Thermophoretic deposition of palladium aerosol nanoparticles for electroless micropatterning of copper

A method for catalytic activation was introduced by producing palladium aerosol nanoparticles via spark generation and then thermophoretically depositing the particles onto a flexible polyimide substrate through a hole in pattern mask, resulting in a line (24 μm in width) and a square (136 μm × 136 μm) patterns. After annealing, the catalytically activated substrate was placed into a solution for electroless copper deposition. Finally, copper micropatterns of a line (35 μm in width) and a square (165 μm × 165 μm) were formed only on the activated regions of the substrate. Both patterns had the height of 1.6 μm.     

N-heterocyclic carbene-catalyzed silyl enol ether formation

N-Heterocyclic carbenes (NHCs) were found to catalyze the silyl transfer from trialkylsilyl ketene acetals to ketones. In the presence of a catalytic amount of NHC 3 (IAd, 0.1 to 5 mol %), a series of enolizable ketones as well as cyclohexanecarboxaldehyde were efficiently converted into the corresponding silyl enol ethers at 23 degrees C in THF.     

Copper-catalyzed aerobic intramolecular carbo- and amino-oxygenation of alkynes for synthesis of azaheterocycles

A synthetic method of highly substituted quinolines has been developed from N-(2-alkynylaryl)enamine carboxylates under Cu-catalyzed aerobic conditions via intramolecular carbo-oxygenation of alkynes. This strategy was further applied for N-alkynylamidines for amino-oxygenation of alkynes, leading to imidazole and quinazoline derivatives.     

Efficient chiral monophosphorus ligands for asymmetric Suzuki-Miyaura coupling reactions

A series of novel P-chiral monophosphorus ligands exhibit efficiency in asymmetric Suzuki-Miyaura coupling reactions, enabling the construction of an array of chiral biaryl products in high yields and excellent enantioselectivities (up to 96% ee) under mild conditions. The carbonyl-benzooxazolidinone moiety in these chiral biaryl products allows facile derivatization for further synthetic applications. A computational study has revealed that a π-π interaction between the two coupling partners can enhance the enantioselectivity of the coupling reaction.     

Carbon-boron bond cross-coupling reaction catalyzed by -PPh(2) containing palladium-indolylphosphine complexes

This study describes the application of indolylphosphine ligands with a diphenylphosphino moiety to the palladium-catalyzed borylation of aryl chlorides. The combination of palladium metal precursor with PPh(2)-Andole-phos, which comprises an inexpensive -PPh(2) group, provides highly effective catalysts for the borylation of aryl chlorides. A range of functional groups such as -CN, -NO(2), -CHO, -COMe, -COOMe, and -CF(3) was compatible, and the catalyst loading down to 0.025 mol % of Pd can be achieved. The Pd/PPh(2)-Andole-phos system is able to catalyze both borylation reaction and Suzuki-Miyaura coupling reaction in a one-pot sequential manner for the direct synthesis of biaryl compounds in excellent yields.     

Amphiphilic poly(phenyleneethynylene)s can mimic antimicrobial peptide membrane disordering effect by membrane insertion

Antimicrobial peptides (AMPs) are a class of peptides that are innate to various organisms and function as a defense agent against harmful microorganisms by means of membrane disordering. Characteristic chemical and structural properties of AMPs allow selective interaction and subsequent disruption of invaders' cell membranes. Polymers based on m-phenylene ethynylenes (mPE) were designed and synthesized to mimic the amphiphilic, cationic, and rigid structure of AMPs and were found to be good mimics of AMPs in terms of their high potency toward microbes and low hemolytic activities. Using a Langmuir monolayer insertion assay, two mPEs are found to readily insert into anionic model bacterial membranes but to differ in the degree of selectivity between bacterial and mammalian erythrocyte model membranes. Comparison of grazing incidence X-ray diffraction (GIXD) data before and after the insertion of mPE clearly indicates that the insertion of mPE disrupts lipid packing, altering the tilt of the lipid tail. X-ray reflectivity (XR) measurements of the lipid/mPE system demonstrate that mPE molecules insert through the headgroup region and partially into the tail group region, thus accounting for the observed disordering of tail packing. This study demonstrates that mPEs can mimic AMP's membrane disordering.     

