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Fluorous solid-phase extraction (FSPE) has been employed to isolate target compounds from complex chemical or biological samples in many research areas. However, the lack of efficient and economical available perfluorinated materials impeded its development. In this study, we present a novel nanographite fluoride-based fluorous solid-phase extraction (GF-FSPE) as a replacement of commercially available cartridge-based FSPE, which showed remarkable selectivity, low LOD, high post enrichment recovery, and large enrichment capacity. To demonstrate the potency of GF-FSPE, it was designed and successfully applied to isolate cysteine-containing peptide subsets from complex protein samples to improve the proteome coverage. Additionally, since graphite fluoride was inexpensive and highly commercialized, this study was expected to promote the popularization of FSPE in both chemical and biological separations as well as encourage the synthesis and broaden the application of highly fluorinated carbon fluoride in material science. [ABSTRACT FROM AUTHOR]

The behavior of n-Si(111) photoanodes covered by monolayer sheets of fluorinated graphene (F-Gr) was investigated under a range of chemical and electrochemical conditions. The electrochemical behavior of n-Si/F-Gr and np+-Si/F-Gr photoanodes was compared to hydride-terminated n-Si (n-Si−H) and np+-Si−H electrodes in contact with aqueous Fe(CN)63-/4- and Br2/HBr electrolytes as well as in contact with a series of outer-sphere, one-electron redox couples in nonaqueous electrolytes. Illuminated n-Si/F-Gr and np+-Si/F-Gr electrodes in contact with an aqueous K3(Fe(CN)6/K4(Fe(CN)6 solutions exhibited stable short-circuit photocurrent densities of ∼10 mA cm-2 for 100,000 s (>24 h), in comparison to bare Si electrodes, which yielded nearly a complete photocurrent decay over ∼100 s. X-ray photoelectron spectra collected before and after exposure to aqueous anodic conditions showed that oxide formation at the Si surface was significantly inhibited for Si electrodes coated with F-Gr relative to bare Si electrodes exposed to the same conditions. The variation of the open-circuit potential for n-Si/F-Gr in contact with a series of nonaqueous electrolytes of varying reduction potential indicated that the n-Si/F-Gr did not form a buried junction with respect to the solution contact. Further, illuminated n-Si/F−Gr electrodes in contact with Br2/HBr(aq) were significantly more electrochemically stable than n-Si−H electrodes, and n-Si/F−Gr electrodes coupled to a Pt catalyst exhibited ideal regenerative cell efficiencies of up to 5% for the oxidation of Br- to Br2. [ABSTRACT FROM AUTHOR]

The crossed molecular beam reactionsof dicarbon, C2(X1Σg+, a3Πu), with propene (C3H6; X1A′) and with the partially deuteratedD3 counterparts (CD3CHCH2, CH3CDCD2) were conducted at collision energies of about 21 kJ mol–1under single collision conditions. The experimentaldata were combined with ab initio and statistical (RRKM) calculationsto reveal the underlying reaction mechanisms. Both on the singletand triplet surfaces, the reactions involve indirect scattering dynamicsand are initiated by the addition of the dicarbon reactant to thecarbon–carbon double bond of propene. These initial additioncomplexes rearrange via multiple isomerization steps leading ultimatelyvia atomic hydrogen elimination from the former methyland vinylgroups to the formation of 1-vinylpropargyland 3-vinylpropargyl. Both triplet and singlet methylbutatriene specieswere identified as important reaction intermediates. On the singletsurface, the unimolecular decomposition of the reaction intermediateswas found to be barrier-less, whereas on the triplet surface, tightexit transition states were involved. In combustion flames, both radicalscan undergo a hydrogen-atom assisted isomerization leading ultimatelyto the thermodynamically most stable cyclopentadienyl isomer. Alternatively,in a third body process, a subsequent reaction of 1-vinylpropargylor 3-vinylpropargyl radicals with the propargyl radical might yieldto the formation of styrene (C6H5C2H3) in an entrance barrier-lessreactionunder combustion-like conditions. This presents a strong alternativeto the formation of styrene via the reaction of phenyl radicals withethylene, which is affiliated with an entrance barrier of about 10kJ mol–1. [ABSTRACT FROM AUTHOR]

Scaling caused by Na2CO3−Na2SO4double salts constitutes a severe problem in black liquor evaporators. The ability to predict the solubility and solid-phase composition of these species would be conclusive in minimizing the adverse effects of scaling. Experimental solubility data for (sodium sulfate) dicarbonate, a carbonate-rich double salt identified in Na2CO3−Na2SO4precipitates, were generated and used for fitting an empirical solubility model. A thermodynamically based approach for predicting the solubility and solid-phase composition, previously used for burkeite precipitates, was applied to solid solutions of dicarbonate. [ABSTRACT FROM AUTHOR]

