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Benzene Solution (benzene + solution)
Selected AbstractsThermodynamic Study of the Binding of Methyltrioxorhenium with Pyridine and Its Derivatives in Benzene SolutionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2005S. Masoud Nabavizadeh Abstract A spectrophotometric study of the interaction of methyltrioxorhenium (MTO) with pyridine and its derivatives in benzene solution has been carried out at various temperatures. The stability constants of the resulting 1:1 complexes were determined by analysis of spectrophotometric data and found to vary in the order 3,4-Me2Py > 4- tBuPy > 4-MePy > 3-MePy > 4-BenzylPy > Py > 3-PhPy > 3-C(O)OMePy > 3-ClPy. The enthalpy and entropy of adduct formation were determined from the temperature dependence of the stability constants. All complexes formed were enthalpy stabilized but entropy destabilized. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Electrospray ionization mass spectrometric study of end-groups in peroxydicarbonate-initiated radical polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2008Michael Buback Abstract Initiation by diethyl peroxydicarbonate (E-PDC), di- n -tetradecyl peroxydicarbonate (nTD-PDC), di- n -hexadecyl peroxydicarbonate (nHD-PDC), and di-2-ethylhexyl peroxydicarbonate (2EH-PDC) of free-radical polymerizations of methyl methacrylate in benzene solution was studied by end-group analysis via electrospray ionization mass spectrometry (ESI-MS). Unambiguous assignment of ESI-MS peaks allows for identification of the type of radical that starts chain growth. In case of initiation by dialkyl peroxydicarbonates with linear alkyl groups, almost exclusively alkoxy carbonyloxyl species, which are the primary fragments from initiator decomposition, occur as end-groups. With 2EH-PDC, however, both the primary 2-ethylhexoxy carbonyloxyl fragment and a second moiety, which is formed by decarboxylation of the 2-ethylhexoxy carbonyloxyl radical, are clearly observed as end-groups. The decarboxylation process is described by a concerted mechanism which involves a 1,5-hydrogen shift reaction. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6071,6081, 2008 [source] Adlayer structure of octa-alkoxy-substituted copper(II) phthalocyanine on Au(111) by electrochemical scanning tunneling microscopyMICROSCOPY RESEARCH AND TECHNIQUE, Issue 1 2008Li Wang Abstract Electrochemical scanning tunneling microscopy (ECSTM) has been used to examine the adlayer of octa-alkoxy-substituted copper(II) phthalocyanines (CuPc(OC8H17)8) on Au(111) in 0.1 M HClO4, where the molecular adlayer was prepared by spontaneous adsorption from a benzene solution containing this molecule. Topography STM scans revealed long-range ordered, interweaved arrays of CuPc(OC8H17)8 with coexistent rectangular and hexagonal symmetries. High-quality STM molecular resolution yielded the internal molecular structure and the orientation of CuPc(OC8H17)8 admolecules. These STM results could shed insight into the method of generating ordered molecular assemblies of phthalocyanine molecules with long-chained substitutes on metal surface. Microsc. Res. Tech., 2008. © 2007 Wiley-Liss, Inc. [source] Alumino-organic derivatives of some dioximesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 10 2002Nicolae Voiculescu Abstract The alumino-organic combinations of the dioximes (DOxH2) examined in this paper result from the substitution of the hydrogen bonds of oximes by alumino-organic groups. Relative to the same alumino-organic derivatives, diphenylglyoxime (DPGH2) behaves similarly to dimethylglyoxime (DMGH2). The chemical reactivity of DPGH2 towards these alumino-organic compounds is, however, less than in the case of DMGH2. An exception is the monomer state of (DPG)[Al(i-C4H9)2]2 in benzene solution. The behavior relative to amines of alkyl derivatives is similar to that found in coordinated oximes. In contrast, phenylaluminum derivatives of DMGH2 and DPGH2 are not soluble in amines. All compounds reported in this paper were separated from the reaction mixture as colored powders and were characterized by chemical analyses, IR spectroscopy, X-ray diffraction spectra and 1H NMR. Finally, a comparison between the reactivity of free and coordinated dioximes is briefly considered. It is hoped that such comparisons will throw light on the problems associated with the reactivity of free and coordinated oxides versus