Molecular aggregation of disklike benzenetricarboxamides containing diacetylenic groups in bulk and organic solvents

We prepared disklike tris(4-alkylbutadiynylphenyl)-1,3,5-benzenetricarboxamide and tris[4-(4-alkyloxyphenyl)butadiynylphenyl]-1,3,5-benzenetricarboxamide, where three phenyl diacetylenic and diphenyl diacetylenic groups are connected to a benzene ring through amide linkages, respectively. The structures of self-assembled substances were investigated by using transmission electron microscopy, scanning electron microscopy, and X-ray diffraction techniques. All the compounds were highly viscous in melt states, and only compound 9 having three phenyl diacetylenic groups and hexyl tails showed a thermotropic mesophase on cooling. The compound with three diphenyl diacetylenic groups and dodecyloxy tails (13) formed a stable gel in THF/cyclohexane. The IR and X-ray analyses showed that in the gel state molecules were assembled into a rectangular columnar lattice and held each other by hydrogen bondings between amide groups. The compound with tetradecyloxy tails (14) formed stable colloidal particles in cyclohexane. The UV irradiation of 13 in a gel and 14 in a colloidal particle did not result in a long conjugated polymer because of the inappropriate alignment of diacetylenic groups for the topochemical polymerization.     

Signals in asbestos related diseases in human breath - preliminary results

Several diseases occur due to asbestos exposure. Until today, asbestos predicted mortality and morbidity will increase because of the long latency period. Actually, the methods to investigate asbestos related disease are mostly invasive. Therefore, the aim of the present paper was to investigate, whether signals in human breath could be correlated to Asbestos related lung diseases using a multi-capillary column (MCC) connected to an ion mobility spectrometer (IMS) as non-invasive method. Here, the breath samples of 10 mL of 25 patients suffering from asbestos related diseases. This group includes patients with asbestos related pleural thickening with and without pulmonary fibrosis. Twelve healthy persons constitute the control group and the breath samples are compared with those of the BK4103 patients. In total 83 peaks are found in the IMS-Chromatogram. A discrimination was possible with p-values <0.001 for two peaks (99.9 %), <0.01 (99 %) for 5 peaks and <0.05 (95 %) for 17 peaks. The most discrimination peaks alpha pinene and 4-ethyltoluol were identified among some others with lower p-values. The corresponding Box-and-Whisker-Plots comparing both groups are presented. In addition, a decision tree including all peaks was created that shows a differentiation with alpha pinene between BK4103 (pleural plaques group) and the control group. In addition, the sensitivity was calculated to 96 %, specificity was 50 %, positive and negative predictive values were 80 % and 86 %. Ion mobility spectrometry was introduced as non-invasive method to separate both groups Asbestos related and healthy. Naturally, the findings need further confirmation on larger population groups, but encourage further investigations, too.     

1,1′,1′′-(2,4,6-Trihydroxybenzene-1,3,5-triyl)triethanone tautomerism revisited

It has recently been suggested that 1,1′,1′′-(2,4,6-trihydroxybenzene-1,3,5-triyl)triethanone may be tautomeric. Using ¹³C NMR chemical shifts and deuterium isotope effects on ¹³C chemical shifts, it is demonstrated that this is not the case. This compound occurs as a strongly hydrogen bonded benzene structure with hydrogen bonds between OH groups and the acetyl groups in both non-polar and hydrogen donating solvents. Quantum-chemical calculations using MP2 and M06-2X methods show substantial preference for the phenol structure in both the gas phase, and in cyclohexane and methanol. In addition, conventional UV–vis spectroscopy data suggest not tautomeric, but aggregation behaviour of the molecule in methanol and acetonitrile.     

