Synthesis, characterization and photodynamic activity of amino-substituted hypocrellin derivatives

Three new hypocrellin derivatives, amino- or amino acid-substituted on the side ring of hypocrellin B (HB), were synthesized by the reactions of HB with 3-methoxypropylamine, 6-aminohexanoic acid and gamma-amino-n-butyric acid, respectively. The structures of these compounds were characterized with proton nuclear magnetic resonance spectra, infrared spectra and mass spectra. The UV-visible absorption spectra, singlet oxygen-generating quantum yield and amphiphilicities of hypocrellin derivatives were measured and compared with HB, the parent compound. These derivatives showed strong absorption in the domain of the phototherapeutic window (600-900 nm) and improved amphiphilicity. HB and the derivatives were preliminarily tested for their photodynamic effects on human oral cavity epithelial carcinoma KB cell line in vitro. Two amino acid-substituted hypocrellins showed phototoxicity to the KB cell line. At an inhibitory dosage of 50% killing only 0.51 mumol L-1 compound 3 (or 0.88 mumol L-1 compound 2) and 0.5 J cm-2 irradiation were required. The hypocrellins exhibited some dark toxicity to the KB cell line. HB and amino acid-substituted hypocrellins showed lower dark toxicity to the KB cell line than amino-substituted hypocrellins in the assessment of cell survival.     

Preparation and crystal structure of Nb6.74 Ta5.26S4 – a new compound in the ternary system Ta?Nb?S

Nb_6.74Ta_5.26S₄ has been prepared by high temperature techniques. The crystal structure has been determined from single crystal X-ray diffraction data (R/R_w = 0.0588/0.0655). The compound crystallizes in the orthorhombic space group Pnma with unit cell dimensions a = 959.11 (26) pm, b = 336.37 (10) pm, and c = 3282.51 (74) pm. The orthorhombic cell contains four formula units. Its structure is similar to that of Nb-rich sulfides, rather than to that of Ta-rich sulfides. The metal coordinations are capped distorted cubic prisms and pentagonal prisms while the coordinations of sulfur are capped trigonal prisms.     

Determinations of combustion and formation enthalpies of C60 and C70

By using a micro-bomb calorimeter, the standard enthalpies of combustion of C₆₀ and C₇₀ have been determined to be - (25 947.1±8.5) and - (29 956.1 ± 8.9) kJ/mol respectively. A g. 1. c. analysis indicated that the amounts of residual organic solvents in the samples were very small, and their effects on the final results were negligible. The energy of combustion ofC60 determined in this work is in agreement in the uncertainty interval with that determined by means of traditional calorimeter using macro amount of sample. The enthalpies of formation of these two substances have been derived. The strain energies in the molecules of C₆₀ and C₇₀ were estimated by a bond energy scheme and by using corannulene as the model compound, the results estimated from different methods are very close. Project supported by the National Natural Science Foundation of China (Grant No. 29473143)     

Diterpene derivative and chromone from Hypericum perforatum

A novel diterpene derivative, 5-methyl-5-(4,8,12-trimethyl-tridecyl)-dihydro-furan-2-one (1) and a new chromone, 5-hydroxy-7-methoxy-3-methyl-chromen-4-one (2), along with a known compound, phytol (3) have been isolated from the aerial parts of Hypericum perforatum. Their structures were established on the basis of spectroscopic analysis and by comparison with published values.     

电感耦合等离子体质谱法测定煤矸石中微量锗和镓

建立了测定煤矸石中微量锗和镓的电感耦合等离子体质谱法。煤矸石试样经高温灰化,用硝酸-氢氟酸-高氯酸-磷酸分解,以电感耦合等离子体质谱法测定其中的锗和镓。通过在线三通加入内标元素铑,消除非质谱干扰;通过选择干扰元素的异质同位素进行定量测定,采用数学公式在线校正,消除质谱干扰。与分光光度法进行比对,锗、镓测定结果的相对偏差为-0.63%~0.28%。克服了常规化学分析方法步骤繁琐、耗时长、工作量大的不足。该法测定结果的相对标准偏差小于3%(n=6),加标回收率为97.4%~102.5%。该方法具有检出限低、快速、简便、线性范围宽、多元素同时测定等优点,分析误差满足化学分析法的要求,可用于煤矸石中锗和镓的测定。     

Synthesis and Characterization of a Novel Organic/Inorganic Hybrid Based on Octamolybdates and Benzimidazole Molecules [Hbenzimi]4 [(benzimi)2Mo8O26] · 2H2O (benzimi?=?benzimidazole)

A novel organic/inorganic compound [Hbenzimi]₄[(benzimi)₂Mo₈O₂₆] · 2H₂O (1) has been prepared hydrothermally and characterized by elemental analyses, i.r., x.p.s., t.g. and single crystal X-ray diffraction. The single crystal X-ray diffraction analysis reveals that compound (1) consists of the [Mo₈O₂₆]⁴⁻ cluster as the structural motif covalently linked by benzimidazole molecules and protonated benzimidazole molecules as charge compensation cations. It is interesting that the benzimidazole molecules were synthesized from 1,2-phenylenediamine and oxalic acid. The [Mo₈O₂₆]⁴⁻ polyoxoanions and organic ligands in compound (1) interact with each other via extensive hydrogen bonds to form a three-dimensional supramolecular framework.     

Optimized Separation of Nine Xanthones by Microemulsion Electrokinetic Chromatography

A microemulsion electrokinetic chromatography method has been firstly used for the separation of the therapeutically important xanthones from Securidaca inappendiculata. The separation of the nine xanthones was systematically optimized with respect to pH, composition of microemulsion,addition of cyclodextrins, applied voltage and column temperature. Baseline separation was successfully achieved for the nine xanthones, which was also compared with that by micellar electrokinetic chromtography.     

A radioanalytical technique to study the behavior of organic toxicants applied to a study of the photodegradation of 2,3,7,8-tetrachlorodibenzo-p-dioxin

A general method for tritium labeling of organic compounds by the use of thermal activation of tritium is described. It allows obtaining uniformly tritium-labeled organic compounds with high specific activity (up to 50 Ci/mmol) which permits tracing the majority of the biodegradation products of compounds studied. More than 40 compounds were labeled using this simple, rapid and inexpensive method. Separation of the biodegradation products is performed by thin layer chromatography. Quantification is performed by direct measurement of the radioactivity by liquid scintillation counting after transfer of the layer from TLC plates into scintillation vials, or by densitometry of autoradiographs. The technique is useful for a wide range of organic compounds, including ones with unknown structure, and can be applied to various in vivo and in vitro studies.     

一些烷氯代烃标准蒸发焓的测定

在进行有机氯化物分子内非键合相互作用的热化学研究中, 为了排除分子间的相互作用, 需要准确的标准蒸发焓或升华焓, 以便把凝聚态的标准生成焓转变为气态的数据。文献中多氯代烷烃的蒸发焓数据不多, 其中由直接量热法得到的准确数据更少, 因此我们测量了一些多氯代烷烃的标准蒸发焓, 并对其规律作了一些探讨。     

Lithium dioxobis[trioxoiodato(V)]vanadate,Li[VO2(IO3)2]

The title compound represents a new structure type, in which distorted VO₆ octa­hedra are bridged by iodate groups to form infinite two‐dimensional [VO₂(IO₃)₂]⁻ layers that are separated by octa­hedrally coordinated Li⁺ cations.