alumino-organic compounds. Copyright © 2002 John Wiley & Sons, Ltd. [source] A Dendrimer Chiroptical Switch Based on the Reversible Intramolecular Photoreaction of Anthracene and Benzene RingsCHEMISTRY - AN ASIAN JOURNAL, Issue 8 2010Wenjie Liu Dr. Abstract A series of Fréchet-type dendrimers with 9-benzyloxymethylanthracene cores were synthesized and characterized. The chiral source for the dendrimers was an (S)-2-methyl-1-butoxy group in the 3-position of the benzene ring. Irradiation at 366,nm of a dilute benzene solution led to the formation of two diastereomers (1:1) through a quantitative intramolecular [4,+4,] cycloaddition between the central anthracene ring and the neighboring benzene ring. The process can be reversed with 254,nm UV light or heat. The benzene rings in the dendrons work as a light-harvesting system. The optical rotation values measured for the reversible process showed fatigue resistance. Thus, a promising new type of chiroptical switch has been created that has optical rotation values as output signals. [source] Exciplex-type Behavior and Partition of 3-Substituted Indole Derivatives in Reverse Micelles Made with Benzylhexadecyldimethylammonium Chloride, Water and Benzene,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2001Claudio D. Borsarelli ABSTRACT The fluorescence properties of 3-methylindole (MI), 3-indoleacetic acid (IAA), 3-indoleethyltrimethylammonium bromide (IETA), l -tryptophan (Trp) and tryptamine hydrochloride (TA) were studied in reverse micelles solutions made with the cationic surfactant benzylhexadecyldimethylammonium chloride (BHDC) in benzene as a function of the molar ratio water/surfactant R (=[H2O]/[BHDC]). The fluorescence quenching of the model compound MI by benzene in cyclohexane solutions and by BHDC in benzene solutions were also studied in detail. The fluorescence of MI in benzene is characteristic of a charge-transfer exciplex. The exciplex is quenched by the presence of BHDC, due to the interactions of the surfactant ion pairs with the polar exciplex. In reverse micelle solutions at low R values, all the indoles show exciplex-type fluorescence. As R increases, the fluorescence behavior strongly depends on the nature of the indole derivative. The anionic IAA remains anchored to the cationic interface and its fluorescence is quenched upon water addition due to the increases of interface's micropolarity. For IETA, TA and Trp an initial fluorescence quenching is observed at increasing R, but a fluorescence recovery is observed at R > 5, indicating a probe partition between the micellar interface and the water pool. For the neutral MI, the fluorescence changes with R indicate the partition of the probe between the micellar interface and the bulk benzene pseudophase. A simple two-site model is proposed for the calculation of the partition constants K as a function of R. In all cases, the calculation showed that even at the highest R value, about 90% of the indole molecules remain associated at the micellar interface. [source] Light-Triggered Self-Assembly of a Spiropyran-Functionalized Dendron into Nano-/Micrometer-Sized Particles and Photoresponsive Organogel with Switchable FluorescenceADVANCED FUNCTIONAL MATERIALS, Issue 1 2010Qun Chen Abstract The synthesis, self-assembly, and spectroscopic investigations of spiropyran (SP)-functionalized dendron 1 are reported. Under UV light irradiation, assembly of 1 into nano-/microparticles occurs due to the transformation of the closed form of SP into the open merocyanine (MC) form. The formation of these nano-/microparticles is confirmed by transmission electron microscopy (TEM) and dynamic light scattering (DLS) experiments in addition to the confocal laser scanning microscopy (CLSM) measurements. These nano-/microparticles exhibit relatively strong red emission. It is interesting to note that the direct cooling of the toluene/benzene solution of 1 to 0,°C leads to gel formation. Multivalent ,,, interactions due to the dendron in 1 may be the driving-force for the gelation. The UV light irradiation cannot destroy the gel phase, and in fact, the gel,gel transition is successfully realized. The purple-blue gel exhibits relatively strong red fluorescence; moreover, the fluorescence can be reversibly switched by alternating UV and visible light irradiation. The results clearly indicate that the MC form after aggregation becomes more stable and fluorescent. [source] | |||||||||||||