A thioxanthone‐based visible photoinitiator

Thioxanthone‐based 9‐(2‐Morpholine‐4yl‐acetyl)‐5‐thia‐napthasen‐12‐one (TX‐MPM) was synthesized and characterized as a one‐component novel visible photoinitiator. Its capability to act as an initiator for the polymerization of methyl methacrylate (MMA) was examined in photoreactor and also daylight. Photophysical properties: fluorescence and phosphorescence emission spectra and fluorescence quantum yield of TX‐MPM (?_f = 0.29) were determined. The phosphorescence lifetime was found 131 ms for TX‐MPM and 110 ms for initiator‐attached polymer (PMMA) at 77 K, indicated a π→π* nature of the lowest triplet state. A model compound, morpholino acetonapthone was used as quencher for the triplet states of TX‐MPM and the quenching rate constant was determined (k_q = 1.26 × 10⁹ M^?1s^?1). According to laser flash photolysis studies, intermolecular hydrogen abstraction process was more dominant path to the formation of the initiating radicals. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Structural study of 3-methyl-2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9β-ol

The infrared spectra in several media and the crystal structure of 3-methyl-2,4-diphenyl-3-azabicyclo[3.3.1]-nonan-9β-ol ( I ) (Scheme I) have been determined, in order to complete the structural study described for the title compound from the ¹H and ¹³C nmr data [1]. The bicyclic system adopts a flattened chair-chair conformation in which the cyclohexane ring is more flattened. The methyl and phenyl groups are in equatorial positions and the OH group in an axial position with respect to the piperidine ring.     

Studies on the matched potential method for determining the selectivity coefficients of ion-selective electrodes based on neutral ionophores: experimental and theoretical verification.

A theory is presented that describes the matched potential method (MPM) for the determination of the potentiometric selectivity coefficients (KA,Bpot) of ion-selective electrodes for two ions with any charge. This MPM theory is based on electrical diffuse layers on both the membrane and the aqueous side of the interface, and is therefore independent of the Nicolsky-Eisenman equation. Instead, the Poisson equation is used and a Boltzmann distribution is assumed with respect to all charged species, including primary, interfering and background electrolyte ions located at the diffuse double layers. In this model, the MPM-selectivity coefficients of ions with equal charge (ZA = ZB) are expressed as the ratio of the concentrations of the primary and interfering ions in aqueous solutions at which the same amounts of the primary and interfering ions permselectively extracted into the membrane surface. For ions with unequal charge (ZA not equal to ZB), the selectivity coefficients are expressed as a function not only of the amounts of the primary and interfering ions permeated into the membrane surface, but also of the primary ion concentration in the initial reference solution and the delta EMF value. Using the measured complexation stability constants and single ion distribution coefficients for the relevant systems, the corresponding MPM selectivity coefficients can be calculated from the developed MPM theory. It was found that this MPM theory is capable of accurately and precisely predicting the MPM selectivity coefficients for a series of ion-selective electrodes (ISEs) with representative ionophore systems, which are generally in complete agreement with independently determined MPM selectivity values from the potentiometric measurements. These results also conclude that the assumption for the Boltzmann distribution was in fact valid in the theory. The recent critical papers on MPM have pointed out that because the MPM selectivity coefficients are highly concentration dependent, the determined selectivity should be used not as "coefficient", but as "factor". Contrary to such a criticism, it was shown theoretically and experimentally that the values of the MPM selectivity coefficient for ions with equal charge (ZA = ZB) never vary with the primary and interfering ion concentrations in the sample solutions even when non-Nernstian responses are observed. This paper is the first comprehensive demonstration of an electrostatics-based theory for the MPM and should be of great value theoretically and experimentally for the audience of the fundamental and applied ISE researchers.     

The first synthesis of (-)-asperpentyn and efficient syntheses of (+)-harveynone, (+)-epiepoformin and (-)-theobroxide

A generally applicable strategy for the synthesis of a range of polyoxygenated cyclohexane natural products has been developed. The enantioselective syntheses of (-)-theobroxide, a polyoxygenated cyclohexane natural compound with potent growth inducing properties in potato microtubers has been achieved via a 1,2 O-silyl migration between trans-hydroxyl groups and a remote hydroxyl directed epoxidation of an enone derived from quinic acid. A thus derived alpha-iodoenone was subjected to Stille coupling with tetramethylstannane to afford the first title compound. A similar strategy enabled a route to the complete asymmetric synthesis of the acetylenic phytotoxin (+)-harveynone. By selective reduction of (-)-theobroxide, (+)-epiepoformin was also prepared in enantiopure form and similarly, stereoselective reduction of (+)-harveynone completed the first enantioselective synthesis of (-)-asperpentyn, another natural compound with antimicrobial activity.     

