A facile synthesis of polypyrrole nanotubes using a template-mediated vapor deposition polymerization and the conversion to carbon nanotubes

Polypyrrole (PPy) nanotubes with highly uniform surface and tunable wall thickness were fabricated by one-step vapor deposition polymerization (VDP) using anodic aluminium oxide (AAO) template membranes, and transformed into carbon nanotubes through a carbonization process.     

Reaction of γ-picoline N-oxide with ketenimines in the presence of organic acids: Preparation of α-acyloxyamides

A synthesis of a-acyloxyamides is described which utilizes the reaction of 7-picoline N-oxide and various organic acids with diphenylketene N-p-tolylimine.     

Phase separation behavior of epoxy resin modified with crosslinked rubber

Low molecular weight liquid rubber (ATBN = amine terminated butadiene acrylonitrile copolymer or CTBN = carboxyl terminated butadiene acrylonitrile copolymer)–DGEBA (diglycidyl ether of bisphenol A) blends indicated upper critical solution temperature (UCST) behavior. The phase separation behavior of the neat and crosslinked rubber (ATBN, CTBN)–epoxy blends was analyzed by a laser light scattering experiment. Lauryl peroxide (LPO) was employed to crosslink the rubber during the initial annealing stage. The onset point of the phase separation in the crosslinked ATBN–epoxy system occurred later than in the case of the neat ATBN–epoxy system. However, the onset point of the phase separation process started earlier in the case of the crosslinked CTBN–epoxy system. The domain correlation length of the crosslinked rubber-added system was smaller than that of the neat rubber-added system.     

Characterization of n-butyl acrylate centered triads in poly(n-butyl acrylate-co-carbon monoxide-co-ethylene) by isotopic labeling and two dimensional NMR

Poly(n-butylacrylate-co-carbon monoxide-co-ethylene) (polyEBC) samples prepared from 13C-labeled monomer, n-butyl acrylate, were characterized using two dimensional (2D) pulsed field gradient (PFG) 750 MHz NMR spectroscopy. To elucidate the complex structure of the terpolymer, 2D-1H/13C-heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond correlation (HMBC) experiments were conducted by selectively exciting the enhanced resonances in the spectra of two polymer samples, one polymer resulting from synthesis with 1-13C-n-butylacrylate monomer and a second polymer obtained from a synthesis with 2-13C-n-butylacrylate monomer. High-resolution 2D-NMR combined with 13C-labeling of the polymer greatly simplifies the 2D-NMR spectra, selectively enhances the weak peaks from low occurrence B-centered triad structures, and aids in their resonance assignments. In all experiments, the sample temperature was 120 degrees C, to ensure a homogeneous solution and sufficient molecular mobility. Electronic Supplementary Material: Supplementary material (1D 13C NMR spectra of the 13C-labeled and unlabeled polymers) is available in the online version of this article at http://dx.doi.org/100.1007/s00216-003-2402-3.     

Charge transfer and electron backdonation in metallofullerenes encapsulating NSc3

Orbital interaction analysis is employed to understand the complex charge transfer mechanism operative in endohedral metallofullerenes of composition NSc₃@C_n (n = 68, 78). This phenomenon combines substantial electron transfer from the core to the cage with electron backdonation, involving the interaction between the occupied orbitals of the negatively charged cage and the unoccupied d orbitals of the positively charged core. This electron backdonation differs fundamentally from conventional orbital hybridization, which takes place primarily between the HOMO of the metal core and the LUMO of the fullerene cage. These findings imply the pronounced stability of NSc₃@C_n (n = 68, 78), especially for NSc₃ encapsulated in the non-IPR C₆₈ enclosure, as experimentally established.     

Synthesis and reactivity of 1,2-bis(chlorodimethylgermyl)carborane and 1,2-bis(bromodimethylstannyl)carborane

The 1,2-bis(chlorogermyl)- (1) and 1,2-bis(bromostannyl)carborane (2) have been prepared by the reaction of dilithio-o-carborane with Me(2)GeCl(2) and Me(2)SnBr(2), respectively. Compounds 1 and 2 are found to be good precursors for the synthesis of a variety of cyclization compounds. The Wurtz-type coupling reaction of 1 and 2 using sodium metal afforded the four-membered digerma compound 3 and five-membered tristanna compound 4, respectively. The salt elimination reactions of 1 and 2 using Li(2)N(t)Bu and Li(2)PC(6)H(5) afforded the cyclic products [structure: see text]. The 1,2-bis(dimethylgermyl)carborane 9 and 1,2-bis(dimethylstannyl)carborane 10 were prepared by the reaction of 1 and 2 with sodium cyanoborohydride. The reactions of 9 and 10 with Pd(PPh(3))(4) afforded the bis(germyl)palladium 12 and bis(stannyl)palladium 13 complexes, respectively.     

