光谱法与共焦荧光成像法研究罗丹明B与ct-DNA的相互作用

采用吸收光谱、荧光光谱以及共焦荧光成像技术研究生理条件下罗丹明B(Rhodamine B,RB)与小牛胸腺DNA(ct-DNA)的相互作用以及相互作用模式。光谱研究结果显示,在450~650 nm的吸收光谱范围内,ct-DNA溶液对罗丹明B有减色作用;在560~660 nm荧光发射光谱范围内,ct-DNA对罗丹明B有荧光猝灭作用。同时,随着ct-DNA的加入,罗丹明B溶液的荧光偏振值发生变化,说明罗丹明B与ct-DNA能发生相互作用。在竞争性实验中,罗丹明B未能将亚甲基蓝(MB)从MB-ct-DNA复合体系中置换出来,说明罗丹明B与ct-DNA通过沟槽结合方式发生相互作用。共焦荧光成像结果显示,ct-DNA加入后,罗丹明B的荧光猝灭十分明显。利用罗丹明B和4',6-二脒基-2-苯基吲哚(DAPI)对He La细胞染色后进行共焦荧光成像,结果进一步证实罗丹明B与ct-DNA是通过沟槽结合作用将细胞核染成红色。     

荧光光谱的罗丹明B校正原理

一般荧光光谱仪推荐的校正方法是罗丹明B法,但仪器说明书对该方法的原理没有介绍。本文通过研究不同浓度罗丹明B溶液的激发光谱、发射光谱和吸收光谱再结合理论分析阐明了罗丹明B浓溶液可作为量子计数器的原因及其校正光谱的原理。     

碘化物-碱性呫吨染料-聚乙烯醇体系高灵敏分光光度法测定铊

研究了在聚乙烯醇存在下,铊(Ⅲ)与碘化钾和罗丹明B,罗丹明6G、乙基罗丹明B、丁基罗丹明B碱性呫吨染料形成离子缔合物的显色反应,讨论了铊(Ⅲ)-碘化钾-罗丹明B-聚乙烯醇体系的反应条件和分析特性,ε_(585)=7.03×10~5L·mol~(-1)·cm~(-1),此法可用于水样中微量铊的测定。     

罗丹明B分子印迹聚合物微球的合成及其在固相萃取中的应用

以罗丹明B为模板分子,丙烯酰胺为功能单体,乙二醇二甲基丙烯酸酯为交联剂,采用沉淀聚合法制备了罗丹明B分子印迹聚合物(MIP)微球,并用扫描电子显微镜表征。 采用紫外分光光度法测定了印迹分子罗丹明B与功能单体丙烯酰胺二者之间的结合常数(K=5.303×103 (mol/L)-1)和化学计量比(n=1)。 考察了沉淀剂的种类和用量对聚合物微球的影响。 将分子印迹聚合物微球应用于固相萃取材料自制固相萃取柱,从加标罗丹明B的红椒粉中萃取罗丹明B。 本文优化了固相萃取条件,高效液相色谱检测表明,在一定的萃取条件下,分子印迹聚合物对加标量为0.479 mg/kg的辣椒中罗丹明B的萃取加标回收率可达91.7％～103.5%。     

高效液相色谱-荧光检测法测定辣椒制品中5种罗丹明染料北大核心CSCD

建立了辣椒制品中罗丹明110、磺酰基罗丹明B、罗丹明B、罗丹明6G和丁基罗丹明B 5种罗丹明染料的高效液相色谱-荧光检测法。方法采用Zorbax SB-C18柱(250×4.6mm,5.0μm),以乙腈和水(均含0.1%的甲酸)为流动相进行梯度洗脱,5种组分可基线分离。结果表明,5种罗丹明染料在相应浓度范围内线性关系良好,线性相关系数均大于0.999,平均加标回收率在84.0%~105.8%之间,相对标准偏差为1.2%~4.8%。该方法简单、准确、灵敏度高,适用于辣椒制品中罗丹明染料含量的同时测定。     

三维荧光光谱的应用研究

本文通过实验探讨了三维荧光光谱在罗丹明B研究中的应用,结果显示,罗丹明B(RhB)三维荧光光谱图较二维荧光光谱图能更详细地描述被测组分的部分性质,可为综合考查罗丹明B的结构特征提供参考。文中还对近年来三维荧光光谱分析技术在不同领域中的应用做了简要介绍。     