Bildung siliciumorganischer Verbindungen. 88. Zur SiH-Addition von 1,3,5-Trisilacyclohexanen an silylierte Alkine

Formation of Organosilicon Compounds. 88. SiH-Addition of 1,3,5-Trisilacyclohexanes to Silylalkynes Catalyzed by means of H₂PtCl₆ the SiH addition of 1,1,3,3,5-pentamethyl-1,3,5-trisilacyclohexane to HC?C? Sime₂CH₂Cl, and of 1,1,3,3,5-pentaphenyl-1,3,5-trisilacyclohexane to HC?C? Sime₂CH₂Br yields a and b , or c and d , resp. (Formulae see Inhaltsübersicht), whereas 1,3,5-trisilacyclohexanes with more SiH groups preferrably yield polymers. The c/d ratio is strongly governed by the solvent: 38% c in n-hexane, 72% c in CCl₄/cyclohexane. Treatment of c and d with HCl/AlCl₃ under cleavage of all of the phenyl groups, addition of HCl to the vinyl group and subsequent β-elimination leads to (Cl₂Si? CH₂)₃ ClSime₂? CH₂Br and compound e , whereas HBr at ?78°C only cleaves one phenyl group per Si atom.     

Free-radical reactions of the tris-dioximate clathrochelates: synthesis and X-ray structure of the first cyclohexyl-substituted monoribbed-functionalized macrobicyclic iron(ii) complex

Quantum chemical calculations were performed at the DFT level for the boron-capped dichloro-substituted tris-dioximate iron(II) clathrochelate and cyclohexane and 1,4-dioxane radicals. The 1,4-dioxane and cyclohexane radicals are nucleophiles towards the macrobicyclic precursor studied. The reaction of this clathrochelate with cyclohexane in the presence of a free-radical initiator resulted in substitution of a chlorine atom by a cyclohexyl fragment. The compound obtained was characterized by elemental analysis, IR spectroscopy, ¹H and ¹³C{¹H} NMR, and single-crystal X-ray diffraction data.     

Effect of Cyclohexane on the Phase Behavior of L64/1-Butyl-3-Methylimidazolium Tetrafluoroborate System

The triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (L64, PEO₁₃PPO₃₀PEO₁₃) in 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF₄]) can form lamellar liquid crystalline (L_α). The effect of apolar cyclohexane molecules on the L_α phase was investigated by using polarized optical microscopy (POM) and small-angle x-ray scattering (SAXS). The results of POM and SAXS show that a suitable amount of cyclohexane can contribute to the formation of lamellar liquid crystals, and the ordering of L_α phase is increased. For comparison, the effect of polar water on L_α phase was explored. After adding water, both EO groups and [BF₄]^– anion can form hydrogen bonds with water molecules, which weakens the electrostatic interactions between L64 and [Bmim][BF₄] and therefore the ordering of lamellar structures is destroyed.     

茂钛/MAO催化体系进行降冰片烯聚合的研究

以降冰片烯为例的环状烯烃的聚合方式主要有两种 :( A) Vinyl-type polymerization;( B) Ring-Opening Polymerization　　 80年代中期以前 ,环烯烃聚合研究主要集中在开环易位聚合 (ROMP)反应 [1] .Kaminsky[2 ] 首次以[En(Ind) 2 Zr Cl2 ]/MAO等为催化剂进行降冰片烯的聚合 ,获得了熔点极高 (高于其 40 0℃的分解温度 )的大分子量加成结构的聚合物 .研究结果表明 ,具有 C2 和 Cs对称性的茂锆催化体系能高活性地得到降冰片烯加成聚合物 [3,4 ] ,但是这些由茂锆催化体系合成的降冰片烯聚合物不溶于有机溶剂 ,难以进行精确定量的结…     