Azido- or hydroxyl-capped half-cubanes containing Cp*Rh fragments: [Cp*3Rh3(mu-X)3(mu3-X)]2+ (X-=OH- or N3-)

Treatment of [Cp*Rh(H(2)O)(3)](OTf)(2) (1) with Me(3)SiNH-t-Bu in acetone gave a hydroxyl-capped half-cubane [Cp*(3)Rh(3)(mu-OH)(3)(mu(3)-OH)](OTf)(3)(t-BuNH(3)) (2). Slow diffusion of Me(3)SiN(3) in diethyl ether into compound in acetone produced an azido-capped half-cubane [Cp*(3)Rh(3)(mu-N(3))(3)(mu(3)-N(3))](OTf)(2) (3). On the other hand, treating 1 with Me(3)SiN(3) in acetone gave an azido-bridged, dinuclear rhodium(III) complex [Cp*Rh(mu-N(3))(OH(2))](2)(OTf)(2) (4). Complexes 2 and 3 represent the first azido- or hydroxyl-capped, incomplete cubane-type Rh clusters. Under appropriate conditions, complexes 2 and 3 could be converted to complex 4. The structures of all products were determined by X-ray diffraction.     

Association behavior of a nitrilotriacetic-acid-modified dye in a poly(vinyl alcohol) film containing Ni(II)-adsorbed gold nanoparticles.

The association behavior of the dyes 5(6)-carboxyfluorescein and nitrilotriacetic acid (NTA)-modified 5(6)-carboxyfluorescein (F-NTA) in a poly(vinyl alcohol) (PVA) film and in a PVA film containing metal nanoparticles is investigated. Well-dispersed gold nanoparticles (AuNps) and Ni(II)-adsorbed AuNps are formed in the PVA film using in situ photochemical fabrication method. 5(6)-carboxyfluorescein and F-NTA are doped into the films. The F-NTA forms an H-aggregate in the PVA film containing Ni(II)-adsorbed AuNps. It is suggested that the interaction between NTA and Ni(II) adsorbed on the AuNps promotes the formation of the H-aggregate.     

In situ Fe K-edge X-ray absorption fine structure of a nitrosyl adduct of iron phthalocyanine irreversibly adsorbed on a high area carbon electrode in an acidic electrolyte

Key aspects of the microenvironment surrounding the Fe center in the nitrosyl adduct of iron phthalocyanine, [Fe(Pc)(NO)], have been elucidated from the analysis of the Fe K-edge extended X-ray absorption fine structure (EXAFS) of the material adsorbed on the surface of a high area carbon electrode recorded in situ, in 0.5 M H(2)SO(4). Statistical best fits to the EXAFS data place the Fe center in a five-coordinated square pyramidal configuration shifted away from the Pc plane toward the axially bound NO bent at an angle of ca. 40 degrees with respect to the normal to the Pc plane. This environment is analogous to that of Fe in the nitrosyl adduct of crystalline [Fe(TPP)], where TPP = meso-tetraphenylporphyrinato(2-), determined from X-ray diffraction.     

Catalytic combustion of chlorobenzene over V2O5/TiO2 catalysts prepared by the precipitation-deposition method

Catalytic combustion of chlorobenzene over supported vanadium oxides has been investigated. TiO₂ was prepared by the sol-gel method from titanium isopropoxide. The supported vanadium oxide catalysts have been prepared by precipitation-deposition and impregnation method and characterized by XRD, FT-Raman and TPR. In the VO_x/TiO₂catalysts prepared using the impregnation method, when vanadium loading reaches 3 wt.%, the activity shows a maximum. However, in the VO_x/TiO₂catalysts prepared by precipitation-deposition, when vanadium loading reaches 7 wt.%, the activity shows a maximum. This result suggests that the precipitation-deposition can yield a higher metal loading on the support and a high dispersion compared to the impregnation method. This revised version was published online in August 2006 with corrections to the Cover Date.