Two new brominated C15-acetogenins from the red alga Laurencia japonensis

Abstract

We report on the chemical characteristics of the red alga Laurencia japonensis, collected off the coast of Yoshio, Katsuura, Boso Peninsula, Japan. We isolated two new brominated C₁₅-acetogenins in this species, which we name katsuurenyne A (1) and katsuurenyne B (2), along with two already known halogenated terpenes [2,10-dibromo-3-chloro-α-chamigrene (7) and aplysiadiol (8)]. We extensively analysed spectral data (from IR, ESI-MS, 1D-NMR and 2D-NMR) to confirm the structure of these compounds.     

New cytotoxic sesquiterpenes from the red algae Laurencia obtusa and Laurencia microcladia

Three new sesquiterpenes (1-3), along with five known (5-9), were isolated from the organic extract of the red alga Laurencia obtusa, collected from the coastal rocks of Serifos in the Aegean Sea. A new dimeric sesquiterpene of the cyclolaurane-type (4) along with four previously reported (7, 10-12) metabolites, were isolated from the extract of Laurencia microcladia, collected at Chios island in the North Aegean Sea. The structures and the relative stereochemistry of the compounds are proposed on the basis of their spectral data. The cytotoxicity of the isolated metabolites was evaluated against several cell lines including human tumor cell lines.     

金属有机框架@介孔分子筛复合材料的构建和性质

通过蒸汽诱导内部水解法(VIH)在介孔分子筛SBA-15孔壁上引入Al_2O_3,合成得到Al_2O_3@SBA-15复合物,随后与对二苯甲酸配体反应,从而制备得到金属有机框架化合物(MIL-53)与介孔分子筛(SBA-15)复合材料(MIL-53@SBA-15)。采用粉末X射线衍射(PXRD)、N_2吸附-脱附测试、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等技术证明成功合成了MIL-53@SBA-15复合材料。染料吸附实验结果表明,MIL-53@SBA-15复合材料相比于SBA-15、MIL-53及其物理混合样品,表现出对丁基罗丹明染料更高效吸附特性。     

金复合介孔SBA-15吸附血红蛋白在H2O2电催化反应中的应用

以P123嵌段共聚物表面活性剂为模板剂制备介孔氧化硅SBA-15,并用沉积-沉淀(DP)法在SBA-15介孔表面负载纳米Au颗粒制备得到金复合介孔SBA-15材料(Au-SBA-15).再以Au-SBA-15材料制备玻碳修饰电极,将血红蛋白固定于修饰电极上用循环伏安法考察其对不同浓度H2O2溶液的电催化反应.在固定了血红蛋白的Hb/Au-SBA-15/GC修饰电极上,H2O2在+0.95 V处出现了氧化峰,且随着H2O2浓度的增大峰电流不断增加,说明金复合介孔氧化硅材料具有良好的生物兼容性,有利于血红蛋白的固定,其修饰电极对H2O2溶液具有一定的电催化作用.     

TiO_2/SBA-15的快速合成法及其催化性能

本文针对传统方法合成TiO2/SBA-15的诸多不足,提出了一种简单而快速合成TiO2/SBA-15的方法。利用孔道内水解法快速合成了不同负载量的TiO2/SBA-15。利用XRD、N2-吸脱附、TEM和UV-Vis对样品的晶体结构、微观形貌、光学吸收特性进行了表征,并研究了不同TiO2负载量催化剂对罗丹明B(RhB)光降解活性的影响。结果表明:利用该方法合成的TiO2/SBA-15光催化活性优于传统浸渍方法合成的TiO2/SBA-15与工业上使用的TiO2纳米颗粒。     

负载型P-Mo-V/SBA-15催化剂上的甲烷选择氧化反应

以磷钼钒杂多酸(H₅PMo₁₀V₂O₄₀)为前驱体、介孔SBA-15为载体, 采用浸渍法制备不同负载量的P-Mo-V氧化物催化剂. 在甲烷选择氧化反应中, 考察了负载量、反应温度、空速等对甲烷转化率和产物选择性的影响. 结果表明, 催化剂对甲烷选择氧化制甲醛具有较高活性, 甲烷转化率随负载量的增大和反应温度的升高而提高, 甲醛的选择性随负载量的增大先升后降. 反应温度为640 ℃、空速为48300 L•kg^－1•h^－1、氧化物负载量w＝2.89%时, 甲醛的时空产率最高(295 g•kg_cat^－1•h^－1). 多种表征表明, 氧化物负载量w≤2.89%时, P-Mo-V氧化物在载体介孔孔道内以高分散形式存在. 催化剂的酸性和氧化还原性质与负载量相关, NH₃-TPD和H₂-TPR的测试结果表明, 较弱的酸性位和较低还原温度的活性组分有利于甲烷选择氧化制甲醛.     

