Study of the Structure of Lithium Thiocyanate Complexes with Benzo-15-Crown-5 by X-ray Diffraction and IR Spectroscopy

The complex formation of lithium thiocyanate with benzo-15-crown-5 (B15C5) was studied. The possibility of formation of both anhydrous and crystal water-containing complexes was demonstrated. The complexes LiB15C5NCS and LiB15C5H₂ONCS were synthesized and characterized by X-ray diffraction and IR spectroscopy.     

ZSM-5-SBA-15复合分子筛制备及甲苯甲醇烷基化性能研究

采用后合成法制备了ZSM-5-SBA-15复合分子筛,通过XRD、FT-IR、BET、NH₃-TPD及吡啶红外等手段表征催化剂的性质。结果表明,ZSM-5-SBA-15既具有微孔结构又具有介孔结构。吡啶吸附和NH₃吸脱附实验结果表明,ZSM-5微孔分子筛的引入使SBA-15介孔分子筛的酸性增强,但与ZSM-5相比,ZSM-5-SBA-15复合分子筛的酸性位没有改变,酸强度有一定的减弱。用固定床评价了该复合分子筛甲苯甲醇烷基化反应的催化性能。结果表明,与常规ZSM-5相比,ZSM-5-SBA-15表现出了较高的对位选择性。     

冠醚配合物热力学性质的研究 X: 用NMR研究15-冠-5-衍生物与钠离子的配位反应

用^2^3Na NMR研究了15-冠-5(15C5), 2,3-苯并-15-冠-5(B-15C5), 2,3-苯并-6-甲基-15-冠-5(BCl-15C5), 2,3-苯并-8,12-二甲基-15-冠-5(BC2-15C5)在丙酮中与Na^+的配位反应, 由此探索甲基的影响, 实验结果表明, 当在金属盐溶液中加入冠醚, 配体为15C5时, 体系表观化学位移移至低场, 配体为B-15C5, BC1-15C5, BC2-15C5时, 体系在表观化学位移移至高场, 后者与苯并-18-冠-6及其甲基衍生物不同, 这是由于苯环在空间排布不同所致, 用Newton-Raphson法和描坑法(Pit-mapping)拟合实验数据, 发现BC1-15C5和BC2-15C5除形成NaL^+和NaL2^+外还有不稳定的Na3L2^3^+形成。本文对形成过程和生成NaL^+反应的平衡常数lgK11与甲基数的关系亦作了讨论, lgK11与甲基数目n近似成直线关系, 可用下式表示: lgK11=3.50-0.80n, n=0,1,2。     

Evaluation of selectivity-determining factors for membrane electrodes based on naphtho-15-crown-5 by liquid-liquid extraction

Liquid-liquid extractions of sodium and potassium picrates with naphtho-15-crown-5 (N15C5) into 1,2-dichloroethane are studied, in order to clarify the factors governing the high potassium ion selectivity of the N15C5-based membrane electrode. The distribution coefficient of N15C5 between water and 1,2-dichloroethane was 1800 at 15°C. The formation constants of the complexes of N15C5 with the sodium ion and the potassium ion in the aqueous phase were less than unity and there was no remarkable difference between their values. Potassium picrate was mainly extracted into 1,2-dichloroethane by forming the 2:1 N15C5-potassium complex, while sodium picrate was extracted by forming the 1:1 complex. The extraction constants for sodium picrate and potassium picrate were 10^3.86 and 10^7.61, respectively, The high potassium selectivity is concluded to be due to the high extractability of the 2:1 potassium complex.     

含苯并15-冠-5的酚醛型和缩醛型聚合物冠醚的合成及其络合与催化性能

合成了两种新聚合物冠醚,研究了它们对钠、钾离子络合容量和催化性能.     

Synthesis of some azacrown derivatives and fabrication of their nanofilms on the glassy carbon surface

The modification of N-phenyl-aza-15-crown-5 (PA15C5) and N-(4-aminophenyl)-aza-15-crown-5 (4APA15C5) on glassy carbon (GC) electrode was performed by the electrochemical oxidation of the corresponding azacrown derivatives in anhydrous acetonitrile media. The electrochemical behavior of the resulting modified GC electrode was investigated in the presence of electroactive redox probes and these results, together with the X-ray photoelectron spectroscopy (XPS) and reflection-absorption infrared spectroscopy were used to confirm the attachment of these molecules onto the GC surface. The ellipsometric thicknesses of PA15C5 and 4APA15C5 films at the GC surface was obtained around 9.28 ± 0.40 and 10.50 ± 1.10 nm, respectively. Azacrown modified nanoscale surfaces serve as alkali metal sensor specific for their cavity in the crown ring.     

