新型含嘧啶的苯氧乙酸酯类衍生物的合成

以对羟基苯甲醛和一氯乙酸为起始原料,经羟醛缩合、关环及酯化等反应合成了6个含有嘧啶杂环的新型苯氧乙酸酯类衍生物,其结构经¹H NMR, ¹³C NMR, IR和HR-ESI-MS表征。     

Orientational ordering in the nematic phase of 4-alkenyl-substituted bicyclohexylnitriles

The orientational ordering of a series of 4-alkenyl-substituted bicyclohexyl liquid crystals was studied by natural abundance ¹³C NMR spectroscopy. A combination of the methods of variable angle spinning (VAS) and separated local field spectroscopy (SLF) was used. Rapid sample spinning about an axis forming an angle of about 65° with respect to the magnetic field forces the nematic director to align parallel to the spinnin axis, leading to narrow peaks in the ¹³C NMR spectrum. The two-dimensional NMR spectroscopic method SLF allows the observation of decoupled ¹³C signals in the ω₂ dimension and first-order C-H splitting patterns in the ω₁ dimension, from which the C-H dipolar coupling constants for individual pairs of nuclei can be obtained. Then, the order parameters for different molecular segments can be calculated. The method was applied to five different 4-alkenyl-substituted cyanobicyclohexanes. For the compounds studied, the dependence of the ring order parameters on the alkenyl chains shows the same trend as the melting and clearing temperatures and the elastic constants.     

新型菲并嗪类有机光伏材料的合成

以菲醌和邻位二胺为核心原料,经烷基化、硼化、Suzuki偶联、还原和关环反应合成了新型菲并嗪类有机光伏材料DTPZ,其结构经¹H NMR, ¹³C NMR, MALDI-TOF-MS和元素分析表征。     

Synthesis, X-ray diffraction analysis and NMR studies of (Z)-2-methyl-3-triphenylstannyl-3-pentene-2-ol

The synthesis of (Z)-2-methyl-3-triphenylstannyl-3-pentene-2-ol and its characterization by an X-ray diffraction study and multinuclear NMR are reported. The tin atom exhibits a distorted tetrahedral SnC₄ geometry with the four Sn---C bond distances experimentally equivalent. The slight distortion from the ideal tetrahedral geometry is because of the presence of a weak intramolecular HO → Sn interaction of 3.012(3) Å which produces a loose four-membered ring. The title compound was characterized in solution by ¹H, ¹³C and ¹¹⁹Sn NMR, and the persistence of the weak intramolecular HO → Sn coordination in solution was revealed by ¹³C and ¹¹⁹Sn secondary isotope multiplet of partially labelled entities (SIMPLE-NMR) experiments.     

A carbon-13 cp/mas NMR investigation of the conformation of substituted cyclohexanes in thiourea inclusion compounds

Inclusion compounds of several monosubstituted cyclohexanes and thiourea have been studied using high-resolution ¹³C CP/MAS NMR spectroscopy. The ¹³C NMR chemical shifts of the substituted cyclohexane ring are sensitive to the conformation of the substituent and allow one to predict qualitatively the relative populations of the axial and equatorial conformers. For methylcyclohexane trapped in thiourea the methyl substituent prefers the equatorial conformation while for the cyclohexyl halides (Cl, Br and I) the axial conformer is preferred. In the case of fluorocyclohexane the equatorial conformer appears to predominate; however, this conformer is in rapid equilibrium with the axial conformer.     

酞侧基聚芳醚酮的核磁共振研究(Ⅰ)──链结构及NMR谱的归属

用1D NMR方法研究酞侧基聚芳醚酮(PEK-C)链结构,用二维同核化学位移相关与二维异核化学位移相关实验方法对1D NMR谱峰进行归属,探讨了二维异核远程相关实验在缩聚高分子研究中的应用,为PEK-C修饰机理以及共混相容机理的研究提供重要信息。溶液NMR谱图数据表明,PEK-C具有较规整的链结构。     

Smenoqualone a novel sesquiterpenoid from the marine sponge Smenospongia sp.

Smenoqualone, a novel quinonic terpenoid with a rearranged drimane skeleton was isolated from a marine sponge Smenospongia sp. The stereostructure was determined by detailed analyses of ¹H and ¹³C NMR spectra, ¹H-¹H COSY, ¹H-¹³C correlations via HMQC, HMBC and NOE difference NMR experiments.     

