Synthesis and structural characterization of novel 2-benzimidazolylthioureas: adducts of natural isothiocyanates and 2-amino-1-methylbenzimidazole

Adducts of natural allyl, phenethyl, and benzyl isothiocyanates and 2-amino-1-methylbenzimidazole were synthesized. After optimization of the reaction conditions, the target 2-benzimidazolylthioureas were obtained in reasonable yields. The detailed molecular and crystal structures of these compounds were characterized by spectroscopic and X-ray methods. Spectral analysis demonstrated that N-(1-methylbenzimidazolyl)-N′-allylthiourea, N-(1-methylbenzimidazolyl)-N′-benzylthiourea, and N-(1-methylbenzimidazolyl)-N′-phenethylthiourea exist in solution in an unprecedented three tautomeric forms, whose structures were corroborated unambiguously.     

Intercalation ofn-alkylamines into α-titanium phosphate from aqueous solutions

Journal of Inclusion Phenomena and Macrocyclic Chemistry - The intercalation reactions betweenn-alkylamines and α-titanium phosphate in aqueous media have been investigated. The compounds with...     

OH˙ loss and molecular rearrangements of quinoxaline N-oxides studied by interpretation of mass spectra and application of linear discriminant analysis

Quinoxaline N-oxides substituted at the ortho position to the NO group give characteristic [M – OH]⁺ fragments. With the di-N-oxides the peak intensities depend on the electron-withdrawing strength of the 2- and 3-substituents. Linear discriminant analysis was used to study the fragmentation of quinoxaline N-oxides as determined by the number of NO groups. Results of peak selection and discriminant analysis (Fisher quotients and discriminant vector coefficients) were interpreted with regard to the mass spectrometric decomposition of quinoxaline and quinoxaline N-oxide molecules. For the substituted quinoxaline TV-oxides, fragmentations involving molecular rearrangements like those observed for unsubstituted quinoxaline N-oxidles were also found. For these compounds, partial rearrangement to quinoxalinones is confirmed.     

On residualities in the set of Markov operators on

We show that the set of those Markov operators on the Schatten class such that , where is one-dimensional projection, is norm open and dense. If we require that the limit projections must be on strictly positive states, then such operators form a norm dense . Surprisingly, for the strong operator topology operators the situation is quite the opposite.

     

Observation of two-neutrino double-beta decay in 136Xe with the EXO-200 detector

We report the observation of two-neutrino double-beta decay in (136)Xe with T(1/2) = 2.11 ± 0.04(stat) ± 0.21(syst) × 10(21) yr. This second-order process, predicted by the standard model, has been observed for several nuclei but not for (136)Xe. The observed decay rate provides new input to matrix element calculations and to the search for the more interesting neutrinoless double-beta decay, the most sensitive probe for the existence of Majorana particles and the measurement of the neutrino mass scale.     

Dupin cyclides osculating surfaces

We study the order of tangency of surfaces and Dupin cyclides. We show that generically the maximal tangency order equals 4 and provide a number of examples.     

A convenient protocol for the synthesis of axially chiral Brønsted acids

Partially hydrogenated binaphthol monophosphoric acids were prepared via an improved four-step sequence. It is demonstrated that typical protection and deprotection of the phenolic groups are dispensable. The vinyl-substituted derivative has been polymerized to give a novel polymerized organocatalyst.     

Phlorotannin production and lipid oxidation as a potential protective function against high photosynthetically active and UV radiation in gametophytes of Alaria esculenta (Alariales, Phaeophyceae)

Radiation damage can inter alia result in lipid peroxidation of macroalgal cell membranes. To prevent photo-oxidation within the cells, photoprotective substances such as phlorotannins are synthesized. In the present study, changes in total fatty acids (FA), FA composition and intra/extracellular phlorotannin contents were determined by gas chromatography and the Folin-Ciocalteu method to investigate the photoprotective potential of phlorotannins to prevent lipid peroxidation. Alaria esculenta juveniles (Phaeophyceae) were exposed over 20 days to high/low photosynthetically active radiation (PAR) in combination with UV radiation (UVR) in the treatments: PAB (low/high PAR + UV-B + UV-A), PA (low/high PAR + UV-A) or low/high PAR only. While extracellular phlorotannins increased after 10 days, intracellular phlorotannins increased with exposure time and PA and decreased under PAB. Interactive effects of time:radiation wavebands, time:PAR dose as well as radiation wavebands:PAR dose were observed. Low FA contents were detected in the PA and PAB treatments; interactive effects were observed between time:high PAR and PAB:high PAR. Total FA contents were correlated to extra/intracellular phlorotannin contents. Our results suggest that phlorotannins might play a role in intra/extracellular protection by absorption and oxidation processes. Changes in FA content/composition upon UVR and high PAR might be considered as an adaptive mechanism of the A. esculenta juveniles subjected to variations in solar irradiance.     

n-Octane Dehydrocyclization on Cr2O3/La2O3/ZrO2 Catalyst Elucidated by H–D-Tracer Experiments

H–D tracer experiments during n-octane aromatization on Cr₂O₃/La₂O₃/ZrO₂ catalysts allow conclusions to be drawn on the reaction mechanism. The rate-determining step is the dissociative adsorption of the paraffin molecule. The following dehydrogenation steps seem to proceed predominantly reversibly.     

On convolution powers on semidirect products

LetK be a compact group of linear operators of thed-dimensional spaceR ^d andG _K,d denote the semidirect productK byR ^d . It is shown that if an adapted probability measureμ onG _K,d is not scattered (i.e. for some compactF we havex ₀ ∈ R ^d (gF)>0), then there exists a nonzero vectorx ₀ ∈R ^d such thatk ₁(x ₀)=k ₂(x ₀) holds for all (k ₁,x ₁) and (k ₂,x ₂) belonging to the topological supportS(μ) of the measureμ. As a result we obtain that every adapted and strictly aperiodic probability measure on the group of all rigid motions of thed-dimensional Euclidian space is scattered. I thank the Foundation for Research Development for financial support.