Characterization of gem-difluoropropargyl synthons through HF loss from protonated molecules in methane chemical ionization mass spectra

Electron impact and methane chemical ionization mass spectra were obtained following gas chromatography/mass spectrometry for several gem-difluoropropargyl compounds, which had been synthesized as potential intermediates for synthesis of gem-difluoromethylene-containing C-3 acetylenes. EI spectra were variable with respect to the presentation of molecular ions, depending on substituent functional groups present. Methane-CI spectra were characterized by loss of 19 mass units from molecular weight with all compounds examined. These [M − 19]⁺ ions often presented as base peaks of the CI spectra, and were more reliably present and abundant than [M + 1]⁺ ions for these compounds. These ions could have been formed by elimination of HF from the protonated molecules under conditions of methane chemical ionization.     

INDUCED DEACTIVATION OF NAPHTHALENE TRIPLETS BY CIS-PIPERYLENE

Abstract— Interaction of naphthalene triplets with trans -piperylene leads to triplet energy transfer with unit efficiency. When cis -piperylene is used as a quencher of naphthalene triplets, the efficiency of triplet energy transfer is found to be 0–76 ± 004. The rest of the quenching encounters in this case lead to deactivation of naphthalene triplets, without energy transfer.     

Controlling cell attachment selectively onto biological polymer-colloid templates using polymer-on-polymer stamping

A new patterning approach using polymer-on-polymer stamping (POPS) has been developed to fabricate polymer-colloid templates for controlling selective cell attachment. In this paper, a polyamine surface patterned onto a poly(acrylic acid)/poly(allylamine hydrochloride) (PAA/PAH) cell resistant multilayer platform serves as a template for the deposition of close- or loose-packed colloidal particles. Peptides containing the RGD adhesion sequence were used to modify the PAH/colloid surface for specific cell attachment. Cell behavior was studied by varying colloidal packing array density, pattern geometry, and surface chemistry. It was found that loose-packed RGD-modified colloidal arrays enhance cell adhesion, as observed through the development of focal adhesion contacts and orientation of actin stress fibers, but close-packed colloidal arrays induce a rounded and nonadhesive cell morphology and yield a smaller number of attached cells. On loose-packed arrays, cells adjust their shapes to the pattern geometry when the stripe width is smaller than 50 microm and increase their extent of attachment when the concentration of surface RGD peptides is increased. This new biomaterials system allows the examination of cell behavior as a function of RGD surface distribution on the molecular to micrometer scale and reveals cellular response to different surface roughnesses.     

X-ray photoelectron spectroscopic evidence of distinctive underpotential deposition states of Ag and Cu on Pt substrates

The underpotential deposition (u.p.d.) of copper and silver ions on platinum electrodes has been studied using X-ray photoelectron spectroscopy (x.p.s.). A significant chemical shift of the x.p.s. binding energies of the u.p.d. copper and silver atoms relative to bulk copper and silver metal is obtained. Analogous spectral results are obtained for in situ vapor deposition of copper and silver atoms on clean platinum substrates which reveal the metallic nature of the u.p.d. species.     

Gårding's Theory of Hyperbolic Polynomials

This paper presents a simple, self‐contained account of Gårding's theory of hyperbolic polynomials, together with a recent convexity result of Bauschke‐Güler‐Lewis‐Sendov and an inequality of Gurvits. This account begins by establishing some new results. The first concerns the existence of a pointwise arrangement of the eigenvalues so that they become global real analytic functions. The second asserts that the associated “branches” are independent of the choice of hyperbolic direction. © 2013 Wiley Periodicals, Inc.     

Thermal Characterizations of Inorganic and Organometallic Polymers

This review emphasizes the breadth of metallic and metallic-like polymers evaluated as to thermal properties. Techniques usefully applied to particular systems are noted with the aim of suggesting their application to other systems.     

Low-lying energy levels of the FeH molecule

Multireference configuration interaction (MRCI) and complete active space second-order perturbation theory (CASPT2) calculations are performed on Fe₂ and Fe^? ₂. Although it is not possible to definitively identify the ground states of Fe₂ and Fe^? ₂, the calculations suggest that the ground state of Fe^? ₂ in ⁸Σ^? _u derived from 3d¹³4σ² _g4σ² _u and that the states observed in photodetachment are the ⁹Σ^? _g and ⁷Σ^? _g states with a 3d¹³4σ² _g4σ¹ _u occupation, but that the ground state of Fe₂ is ⁷Δ_u(3d¹⁴4σ² _g) and is not observed in the photo-detachment spectra.     

THE ISOMERIZATION OF 3-PHOSPHOLENS IN DEUTERIOCHLOROFORM

Abstract

Cis-1-alkyl (or aryl)-2,5-dimethyl-3-phospholens isomerize to the trans-isomers in deuteriochloroform and the isomerization is probably due to small quantities of phosgene in the solvent.