Nb-P/SBA-15催化剂的制备及其对果糖水解制5-羟甲基糠醛的催化性能

果糖催化脱水制5-羟甲基糠醛（5-HMF）是生物质转化制高附加值化合物过程中的一个重要反应。采用自制的介孔SBA-15,浸渍法制备了Nb/SBA-15催化剂,再经磷酸化处理制得Nb-P/SBA-15催化剂,研究了该催化剂在果糖脱水制5-HMF反应中的性能。SEM、TEM、BET和XRD表征结果表明,Nb/SBA-15和Nb-P/SBA-15完好地保留了SBA-15的微观结构,其内孔道直径为10 nm,铌酸在孔内表面分布均匀;负载铌和磷酸化后,孔壁变薄。NH₃-TPD结果显示,Nb/SBA-15经磷酸预处理后,不仅弱酸性位有所增加,而且产生了中强酸和强酸性位,使得在含水两相体系果糖脱水反应中,Nb-P/SBA-15比Nb/SBA-15具有更高的催化活性和5-HMF选择性。同时考察了反应温度、溶剂比例、反应时间对果糖脱水的影响,结果表明,以水/MIBK（V/V=1/2）为溶剂时,160 ℃下反应1.5 h,果糖转化率和5-HMF收率分别高达96.1%和92.6%。Nb-P/SBA-15经循环使用四次后仍具有较好的催化活性,表明该催化剂具有较高的耐水稳定性。     

A comparison of complexation of Li+ ion with macrocyclic ligands 15-crown-5 and 12-crown-4 in binary nitromethane-acetonitrile mixtures by using lithium-7 NMR technique and ab initio calculation

Lithium-7 NMR measurements were used to investigate the stoichiometry and stability of Li+ complexes with 15-crown-5 (15C5), benzo-15-crown-5 (B15C5), dibenzo-15-crown-5 (DB15C5) and 12-crown-4 (12C4) in a number of nitromethane (NM)-acetonitrile (AN) binary mixtures. In all cases, the exchange between the free and complexed lithium ion was fast on the NMR time scale and a single population average resonance was observed. While all crown ethers form 1:1 complexes with Li+ ion in the binary mixtures used, both 1:1 and 2:1 (sandwich) complexes were observed between lithium ion and 12C4 in pure nitromethane solution. Stepwise formation constants of the 1:1 and 2:1 (ligand/metal) complexes were evaluated from computer fitting of the NMR-mole ratio data to equations which relate the observed metal ion chemical shifts to formation constants. There is an inverse linear relationship between the logarithms of the stability constants and the mole fraction of acetonitrile in the solvent mixtures. The stability order of the 1:1 complexes was found to be 15C5·Li+>B15C5·Li+>DB15C5·Li+>12C4·Li+. The optimized structures of the free ligands and their 1:1 and 2:1 complexes with Li+ ion were predicted by ab initio theoretical calculations using the Gaussian 98 software, and the results are discussed.     

Preparation and gas chromatographic characterization of dibenzyl crown ether stationary phases

Summary Two crown ethers, di(tert-butylbenzo)-propyl-15-crown-5 polysiloxane (PSO-DTB-15C5) and dibenzo-propyl-15-crown-5 polysiloxane (PSO-DB-15C5) have been synthesized and coated onto fused-silica capillary columns. The chromatographic characteristics, including column efficiency, polarity, phase transition temperature, operating temperature range and selectivity, were studied.Excellent selectivity was obtained for the separation of polar position isomers, especially phenol and dinitrotoluene isomers. The separation mechanism is discussed.     

SBA-15介孔分子筛的乙基化修饰

20世纪90年代初,美孚公司的研究者们用烷基季铵盐阳离子表面活性剂作模板剂,在碱性条件下合成出M41S系列介孔分子筛。近几年,合成出了MCM,HMS,MSU、SBA等硅基分子筛系列。由于介孔材料表面有许多端羟基,可用来固定活性基团,使其在吸附、分离、催化和主客体化学等方面具有广泛的潜在应用价值。对介孔材料孔道进行有机改性的无机-有机复合材料的研究正在兴起,本文采用分步合成法,以乙基三乙氧基硅烷为偶联剂,     

Thermochemical behaviour of crown ethers aqueous organic solvents: Part IV: Propanol and acetonitrile with water mixtures

