Nickel-catalyzed, cascade cycloadditions of 1-ethynyl-8-halonaphthalenes with nitriles: synthesis, structure, and physical properties of new pyrroloarenes.

The reaction of 1-ethynyl-8-halonaphthalenes 1 with nitriles in the presence of the catalytic system [NiBr(2)(dppe)]/Zn (dppe=1,2-bis(diphenylphosphino)ethane) is found to produce unusual pyrroloarenes 2. The carbon-nitrogen triple bond in nitrile is activated twice, and five new bonds are formed in a one-pot transformation, which causes a pyrrole and two six-membered rings to be generated simultaneously. The scope and limitations of this reaction are examined. Similarly, alkyl-bridged diynes also furnish the corresponding polycycles. Diaryl-substituted cycloadducts 2 (R(1)=Ar) are fluxional, because of the restriction in rotation of the aryl groups. The rotational barrier is studied by performing (1)H NMR experiments at various temperatures. The structures of several compounds are determined by X-ray crystallographic analysis. The photophysical and electrochemical properties of the pyrroloarenes are also investigated.

Palladium-catalyzed cycloisomerizations of diarylacetylenes: synthesis, structures, and physical properties of highly substituted naphthalenes and 8,8 a-dihydrocyclopenta[a]indenes.

Depending on the electronic properties of their substituents, the major products generated by palladium-catalyzed cycloisomerizations of diarylalkynes are either highly substituted 8,8a-dihydrocyclopenta[a]indenes 3 or naphthalenes 4. The structures of these compounds were verified by X-ray crystallographic analysis. Many functional groups tolerated the reaction conditions evaluated in this study. The isotope-labeled experiments indicated that added water has a critical role in forming both classes of compounds. The photophysical and electrochemical properties of cycloadducts 3 and their analogues were systematically studied and compared with computational predictions based on density functional theory. Dihydrocyclopenta[a]indenes 3 in either solid or liquid form display strong luminescence, whereas cyclopenta[a]indene 11 j is practically nonfluorescent. The functional groups directly attached to the backbone of compound 3 significantly influenced physical properties. The steric effect arising from the aryl substituents caused different luminescence phenomena, including aggregation-induced and -enhanced emission.

Synthesis, structures, and physical properties of benzo[k]fluoranthene-based linear acenes.

This work describes the syntheses, crystal structures, photophysical properties, and electro-chemical analyses of benzo[k]fluoranthene-based linear acenes, together with ab initio density functional theory computations on them. The molecules were prepared in generally moderate to good yields through Pd-catalyzed cycloadditions between 1,8-diethynylnaphthalene derivatives and aryl iodides. This protocol is simpler and more efficient than conventional methods. The scope and limitations of this reaction were examined. The structures of compounds 4hb, 15ac, 17ab, 19ac, and 24je were determined by X-ray analysis; they are either bent or twisted, rather than planar. The photophysical and electrochemical properties of these cycloadducts were also investigated and compared with computational predictions based on density functional theory.

1,3,4,6,7,9-Hexamethylbenzo[1,2-c:3,4-c':5,6-c'']trithiophene: a twisted heteroarene.

1,3,4,6,7,9-Hexamethylbenzo[1,2-c:3,4-c':5,6-c'']trithiophene (C-Me) was prepared by palladium-catalyzed methylations of the corresponding hexabromide C-Br. The twisted structure of C-Me has been confirmed by X-ray crystal analysis. The physical properties of twisted C-Me and planar benzo[1,2-c:3,4-c':5,6-c'']trithiophene (C-H) were studied and compared. Crystal structures are compared to computational structures determined using density functional theory, with both the M06-2X and B3PW91 functionals.

Formation of porous silver by electrochemical alloying/dealloying in a water-insensitive zinc chloride-1-ethyl-3-methyl imidazolium chloride ionic liquid.

This paper describes the formation of a porous silver surface by a convenient two-step process involving electrochemical formation of a binary silver-zinc alloy film on a silver surface followed by electrochemical etching of the zinc from the alloy. Both the deposition and the dealloying steps were performed in a single bath of low-temperature zinc chloride-1-ethyl-3-methylimidazolium chloride ionic liquid at temperatures below 150 degrees C without using any other corrosive acids or bases. The effects of the deposited zinc quantity, deposition potential, current, and temperature on the structures and morphologies of the porous silver film were examined. In comparison with conventional molecular electrolyte solutions, ionic liquids provide a more versatile environment for fabricating porous metals. Because the zinc(II) species consumed during the deposition step was recovered during the dealloying step, the ionic liquid is reusable.

Synthesis of a guanidine NHC complex and its application in borylation reactions.

Synthesis of guanidine-linked NHC can be achieved easily through reacting amino-NHC with carbodiimide. Subsequently, guanidine-NHC Ag and Cu complexes were isolated and fully characterized. These Cu complexes are found to be versatile catalysts for hydroboration, semihydrogenation and carboboration of alkynes in a highly stereo- and regioselective fashion.