Theoretical study on the rearrangement of metallabenzenes to cyclopentadienyl complexes

The thermodynamic and kinetic aspects of the rearrangement reactions of a series of metallabenzenes to cyclopentadienyl complexes have been investigated by DFT computational study in order to reveal how substituents on the metallacycle, ligands around the metal center, and metals affect the transformation. We found that substitutents and their locations on the metallacycle have a significant effect on the thermodynamics and kinetics of the rearrangement reactions.     

Design, synthesis, characterization, luminescence and non-linear optical (NLO) properties of multinuclear platinum(II) alkynyl complexes

A series of luminescent multinuclear platinum(II) alkynyl complexes containing triethynylbenzene or 1,4-bis(3,5-diethynylphenyl)buta-1,3-diyne as cores has been successfully synthesized and characterized. The electronic absorption, emission, nanosecond transient absorption and electrochemical properties of these complexes have been reported. These complexes show long-lived emissions in degassed benzene solution and in alcoholic glass at 77 K. Moreover, they are found to exhibit two-photon absorption (2PA) and two-photon induced luminescence (TPIL) properties, and their two-photon absorption cross-sections have been determined to be 6-191 GM upon excitation at 720 nm. Through a systematic comparison, it has been found that tetra- and hexanuclear platinum(II) complexes show better 2PA and TPIL properties than their di- and trinuclear counterparts.     

Finiteness of circulant weighing matrices of fixed weight

Let n be a fixed positive integer. Every circulant weighing matrix of weight n arises from what we call an irreducible orthogonal family of weight n. We show that the number of irreducible orthogonal families of weight n is finite and thus obtain a finite algorithm for classifying all circulant weighing matrices of weight n. We also show that, for every odd prime power q, there are at most finitely many proper circulant weighing matrices of weight q.     

On the weak topology of Banach spaces over non-archimedean fields

It is known that within metric spaces analyticity and K-analyticity are equivalent concepts. It is known also that non-separable weakly compactly generated (shortly WCG) Banach spaces over R or C provide concrete examples of weakly K-analytic spaces which are not weakly analytic. We study the case which totally differs from the above one. A general theorem is provided which shows that a Banach space E over a locally compact non-archimedean non-trivially valued field is weakly Lindelöf iff E is separable iff E is WCG iff E is weakly web-compact (in the sense of Orihuela). This provides a non-archimedean version of a remarkable Amir-Lindenstrauss theorem.     

LC-ESI-MS-MS Method for Monitoring Dopamine,Serotonin and Their Metabolites in Brain Tissue

A rapid and precise LC-ESI-MS-MS method for the parallel identification and quantification of dopamine, serotonin and their metabolites (homovanillic acid, 3-methoxytyramine, 3,4-dihydroxyphenylacetic acid and 5-hydroxyindolacetic acid) from rat brain tissue without any pre-analysis adjustment of the sample such as pre-concentration or derivatization has been developed. In particular, the reaction-monitoring mode was selected for its extremely high degree of selectivity and the stable-isotope-dilution assay for its high precision of quantification. Alternation the ionization polarity in the course of mass spectrometry detection enabled to determine substances susceptible to various ionization modes in only one analysis run. This fact, in combination with an easy pre-treatment step, constitutes the method straightforward and time undemanding. The developed method was characterized with a high precision (≤19.5%, determined as RSD), an acceptable accuracy (≥82.0%, determined as recovery), a low limit of detection (≤0.40 ng/100 mg brain tissue) and a low limit of quantification (≤0.42 ng/100 mg brain tissue). The method has been applied in a recent animal study. The levels of the studied neurotransmitters have been determined in the rat brain hippocampus, prefrontal cortex, and striatum in an animal model of schizophrenia induced by an acute dose of a dizocilpine.     

Palladium catalyzed ring opening of furans as a route to α,β-unsaturated aldehydes

Furans may be ring opened via pallado-catalyzed reactions leading to α,β-unsaturated aldehydes and ketones tethered to indole and isoquinoline moieties. Besides their synthetic interest, these fragmentations bring interesting elements into the discussion around the reaction mechanisms involved in palladium C-H activations of electron-rich heterocycles.     

On mixed joint discrete universality for a class of zeta-functions. II

We investigate the mixed joint discrete value distribution and the mixed joint discrete universality for the pair consisting of a rather general form of zeta-function with an Euler product and a periodic Hurwitz zeta-function with transcendental parameter. The common differences of relevant arithmetic progressions are not necessarily the same. Also some generalizations are given. For this purpose, certain arithmetic conditions on the common differences are used.

     

Carbon-14 kinetic isotope effects in the debromination of p-methyldibromocinnamic acid

The kinetic isotope effect (KIE) was applied in the study of the mechanism of bromine elimination from p-methyl-erythro-a,b-dibromocinnamic acid, successively labeled at the a and b carbons. The large ¹⁴C KIE for the b-position and small KIE for the a one of side chain of p-methyl-erythro-a,b-dibromocinamic acid proves that elimination of bromine leading to the formation of (E)-p-methylcinnamic acid proceeds via the E1 mechanism.     

Equipment for measurements of radial profiles of excited species in DC glow discharge

The original experimental device for studying the radial dependences of emitted radiation, generated by the cylindrically symmetric positive column of the DC glow discharge, is proposed. Principle of detection of the radial intensity profiles of the spectral lines by means of the special scanner with two movable conic mirrors is described. The function of the scanner was verified experimentally and by the method of raytracing. As an example, the radial profiles of lines emitted by the positive column of the neon glow discharge are presented. No significant changes were found. This work is a part of the research plan MSM 0021620834, that is financed by the Ministry of Education of the Czech Republic.