized by intermolecular hydrogen bonds.

Formation of the inclusion complex of Orange II with β-Cyclodextrin and its photostability

Inclusion complex of Orange II with β-Cyclodextrin (β-CD) and the anti-photolysis effect under UV-light were investigated. The molar ratio of inclusion complex of β-Cyclodextrin and Orange II is 1∶1. The formation constantK = 1.236×103 L/mol was determined by the UV and Fluorescence spectra respectively, which was quite in accordance with the calculation with a modified Benesi-Hildbrand equation. The inclusion complex was characterized by the IR spectra and the molar ratio of inclusion complex is 1∶1 too. The formation constantK = 1.266×103 L/mol was determined by1H NMR analysis and was nearly the same by UV and fluorescence spectra. The photocatalytic decolorization rate of Orange II solutions containing β-CD and TiO2 was smaller by 51.9% than that of the Orange II solutions only containing TiO2, while in the case of direct photolysis of Orange II solutions, β-CD can lower the photolysis rate by 48.1% under UV-light. This result indicates β-CD can inhibit the photolysis and photocatalytic decolorization of Orange II under UV-light. The β-CD inclusion complex was found to be persistent to UV-light photolysis.

Three-dimensional solution structure of ω-conotoxin SO3 determined by1H NMR

Cone snails (Conus) elaborate a series of conotoxin (CTX) peptides in their venoms to paralyze their prey. Among these toxins, ω-CTX’s specifically target to presynaptic voltage-gated calcium channel subsets, causing inhibition of neurotransmitter release. e-CTX SO3 was isolated from the venom ofConus striatus, which is the only available fish-hunting snail near the coast of the South China Sea. The three-dimensional solution structure of ω-CTX SO3, a peptide which is the only ω-conotoxin reported to show high homology with another ω-CTX (MVIIA fromC. Magus), has been determined by1H NMR techniques. The molecular structure of ω-CTX SO3 is stabilized by three disulfide bridges and a short triple-stranded antiparallel β-sheet with four turns. A comprehensive comparison suggested that the backbone conformation of ω-CTX’s was quite conserved, while the length of β-sheet and the type of some turns might have minor differences.

Bis-phenol A Cyclophanes: Synthesis, Crystal Structures and Binding Studies

The synthesis and structural characterisation of three new macrocyclicbis-phenol A cyclophane ethers are described. The solid state structuresof two of the cyclophanes were determined by single crystal X-raydiffraction. Cyclophane 3 crystallises in the orthorhombic spacegroup Pbca with unit cell dimensions of a = 11.533(7), b = 29.383(8),c = 14.927(8) A and cyclophane 4 in the monoclinic spacegroup P21/n with cell dimensions of a = 11.585(4), b = 11.839(2), c = 18.866(2) A, β = 94.48(2)°.The X-ray crystalstructures reveal distorted conformations, thus supporting the weak bindingof quats in solution observed by the NMR studies. In the crystalline state bothmacrocycles were found to form self-complementary dimers held together byweak intermolecular π-π and CH-π interactions. The bindingbehaviour towards a series of tetralkylammonium cations was determinedby 1H NMR titration in CDCl3 solution. The interactions between the hosts and the quats were clearly detectable but too weak to be translated into meaningful equilibrium constants.

Three-dimensional structure of α-conotoxin EI determined by1H NMR spectroscopy

α-conotoxin EI is an 18-residue peptide (RDOCCYHPTCNMSNPQIC; 4–10, 5–18) isolated from the venom ofConus ermineus, the only fish-hunting cone snail of the Atlantic Ocean. This peptide targets specifically the nicotinic acetylcholine receptor (nAChR) found in mammalian skeletal muscle and the electric organTorpedo, showing a novel selectivity profile when compared to other α-conotoxins. The 3D structure of EI has been determined by 2D-NMR methods in combination with dynamical simulated annealing protocols. A total of 133 NOE-derived distances were used to produce 13 structures with minimum energy that complied with the NOE restraints. The structure of EI is characterized by a helical loop between THr9 and Met12 that is stabilized by the Cys4-Cys10 disulfide bond and turns involving Cys4-Cys5 and Asn14-Pro15. Other regions of the peptide appear to be flexible. The overall fold of EI is similar to that of other α4/7-conotoxins (PnIA/B, MII, EpI). However, unlike these other α4/7-conotoxins, EI targets the muscular type nAChR. The differences in selectivity can be attributed to differences in the surface charge distribution among these α4/7-conotoxins. The implications for binding of EI to the muscular nAChR are discussed with respect to the current NMR structure of EI.

