Four distinctive 1-D lanthanide carboxylate coordination polymers: Synthesis,crystal structures and spectral properties

Four novel lanthanide coordination polymers [Pr(mal)(OH)(bipy) · 2H₂O]_n (1), {[Dy¹(SBA)₃(H₂O)₂][Dy²(SBA)₃(H₂O)₂] · 4H₂O}_n (2), {[Tb(OHnic)(Onic)(H₂O)₅ · (OHnicH)] · H₂O}_n (3) and {[Sm(OHnic)(Onic)(H₂O)₅ · (OHnicH)] · H₂O}_n (4) (Hmal = maleic acid, HSBA = 4-sulfobenzoic acid, OHnicH = 6-hydroxynicotinic acid and bipy = 2,2′-bipyridine) have been synthesized and determined by single crystal X-ray diffraction. Complex 1 is a 1-D helical chain with seven-coordinated praseodymium centers. Complex 2 forms 1-D chain-like molecular structure containing two crystallographically unique dysprosium centers, the Dy¹ center is seven-coordinated while Dy² is eight-coordinated. The isomorphous complexes 3 and 4 exhibit an unprecedented 1-D chain-like polymeric structure through hydroxyl oxygen atoms of bridging Onic²⁻ anions linking up the neighboring central ions, and there exist three types of 6-OHnicH ligands in the structural unit which is rare for lanthanide carboxylate complexes. The photophysical properties of these complexes were studied using ultraviolet absorption spectra, fluorescence excitation and emission spectra.     

High speed liquid chromatography with small bore columns

Using a specially designed column system, we have systematically investigated the effect of mobile phase velocity on column efficiency. The performance of small bore columns operated at different linear velocities of mobile phase was examined for three different types of injection system. Using the value of H^∞/u or n^∞/t${}_{\text{r}}^{\text{º}}$ as a criterion of a high speed separation, we calculated values of n/t${}_{\text{r}}^{\text{º}}$ for different solutes according to the equation \documentclass{article}\pagestyle{empty}\begin{document}$ {{\rm n}\mathord{\left/ {\vphantom {{\rm n} {{\rm t}_{\rm r}^ \circ }}}\right. \kern-\nulldelimiterspace} {{\rm t}_{\rm r}^ \circ }} = {{{\rm n}^\infty } \mathord{\left/ {\vphantom {{{\rm n}^\infty } {{\rm t}_{\rm r}^ \circ }}} \right. \kern-\nulldelimiterspace} {{\rm t}_{\rm r}^ \circ }}\left({\frac{{1 + {\rm k'}}}{{{\rm k' + }\beta }}} \right)^2 $\end{document}; the results obtained are in agreement with the experimentally determined values. These systematic investigations culminated in the separation of seven compounds in less than 10 s; the respective chromatogram is shown.     

Seven membered ring chelates derived from γ-hydroxyamides and triphenyltin or diphenylboron

N-Benzyl-4-hydroxy-butyramide (1), 4-hydroxy-N-[(R)-1-phenyl-ethyl]-butyramide (2), and (R)-4-hydroxy-2-methyl-N-[(R)-1-phenyl-ethyl]-butyramide (3a) were used to prepare new diphenylboron and triphenyltinoxy compounds: diphenylborinic acid 3-benzylcarbamoyl-propyl ester (4), diphenylborinic acid 3-[(R)-1-phenyl-ethylcarbamoyl]-propyl ester (5) and diphenylborinic acid (R)-3-[(R)-1-phenyl-ethylcarbamoyl]-butyl ester (6), N-benzyl-4-triphenyltinoxy-butyramide (7), 4-triphenyltinoxy-N-[(R)-1-phenyl-ethyl]-butyramide (8), and (R)-4-triphenyltinoxy-2-methyl-N-[(R)-1-phenyl-ethyl]-butyramide (9). The X-ray diffraction analysis of a crystalline structure of the new γ-hydroxyamide 3a is reported, as well as that of the first example of a crystalline structure where a diphenylborinic ester forms a seven membered chelate, by a carbonyl coordination to boron (4). Structural studies of tin and boron esters were performed by NMR. The CO internal coordination to tin atoms, affording seven membered rings, was observed by ¹¹⁹Sn NMR experiments at low temperature.     

A note on “New kink-shaped solutions and periodic wave solutions for the (2 + 1)-dimensional Sine-Gordon equation”

Exact solutions of the Nizhnik-Novikov-Veselov equation by Li [New kink-shaped solutions and periodic wave solutions for the (2 + 1)-dimensional Sine-Gordon equation, Appl. Math. Comput. 215 (2009) 3777-3781] are analyzed. We have observed that fourteen solutions by Li from 30 do not satisfy the equation. The other 16 exact solutions by Li can be found from the general solutions of the well-known solution of the equation for the Weierstrass elliptic function.     

