title: Crystalline-Amorphous-Crystalline Transformation in a Highly Brilliant Luminescent System with Trigonal-Planar Gold(I) Centers.
abstract: Photoluminescent compounds showing emission color changes in response to external stimuli have received considerable attention because of their wide range of applications. Here, we report the unique photoluminescence behavior of a digold(I) coordination system with trigonal-planar Au(I) centers, [Au2(dppm)3](2+) (dppm = bis(diphenylphosphino)methane). This system shows an extremely intense phosphorescence, with a quantum yield of >95% in the solid state. Both the emission color and thermal stability vary due to changing counter ions (Cl(-) vs. OTf(-)). Of particular note is the thermal crystalline-amorphous-crystalline transformation for the chloride salt, which is accompanied by drastic emission color changes. Single-crystal and powder X-ray diffractions demonstrate that the two-step transformation is induced by the loss of water molecules of crystallization with the subsequent removal of a dppm ligand to form [Au2(dppm)2](2+), which is mechanically reverted back to [Au2(dppm)3](2+).
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Igawa
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Nobuto
authors.initials: N
authors.lastname: Yoshinari
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Mitsutaka
authors.initials: M
authors.lastname: Okumura
authors.affiliation: The Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784, Korea.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Ohtsu
authors.affiliation: The Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784, Korea.|Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Kawano
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Konno