Stemmosides C and D, two novel unusual pregnane glycosides from Solenostemma argel: structural elucidation and configurational study by a combined NMR-quantum mechanical strategy

Stemmosides C and D, two novel pregnane glycosides characterized by an unusual C-17 side chain were isolated from the pericarps of Solenostemma argel. In addition, stemmoside D displays an uncommon 14β proton configuration, apparently being the first pregnane isolated from plants known to have a 15 keto, cis CD ring junction. Their structures have been established by ESIMS and NMR experiments. The relative configuration of the molecules was determined using a strategy based on the simulation of ¹H, ¹³C, and J coupling NMR parameters. DFT calculations of ¹H and ¹³C chemical shifts, and of the ¹H homonuclear spin–spin coupling constants were performed with the mPW1PW91 functional using the 6-31G(d,p) basis set on the fully optimized geometries of all the possible stereoisomers.     

C and H nuclear magnetic shielding and spin–spin coupling constants of C-enriched bromomethane in the gas phase

¹³C and ¹H NMR spectral parameters are investigated for ¹³CH₃Br in gaseous matrices. It is found that both the ¹³C and ¹H chemical shifts of ¹³CH₃Br are linearly dependent on solvent density. Similar dependence is also detected for one-bond spin–spin coupling, ¹J(CH). For the first time the ¹³C and ¹H magnetic shielding constants and ¹J(CH) spin–spin coupling are obtained for an isolated ¹³CH₃Br molecule together with the coefficients responsible for solute–solvent molecular interactions in gaseous matrices. The present experimental results confirm the accuracy of some recent ab initio calculations of nuclear magnetic shielding performed for bromomethane.     

The N and C solid state NMR study of intramolecular hydrogen bond in some Schiff bases

In present work set of eight Schiff bases derived from substituted salicylaldehydes and aliphatic and aromatic amines has been studied in the solid state by ¹⁵N and ¹³C CPMAS NMR methods. ¹⁵N CPMAS NMR measurement is especially useful for investigation of the tautomerism in the compounds considered, owing to the large difference in the nitrogen chemical shifts of OH and NH tautomers. In the solid state, four of the compounds examined were shown by ¹⁵N CPMAS NMR to exist as OH tautomeric forms, and the remaining four as the corresponding NH forms with different stage of proton transfer process, from oxygen to nitrogen site.

This was confirmed by ¹³C CPMAS. The results reported were compared with those obtained for only two compounds in CDCl₃ solutions (solubility problems).     

2-二氟甲氧(硫)基吡啶-5-硼酸频哪醇酯类化合物的合成

以吡啶类化合物作为起始原料,先经二氟甲基化反应在羟基或巯基上引入二氟甲基基团,再用铱催化剂活化吡啶环的C-H并直接引入硼酸频哪醇酯基团,得到目标化合物,其产物结构经¹H NMR、¹³C NMR、MS和元素分析确证。该方法具有合成路线较短、反应条件温和、原料廉价易得以及产率较高等优点。     

Synthesis,structural characterization and solubility of 2-(1-substituted-1,11-undecylidene)-5-arylimino-△~3 -1,3,4-thiadiazolines

A series of novel 2-(1-substituted-1,11-undecylidene)-5-arylimino-△~3-1,3,4-thiadiazolines(4) were synthesized and their structure was characterized by ~1H NMR,~(13)C NMR and elemental analysis.Their solubility in both polar and non-polar solvents is significantly improved owing to the introduction of ethyl or methylthio group at cyclododecyl ring as compared with parent compounds[1,2-(1,11-undecylidene)-5-arylimino-△~3-1,3,4-miadiazolines].However,their fungicidal activity against Rhizoctonia solani is ...     

The dynamics of the CH3CN molecule in the isotropic phase and in a nematic solution

NMR lineshape studies of acelonitrile in the isotropic and the liquid-crystalline nematic phase of PCH have been performed. The scalar relaxation of the second kind due to the presence of the ¹⁴N quadrupolar nucleus has been confirmed as the most important relaxation mechanism for this molecule in both the isotropic and the anisotropic phase. It has been found largely responsible for the selective broadening on ¹³C and ¹H transitions. A minor contribution arising from intramolecular dipolar relaxation mechanism has also been investigated. Linewidth analysis of the NMR spectra allowed us to determine the quadrupolar relaxation time T_IN of the ¹⁴N nucleus. This is connected to the correlation time for rotational diffusion perpendicular to the molecular symmetry axis. A possible explanation of a residual selective broadeining which effects the ¹³C and ¹H NMR transitions and is not taken into account by this mechanism, is also given.     

Synthesis and Biological Evaluation of Novel Saccharin Derivatives Containing 1,2,3-Triazole Moiety

A series of novel saccharin derivatives containing 1,2,3-triazole moiety was synthesized in satisfactory yields. The structures of all the compounds were elucidated and confirmed by Fourier transform infrared(FTIR) spectroscopy, ¹H and ¹³C nuclear magnetic resonance(¹H NMR, ¹³C NMR) spectroscopy, and high resolution mass spectrometry(HRMS). The bioassays indicated that most of the title compounds displayed some extent herbicidal activities at 100 μg/mL.     