罗丹明B分子印迹固相萃取小柱的研制及应用

研制一种对罗丹明B具有特异性识别性能的分子印迹固相萃取小柱。用沉淀聚合法制备罗丹明B分子印迹聚合物,通过静态平衡吸附实验及固相萃取实验表征其性能,并对市售辣椒样品中的罗丹明B进行测量。罗丹明B模板聚合物的吸附能力明显优于空白聚合物;印迹固相萃取小柱对罗丹明B标准溶液(0.05 mmol/L)一次性萃取率为98.24%,实际样品测量的回收率为90.0%~95.0%,测定结果的相对标准偏差为0.9%~1.7%(n=3)。罗丹明B分子印迹固相萃取小柱选择性好、萃取率高,可应用于食品、化妆品检测等相关领域。     

酸酐改性巴旦木壳在罗丹明B分析中的应用

采用邻苯二甲酸酐改性的巴旦木壳,作为吸附剂对稀溶液中罗丹明B进行富集与近红外光谱分析方法研究。首先考察了pH值和吸附时间对罗丹明B吸附率的影响;其次,富集了罗丹明B的吸附剂经近红外漫反射光谱可直接检测,最后以偏最小二乘回归法建立其定量校正模型进行含量预测。结果表明,在中性或偏碱性条件下,常温吸附10 min,罗丹明B的吸附率达到90%;光谱经标准正态变化处理后,罗丹明B校正模型的参考浓度和预测浓度之间的相关系数为0.9643,在0.8～20.0 mg·L~(-1)的较低浓度范围内,剔除奇异样本,预测集的回收率可以达到92.8～110.4%。基于以上结果,邻苯二甲酸酐改性的巴旦木壳可用于稀溶液中微量的罗丹明B的富集与近红外光谱灵敏检测。     

金纳米颗粒表面能量转移及巯基化合物的检测

二氧化硅稳定的金纳米颗粒(Au-SiO₂)与罗丹明B之间发生表面能量转移,使罗丹明B荧光猝灭。 金纳米颗粒对罗丹明B的Stern-Volmer猝灭常数为4.3×10³ L/mol。 当荧光猝灭的混合体系中加入巯基化合物时,巯基化合物与金纳米颗粒发生强相互作用阻断罗丹明B-金纳米颗粒之间的能量转移,罗丹明B荧光恢复。 基于罗丹明B-Au-SiO₂体系对巯基化合物的单一响应,建立了一种简单快速检测巯基化合物的方法;并且由于二氧化硅对金纳米颗粒的稳定作用,金纳米颗粒成为一种可以回收利用的检测探针。     

pH对TiO2光催化降解罗丹明B的影响

将分光光度法用于TiO2光催化降解罗丹明B的研究，探索pH对光催化降解罗丹明B反应的影响。     

Rhodamine B as ligand for affinity chromatography. Fixation studies onto cellulose by a curing method

Rhodamine B was post-grafted onto cellulose in order to be lately used for affinity chromatography as a biomimetic ligand. A curing method has been developed to bound rhodamine onto cellulose via esterification, by heating an intimate mixture of both, at different temperatures above 180 °C. The lactone form of rhodamine B has been proposed as the effective reactant generated in situ during the experimental conditions. Pursuing further improvements of the amount of rhodamine bound onto cellulose, identical experiments were carried out in the presence of catalytic amounts of zinc chloride and sodium hypophosphite. The grafted materials obtained were quantitatively and qualitatively characterized using SEM, tlc, GPC, EA, FT-IR and Vis spectroscopy.     

Crystal structure of an optically active non-symmetric liquid crystal dimer: cholesteryl 5-[4-(4-n-heptylphenylethynyl)phenoxy]pentanoate

The crystal structure of cholesteryl 5-[4-(4-n-heptylphenylethynyl)phenoxy]- pentanoate (C₅₃H₇₆O₃) was determined by direct methods using single crystal X-ray diffraction data. It crystallises in the triclinic system with space group P1 and Z?=?2. The unit cell parameters are: a?=?10.6791(5), b?=?13.0903(7), c?=?18.6430(9)Å, α?=?94.413(3), β?=?98.222(3), γ?=?112.987(3)°. The final reliability factor was R?=?0.0510 for 7284 observed reflections and the goodness of fit was equal to 1.062. The asymmetric unit cell of the compound was found to contain two symmetry-independent molecules, A and B. In both molecules, the six-membered rings of the cholesterol moiety are conformationally very similar. However, pronounced differences were observed in the conformation of the five-membered ring, which is a half-chair in molecule A and assumes an envelope conformation in molecule B. In both molecules, the phenyl rings are planar. The dihedral angle between the two phenyl rings is 43.4(2) and 42.7(2)° for molecules A and B, respectively. The packing of molecules in the crystalline state was found to be a precursor to the smectic A phase structure. The crystal structure is stabilised by inter-molecular C–H…O and C?H…π interactions.     