Raman scattering investigations on lanthanum-doped Bi4Ti3O12-SrBi4Ti4O15 intergrowth ferroelectrics

The ferroelectric ceramics of Bi₄Ti₃O₁₂, SrBi₄Ti₄O₁₅, and lanthanum-doped Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅ were synthesized, and their Raman spectra were investigated. La-doping resulted in the enlargement of remnant polarization of Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅. The structure of the Bi₂O₂ layers and TiO₆ octahedra of the intergrowth was found to be different from those of Bi₄Ti₃O₁₂ and SrBi₄Ti₄O₁₅. La³⁺ ions exhibit pronounced selectivity for the occupation of A site as La content is lower than 0.50, and tend to be incorporated into Bi₂O₂ layers when the La content is higher than 0.50. Lanthanum substitution brings about the structural phase transition in Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅. The variation of ferroelectric property may be attributed to combined contribution from the decreasing of the oxygen vacancies, the relaxation of the lattice distortion, the destroying of the insulation and the space charge compensation effects of the Bi₂O₂ slabs.     

A hydrogen-1, nitrogen-15, and chlorine-35 NMR coordination study of Lu(ClO4)3 and Lu(NO3)3 in aqueous solvent mixtures

A coordination study of Lu(III) has been carried out for the nitrate and perchlorate salts in aqueous mixtures of acetone-d₆ and Freon-12 by¹H,¹⁵N and³⁵Cl NMR spectroscopy. At temperatures lower than –90°C, proton and ligand exchange are slow enough to permit the direct observation of¹H resonance signals for coordinated and free water molecules, leading to an accurate measure of the Lu(III) hydration number. In perchlorate solution, in the absence of inner-shell ion-pairing, Lu(III) exhibits a maximum coordination number of six over the allowable concentration range of study, contrasting markedly with the report of values of six to nine or greater as determined by a similar NMR method. The absence of contact ion-pairing was confirmed by³⁵Cl NMR chemical shift and linewidth measurements. Extensive ion-pairing was observed in the nitrate solutions as reflected by the lower Lu(III) hydration numbers of two to three in these systems, the observation of two coordinated water signals, and¹⁵N NMR signals for two complexes. The¹H and¹⁵N NMR spectra and the hydration number could be accounted for by the presence of (H₂O)₄Lu(NO₃)²⁺ and (H₂O)₂Lu(NO₃) ₂ ¹⁺ .     

The Synthesis of 13C9-15N-Labeled 3,5-Diiodothyronine and Thyroxine

Thyroid hormones undergo extensive metabolism to regulate hormone activity. A labeled thyroid hormone would be useful to track hormone metabolism through various pathways. While radiolabeled thyroid hormones have been synthesized and used for in vivo studies, a stable isotope labeled form of thyroid hormone is required for studying thyroid hormone metabolism by LC-MS/MS, an analytical technique that has certain advantages without the complications of radioactivity. Here we report the synthesis of ¹³C₉-¹⁵N-T₂ and ¹³C₉-¹⁵N-T₄, two labeled thyroid hormone derivatives suitable for in vivo LC-MS/MS studies.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Isomorphism of bis(diethyldithiocarbamato)zinc(II) adduct with pyridine, [Zn(Py)(EDtc)2]: hysteresis in the reaction of the adduct formation

The structure of the polycrystalline adduct bis(diethyldithiocarbamato)-pyridine zinc(II) depends on the pathway of physico-chemical conditions during the preparation procedure, as was revealed by solid state ¹⁵N CP/MAS spectroscopy in good correlation with known single crystal X-ray diffraction structures of this adduct. Two isomorphs of the adduct, namely α-[Zn(Py)(S₂CNEt₂)₂] and β-[Zn(Py)(S₂CNEt₂)₂], are the two molecules in the asymmetric unit of a single crystal (or polycrystalline) sample that can be obtained by recrystallization from toluene of the equimolar solution of the initial diethyldithiocarbamate zinc(II) complex and pyridine. The third isomorph, γ-[Zn(Py)(S₂CNEt₂)₂], can be obtained by recrystallization from pure pyridine of the diethyldithiocarbamate zinc(II) complex, or by its equimolar absorption of pyridine, or by desorption of pyridine from the clathrated adduct, [Zn(Py)(S₂CNEt₂)₂]·Py. Finally, the γ-[Zn(Py)(S₂CNEt₂)₂] isomorph recrystallizes from the melt into α/β-isomorphs of the adduct.     