NEW TRITERPENOIDAL SAPONINS FROM MUSSAENDA PUBESECUS

A cyclolanostene-type triterpene and two saponins derived thereform, namely MP-C, D and F, were isolated from the acid-hydrolyzate of the mixture ofsaponins of Mussaenda pubesecus.Their structures were elucidated on the basis of chemical and UV, IR, ¹H, ¹³C NMR and MS spectral evidence.The two newsaponins MP-D and F were named Mussaendoside A and C, respectively.     

Keto-enolic tautomerism and spectral data of prenylated anthranoids from Vismia genus

A keto-enolic tautomerism is present in ring C of ferruginins, as demonstrated by chemical and physico-chemical methods. In particular, spectroscopic data of ferruginins, vismiones and their derivatives are reported and discussed. This study constitutes the first report on the application of ¹³C NMR spectroscopy to this type of structure.     

Design,Synthesis and Herbicidal Activity of Novel Sulfonylureas Containing Triazole and Oxadiazole Moieties

Three novel series of 5-substituted sulfonylurea derivatives were designed and synthesized via introducing a triazole or oxadiazole ring at the 5th position of the benzene ring in classical sulfonylurea herbicides. All the target compounds were confirmed by means of ¹H nuclear magnetic resonance(NMR), ¹³C NMR and elemental analysis. The bioassay results show that the target compounds containing an oxadiazole ring at the 5th position display moderate to excellent herbicidal activities against Brassica campestris and Amaranthus retroflexus under soil treatment. Especially, compounds zdk20, zdk21 and zdk22 possess 98.6%, 96.5% and 94.5% inhibition rates, respectively, against Amaranthus retroflexus at a concentration of 75 g/ha(1 ha=1×10⁴ m²) under soil treatment, which approach to those of the commercial herbicide chlorsulfuron.     

H MAS NMR monitoring of the C-labeled carbon scrambling for propane in zeolite H-ZSM-5

It has been demonstrated that ¹H MAS NMR spectroscopy can be used as a tool for in situ monitoring the reaction kinetics of ¹³C-labeled carbon scrambling in alkane molecules adsorbed on zeolite catalysts at the reaction temperature of 540–570 K. The accuracy of the results and the time resolution are improved compared to ¹³C MAS NMR spectroscopy.     

Conformational study of N-substituted 8-azabicyclo[3.2.1]octan-3-ones

N-Substituted 8-azabicyclo[3.2.1]octan-3-ones have been studied by ¹H and ¹³C NMR spectroscopy. In CDCl₃ solutions, these ketones display the same preferred conformation. The pyrrolidine and piperidone rings adopt a flattened N-8 envelope and distorted chair conformation, puckered at N-8 and flattened at C-3, respectively, with the N-substituent in axial position with respect to the piperidone ring.     

Molecular structure of meso-tetraphenylporphyrinatothallium(III) cyanide: Tl(tpp) (CN)

meso-Tetraphenylporphyrinatothallium(III) cyanide, Tl(tpp)(CN), was previously assumed to be monomeric and has been confirmed by X-ray analysis to exist as two independent molecules in one asymmetric unit. This unit displays two square-pyramidal coordination geometries for the thallium atoms with the cyano ligand coordinated to both Tl atoms. It crystallizes in the triclinic space group P , with a 10.003(3), b 16.231(7), c 21.277(8) Å, 89.98(3), β 90.57(3), γ 90.31(3)°' and z = 4. The structure was solved by direct methods. A total of 7995 unique reflections having I > 3σ(I) was measured with an automated diffractometer and used to refine the crystal structure to a conventional R factor of 6.05 %. The thallium-cyanide distances are 2.140(14) Å (for thallium(I)) and 2.277(14) Å (for thallium(2)) respectively, with thallium(1) situated 0.908 Å above the porphyrin ring and thallium(2) located 1.027 Å below the ring. IR and NMR spectroscopy p rovide complementary methods for investigation of the CN ligand. The characteristic band observed at 2160 cm⁻¹ in the FTIR spectrum is assigned to the CN stretching in the Tl(tpp)(CN) complex. The ¹³C resonance of axial cyano ligand is observed with a pulse delay of 3.5 s at 24°C at 139.2 ppm (with ¹J(²⁰⁵Tl-¹³C) 5394 and ¹J(²⁰³Tl-¹³C) 5344 Hz). This observation disagrees with the conclusion, drawn from previous work, in that an exchange process involving the apical ligand explains the invisibility due to line broadening at 35°C of the ¹³C signal.