Vapochromism and Crystal Structures of Luminescent Dicyano(2,2′-Bipyridine)Platinum(II)

Vapochromic behavior of the crystal of dicyano(2,2'-bipyridine)platinum(II), [Pt(CN) 2 (bpy)], has been investigated structurally and emission spectroscopically. Red Form with an infinite PtPt chain transforms to Yellow Form reversibly by taking up water vapor. The crystal structure of Yellow Form ([Pt(CN) 2 (bpy)]H 2 O) was determined by X-ray analysis: the square-planar complexes form the inclined stack with short and long PtPt distances (3.3279(3) and 4.6814(3) Å). The crystal water makes hydrogen bonds with CN m ligands connecting the stacks. The transformation is accompanied by the sensitive luminescence change as well as the color change, which reflects the change of the Pt > Pt electronic interactions. The sensitive vapochromism for this system is attributable to the slight deformation of the stacking structure induced by water molecules. platinum complex luminescence spectrum vapochromism metal-metal interaction crystal structure