Structure of 1-β-d-xylofuranosyluracil in the crystal and in solution

The molecular and crystal structure of 1-β-d-xylofuranosyluracil hydrate was established by X-ray diffraction analysis. The mutual arrangement of the xylofuranose fragment and the nucleic base corresponds to the anti conformation. The furanose ring adopts a C-envelope conformation. The structure of the nucleoside in a DMSO-d6 solution has been determined by1H NMR spectroscopy.

Novel synthetic phospholipid protects lipid bilayers against oxidation damage: role of hydration layer and bound water

The role of the membrane hydration layer in preventing membrane oxidative damage has been evaluated by comparing bilayers with and without an extended hydration layer. The extended hydration layer was obtained through the use of a novel phospholipid in which polyethylene glycol of 2000 Da molecular mass (PEG2000) was covalently attached to the phosphate headgroup of a phospholipid backbone to form dihexadecylphosphatidyl PEG2000—α-{[2,3-bis(hexadecyloxy)propoxy](h ydroxyphosphinoyl}-ω-methoxypoly(oxyethane-1,2-diyl) monosodium salt. The amount of water bound to free PEG and to the DHP-PEG2000 was determined by differential scanning calorimetry. Small unilamellar liposomes composed of egg phosphatidylcholine and DHP-PEG2000 were prepared. 44% of the phospholipid contained one polyunsaturated acyl chain. Oxidative damage to liposomes after exposure to three different oxidation procedures was measured by the disappearance of polyunsaturated acyl chains, as determined by GC. Oxidation procedures used were: (i) exposure to ionizing γ-irradiation (9200 Gy), for which the grafted PEG2000 provided significant protection against oxidation, with minimal damage to the PEG2000 as determined by 1H NMR and TLC. (ii) Storage for 6 months at 4 °C or for 4 months at 4 °C followed by 4 d at 37 °C, for which the presence of DHP-PEG2000retarded acyl chain peroxidation. (iii) Oxidation of the liposomes by 2,2′-azo(2-amidinopropane) dihydrochloride (a positively charged water-soluble peroxyl radical initiator), for which there was no protection by DHP-PEG2000 (probably due to electrostatic binding of the AAPH to the negatively charged membranes, thereby overriding the hydration layer protection barrier).

Ruthenium-mediated selective activation of a C–H bond. Direct aromatic thiolation in the complexes [RuII{o-SC6H3(R)NNC 5H4N}2] (R = H, Me or Cl)