Guest exchange in dimeric capsules formed by tetra-urea calix[4]arenes

Ten tetra-urea calix[4]arene derivatives with different ether residues (methyl, pentyl, benzyl, all combinations of methyl and pentyl, 1,3-dibenzyl-2,4-dipentyl), including also the tetrahydroxy compound and the 1,3-dipentyl ether, were synthesised. Their urea groups were substituted with a lipophilic residue to ensure sufficient solubility in cyclohexane. Thus, kinetics for the exchange of the included guest (benzene) against the solvent (cyclohexane) could be followed by 1H NMR spectroscopy. The apparent first order rate constants decrease with increasing size of the ether residues from methyl to benzyl by more than three orders of magnitude. This can be understood by a decreasing flexibility/mobility of the calixarene skeleton. In line with this explanation is the rather slow exchange for the tetrahydroxy compound, where the cone conformation is stabilised by a cyclic array of intramolecular OH...OH hydrogen bonds.     

On the CH...Cu agostic interaction: chiral copper(II) compounds with ephedrine and pseudoephedrine derivatives

The ephedrine derivative, (H2ceph), yields [Cu(Hceph)2], showing a CH...Cu(II) agostic interaction; while in the analogous compound [Cu(Hcpse)2], with pseudoephedrine (H2cpse), that interaction is absent, despite the fact that these two diasteromers differ only in the orientation of the methyl and phenyl groups: erythro in H2ceph and threo in H2cpse. The X-ray crystal structure of [Cu(Hceph)2], indicates a Cu...HC length of 2.454 A and the theoretical study reveals the formation of a Cu...HC bond since the associated electronic density shows both a bond critical point and a bond ring critical point.     

Validated reference standards to support the identification of asbestos fibers

National Institute for Occupational Health and Safety stated: "all levels of asbestos exposure demonstrated asbestos-related diseases and there is no level of exposure below which clinical effects do not occur". New legislation in European Community and the United Nations Environment Program states that all forms of asbestos should be banned and added to an international list of chemicals submitted to trade controls. The asbestos reference standards have been prepared and validated by Institute of Occupational Medicine under contact to the Health and Safety Executive, UK. The identification of commonly encountered asbestos fibers is performed with a dispersion staining objective using well matched high dispersion liquids. The certainty of the method is analyst dependent, since the subjective nature of asbestos analysis is involved. Appropriate training is of fundamental importance to both sampling and analysts. Microscopic determination of asbestos requires the analyst to make repeated assessments of a number of physical properties and maintain consistent diligence in the search for fibers. Analysts should be thoroughly familiar with the appearance and characteristic of asbestos. Misidentification occurs not only when other kinds of fibrous material are incorporated into a bulk material, but also when more than one kind of asbestos are present in such a material. For routine purposes the examinations by means of polarized light microscopy (PLM) are usually sufficient to identify positively whether asbestos is present and its type.     

Influence of compound danshen tablet on the pharmacokinetics of losartan and its metabolite EXP3174 by liquid chromatography coupled with mass spectrometry

Losartan is an effective anti‐hypotension drug frequently used in clinic. Compound danshen tablet (CDST) is an important traditional Chinese multiherbal formula composed of Danshen, Sanqi and Bingpian, which is widely used for the treatment of cardiovascular and cerebrovascular diseases in China. More often, losartan and CDST are simultaneously used for the treatment of anti‐hypertension in the clinic. The aim of this study was to compare the pharmacokinetics of losartan and EXP3174 after oral administration of single losartan and both losartan and CDST, and to investigate the influence of CDST on the pharmacokinetics of losartan and its metabolite EXP3174. Male Sprague–Dawley rats were randomly assigned to two groups: a losartan‐only group and a losartan and CDST group. Plasma concentrations of losartan and EXP3174 were determined by LC‐MS at designated points after drug administration, and the main pharmacokinetic parameters were estimated. It was found that there were significant differences (p < 0.05) between the pharmacokinetic parameters of losartan and EXP3174, which showed that CDST influenced the metabolism and excretion of losartan in vivo. The result could be used for clinical medication guidance of losartan and CDST to avoid the occurrence of adverse reactions. Copyright © 2013 John Wiley & Sons, Ltd.     

