Synthesis and photochemical properties of 3,6-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-9<Emphasis Type="Italic">H</Emphasis>-carbazole derivatives

Method of synthesis has been developed for a series of 3,6-di-tert-butyl-9H-carbazole derivatives and their photochemical properties have been investigated. The dependence of the Steglich esterification reaction on the nature of the catalyst was studied. The synthesized compounds show fluorescent emission in the range 400–600 nm with a high quantum yield.     

Lead,cadmium, and arsenic in commercial algae of the Sea of Japan

The concentrations of toxic elements (arsenic, cadmium, lead) in commercial algae Saccharina japonica and Ahnfeltia tobuchiensis from different habitats of the Sea of Japan have been determined. Bioaccumulation of heavy metals has been analyzed with respect to the habitat and growth conditions. The lead content of Sascharina japonica from all habitats and arsenic content of the same alga species from the Ol’ga Bay, Kievka Bay, and Tatar Strait have been found to exceed maximum permissible levels. Increased lead concentrations have been detected in Ahnfeltia tobuchiensis. Samples of Ahnfeltia tobuchiensis collected from the bottom layer contain more toxic elements than those from the upper layer.     

Advances in the synthesis of 7-(3-cyclopentyloxy-4-methoxyphenyl)-hexahydro-3<Emphasis Type="Italic">H</Emphasis>-pyrrolizin-3-one (Pyrromilast)–a promising agent for treatment of chronic obstructive pulmonary disease

The review summarizes the known approaches to diastereo- and enantioselective synthesis of 7-(3-cyclopentyloxy-4-methoxyphenyl)hexahydro-3H-pyrrolizin-3-one (Pyrromilast), a highly active inhibitor of subtype 4B phosphodiesterase and a promising agent for treatment of chronic obstructive pulmonary disease.     

Quantum chemical studies of azoles 4. A novel elimination–addition mechanism of tetrazole and 1,2,4-triazole electrophilic substitution

Thermodynamic parameters of the addition–elimination and elimination–addition electrophilic substitution reactions of 1H-tetrazole and 1,2,4-1H-triazole obtained from DFT B3LYP/ 6-31G(d,p) quantum chemical calculations with proton as model electrophile are compared. According to calculations, the elimination–addition reactions can proceed without preliminary formation of N-protonated azolium salts.     

Alkylation of toluene with dichloromethane in the presence of triisobutylaluminum and perfluorophenylborates

¹H NMR method showed that in systems based on triisobutylaluminum (TIBA) and triphenylcyclopropenylium [Ph₃C₃]⁺[B(C₆F₅)₄]–(CPB) or triphenylmethylium [Ph₃C]⁺[B(C₆F₅)₄]–(TB) perfluorophenylborates in a toluene–dichloromethane mixture the Friedel–Crafts process occurs with the formation of ditolylmethane (DTM) accompanied by the complete decomposition of TIBA to form isobutane. ¹⁹F NMR spectroscopy showed that the [B(C₆F₅)₄]–anion decomposes in the systems to form B(C₆F₅)₃ and HC₆F₅. The short-living [AlBu₂ ⁱ]+ cation formed in the reaction of perfluorophenylborates with TIBA is assumed to be the species initiating the process. It has been shown that CPB is less reactive than TB. The addition of a stoichiometric amount of Ph₂CCpFluHfMe₂ exerts no effect on the process with the CPB-containing system but inhibits the reaction in the case of TB.     

Chalcogenation of 1,4-dichlorobut-2-yne with organic dichalcogenides in the system hydrazine hydrate–KOH

A reaction of organic dichalcogenides R₂Y₂ (R = Ph, Bn, Pr; Y = S, Se) with 1,4-dichlorobut-2-yne in the system hydrazine hydrate–KOH leads to four principal products: 1,4-bis(organylchalcogenyl)but-2-ynes, 1-organylchalcogenylbut-1-en-3-ynes, 4-organylchalcogenylbut-1-en-3-ynes, and 3(5)-methylpyrazole. The selectivity of the formation of individual products is determined by the ratio of the substrates used and the reaction temperature. A plausible mechanism of chalcogenation considered in the work agrees with the effect of the nature of chalcogene atoms and organic substituents R on stability of intermediates and products. The stabilization of carbanions by α chalcogene-containing groups corresponds to the following order: PhS > PhSe > BnS > BnSe > PrS.     

Interaction of amorphous and crystalline nickel nanoparticles with hydrogen

Nickel nanoparticles were deposited on the surface of highly oriented pyrolytical graphite by laser electrodispersion and precipitation from a solution of reverse micelles. The particles were studied using scanning tunneling microscopy and spectroscopy as well as Auger spectroscopy. The elemental composition of the nanoparticles and specific features of the electronic structure of their surface were determined. Adsorption of molecular hydrogen was also studied.     

Sunlight curable hybrid organic–inorganic methacrylic‐based coatings: analysis of the cure mechanism and functional properties

An experimental ultraviolet (UV) polymerizable hybrid organic–inorganic protective coating, mainly intended for the surface protection of porous calcareous stone substrates, has been recently proposed and patented. The hybrid product evidenced an extraordinary hydrophobicity character, able to guarantee a high protection of the stone against water actions, as well as a high traspirability. Furthermore, it is able to equal the performance of commercial available coatings, with the important adjunctive advantage to be free solvent. The application of this product involves the use of a “dual curing” treatment, necessary to harden the coating applied on the substrate, representing this latter a technological limit. The dual curing treatment consists of 6 hr of exposure to a UV‐lamp plus 1 hr at 140°C in oven. In order to avoid this procedure, not easy to realize in situ, two different modifications of the composition of the hybrid product are proposed in this paper. The first one allows the photopolymerization of the hybrid coating only by sunlight exposure. The second one, even though requiring a UV exposure to photo‐polymerize the coating, does not need the subsequent thermal treatment at 140°C. Several experimental characterizations were performed on the newly developed hybrid products, in order to select an optimal composition for the formulations. The selected innovative products were, finally, applied on a calcareous stone substrate, typical of Apulia Region (Pietra Leccese, PL). Both coatings exhibit excellent water‐repellent action and a slight variation of the natural stone color. Copyright © 2014 John Wiley & Sons, Ltd.