We studied the isotope effect of crystal water on the emission lifetime of Ru(dbb)2(CN)2·2H2O in the solid state. The emission lifetime ratio of Ru(dbb)2(CN)2· 2D2O (dbb = 4,4′-di-tert-butyl-2,2′-bipyridine) and Ru(dbb)2(CN)2·2H2O was determined to be τD/τH = 1.14 ± 0.05 at 298 K. From a crystal structural analysis, it was concluded that hydrogen bonding between crystal water and the 5,5′- and/or 3,3′-H atoms of the dbb ligands contributed more effectively to the isotope effect of crystal water on emission lifetime than that between water and the CN ligands. With increasing temperature, two water molecules were released at 310-345 K and over 385 K stepwise from hydrophobic channels constructed from dbb moieties. Exposure of the non-hydrated crystal, Ru(dbb)2(CN)2, to H2O or D2O vapor at 298 K gave Ru(dbb)2(CN) 2·2H2O or Ru(dbb)2(CN) 2·2D2O, respectively. Under a H2O-D 2O mixed atmosphere, there was no correlation between the ratio of H2O and D2O in crystal water and the statistical distribution of H2O and D2O in the mixed atmosphere. Even under a 70% D2O atmosphere, selective sorption of H2O in the crystal of Ru(dbb)2(CN)2 was observed.
ASJC Scopus subject areas
- Chemical Engineering(all)