The reaction of the complexes ctc-[Ru II L 2 Cl 2 ] (L = arylazopyridine, RC 6 H 4 NNC 5 H 4 N, where R = H, m-Me, p-Me or p-Cl; ctc = cis-trans-cis with respect to chlorides, pyridine and azo nitrogens respectively) with KS 2 COR′ (R′ = Me, Et, Pr n , Bu n or CH 2 Ph) in boiling dimethylformamide afforded [Ru II {o-SC 6 H 3 (R)NNC 5 H 4 N} 2 ] where the o-carbon atom of the pendant phenyl ring of both ligands L has been selectively and directly thiolated. The newly formed tridentate thiolated ligands are bound in a meridional fashion. When one methyl group is present at the meta position of the pendant phenyl ring of L the reaction resulted in two isomeric complexes due to free rotation of the singly bonded meta-substituted phenyl ring with respect to the azo group. The molecular geometry of the complexes in solution has been determined by 1 H NMR spectroscopy. This revealed the presence of an intimate mixture of the two isomers in solution in a 2∶1 ratio. In the visible region the complexes exhibit two metal-to-ligand charge-transfer transitions at ≈700 and ≈560 nm respectively and in the UV region intraligand (π–π*, n–π*) transitions. In acetonitrile solution the complexes exhibit one reversible ruthenium(II) ruthenium(III) oxidation couple near 0.4 V and an irreversible oxidative response near 1 V due to oxidation of the co-ordinated thiol group. Reduction of the co-ordinated azo groups occurs at ca. -0.8 and -1.4 V respectively. Coulometric oxidation of the complexes [Ru II {o-SC 6 H 3 (R)NNC 5 H 4 N} 2 ] at 0.6 V versus the saturated calomel electrode in dichloromethane produced unstable ruthenium(III) congeners. When R = p-Me, the presence of trivalent ruthenium in the oxidised solution was evidenced by a rhombic EPR spectrum having g 1 = 2.359, g 2 = 2.300 and g 3 = 1.952.

Fourier Transform Infrared Quantitative Determination of the Total Branched Chain of Poly(Ethylene/Butyl Acrylate/Vinyl Acetate)

An FTIR method has been developed for quantitative analysis of the total branched chainnmethylof ethylene/butyl acrylate/vinyl acetate tercopolymer. In this work, mixtures of atactic polypropylene and straight-chain alkane C27H56were chosen as model compounds and the 1378 cm−1band of the methyl side group as the key band for determination of the number of branched chains of the tercopolymer. A calibration equation correlation coefficient of 0.995 was obtained as follows:nmethyl= 0.51 (A1376/D·t) − 1.02.nmethylof the tercopolymer can be determined by FTIR; the results are in agreement with those determined by1H NMR.

Bioengineering of poly(β-hydroxyalkanoates) for advanced material applications: incorporation of cyano and nitrophenoxy side chain substituents

Novel functional poly(β-hydroxyalkanoates), PHAs, with hyperpolarizable side groups were prepared. Pseudomonas oleovorans ATCC 29347 and Pseudomonas putida KT 2442 were selected as biocatalysts. These organisms were first grown on citrate (40 mM) before polymer formation was studied in a second stage. The carbon sources in second-stage cultivations were mixtures (total of 15 mM) of octanoate (OA) with either 7.5 or 10 mM para-cyanophenoxyhexanoate (CPH), para-cyanophenoxyvalerate (CPV), para-cyanophenoxybutyrate (CPB), or para-nitrophenoxyhexanoate (NPH). For both organisms, only small deviations in the number of colony-forming units per millilitre were observed when second-stage cultivations containing only 15 mM octanoate were compared with those using mixtures of OA with either CPB, CPV, CPH, or NPH. PHA volumetric yields as a function of organism, carbon source mixture, and culture time are reported. The percent incorporations of substituted phenoxy side groups in the polymer products were determined by1H NMR spectroscopy. Pseudomonas putida formed PHAs with up to 24.2% 3-hydroxy-6-(para-cyanophenoxy)hexanoate side groups when 5 mM OA and 10 mM CPH were used. A dramatic decrease in the percent incorporation of para-cyanophenoxy (CP) by P. putida was observed when the relatively shorter CP-substituted n-alkanoate chain CPV and CPB cosubstrates were used. Use of NPH in place of CPH had deleterious effects on both polymer formation and percent incorporation of substituted phenoxy side groups in P. putida. Pseudomonas oleovorans formed PHAs with only up to ~2% CP side chains when a combination of OA and CPH was used and little to no CP side groups when a combination of OA and CPV or CPB was used. Substitution of NPH in place of CPH led to a modest increase (up to ~5%) in substituted phenoxy side groups. Thus, a new route to first-generation chiral polymer structures for nonlinear optical applications was demonstrated.Key words: Pseudomonas oleovorans, Pseudomonas putida, poly(β-hydroxyalkanoate), poly(3-hydroxy-6-para-cyanophenoxyhexanoate), poly(3-hydroxy-6-para-nitrophenoxyhexanoate), poly(β-hydroxy-para-cyanophenoxyvalerate).