A spectroscopic/thermodynamic study of the rhodamine B lactone ⇌ zwitterion equilibrium

Temperature dependences of the visible absorption spectra of rhodamine B (RB) in water and 18 alcohol solvents have been examined and utilized to estimate thermodynamic parameters (ΔG°, ΔH°, ΔS°) for the RB lactone ⇌ zwitterion (L ⇌ Z) equilibria in these sol From the L ⇌ Z equilibrium in the strong hydrogen-bonding solvent trifluoroethanol an intrinsic RB zwitterion molar absorptivity of ε = 1.30 × 1O⁵ dm³/mol·cm is estimated. The thermodynamic results suggest that the position of the RB L ⇌ Z equilibrium is strongly influence by self-association of the solvent. The position of the equilibrium in aliphatic alcohols can be predicted from simple features of the solvent molecules. Consequences of the results regarding calculation of the natural radiative lifetime of the fluorescent state from the absorption spectrum are discussed.     

Crystal and Molecular Structure of Cyanuric Acid

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THE REACTION BETWEEN π-CYCLOPENTADIENYLDI-CARBONYLCOBALT AND PHENYLETHYNYLSILANE,AND AN X-RAY CRYSTALLOGRAPHIC INVESTIGATION OF ONE OF THE PRODUCTS, (π-CYCLOPENTADIENYL)-[trans-DIPHENYL-DI(TRIMETHYLSILYL)-CYCLOBUTADIENE]-COBALT

Abstract

This is a report of the broad range of reactions and products that occur in refluxing xylene when π-cyclopentadienylcobalt or (π-cyclopentadienyl)-dicarbonylcobalt react with either symmetric or unsymmetrical acetylenes, specially when one of the substituents of the acetylene is an aromatic moeity. Since these reactions produce a variety of products, several of which are cis- and trans- tetrasubstituted cyclobutadiene-cobalt isomers, mnr and mass spectral methods were used to distinguish between them. In order to obtain an independent and indisputable structure assignment for the structural isomers investigated by spectral techniques, the crystal structure of the title compound was investigated by x-ray crystallographic techniques. The compound crystallizes in space group Pbca with the following cell dimensions: a = 29.622(7), b = 9.967(2) and c = 17.140(3) Å; V = 5060.46 ų; D(exp) = 1.23(2) gm-cm^?3, D(calc) = 1.24 gm-cm^?3 for Z = 8 molecules/unit cell. The intensity data were collected with MoKα radiation (Λ = 0.71069 Å) using a computer-controlled diffractometer equipped with a graphite monochromator. In all 6331 reflections were collected of which 3173 were independent and had F ₀ ² ± 3[sgrave] (F ₀ ²). The data were corrected for absorption and the transmission coefficients ranged from 0.72 to 0.79. The (π-cyclopentadienyl) ring is planar and has normal Co–C and C–C distances which average 2.049(7) and 1.389(17) Å, respectively. The Co–(Cp ring centroid) distance is 1.67 Å and the ring librates about this axis to a small degree which is not, however, large enough to affect the C–C distances. The average value of the C–C–C angle in the π-cyclopentadienyl ring is 108° indicating that it is planar and, in fact, the largest deviation of any carbon from the least-squares plane is 0.006 Å. In the Co-cyclobutadiene moiety, the Co–C and C–C distances are 1.982(15) and 1.467(3) Å and the Co–(cyclobutadiene ring centroid) distance is 1.69 Å. The angle between the normals of the five- and four-membered rings is 1.6°. The phenyl rings and trimethylsilyl fragments have normal distances and angles and the phenyl rings are planar. The two silicon and two carbon atoms of the phenyl rings linked to the π-cyclobutadiene moeity are out of the mean plane of the ring and bend away from the Co atom.

Finally, and most important, the four-membered ring is planar (the largest deviation from planarity is 0.003 Å) and the four C–C distances are the same length; however, the internal angles are not 90.0°. Instead, the two angles at carbons bonded to phenyl rings have values of 88.1(2)° and 88.4(2)° while those at carbon atoms bonded by silicons have values of 91.6(2)° and 91.8(2)°. The final discrepancy indices for this structural analysis were R ₁ = 0.038 and R ₂(F) = 0.044.     

