Alkoholyse aromatischer Carbonsäureester

The alcoholysis of various esters of aromatic carboxylic esters with octadecanol in the presence of lead stearate was investigated by chromatographic analysis of the reaction mixtures. The reactivity of the esters was found to be strongly affected by the substitution pattern of the aromatic nucleus as well as by the structure of the alkoxy group. Electron donating substituents in a suitable position lead to a remarkable increase in reactivity compared to the unsubstituted alkyl esters.

Herrn Prof. Dr.K. Schlögl zum 60. Geburtstag gewidmet.     

Zur Kenntnis der Neutrallipide aus Säuglingshirnen

Five brains of 6 weeks old children have been examined by previously published methods. Pure lipids from different brain regions have been separated into various fractions.     

Extending the nitrogen-heterosuperbenzene family: the spectroscopic, redox, and photophysical properties of "half-cyclized" N-1/2HSB and Its Ru(II) complex

Oxidative cyclodehydrogenation is an important process in the formation of the new graphene, N-(1)/(2)HSB 2. This heteropolyaromatic results from the FeCl(3)-catalyzed oxidative cyclodehydrogenation of 1,2-dipyrimidyl-3,4,5,6-tetra-(4-tert-butylphenyl)benzene. Three new C-C bonds are formed that lock the two pyrimidines in a molecular platform comprising eight fused aromatic rings flanked by two remaining "uncyclized" phenyl rings. Mechanistically intriguing is the fact that N-HSB 1, the product of six C-C bond fusions, is co-synthesized with its "half-cyclized" daughter in this reaction. 1 and 2 have the same bidentate N-atom arrangement. This facilitates formation of the heteroleptic Ru(II) complexes, [Ru(bpy)(2)(2)](PF(6))(2) 4 and [Ru(bpy)(2)(1)](PF(6))(2) 3, which differ in the size and planarity of their aromatic ligands. The new ligand 2 and its complex 4 are characterized by (1)H NMR, IR, ESI-MS, and accurate mass methods. 2 exhibits photophysical properties that are consistent with a reduction of the pi/pi framework, a concomitant increase in the energy of the LUMO, and a blue-shift of the solvent-dependent fluorescence (lambda(em) = 474 nm, phi(F) = 0.55, toluene) as compared to its parent. Complex 4 absorbs throughout the visible region and borders on near-IR emitter character, exhibiting a slightly blue-shifted (3)MLCT emission (868 nm, CH(3)CN) as compared to that of [Ru(bpy)(2)(1)](PF(6))(2) 3 (880 nm, CH(3)CN). Electrochemical analyses permit further elucidation of the intermolecular interactions of 3 and 4. These and the concentration and temperature-dependent NMR spectra of 4 confirm it to be nonaggregating, a direct result of the two uncyclized and rotatable phenyl rings in 2.     

A novel femtosecond-laser formation of CdS nanocrystallites in zirconia matrices

A novel method for direct laser writing of two-dimensional cadmium sulfide (CdS) semiconductor nanoparticle microstructures is reported. A two photon or a higher-order multiphoton absorption process, originating from femtosecond laser pulses, was used to decompose CdS precursors dispersed in a zirconia thin film previously dip-coated on a glass substrate. The kinetics of nanoparticle formation as a function of laser power were monitored in situ by photoluminescence spectroscopy. Raman spectroscopy was also performed to characterize the structural changes of the zirconia matrix under irradiation and to verify the formation of CdS nanoparticles. Results show that CdS nanoparticles were formed by two-photon absorption (TPA) with or without the help of an additional carbazole photoinitiator.     

Monotone {sigma}-Complete RC-Groups

An RC-group is a unital group G with a distinguished compressionbase with respect to which G satisfies the Rickart projectionand general comparison properties. We prove that a monotone-complete RC-group is a union of subgroups each of which isa lattice-ordered Dedekind -complete RC-group.     

ClcR-based biosensing system in the detection of cis-dihydroxylated (chloro-)biphenyls

Polychlorinated biphenyls (PCBs) are a group of organic pollutants that are persistent when released into the environment. Among the metabolites of PCBs, dihydroxylated PCBs are also considered as toxic compounds. Various studies have shown that dihydroxylated PCBs affect the reproductive, immune, nervous, and endocrine systems. Detection of these chemicals in environmental and biological samples could provide first-hand information about their levels and lead to a better understanding of their role in toxicity. To that end, we developed a sensing system for the detection of dihydroxylated PCBs based on the clc operon. The Pseudomonas putida clc operon encodes a catabolic pathway for degradation of chlorocatechols, which are major metabolites of a large number of chlorinated compounds. In P. putida, the expression of these genes is regulated by a protein encoded by the gene clcR located upstream from the clcABD genes. We demonstrate here for the first time that dihydroxy PCBs can also induce the clc operon. Our sensing system employs P. putida bacteria harboring a plasmid in which the reporter gene, lacZ, is under the control of the regulatory protein ClcR. Consequently, when exposed to dihydroxy PCBs, the bacteria express β-galactosidase in an amount related to the concentration of the corresponding dihydroxy PCB. Various dihydroxylated PCBs, differing in the number and position of chlorines and in the position of hydroxyls, were tested for their ability to induce expression of β-galactosidase. Detection limits as low as 1×10⁻⁶ mol L⁻¹ were obtained for various dihydroxylated PCBs. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.