Vapor-Phase Synthesis of ZIF-8 MOF Thick Film by Conversion of ZnO Nanorod Array.

ZIF-8 metal organic framework "micrometer-thick" films were constructed from ZnO precursor by a vapor-phase synthesis. The ZnO-to-ZIF-8 crystal transformation proceeded in the presence of 2-methylimidazole (Hmim) vapor. Continuous coatings of intergrown ZIF-8 crystals require control of a nucleation density. The dependence of ZnO crystal plane on the ZnO-to-ZIF-8 crystal transformation was investigated using four bulk ZnO single crystals: a-plane (11-20), c-plane (0001), m-plane (10-10), and r-plane (10-11). It was revealed that the m-plane (10-10) of ZnO is more effectively transformed into ZIF-8. In this work, highly oriented ZnO nanorod array film was used to provide the transport pathway of Hmim molecules and volume expansion space of ZnO-to-ZIF-8 crystal transformation for nucleation and crystal intergrowth. The high conversion of ZnO nanorod array into ZIF-8 in a short time could be achieved because (1) such mass transfer is easy due to the uniform internanorod distance being maintained during reaction and (2) the surface of the nanorod array is dominated by the highly reactive m-plane (10-10).

Discovery of Peripheral κ-Opioid Receptor Agonists as Novel Analgesics.

κ-Opioid receptor agonists with high selectivity over the µ-opioid receptor and peripheral selectivity are attractive targets in the development of drugs for pain. We have previously attempted to create novel analgesics with peripheral selective κ-opioid receptor agonist on the basis of TRK-820. In this study, we elucidated the biological properties of 17-hydroxy-cyclopropylmethyl and 10α-hydroxy derivatives. These compounds were found to have better κ-opioid receptor selectivity and peripheral selectivity than TRK-820.