(E)-[4,4,4-Trifluor-1-(trifluormethyl)-1,3-bis(trimethylsiloxy)-2-butenyl]diphenylphosphin als Ligand

The Ligand (E)-[4,4,4-Trifluoro-1-(trifluoromethyl)-1,3-bis(trimethylsiloxy)-2-butenyl]di-phenylphosphine The tertiary phosphine (E)-Ph₂PC(OSiMe₃)(CF₃)CH = C(OSiMe₃)CF₃ (L), 1 and the carbonyl Fe₂(CO)₉ react to give (OC)₄FeL, 2. Bis( 1,1,1,5,5,5-hexafluoropentane-2,4-dionato)palladium(II) and 1 furnish the diphenylphosphido group bridged palladium(II) complex 3 crystallizing from chloroform triclinic in the space group P1 with a = 12.600(3), b = 13.298(3), c = 13.975(3) Å, α = 93.27(2), β = 111.67(2), γ = 106.71(2)° The elementary cell contains Z = 2 formular units and two molecules CHCl₃ with two independent molecules 3 each showing an inversion centre. The planar [PdP], four membered ring system and the planar chelate units, exhibit a torsional angle of 6.75°     

Synthesis and Structure of N-Ethoxycarbonyl-N′-O-Methoxyphenylthiourea

N-ethoxycarbonyl-N′-o-methoxyphenylthiourea was synthesized and characterized by elemental analysis, TG-DTA analysis, IR, and ¹H NMR spectrum, and single crystal X-ray diffraction analysis. The compound crystallizes as a planar molecule in the monoclinic space group P2(1)/c, with a = 9.690(2)Å, b = 8.595(2)Å, c = 15.944(4)Å, α = 90°, β = 106.467(4)°, γ = 90°, and D_calc = 1.326 g/cm³ for Z = 4. Intramolecular H-bonds promote the stability of the title compound and change the coordination ability of the thiourea ligand. Intermolecular N─H…S H-bonds link pairs of two molecules.     

New guaianolides from Berlandiera Pumila and B. Texana,and the X-ray crystal structure of pumilin

The isolation and structure determination of two new guaianolides, pumilin and its 2,3-epoxide, from Berlandiera pumila and B. texana are reported. The structure of pumilin was determined from nmr and mass spectral data, and from an X-ray single crystal study; the structure of the epoxide was found by comparison of nmr spectra. Pumilin is shown to be a Δ¹⁽¹⁰⁾-cis-guaianolide with a cyclopentenone ring attached to C1 and C5, and an α-methylene-γ-lactone ring trans-fused to C6 and C7. The absolute configuration was inferred from spectral considerations and knowledge of previous structural determinations. The cd spectrum of pumilin exhibits a negative Cotton effect, and the lactone chromophore has left-handed chirality. The cyclo-heptene ring is in the chair configuration, with the lactone a half-chair and the cyclopentenone essentially planar. Crystals are orthorhombic, a = 7.065, b = 13.652, c = 19.586 Å, space group P2₁2₁2₁, Z = 4, and the final R value is 3.9%. The crystal structure is strengthened by an O···O hydrogen bond linking the molecules into infinite chains.     

Ga8Ir4B – ein Gallium-Iridiumborid mit isolierten,annähernd quadratisch planaren Ir4B-Gruppen in einer vom CaF2-Typ abgeleiteten Struktur

Ga₈Ir₄B – a Gallium Iridium Boride with isolated, nearly square planar Ir₄B Groups in a Structure derived from the CaF₂ Type The new compound Ga₈Ir₄B (tetragonal, I4₁/acd, a = 853.69(2) pm, c = 2 105.69(6) pm, Z = 8, 614 reflections, 31 parameters, R = 0.034) was prepared by reaction of the elements at 1 100°C. The structure is derived from the CaF₂ type. It contains isolated Ir₄B groups with boron in an unusual, nearly square planar coordination.     

Crystal structure and mesogenic behaviour of a new fluorene derivative: 9,9‐dimethyl‐2,7‐bis(4‐pentylphenyl)‐9H‐fluorene

The title compound, C₃₇H₄₂, is a new mesogenic compound containing the fluorene moiety. It exhibits enantiotropic nematic liquid crystalline behaviour with melting at 125 °C and isotropization at 175 °C. The crystallographically independent unit contains two molecules oriented face‐to‐edge with respect to each other. The two molecules have nearly the same conformation of the bis‐phenyl fluorene moiety. The molecular packing in the crystal phase is nematic‐like.