Acta Crystallographica Section E 01/2010; DOI:10.1107/S1600536810025857/pv2302sup0.html
ABSTRACT In the title compound, C2H5N2+·BF4−, the cations and anions are connected via intermolecular N—H...F and C—H...F hydrogen bonds, forming a three-dimensional network.
- [show abstract] [hide abstract]
ABSTRACT: The fern-like 1D coordination polymer, [K(2-PTA)(H2O)]n (1), which is constructed by an inorganic skeleton chain [KO2]n with organic 2-PTA wings on both sides, has been synthesized and characterized by single crystal X-ray crystallography and dielectric constant (ε) measurement (2-PTA=2-(5-(pyridin-2-yl)-2H-tetrazol-2-yl) acetic acid). The ε of temperature dependence maintains unchanged, and ε of frequency dependence shows a significant decline, which is attributed to the highly ordered polarization mechanism.Inorganic Chemistry Communications - INORG CHEM COMMUN. 01/2009; 12(10):994-997.
Article: A short history of SHELX.[show abstract] [hide abstract]
ABSTRACT: An account is given of the development of the SHELX system of computer programs from SHELX-76 to the present day. In addition to identifying useful innovations that have come into general use through their implementation in SHELX, a critical analysis is presented of the less-successful features, missed opportunities and desirable improvements for future releases of the software. An attempt is made to understand how a program originally designed for photographic intensity data, punched cards and computers over 10000 times slower than an average modern personal computer has managed to survive for so long. SHELXL is the most widely used program for small-molecule refinement and SHELXS and SHELXD are often employed for structure solution despite the availability of objectively superior programs. SHELXL also finds a niche for the refinement of macromolecules against high-resolution or twinned data; SHELXPRO acts as an interface for macromolecular applications. SHELXC, SHELXD and SHELXE are proving useful for the experimental phasing of macromolecules, especially because they are fast and robust and so are often employed in pipelines for high-throughput phasing. This paper could serve as a general literature citation when one or more of the open-source SHELX programs (and the Bruker AXS version SHELXTL) are employed in the course of a crystal-structure determination.Acta Crystallographica Section A Foundations of Crystallography 02/2008; 64(Pt 1):112-22. · 2.24 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Optical conductivity measurements on the perovskite-related oxide CaCu3Ti4O12 provide a hint of the physics underlying the observed giant dielectric effect in this material. A low-frequency vibration displays anomalous behavior, implying that there is a redistribution of charge within the unit cell at low temperature. At infrared frequencies (terahertz), the value for the dielectric constant is approximately 80 at room temperature, which is far smaller than the value of approximately 10(5) obtained at lower radio frequencies (kilohertz). This discrepancy implies the presence of a strong absorption at very low frequencies due to dipole relaxation. At room temperature, the characteristic relaxation times are fast (less than or approximately 500 nanoseconds) but increase dramatically at low temperature, suggesting that the large change in dielectric constant may be due to a relaxor-like dynamical slowing down of dipolar fluctuations in nanosize domains.Science 08/2001; 293(5530):673-6. · 31.03 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.