On/off luminescence vapochromic selective sensing of benzene and its methylated derivatives by a trinuclear silver(I) pyrazolate sensor

{[3,5-(CF(3))(2)Pz]Ag}(3) (1) films exhibit selective/reversible sensing of small-organic-molecule (SAM) vapors, which readily switch-on bright-green (benzene or toluene) or bright-blue (mesitylene) luminescence that switches-off upon vapor removal. Vapors of electron-deficient SAMs or non-aromatic solvents did not attain luminescence switching and were not adsorbed.     

Synthesis of some novel pyrazolo[1,5-a]pyrimidine derivatives and their application as disperse dyes

A series of novel monoazo-disperse dyes containing pyrazolo[1,5-a]pyrimidine structures were synthesized starting with the coupling reaction between ethyl cyanoacetate and 4-hydroxybenzenediazonium chloride, followed by treatment of the resulting hydrazone product with hydrazine hydrate. The pyrazolohydrazone 6 is then treated with either 2,4-pentandione and enaminonitrile or aryl-substituted enaminoketones to give the target pyrazolo[1,5-a]pyrimidine dyes 7 and 15a-d. Structural assignments to the dyes were made using NMR spectroscopic methods. A new high temperature method, using microwave heating, was employed to apply these dyes to polyester fibers. Most of the dyed fabrics tested displayed moderate light fastness and excellent washing fastness properties.     

Effect of molecular structure on the phase behaviour of some liquid crystalline compounds and their mixtures XIV. Binary mixtures of 4-(4-substituted phenylazo) phenyl-4-alkoxybenzoates

Binary mixtures formed from components of the five homologous series of the 4-(4-substituted phenylazo)phenyl-4-alkoxybenzoates Ia-e were prepared and their mesophase behaviour characterized. Transition temperatures of the mixtures prepared were measured by differential scanning calorimetry and identified by polarizing optical microscopy. Each binary combination was made from components bearing a terminal alkoxy group with the same number of carbon atoms (kept constant at n = 6, 8, 10, 12, 14 or 16), while the other substituent (X) was different—CH₃O, CH₃, Cl, NO₂, or CN. Phase diagrams were constructed for the various systems in order to investigate the effect of the terminal substituent X, as well as of the alkoxy chain length, on the phase behaviour of mixed systems.     

Gas-phase thermolysis of benzotriazole derivatives. Part 3: Kinetic and mechanistic evidence for biradical intermediates in pyrolysis of aroylbenzotriazoles and related compounds

Gas-phase pyrolysis (static and FVP) of 1-aroylbenzotriazoles gave the corresponding substituted benzoxazole, benzimidazole, benzamide, N-phenylbenzamide, phenanthridin-6(5H)-one derivatives and 1-cyanocyclopentadiene. The present kinetic and mechanistic findings also provide further evidence of the involvement of biradical or carbene reactive intermediates in the reaction pathway of gas-phase pyrolysis of benzotriazoles.     

Pyrolysis of 1-methacryloyl-3-phenylthiourea and its polymer: rate and mechanism

The rates of thermal decomposition of 1-methacryloyl-3-phenylthiourea (1a), 1-methacryloyl-3-(4-nitrophenyl)thiourea (1b), 1-methacryloyl-3-(4-chloro phenyl)thiourea (1c), 1-methacryloyl-3-(4-methylphenyl)thiourea (1d), 1-methacryloyl-3-(4-methoxyphenyl)thiourea (1e), poly-1-methacryloyl-3-phenylthiourea (2) and 1-acryloyl-3-phenylthiourea (3) have been measured between 390 and 465 K. The reactions were homogeneous and unimolecular with log A = 11.48, 11.48, 11.81, 11.43, 11.11, 11.21 and 11.87s⁻¹ and E_a = 119.7, 111.93, 120.07, 121.94, 120.84, 124.64 and 122.68 kJ mol⁻¹, respectively. Product analysis was used to outline feasible pathways for the elimination reaction of the compounds under study.     

A determination of the lowest frequency of an unconstrained discrete system

A simple approximation, with allowance for rigid body motion, is presented for the lowest non-zero frequency of a discrete system. The procedure is an extension and modification of that previously used to obtain a bound formula [1]. Illustrative examples and comparisons with known results are presented.     

Characteristics of selenium in australian marine biota

The occurrence, distribution and speciation of selenium in Australian marine biota is discussed. Biochemical pathways for the accumulation of selenium by marine organisms are also postulated. Comparison of the levels of selenium in macroalgae, fish, crustaceans and molluscs indicates that preferential accumulation of selenium by particular taxa does not occur. Phaeophyta have significantly lower selenium concentrations than Rhodophyta and Chlorophyta. Fish have lower selenium contents in muscle tissues than molluscs and crustaceans. Marine animals with different dietary intake (planktonic vs herbivorous vs carnivorous) are not observed to have significantly different levels of selenium (P>0.05). Selenium in all the organisms studied was predominantly associated with free amino-acids or protein residues and was not present as characterizable inorganic selenium species (SeO₃^2?, SeO₄^2?). These results indicate that selenium is probably only incorporated into biota for specific biochemical purposes with any exces selenium being excreted or eliminated.     

Perturbation of normally solvable linear relations in paracomplete spaces

In this paper we investigate the stability of the index, the nullity and the deficiency of normally solvable linear relations in paracomplete spaces under perturbation by strictly singular and T-strictly singular linear relations. This study led us to generalize some well-known results for operators and extend some results of small perturbation of normally solvable linear relations given by T. Alvarez (2012) [3].