3-Oxo-1,3-oxathiolanes-synthesis and stereochemistry

The compound 3-oxo-1,3-oxathiolane (6) and its cis - and trans - 2-methyl (7,8), 4-methyl (9,10), 5-methyl (11,12) and 2-p-nitrophenyl (13,14) derivatives were prepared by oxidizing the corresponding 1,3-oxathiolanes (1-5) with NaIO4 in water. The oxides were purified and their isomers separated using thin layer chromatography. The structural characterization was carried out with 1H NMR spectroscopy and molecular modeling. Compounds 8-10, 12, and 14 attain the half-chair type conformation with O1 above and C5 below the plane (HC1), but 6, 7, 11, and 13 are, for steric reasons, the mixtures with the alternative half-chair (HC2), where O1 is below and C5 above this plane. Accordingly, 6 appears based on the values of experimental coupling constants as an 81:19, 7 as a 37:63, 11 as a 33:67 and 13 as a 54:46 mixture of HC1 and HC2, respectively. The relative energies of these conformations, the values of the vicinal H,H-coupling constants and 1H chemical shifts were estimated for compounds 6-12 also by computational methods and they support nicely the conclusions based on experimental data.     

Selective cleavage of primary MPM ethers with TMSI/Et3N

A useful method for the selective cleavage of primary MPM ethers by using TMSI/Et₃N is described. Other protective groups such as secondary MPM ethers, silyl ethers, and benzylidene acetal were stable under the reaction conditions.     

Synthesis and Structure Analysis of N-（Dehydroabietyl）maleamic Acid

N-(Dehydroabietyl)maleamic acid was synthesized from dehydroabietylamine and maleic anhydride.Its structure was characterized by IR,1 H-and 13 C-NMR spectra.The stereo structure of the title compound was also unambiguously confirmed by X-ray crystal structure analysis.The white crystal crystallizes in the monoclinic system,space group P2 1 with a=12.075(2),b=10.377(2),c=17.840(4),β=100.31(3) °,V=2199.3(8) 3,R=0.0618 and wR=0.1437.Two crystallographically independent molecules with different conformations co-exist in the unit.In each molecule,the two cyclohexane rings form a trans ring junction with chair and half-chair conformations,respectively.The C=C double bond between two carbonyl groups is in a Z configuration.Intermolecular and intramolecular hydrogen bonds coexist to stabilize the structure.     

蓝光材料2-叔丁基-9,10-二(9,9-二正丙基芴基)蒽的合成与性能表征

本文设计并合成了一种新型蒽衍生物蓝光材料2-叔丁基-9,10-二(9,9-二正丙基芴基)蒽.化合物中引入的柔性烷基链有效抑制了分子间的相互作用,使该化合物不易结晶,同时提高了化合物在有机溶剂中的溶解度.通过量子力学方法计算发现,化合物具有顺反两种稳定构型,分子的平面性差,能减弱分子间相互作用.化合物在二氯甲烷溶液中的最大荧光发射峰在443 nm,在环己烷溶液中测得荧光量子效率为0.78,固态薄膜的最大发射峰波长相对溶液有少量红移(450 nm).热失重和差热分析结果表明,该化合物具有较高的热稳定性,分解温度和玻璃化转变温度分别为365℃和126℃.     

Synthesis and Inclusion Properties of Macrocyclic Polyethers Containing Phosphonic Groups

Abstract

Three novel polyether macrocycles II-IV bearing phosphonic groups have been synthesised in satisfactory yields. Macrocycle II was found to form a 1:1 inclusion compound with cyclohexane and thus was easily isolated from the reaction mixture as a clathrate. The crystal and molecular structure of the cyclohexane solvate has been determined by single crystal X-ray analyses and refined to an R of 0.028 for 3199 reflection. The compound is monoclinic, space group P2₁n with a = 15.886(6) Å, b = 11.657(5) Å, c = 18.621 (6) Å, β = 90.12(3)°, Z = 2. The whole molecule exhibits a great deal of disorder and the different conformations were modelled as consisting of two different primary conformers with population approximately 60:40.