Enthalpies of solution of 15-crown-5 (15C5) in the mixtures of water with acetonitrile (AN) or propan-1-ol (PrOH) and benzo-15-crown-5 ether (B15C5) in the PrOH-water mixtures have been measured at 298.15 K. The values of standard enthalpies of solution of 15C5 are negative in the mixtures of water with AN within the whole range of mixture composition and in the mixtures water-PrOH for water content x_w>0.1 and those of B15C5 are positive (except the standard enthalpy of B15C5 in pure water) in the system water-PrOH. The results of the calorimetric measurements together with the earlier data for B15C5 in water-acetonitrile mixtures are discussed with regard to the intermolecular interactions that occur in these systems.This revised version was published online in November 2005 with corrections to the Cover Date.     

Study of complexation of phenylaza-15-crwon-5, 4-nitrobenzo- 15-crown-5, and benzo-15-crown-5 with Ag+, Tl+ and Pb2+ ions in methanol by competitive potentiometry

The complexation reaction of phenylaza-15-crwon-5, 4- nitrobenzo- 15-crown-5, and benzo-15-crown-5 with Ag⁺, Tl⁺ and Pb²⁺ ions in methanol solution have been studied by a competitive potentiometric method. The Ag⁺/Ag electrode used both as an indicator and reference electrode in a concentration cell. The emf of cell monitored as the crown ethers concentration varies through the titration. The stoichiometry and stability constants of resulting complexes have been evaluated by MINIQUAD. The stoichiometry for all resulting complexes was 1:1. The stability of these metal ions with derivatives of 15-crown-5 are in order phenylaza-15-crown-5 > Benzo-15-crown-5 > 4-nitrobenzo-15-crown-5, and for the each used crown ethers are as Pb²⁺ > Ag⁺ > Tl⁺. The effect of the substituted group on the stability of resulting complexes was considered. The obtained results are novel and interesting.     

Hydration effect on the ion-pair extraction of lithium picrate by hydrophobic benzo-15-crown-5 ether into various less-polar diluents.

The ion-pair formation constant (K(MLA)(0) in mol(-1) dm(3)) for Li(B15C5)(+) with a picrate ion (Pic(-)) in water was determined by potentiometry with a K(+)-selective electrode at 25 degrees C and an ionic strength of 0, where B15C5 denotes benzo-15-crown-5 ether. Using the concentration equilibrium constants, K(MLA), estimated from this value, the extraction constants (mol(-2) dm(6) unit) of about ten diluents were re-calculated from previously reported extraction data. Also, the distribution constants of an ion-pair complex, Li(B15C5)Pic, between water and the diluents were re-estimated. A disagreement in the determined K(MLA) value between a solvent-extraction method and potentiometry was explained in terms of the Scatchard-Hildebrand equation; it came from the fact that the hydration of Li(I) in Li(B15C5)Pic was larger than that of free B15C5 in water. Then, the previously determined value by the former method was re-estimated using the potentiometric K(MLA) value.     

Guest-host encapsulation of microporous zeolites in ordered mesoporous materials by molecular simulations

The present work provides the first study of ordered mesoporous materials SBA-15 coated with microporous zeolites ZSM-5 using molecular simulations. Several model structures with characteristics such as periodic arrangement of mesopores, randomly arranged micropores, surface hydroxyls and bulk deformations of SBA-15 were used. Cartesian coordinates of ZSM-5 unit lattice were obtained from the literature and the 100 face of H-ZSM-5 unit cell was then placed on the surface of SBA-15 and the entire structure was equilibrated to obtain final configuration. The resulting structure was characterized using simulated small angle and wide angle X-ray diffraction, Connolly surface area (to compare BET area), accessible pore volume for nitrogen molecules (to compare with t-plot volume of micro and mesopores) and methane adsorption at 303 K. The orientation of ZSM-5 on the SBA-15 had no effect on the surface area, pore volume or adsorption capacity. In order to find out if the addition of microporous ZSM-5 should increase the total methane adsorption capacity due to addition of micropores, we studied adsorption on bare and coated SBA-15. However, total adsorption capacity was found to decrease, while the number of methane molecules adsorbed per unit cell of the SBA-15 structure increased. An existing experimental method (J. Am. Chem. Soc., 2004, 126, 14324) of the synthesizing hybrid ZSM-5/SBA-15 structure was studied using accessible micropore volume (by t-plot). It was found that the procedure made all the micropores inaccessible. A modification of the method or use of other host materials is suggested to use the benefits of narrow micropore distribution in ZSM-5.     