Ultrasound-promoted green approach for the synthesis of multisubstituted pyridines using stable and reusable SBA-15@ADMPT/H5PW10V2O40 nanocatalyst at room temperature

ABSTRACT

A facile one-pot protocol for the synthesis of 2-amino-3-cyanopyridins using SBA-15@Triazine/H₅PW₁₀V₂O₄₀ as an efficient catalyst under ultrasonic conditions has been developed. The nanohybrid catalyst was prepared by the chemical anchoring of Keggin heteropolyacid H₅PW₁₀V₂O₄₀ onto the surface of SBA-15 mesoporous silica modified with 2-APTS -4,6-bis(3,5-dimethyl-1H-pyrazol- 1-yl)-1,3,5-triazine (ADMPT) linker. Then the nanohybrid was used as a green, efficient, eco-friendly, and highly recyclable catalyst for the one-pot and multi-component synthesis of 2-amino-3-cyanopyridin derivatives from the reaction of aldehydes, malononitrile, cyclic ketones and ammonium acetate under ultrasound waves with good to excellent yields (79–95%) and in a short span of time. This nanocatalyst was characterized by using FT-IR, XRD, SEM, TEM, BET, and EDX techniques.     

Thermal degradation of iron chelate complexes adsorbed on mesoporous silica and alumina

Nanometric Fe₂O₃ particles could be inserted inside the internal pore volume of SBA-15 mesoporous silica and mesoporous alumina supports, when Fe(III) chelates (EDTA, gluconate or citrate) were used as impregnating precursors. The oxidative degradation of the chelating anions was followed by combined TG-DTA. Strong chelate-SiOH interactions (case of bulky EDTA), favored by the mesopore curvature, yield sub-nanometric extremely well dispersed Fe₂O₃ particles preferentially located at the micropore mouths (confinement effect). Fe₂O₃ even more strongly interacts with alumina walls, generating either (Fe,Al)₂O₃ mixed phases or Fe-aluminate micro domains. These iron-based mesoporous alumina composites proved very active catalysts in total oxidation of phenol at ambient conditions, with extremely low iron leaching (0.2%).     

电感耦合等离子体光谱法(ICP-AES)测定银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量

针对银精矿样品复杂,难消解的特点,研究了不同酸溶法和碱熔法对样品的消解情况,建立了硝酸,盐酸,氢氟酸,高氯酸消解银精矿的方法。根据元素灵敏度和抗干扰性,选定各元素的测定波长。通过酸溶样和碱熔样测定结果比对,验证了方法准确性。建立了四酸消解-电感耦合等离子体光谱法测定银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量的方法,元素的线性相关系数均在0.9999以上。通过共存元素干扰实验,确定了银精矿中高含量元素(铜、铅、锌、铁、锑、铋等)对测定元素结果没有影响。方法检出限：Cu 0.0063 mg/L, Pb 0.0159 mg/L ,Zn 0.0090 mg/L,As 0.0192 mg/L, Cd 0.0093 mg/L ,Ca 0.0084 mg/L, Mg 0.0075 mg/L, Mn 0.0081 mg/L。测定下限：Cu 0.0105mg/L,Pb 0.0265 mg/L, Zn 0.0150 mg/L, As 0.0320 mg/L, Cd 0.0155 mg/L, Ca 0.0140 mg/L, Mg 0.0125 mg/L,Mn 0.0135 mg/L。3个样品的相对标准偏差在0.87%~3.56%之间,加标回收率在95.00%~103.56%之间。方法流程短,操作简单,快速,灵敏度和再现性高,结果准确可靠,可以满足银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量的测定。     

Studies on hydrolyzable carbides. XXII: The carbothermal reduction of scandium oxide Sc2O3

