A Wall Effect in the Photothermal Beam Deflection Response of Infrared-Absorbing Gases

FTIR photothermal beam deflection (PBD) spectroscopy was used to record PBD spectra of IR-absorbing gases in presence of IR-absorbing and non-absorbing solids. The presence of the solid, IR-absorbing or not, causes asymmetry at the juncture of the IR and probe laser     

Infrared Observation of the Effects of Aqueous Oxidizing Agents on the Functional Groups on Carbon Surfaces

FTIR photothermal beam deflection spectroscopy (PBDS) was used to record infrared spectra of medium-temperature carbons before and after they had been subjected to treatments with aqueous HNO₃ or H₂O₂ solution. Changes in the functional groups present on the carbon surfaces can be clearly observed.     

Expanding the Topological Landscape by a G-Column Flip of a Parallel G-Quadruplex

Canonical G-quadruplexes can adopt a variety of different topologies depending on the arrangement of propeller, lateral, or diagonal loops connecting the four G-columns. A novel intramolecular G-quadruplex structure is derived through inversion of the last G-tract of a three-layered parallel fold, associated with the transition of a single propeller into a lateral loop. The resulting (3+1) hybrid fold features three syn⋅anti⋅anti⋅anti G-tetrads with a 3’-terminal all-syn G-column. Although the ability of forming a duplex stem-loop between G-tracts seems beneficial for a propeller-to-lateral loop rearrangement, unmodified G-rich sequences resist folding into the new (3+1) topology. However, refolding can be driven by the incorporation of syn-favoring guanosine analogues into positions of the fourth G-stretch. The presented hybrid-type G-quadruplex structure as determined by NMR spectroscopy may provide for an additional scaffold in quadruplex-based technologies.     

Electrical Conduction Mechanisms of MxPS3, M1−xM'xPS3 and their Intercalation Compounds

Abstract

In the M_xPS₃ and M_1?xM'_xPS₃ systems, the P₂S₆ cluster contributes to the poor electrical conductivity for the compounds in which the energy level of the metal 3d orbital is deeper than those of the P, S 3p orbitals. For the compounds in which metal 3d orbital is closed to P and S 3p orbitals and has mixed valency, the induced mixed valency of P₂S₆, cluster and/or hopping mechanism contribute to the electrical conductivity. In the organic electron donor intercalation into M_xPS₃ and M_1?xM'_xPS₃ compounds, the new intercalation reaction is discovered, in which formation of tris-complexes of metal ions with guest molecules occurs in the host interlayer.     

Synthesis,Crystal Structure,and Characterization of Na7Cu4(AsO4)5

Abstract

Sodium copper (II) arsenate Na₇Cu₄(AsO₄)₅ has been grown by conventional high-temperature, solid-state methods in molten-salt media. It was characterized by single crystal X-ray diffraction (XRD), thermal analysis (DTA–TGA), scanning electron microscopy (SEM), semiquantitative energy dispersive spectroscopy analysis (EDS), and vibrational spectroscopy. Na₇Cu₄(AsO₄)₅ exhibits a three-dimensional framework built up of CuO₅, CuO₄, and AsO₄ polyhedra, with intersecting channels in which the Na⁺ cations are located. The three-dimensional cohesion of the framework results from Cu–O–As bridges. CuO₅ and CuO₄ polyhedra are elongated due to the Jahn–Teller effect, whereas AsO₄ tetrahedra are almost regular. This new structural model is validated by the charge distribution (CD) analysis. The infrared and Raman spectra confirmed the presence of AsO₄ tetrahedra.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional tables and figures.]     

Structure-Directing Roles of Organic Molecules in the Formation of Aluminosilicate and Aluminophosphate Molecular Sieves Revealed by 2D 1H DQ-SQ NMR Spectroscopy

Understanding of crystallization mechanisms of molecular sieves is driven by the broad range of usefulness and unique properties they possess. It is still difficult to obtain information related to the crystallization mechanism of molecular sieves, partly because the materials are generally prepared under hydrothermal conditions and the whole reaction happens in the “black box” autoclave. In this work, 2D ¹H DQ-SQ NMR results clearly demonstrate that it is not only the electrostatic interactions between organic structure-directing agents (OSDAs) and the framework, but also the correlation among OSDAs playing the dominant structural directing roles during the crystallization process. Our fundamental understanding of the crystallization mechanism of molecular sieves could be of great value to design and synthesize new molecular sieves with desirable structural properties.     

Structure Analysis of Needle-like Copper Tantalum Trisulfide Crystals by XPS and Raman Spectroscopy

High-quality needle-like CuTaS3 single crystals have been synthesized through a chemical vapor transport(CVT)process.Crystallographic data show the special double chains of edge-sharing TaS6 octahedra....