Production of highly specific anti-testosterone antiserum by an immunotolerance method

Anti-testosterone antisera were produced by pretreatment of rabbits with 15 alpha-carboxymethyl-5 alpha-dihydrotestosterone linked to a copolymer of D-glutamic acid and D-lysine (D-GL) before immunization with the bovine serum albumin conjugate of 15 alpha- and 15 beta-carboxymethyltestosterone. The specificity for 5 alpha-dihydrotestosterone of the antitestosterone antisera was considerably improved.     

Synthesis and structure of heteroleptic triple-decker neodymium,europium, holmium,erbium, and ytterbium crown phthalocyaninates

Two series of heteroleptic crown-substituted tris(phthalocyaninate) complexes (Pc)Ln[(15C5)₄Pc]Ln(Pc) and [(15C5)₄Pc]Ln[(15C5)₄Pc]Ln(Pc), where 15C5 is 15-crown-5, (Pc²⁻) is the phthalocyaninate dianion, Ln = Nd, Eu, Ho, Er, and Yb, were prepared by the reaction of tetra-15-crown-5-phthalocyanine H₂[(15C5)₄Pc] with the corresponding lanthanide acetylacetonates and lanthanum bis(phthalocyaninate) La(Pc)₂, which was used as a phthalocyaninate dianion donor. The composition and structure of the synthesized complexes were confirmed by MALDI TOF mass spectrometry, UV-Vis absorption spectroscopy, and ¹H NMR. Complete assignment of the proton resonance signals of the paramagnetic lanthanide complexes was based on analysis of lanthanide-induced shifts.     

两种偶氮苯冠醚的合成及其光致变色机理

报道了4-氮杂15-冠-5-4'-甲氧基偶氮苯和4-氮杂15-冠-5-4'-硝基偶氮苯的合成及其分子内扭曲电荷转移的光致变色机理.     

MoCl_5与n－C_7H_（15）COOH的取代反应及其产物对丁二烯聚合活性

研究了ＭｏＣｌ５与ｎ－Ｃ７Ｈ１５ＣＯＯＨ间的取代反应条件，如反应温度和时间等，对取代反应产物ＭｏＣｌ５－ｍ（ｎ－Ｃ７Ｈ１５ＣＯＯ）ｍ的影响，讨论了产物的紫外可见光谱，测定了由取代产物组成的铝催化剂对丁二烯聚合反应的活性，结果表明，随着ＭｏＣｌ５中氯的取代量（ｍ＝２～４）的增加聚合活性迅速降低。     

Convenient Synthesis of Host Molecule Containing Se-Se Bond

OrganoseleniumcompoundscontaininganSe-Sebondareofparticularinterest1-3.In1990,ShujiTomodaandco-workerfirstlysynthesizedaclassofcrown-ethertypehostmoleculesintowhichtheSe-Sebondsareincorporated.Thisndghtprovideauniqueopportunityforanewmoleculardevice,whichwouldactasacatalystinaphotochendcallyinducedredoxcycleorundergoselectivemembranetransportofspecificmetalionsunderlightirradiation.Inthispaper,aconvenientapproachtosynthesizethiskindofmoleculewasreported.Thehostmoleculewhichwassynthesizedcon…     

Crowned polyacetylene. I. Synthesis and characterization of poly(4′-ethynylbenzo-15-crown-5)

4′-Ethynylbenzo-15-crown-5 ( EB15C5 ) polymerized with high yields in the presence of (bicyclo[2.2.1] hepta-2,5-diene) rhodium(I) chloride dimer and triethylamine as a cocatalyst in chloroform at 30°C. Common catalysts for the polymerization of substituted acetylenes, WCl₆ and MoCl₅, did not produce any polymer from EB15C5 . The structure of the main chain for poly(4′-ethynylbenzo-15-crown-5) ( PEB15C5 ) was determined to be predomi-nantly cis form, based upon the relatively sharp signals attributed to the main chain atoms that was observed in the ¹H and ¹³C NMR spectra. The cation-binding properties of PEB15C5 are very similar to that of poly(4′-vinylbenzo-15-crown-5), and the selectivity is in the order of K⁺> Rb⁺ ? Cs⁺ ? Na⁺, Li⁺. The electrical conductivity of PEB15C5 increased from 1.3 × 10^?10 to 1.3 × 10^?6 S. cm^?1, when the polymer was doped with iodine. © 1995 John Wiley & Sons, Inc.