Ethynylgold(I) complexes

Reactions between R₃PAuCl, NaOEt, and HCCR′ under mild conditions produce R₃PAuCCR′ in excellent yield. When R′ = H, a second step leading to the formation of R₃PAuCCAuPR₃ can take place. Exchange reactions of ethynyl for chloride between the ethynylgold complexes and HgCl₂, cis-[PtCl₂L₂cis-[PtCl₂(CO)L], and R₂″PAuCl have been monitored, revealing R₃PAuCCR′ to be useful alkynylating agents. In the reaction with cis-[PtCl₂(CO)L], the first substitution step is non-specific.     

Electrostrictive effects in non-polar perovskites

Polarization-related electrostrictive coefficients Q_h have been determined for relaxation dielectrics 0.856Sr TiO₃-0.144 Bi_2/3 TiO₃ and (K_3/4Bi_1/4) (Zn_1/6Nb_5/6)O₃, and for a simple non-polar perovskite BaZrO₃ by measuring the hydrostatic pressure dependence of the dielectric permittivity. Anomalous variation in the electrostrictive coefficient with temperature and frequency were observed in (K_3/4Bi_1/4) (Zn_1/6Nb_5/6)O₃ in the relaxation-temperature region. This behavior can be explained qualitatively with a simple model based on potential barriers separating alternative cation sites. The empirical rule noted previously for ferroelectric perovskites, that the electrostrictive Q coefficient increases with cation order from disordered, through simple and then ordered perovskites is confirmed again in non-polar perovskites.     

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Quantum mechanical approaches to structurally informed design

This review focuses on the application of molecular modeling and structure‐informed design (SID) to drug discovery. Routine utilization of quantum mechanical techniques allows generation of SID hypotheses, based on first principles. The authors introduce the concept of combining information from electrostatic potential surfaces and nonbonding orbitals to determine the nature and directionality of intermolecular interactions, particularly those that are infrequently exemplified in the protein data bank. © 2013 Wiley Periodicals, Inc.     

13C selective polarization and spin diffusion in a lipid bilayer-bound polypeptide by solid-state NMR.

While (15)N solid-state NMR has proven to be very advantageous for the development of structural biological methods, (13)C spectroscopy has increased sensitivity and spectral dispersion. However, large natural abundance signals and homonuclear dipolar interactions pose significant problems. Here we have used a pair of (13)C-labeled sites in a lipid-solubilized polypeptide to show the selective polarization can be used in combination with spin diffusion to achieve simplified spectra. Both unoriented and oriented samples have been used, with the latter providing a well-resolved homonuclear dipolar splitting.