Facile synthesis of (�)-2,6-dimethyloctan-1-ol formate, the biologically active analog of the smaller flour beetle aggregation pheromone, from 1-allyloxy- and 1-benzyloxy-2,6-dimethyl-2,7-octadienes, the telomers of isoprene with allyl and benzyl alcohols

A careful investigation of the telomerization of isoprene with allyl, benzyl, 2-chloroethyl and methyl alcohols on π-allylpalladium complex catalysts was carried out. The structures of the obtained telomers were determined by1H NMR spectroscopy. 1-Alkoxy-2,6-dimethyl-2,7-octadiene is a predominant telomer. 2,6-Dimethyloctan-1-ol, which reacts with HCOOH to give (±)-2,6-dimethyloctan-1-ol formate in high yield, was obtained from 1-allyloxy- and 1-benzyloxy-2,6-dimethyl-2,7-octadienes by the removal of allyl and benzyl protective groups and by the hydrogenation of double bonds.

Cardenolide glycosides from the adults and eggs ofChrysolina fuliginosa (Coleoptera: Chrysomelidae)

Besides the known sarmentogenin 3-O-β-D-allopyranoside (1) and digitoxigenin-3-O-[β-D-xylopyranosyl-(1→4)-2′, 3′-di-O-acetyl-β-D-allopyranoside] (4), four new cardiac glycosides (2, 3, 5 and6) have been isolated from the defensive glands of adults ofChrysolina fuliginosa. The structures of the new compounds were determined by1H NMR at 600 MHz and FABMS. Compounds1–6, present in the adults ofC. fuliginosa, have also been identified in the eggs.

Thermal behaviour of copolymers of methyl methacrylate and 2-ethylhexyl methacrylate

Five copolymer samples containing different mole fractions of methyl methacrylate (MMA) and 2-ethylhexyl methacrylate (EHMA) were prepared by bulk polymerisation at 70°C using 0.2% benzoyl peroxide as an initiator. The copolymer composition was determined by1H NMR spectroscopy. Molecular weight of copolymers was determined by gel permeation chromatography and viscosity measurements. Thermogravimetric experiments were conducted to evaluate activation energy for the degradation of copolymers. Two to four reaction stages for the weight loss were observed in the copolymers. A decrease in thermal stability was observed by an increase in EHMA content.

Reductive silylation of chloroprene

Copolymers made up of 1,4-(2-trimethylsilyl-1,3-butadiene) (I) and 1,4-(2-chloro-1,3-butadiene) (II) units have been prepared by reaction of chloroprene with trimethylchlorosilane and sodium dispersion in THF. The ratio of I∶II units in the copolymers have been determined by IR,1H NMR and elemental analysis. The E∶Z ratio of these units has been determined by1H NMR.13C and29Si NMR of these copolymers is discussed.

Structure of the proton skeleton of nitrobenzene, determined by1H NMR in the nematic phase

As a structural method NMR spectroscopy in LC solvents in primarily intended for determination of the geometry of the proton skeleton of the molecule and makes it possible to refine the data from other structural methods by the introduction of information on the proton coordinates. The authors determined the structure of the proton skeleton of nitrobenzene in two thermotropic nematic liquid crystals. These data, together with published data, make it possible to take account of the effect of the solvent and to calculate the supposed geometry of the proton skeleton of nitrobenzene in a hypothetical solvent.

Terephthalate copolyesters of ethylene glycol and propane-1,3-diol

Terephthalate copolyesters of ethylene glycol and propane-1,3-diol of various compositions were prepared by trans-esterification of poly(ethylene terephthalate) (PET) with propane-1,3-diol [PrG(1,3)] . The compositions of the coDolyesters were determined by1H NMR. The melting and crystallization temperatures were measured by differential thermal analysis (DTA). Intrinsic viscosities were measured in orthochlorophenol at 30°C.