The composition of the products of carbothermal reduction of Sc₂O₃ is examined by X-ray diffraction and chemical analysis and by the hydrolysis method. At pressures of 10^–2-1 Pa, the reaction starts in the temperature region of 1 000–1 200°C. The first product is Sc₂OC of NaCl type; at 1 Pa and 1 400–1 500°C this substance is formed quantitatively (according to stoichiometry) within 50–100 h, repeated homogenization, however, is necessary, or else Sc₂OC reacts locally with Sc₂O₃ giving Sc₂O_1+x C_1–x . The lattice parameter of Sc₂OC in the presence of Sc₁₅C₁₉ is 457.6₃pm. At temperatures above 1 500°C, Sc₁₅C₁₉ is incompletely formed by subsequent reaction with carbon. The product melts at cca. 1 800°C; carbon dissolves and the final composition approaches ScC₂. Carbon separates during solidification. The phase fractions in the products are affected by evaporation, the vapour pressures above both Sc₂OC and Sc₁₅C₁₉ being comparable with the pressure requisite for the carboreduction process. The results are discussed with respect to the often ambiguous published data.

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Untersuchung hydrolysierbarer Carbide, XXII. Die karbothermische Reduktion von Scandiumoxid

Zusammenfassung Zur Untersuchung von Produkten der karbothermischen Reduktion von Scandiumoxid wurden sowohl röntgenographische und chemische Analyse als auch die hydrolytische Methode verwendet. Bei 10^–2 bis 1 Pa beginnt die Reaktion im Temperaturintervall von 1 000–1 200°C. Das erste Reaktionsprodukt ist das Scandiumoxidcarbid Sc₂OC von NaCl-Typ, das quantitativ (der Stöchiometrie entsprechend) bei 1 400–1 500°C und 1 Pa in 50–100 Stunden entsteht. Eine wiederholte Homogenisierung ist allerdings notwendig, damit es zu keiner lokalen Reaktion zwischen Sc₂OC und Sc₂O₃ kommt, bei der dann die Phase Sc₂O_1+x C_1–x entsteht. In Gegenwart von Sc₁₅C₁₉ ist der Gitterparameter von Sc₂OCa=457.6₃pm. Über 1 500°C führt eine weitere Reaktion mit Kohlenstoff zu einer nicht ganz vollendeten Bildung von Sc₁₅C₁₉. Bei cca. 1 800°C schmilzt das Reaktionsprodukt bei gleichzeitiger Auflösung von weiterem Kohlenstoff und die Zusammensetzung nähert sich der Formel ScC₂, beim Erstarren fällt der Kohlenstoff wieder aus. Die Verteilung der Phasen im Produkt wird von der Verdampfung beeinflußt, da die Dampfdrucke von Sc₂OC und Sc₁₅C₁₉ mit dem zum Karboreduktionverlauf notwendigen Druck vergleichbar sind. Die erhaltenen Ergebnisse werden in Relation mit den nicht eindeutigen Angaben in der Literatur diskutiert.

     

New sesquiterpenes from the red alga Laurencia microcladia

Three new aromatic sesquiterpenes (1, 2, and 4), one new dimeric sesquiterpene of the cyclolaurane-type (3), one sesquiterpene alcohol of bisabolene type (8) along with three previously reported metabolites (5-7), were isolated from the organic extracts of Laurencia microcladia, collected from the Chios island in the North Aegean Sea. The structures of the new natural products, as well as their relative stereochemistries, were established by means of spectral data analyses, including 2D experiments. The cytotoxicity of the isolated metabolites was evaluated against five human tumor cell lines.     

Structure and Ionic Conductivity of Bi6Cr2O15, a New Structure Type Containing (Bi12O14)n Columns and CrO4 Tetrahedra

Powder samples of the Cr⁶⁺-containing compound Bi₆Cr₂O₁₅ were prepared by solid state reaction of Bi₂O₃ and Cr₂O₃ in air at 650°C. The structure was solved and refined using high-resolution neutron powder diffraction data in space group Ccc2, with anisotropic thermal displacement parameters a=12.30184(5), b=19.87492(7), and c=5.88162(2) Å, V=1438.0 ų, and 126 variables to R_F=1.8%. Bi₆Cr₂O₁₅ exhibits a new structure type that contains (Bi₁₂O₁₄)⁸ⁿ⁺_n columns, of the kind previously found only for phases isotypic with Bi₁₃Mo₄VO₃₄. Each column is surrounded by eight CrO²⁻₄ tetrahedra. The ionic conductivity of Bi₆Cr₂O₁₅ was determined by impedance measurements to be 3.5×10⁻⁵ (Ω cm)⁻¹ at 600°C.     