The detailed geometrical structures of zigzag and armchair type single-walled carbon nanotubes (SWCNTs) with infinite tubular length were investigated using localized Gaussian type orbital−periodic boundary condition−density functional theory (LGTO−PBC−DFT) method. The structures of (n,0) zigzag SWCNTs were optimized for n5−21, (n, n) armchair SWCNTs for n3−12. For comparison, the optimized geometry of a two-dimensional graphite sheet was also calculated. It was found that the optimized structures of the SWCNTs showed two C−C bond lengths that decrease with an increase in the tubular diameter. More specifically, the two bond lengths converged with those found in the two-dimensional graphite sheet. We also found a degeneracy in the highest occupied crystal orbitals if identical bond lengths were employed for the zigzag SWCNTs and the two-dimensional graphite sheet. This implies that the two different bond lengths found in the zigzag SWCNTs and the two-dimensional graphite sheet are probably due to the Jahn−Teller effect. The armchair SWCNTs show two slightly different bond lengths if the diameter is less than 12 Å; otherwise they are almost identical, approaching the longer bond length of the two-dimensional graphite sheet. This can be due to the fact that the armchair SWCNTs do not have degeneracy in occupied crystal orbitals for identical C−C bond lengths. The crossing point of the conducting and valence bands of each armchair SWCNT were also calculated and show a diameter dependence in which the deviation from 2/3a decreases as diameter increases. [ABSTRACT FROM AUTHOR]

Quantum effects in the scattering and desorption process of a water molecule from a graphite surface are investigated using the linearized path integral model. The graphite surface is quantized rigorously using the fully quantum many-body Wigner transform of the surface Boltzmann operator, while the water molecule is treated as rigid. Classical dynamics with these quantized initial conditions show that quantizing the surface at 100 and 300 K results in markedly different results, compared to a fully classical analysis. The trapping probability (defined as the probability of multiple encounters with the surface) is not sensitive to the choice of dynamical treatment, but the residence time on the surface is much shorter in the quantum case. At 300 K the transiently trapped molecules desorb from the surface with a rate constant which is 60−70% larger than the corresponding classical value. Lowering the surface temperature to 100 K decreases the quantum rate constant by approximately a factor of 3 while all trapped molecules stick to the surface in the classical case. The stability of the quantum initial state for the highly anisotropic graphite crystal is discussed in detail as well as the dynamical consequences of energy redistribution during the scattering process. The graphite surface application demonstrates that the Boltzmann operator Wigner transform for a system with 900 degrees of freedom can be obtained by the so-called gradient implementation Poulsen et al. J. Chem. Theory Comput.2006, 2, 1482 of the underlying Feynman−Kleinert effective frequency theory, an implementation that only requires a force and potential routine for the system at hand, and hence is applicable to any molecule−surface collision problem. [ABSTRACT FROM AUTHOR]

The chemical dynamics to synthesize the 2,4-pentadiynyl-1 radical, HCCCCCH2(X2B1), via the neutral−neutral reaction of dicarbon with methylacetylene, was examined in a crossed molecular beams experiment at a collision energy of 37.6 kJ mol-1. The laboratory angular distribution and time-of-flight spectra of the 2,4-pentadiynyl-1 radical and its fragmentation patterns were recorded at m/z = 63−60 and m/z = 51−48. Our findings suggest that the reaction dynamics are indirect and dictated by an initial attack of the dicarbon molecule to the π electron density of the methylacetylene molecule to form cyclic collision complexes. The latter ultimately rearranged via ring opening to methyldiacetylene, CH3−C≡C−C≡C−H. This structure decomposed via atomic hydrogen emission to the 2,4-pentadiynyl-1 radical; here, the hydrogen atom was found to be emitted almost parallel to the total angular momentum as suggested by the experimentally observed sideways scattering. The overall reaction was strongly exoergic by 182 ± 10 kJ mol-1. The identification of the resonance-stabilized free 2,4-pentadiynyl-1 radical represents a solid background for the title reaction to be included into more refined reaction networks modeling the chemistry of circumstellar envelopes and also of sooting combustion flames. [ABSTRACT FROM AUTHOR]

The thermal decomposition of fluorinated single-walled carbon nanotubes (F−SWNTs), known to result in pristine SWNTs, has been investigated by freezing the gaseous products formed at temperatures between 50 and 500 °C under high vacuum in an argon matrix at 10−20 K and analyzing the trapped species by IR spectroscopy. The major products of F−SWNT decomposition are carbonyl fluoride (COF2) below 300 °C and CF4 above 300 °C. For comparison, graphite fluoride is stable thermally up to 300 °C under these conditions, and the major gas-phase species at temperatures below 500 °C are CF4 and the CF3 radical. F−SWNTs are thermally less stable than graphite fluoride, and etching of the nanotubes is observed at lower thermolysis temperatures. [ABSTRACT FROM AUTHOR]

We present a method for performing polymerase chain reaction (PCR) using isolated droplets flowing in an immiscible fluorinated solvent system. Thanks to an optimized control of interfacial properties, we could achieve in this capillary-based system reproducible amplification factors, without any detectable contamination between neighboring droplets. The system is readily amenable to further miniaturization and automation and serves as the first step toward a clinically viable, high-throughput, quantitative continuous flow PCR apparatus. [ABSTRACT FROM AUTHOR]

Analyzes solid-state and solution photophysical properties of a platinum(II) biphenyl dicarbonyl complex. Methods and materials used in the study; Statistics on physical measurements; Information on absorption spectra.

Fluorinated graphite (CF X) was alkylated reductively to yield functionalized graphite platelets comprised of six to 23 graphene sheets. A free radical mechanism involving a single electron transfer was proposed. The higher level of functionalization that resulted from the fluorinated substrate led to materials that exhibited an enhanced solubility in organic solvents. [ABSTRACT FROM AUTHOR]