Search

The fluorescence and other photophysical parameters of highly polarized, quadrupolar bis-coumarins possessing an electron-rich pyrrolo[3,2-b]pyrrole bridging unit are highly dependent on the linking position between both chromophores. Delocalization of the LUMO on the entire π-system results in intense emission and strong two-photon absorption.

A thorough investigation has enabled the optimization of the synthesis of 1,4-dihydro-pyrrolo[3,2-b]pyrroles. Although salts of such metals as vanadium, niobium, cerium, and manganese were found to facilitate the formation of 1,4-dihydro-pyrrolo[3,2-b]pyrroles from amines, aldehydes, and diacetyl, we confirmed that iron salts are the most efficient catalysts. The conditions identified (first step: toluene/AcOH = 1:1, 1 h, 50 °C; second step: toluene/AcOH = 1:1, Fe(ClO4)3·H2O, 16 h, 50 °C) resulted in the formation of tetraarylpyrrolo[3,2-b]pyrroles in a 6–69% yield. For the first time, very electron-rich substituents (4-Me2NC6H4, 3-(OH)C6H4, pyrrol-2-yl) originating from aldehydes and sterically hindered substituents (2-ClC6H4, 2-BrC6H4, 2-CNC6H4, 2-(CO2Me)C6H4, 2-(TMS-C≡C)C6H4) present on anilines can be appended to the pyrrolo[3,2-b]pyrrole core. It is now also possible to prepare 1,4-dihydropyrrolo[3,2-b]pyrroles bearing an ordered arrangement of N-substituents and C-substituents ranging from coumarin, quinoline, phthalimide to truxene. These advances in scope enable independent regulations of many desired photophysical properties, including the Stokes shift value and emission color ranging from violet-blue through deep blue, green, yellow to red. Simultaneously, the optimized conditions have finally allowed the synthesis of these extremely promising heterocycles in amounts of more than 10 g per run without a concomitant decrease in yield or product contamination. Empowered with better functional group compatibility, novel derivatization strategies were developed.

The following work presents three general approaches allowing, for the first time, the synthesis of 5,10-diheterotruxene derivatives containing two identical heteroatoms, namely, oxygen OOC, nitrogen NNC, or sulfur SSC. Two of described pathways involve the photocyclization of the corresponding triene 2as a key step leading to a heptacyclic aromatic system. The third approach is based on the acidic condensation between ninhydrin 14and benzo[b]heteroole 15. Typical functionalizations of the 5,10-diheterotruxene core have also been presented. In addition, the article discusses the advantages and limitations of the three suggested paths for receiving specific 5,10-diheterotruxene derivatives because the universal method suitable for obtaining molecules with any type of heteroatoms is not known so far.

This paper presents an alternative path for the synthesis of 5-thiatruxene and the synthetic approach for 5-azatruxene not known so far. A new method for 5-thiatruxene improves the overall reaction yield from 17.5 to 22.6%, diminishes the synthesis time and costs by reducing synthetic steps from 5 to 2, and simplifies the isolation of intermediate and final products. The overall reaction yield for 5-azatruxene is 32.4%. The typical reactivity of both aromatic systems is also demonstrated. Recent research results suggest the use of 5-thiatruxene as the acceptor subunit of soluble blue emitters.

In this paper, selected physicochemical properties such as kinematic viscosity (ν), density (ρ), lower heating value (LHV), cold filter plugging point (CFPP), miscibility, flash point (FP), coefficient of friction (μ), lubricity (WS1.4), surface tension (σ), and copper strip corrosion (CSC) of diethyl ether/rapeseed oil blends were experimentally determined. Diethyl ether (DEE) was blended with rapeseed oil (RO) in volumetric ratios of 10, 20, 30, and 40%. The values of the LHV, kinematic viscosity, surface tension, and density of the blends were lower than the values obtained for the tested rapeseed oil. Especially, it was found that DEE has significant influence on the rapeseed oil viscosity value. The addition of merely 10% DEE to rapeseed oil decreased its viscosity by 50%. It was shown that the lubricity of all tested blends is reduced, but not as significantly as viscosity. Also, we confirmed that tested blends do not promote the corrosion processes. What is more, it was found that the temperature of the CFPP decreased when DEE was added to RO and the miscibility of all tested fuel blends is excellent in a wide range of temperature changes. For this reason the results of our research suggest that DEE/RO blends seem to be usable for engines operated in the winter season. However, it should be confirmed in further engine research carried out in low temperature conditions. In this study the diesel smoke opacity (SO) was also measured in the condition of a free acceleration test according to requirements of the United Nations Economic Commission for Europe (ECE) Regulation No. 24. Results of these tests demonstrate that the diesel smoke opacity is reduced even by 55% for DEE40 blend compared with RO.

Reproductive efficiency in pigs is largely dependent on the fertility of the boar. Boars used at insemination stations should produce a large amount of semen with high fertilization capacity. The sperm count influences the conception rate and the number of insemination doses produced. The aim of this study was to evaluate the morphological and morphometric characteristics of boars of the Hypor breed in relation to the total sperm count in the ejaculate. An analysis was performed of 120 ejaculates collected from 12 Hypor boars used at three insemination stations. The ejaculate sperm count was found to affect the morphometric characteristics of spermatozoa from boars. In the ejaculates with the lowest sperm count the spermatozoa heads were significantly shorter and narrower and had a smaller surface area. The sperm from ejaculates with the lowest sperm count had relatively small head dimensions in relation to the tail length and total sperm length. In the ejaculates with the most sperm cells, the proportion of spermatozoa with major defects was significantly greater than in the ejaculates from other groups. In the ejaculates with the lowest sperm count the frequency of sperm with progressive motility was significantly lower. The fewest insemination doses can be prepared from these ejaculates.

New ternary Eu(III) 5-(2-pyridyl-1-oxide)tetrazolate complexes with phosphine oxide co-ligands have been synthesized and characterized by elemental analysis, and IR and 1H NMR spectroscopic techniques. The analytical data revealed that these complexes are mononuclear, and the central Eu(III) ion is coordinated by three oxygen and three nitrogen atoms of the tetrazolate and two oxygen atoms from the phosphine oxide ligands. The ancillary ligands increased remarkably the luminescence efficiency of the Eu(III) tetrazolate.

We present a novel approach to quantifying the morphology of cosmic microwave background (CMB) anisotropy maps. As morphological descriptors, we use shape parameters known as Minkowski functionals. Using the mathematical framework provided by the theory of integral geometry on arbitrary curved supports, we point out the differences in their characterization and interpretation in the case of flat space. With the restrictions of real data — such as pixelization and incomplete sky coverage, to mention just a few — in mind, we derive and test unbiased estimators for all Minkowski functionals. Various examples, among them the analysis of the four‐year COBEDMR data, illustrate the application of our method.

Recent progress in observational techniques has made it possible to confront quantitatively various models for the large-scale structure of the Universe with detailed observational data. In particular, there are well–established galaxy–galaxy and cluster-cluster correlations1–3, stringent upper limits on (and one tentative measurement of) the anisotropy of the cosmic microwave background radiation (CBR) on various angular scales4,5, and large-scale bulk motions reported by several groups6–8. These three observables place important constraints on cosmological parameters, most notably the amplitude and shape of the density fluctuation spectrum in the very early Universe. We develop a general formalism to show that the gravitational instability theory for the origin of large-scale structure is now capable of critically confronting observational results on CBR angular anisotropies, large-scale bulk motions and large-scale dumpiness in the galaxy counts.