《七录序》与阮孝绪的知识、思想世界

南朝时期,由于纸的普及,相比于使用简牍的时代,获取知识的途径已大为便捷。在这种背景下,私家藏书兴盛。家有文史、拥书万卷者,也不罕见。“知识下移”成为一种趋势。因此,带有“博”的词汇,如“渊博综广”等,常常被用来形容当时的知识人。阮孝绪阅读量惊人,号称“博极群书”。保留在《广弘明集》中的《七录序》就对阮孝绪的阅读过程、知识构成有所记录。从《七录序》可知,书籍总目《七录》因其穷“天下之遗书秘记”的性质,在某种程度上反映了梁武帝大同二年（536）以前,整个南朝的藏书规模。从私人阅读的角度来讲,《七录》是阮孝绪个人“阅读史”的总结,包含了他自身的“知识轮廓”。不过,阮孝绪博极群书,“阅读领域”几乎涉及了当时各个学术门类。因此,探讨阮孝绪私人阅读的历程以及《七录》的目录构成,也就具备了更大的意义。阮孝绪个人的“阅读史”与精神前进的历程,其实也是整个南朝学术文化、精神世界变化的缩影。     

圆柱坐标系下生物组织中激光传输的七流模拟

提出了圆柱坐标系下生物组织中激光传输的七流模型,根据此模型进行的计算结果与直角坐标系下七流模型的计算结果比较,二者吻合较好.在此基础上,研究了组织光学性质对激光在组织内传输过程的影响,结果表明:散射效应使入射激光分布到更大的组织范围内,并使激光的穿透率降低,但其影响是有限的,即当散射系数增大到一定程度后,组织内的激光能量分布就不再有明显的变化.相对而言,吸收系数对组织内激光能量分布的影响比散射系数要大,各向异性系数增大使组织内的散射趋于前向散射,激光能量分布也更深入组织内部.     

A seven membered chelate ring complex of Mn(II) derived from bis(5-phenyl-2H-1,2,4-triazole)-3-yl-disulfane and cleavage of the S-S bond in a Co(II) complex: Synthesis, spectral and structural characterization

The reaction of Mn(OAc)₂·4H₂O with bis(5-phenyl-2H-1,2,4-triazole)-3-yl-disulfane (H₂ptds·2H₂O) (1) yielded new complex [Mn(ptds)(o-phen)₂] (2). It is observed that under similar conditions the reaction of Co(OAc)₂ with H₂ptds·2H₂O (1) leads to thermolysis of the S-S bond of the disulfane to yield [Co(pts)(o-phen)₂]·H₂O·0.5C₂H₅OH, with the newly generated organic ligand 5-phenyl-2H-1,2,4-triazole-3-sulfinate, (pts)²⁻. The ligand H₂ptds·2H₂O (1), [Mn(ptds)(o-phen)₂] (2) and [Co(pts)(o-phen)₂]·H₂O·0.5C₂H₅OH (3) crystallized into monoclinic, trigonal and triclinic crystal systems, respectively. The triazole ring nitrogen of the bidentate ligand chelates the Mn(II) center forming a seven membered chelate ring, while N, O donor sites of the resulting triazole sulfinate bond Co(II) to form a five membered chelate. The resulting complexes are paramagnetic and have a distorted octahedral geometry.     

Bifurcation of limit cycles at the equator

This paper studies center conditions and bifurcation of limit cycles from the equator for a class of polynomial differential system of order seven. By converting real planar system into complex system, we established the relation of focal values of a real system with singular point quantities of its concomitant system, and the recursion formula for the computation of singular point quantities of a complex system at the infinity. Therefore, the first 14 singular point quantities of a complex system at the infinity are deduced by using computer algebra system Mathematica. What’s more, the conditions for the infinity of the real system to be a center or 14 degree fine focus are derived, respectively. A system of order seven that bifurcates 12 limit cycles from the infinity is constructed for the first time.     

Carbon-13 nuclear magnetic resonance of some derivatives of 3-methyl-4,1-benzoxazepine-2,5-dione

Summary ¹³C chemical shift assignment of seven N-derivatives of 3-methyl-4,1-benzoxazepine-2,5-dione is reported. The assignment has been done with the help of J-modulated spectra and by comparison with the values of resembling segments reported in the reference. It has been found that the substituent on nitrogen atom has no significant effect on the¹³C chemical shift of the skeleton.

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¹³C-NMR einiger Derivative des 3-Methyl-4,1-benzoxazepin-2,5-dions

Zusammenfassung Es werden die¹³C-NMR-Verschiebungszuordnungen von sieben N-Derivaten von 3-Methyl-4,1-benzoxazepin-2,5-dionen diskutiert. Die Zuordnungen erfolgten über J-modulierte Spektren und Vergleich von entsprechenden Literaturdaten ähnlicher Molekülsegmente. Es zeigte sich, daß die Substitution am Stickstoff keinen signifikanten Einfluß auf die¹³C-chemischen Verschiebungen der Skelettkohlenstoffatome hat.

     

在线净化液相色谱-串联质谱法测定畜禽粪便中7种β2-受体激动剂

建立了同时测定畜禽粪便中福莫特罗、沙美特罗、卡布特罗、克伦异磅特罗、克伦潘特、克伦塞罗和羟甲基克伦特罗7种β2-受体激动剂的超高效液相色谱-串联质谱( UPLC-MS/MS)分析方法。样品经酸性乙腈充分提取后,再用0.2％甲酸溶液稀释,提取液用阳离子交换在线净化柱( HyperSep Retain CX)净化,2％氨水-甲醇溶液将分析物洗脱转入至Hypersil Gold C18分析柱,经色谱分离后,用串联质谱检测。在正离子电喷雾条件下,采用选择反应监测模式检测,以外标法定量。结果表明,7种β受体激动剂在0.5~100μg/L的浓度范围内线性良好,线性相关系数均大于0.9928。取3倍信噪比下,畜禽粪便中7种β2受体激动剂的检出限为1μg/kg,定量限为5μg/kg。在空白猪、鸡粪便中添加5~50μg/kg水平的7种β2受体激动剂,得到平均回收率为67％~112％,其相对标准偏差为2.9％~10.2％。本方法简单快速,适用于畜禽粪便中β2-受体激动剂残留的定量及确证分析。