Selective formation of integrated stacks of (α-diimine)(ethylenediamine)platinum(II) and neutral π systems of the phenanthrene type

The [Pt(en)(L)](2+) (L=bipy or phen) complexes with a planar alpha -diimine ligand and a non-planar diamine ligand formed 1:1 integrated stacks taking up free phen and phenanthrene (phe) selectively. The stacking structures of the composite crystals [Pt(en)(L)][PF6](2). phen . 2H(2)O (L=bipy or phen) and [Pt(en)(bipy)][PF6](2). phe have been elucidated by X-ray analysis. Both pi-pi interactions and hydrogen bonds lead to easy and selective uptake of phen to form the integrated stack while it is possible for phe with no hydrogen bonding ability to form a similar integrated stack. The composite crystals exhibit emission spectra which originate from the (3)pi pi*(L) state of [Pt(en)(L)](2+) in the integrated stack. The emission properties indicate facile energy transfer from free phen or phe to [Pt(en)(L)](2+) in the stacks.