Synthesis and spectroscopic and magnetic characterization of tris(3,5-dimethylpyrazol-1-yl)borate iron tricyanide building blocks, a cluster, and a one-dimensional chain of squares

The synthesis and spectroscopic and magnetic characterization of several hydridotris(3,5-dimethylpyrazol-1yl)borate (Tp*) iron(II) and iron(III) tricyanide complexes, a rectangular cluster, and a one-dimensional chain of squares are described. Treatment of [NEt4][(Tp*)Fe(III)(CN)3] (3) with manganese(II) triflate in dimethylformamide (DMF) affords rectangular clusters (6, {[(Tp)Fe(CN)2(mu-CN)Mn(DMF)4]2[OTf]2}.2DMF), while tosylate salts afford one-dimensional networks (5, {Mn(II)(DMF)2(mu-OTs)(mu-NC)2(NC)Fe(III)(Tp*)}n) containing embedded [(Tp*)2Fe(III)2Mn(II)2(CN)6]2+ clusters via in situ trapping; the cluster and network crystallize in the monoclinic (6, P2(1)/n) and triclinic (5, P1) space groups, respectively. The 1-D network (5) appears to be derived from {cis-(mu-O3SC6H4Me)2Mn(II)(DMF)4}n (4, P2(1)/n), which is obtained via crystallization of Mn(OTs)2 from DMF/Et2O mixtures. For 4, magnetic studies indicate that the Mn(II) centers are magnetically isolated, with calculated J, g, and theta constants of 6.7 x 10(-3) cm(-1), 2.03, and -0.52 K. Additional magnetic studies of 5 and 6 indicate that the [(Tp*)Fe(III)(CN)3]- centers are highly anisotropic (g = 2.9) and are antiferromagnetically coupled to adjacent Mn(II) centers. For 5 and 6, fitting of the chiT vs T data via the Curie-Weiss expression affords Curie (6.25 and 10.8 cm(3) K mol(-1)) and Weiss (-14.37 and -8.80 K) constants that are consistent with antiferromagnetically coupled low-spin Fe(III) and high-spin Mn(II) centers; least-squares fitting of the chiT vs T data using molecular field theory affords g(avg.), J1, J2, and J' values of 2.25, -1.72, -0.58, and -0.12 cm(-1) for 5. Overall, bridging tosylates appear to be poor communicators of spin information. For 6, the g, J1, and J2 (2.15, -2.02, and -0.78 cm(-1)) values were obtained via least-squares fitting of the chiT vs T data using an expression derived using the Kambe vector coupling method; simulations of the data via MAGPACK afford g(avg.) and J(iso) values of 2.1 and -2.1 cm(-1).     

Coordination complexes with cis-TCNE radical anion ligands. models of M[TCNE]2 magnets

The synthesis and characterization of two manganese(II) complexes formally each featuring two cis-tetracyanoethylenide radical anionic ligands (TCNE*/-) are reported. In each case, tris(pyrazol-1-ylmethyl)amine serves as a capping ligand, blocking three facial coordination sites. Crystal structures show that the two TCNE anions in each molecule exhibit an intramolecular stacking interaction that forms what can be considered a coordinated (TCNE2)2- moiety. These molecules are presumed to be structural models of some of the local bonding in the family of amorphous, ferrimagnetic, M[TCNE]2.y(solvent) coordination polymer magnets. Magnetic measurements indicate that the (TCNE2)2- bridge is diamagnetic and not a good mediator of magnetic exchange, a result that might explain the observed lower ordering temperatures in some of the polymer magnets.     

Lipid lateral mobility and membrane phase structure modulation by protein binding

Using a combination of fluorescence correlation and infrared absorption spectroscopies, we characterize lipid lateral diffusion and membrane phase structure as a function of protein binding to the membrane surface. In a supported membrane configuration, cholera toxin binding to the pentasaccharaide headgroup of membrane-incorporated GM1 lipid alters the long-range lateral diffusion of fluorescently labeled probe lipids, which are not involved in the binding interaction. This effect is prominently amplified near the gel-fluid transition temperature, Tm, of the majority lipid component. At temperatures near Tm, large changes in probe lipid diffusion are measured at average protein coverage densities as low as 0.02 area fraction. Spectral shifts of the methylene symmetric and asymmetric stretching modes in the lipid acyl chain confirm that protein binding alters the fraction of lipid in the gel phase.