La2Ti6O15-CeTi21O38-PbTiO3 ceramics formed in gaseous penetration of La-Ce into PbTiO3 and their electric properties

The gaseous penetration of La-Ce into PbTiO₃ ceramics is reported. The compounds of La₂Ti₆O₁₅ and CeTi₂₁O₃₈ are formed and the new La₂Ti₆O₁₅-CeTi₂₁O₃₈-PbTiO₃ ceramics are prepared by the penetration of La and Ce in the gaseous state. The new ceramic materials have a significant change in electric properties. The room temperature resistivity decreases from 2.0×10¹⁰ to 0.248 Ω. m, and the grain resistance exhibits an obvious PTCR effect with the change of temperature. However, the grain boundary resistance decreases rapidly with increase in temperature. The change rule of the total resistance is similar to that of the grain boundary, and the PTCR effect disappears and the tendency of transition to a conductive body is manifest. The XPS analysis suggests that the particles that are Pb, Ti, La and Ce in La₂Ti₆O₁₅-CeTi₂₁O₃₈-PbTiO₃ ceramics all change their valence and lead to decreasing resistivity, and the bound energy peak values of elements in La₂Ti₆O₁₅-CeTi₂₁O₃₈-PbTiO₃ ceramics are also reported. The La₂Ti₆O₁₅-CeTi₂₁O₃₈-PbTiO₃ ceramics have a better thermal stability in high temperatures through TG-DTA analysis.     

电感耦合等离子体光谱法测定铜冶炼烟尘中锌

本实验介绍了电感耦合等离子体光谱法测定铜冶炼烟尘中锌含量的分析方法。针对样品碳,硅含量高的特点,有针对性的研究了样品的消解方法,确定采用盐酸、硝酸、氢氟酸、高氯酸对铜冶炼烟尘样品进行消解。同时进行了干扰试验,确定样品中高含量的铜,铅,砷等对样品测定结果没有影响。并对仪器的工作参数进行了优化。方法检出限为为0.011 mg/L,测定下限为0.019 mg/L,3个样品的相对标准偏差在0.54%~0.92%之间,加标回收率在96%~101.14%之间。该方法样品消解完全,流程短,操作简单,快速,测定准确度高,可以满足铜冶炼烟尘中锌含量的测定。     

Preparation, Characterization and Catalytic Performance of La-SO4/SBA-15 in Esterification of Acetic Acid with n-Butanol

La-SO42-/SBA-15 was synthesized with various amounts of lanthanum via incipient-wetness impregnation. Characterization was done by X-ray diffraction（XRD）, transmission electron micrographs（TEM）, nitrogen adsorption, FTIR spectroscopic analysis, thermogravimetric analysis, and the total amount of acidity of catalyst was estimated by TPD of NH3. The results indicate that lanthanum has been incorporated into SBA-15 molecular sieve. The prepared materials（La-SO42-/SBA-15） keep the highly ordered mesoporous two-dimensional hexagonal structure and do not change the mesoporous channel structure of the support SBA-15. The catalyst showed best catalytic activity in the synthesis of n-butyl acetate. The optimum conditions of the esterification by orthogonal experiments were studied： the molar ratio of n-butanol to acetic acid 1：1.2, the amount of catalyst 7.5%, reaction time 80 min. The yield of n-butyl acetate could reach 93.2% under the optimum conditions. The catalyst was recyclable, cost effective and environmental friendly.     

Cytotoxic cuparene sesquiterpenes from Laurencia microcladia

Three new cuparene sesquiterpenes 1-3 were isolated from the organic extract of the red alga Laurencia microcladia, collected at Chios island in the North Aegean Sea, Greece. The structures and the relative stereochemistry of the compounds are proposed on the basis of their spectral data. Metabolite 2 shows an unprecedented (for the cuparene class of sesquiterpenes) migration of the C-1 methyl group. All metabolites 1-3 were found to exhibit significant cytotoxic activity against two lung cancer cell lines.