Mono- and bilayered lead(II)-bpno polymers with unusual low energy emission properties (bpno=4,4′-bipyridine N,N′-dioxide)

Reaction of 4,4'-bipyridine N,N'-dioxide (bpno) and lead(II) nitrate with or without dicyanamido ions (dca) in aqueous solution yielded polymeric complexes {Pb-2(bpno)(4)(dca)(2)(-)(NO3)(2)Pb-2(bpno)(4)(NO3)(4)center dot 5H(2)O}(n) (1) and {Pb(bpno)(NO3)(2)(center dot) H2O}, (2), respectively. The single-crystal X-ray analyses show that the structures of both complexes consist of dinuclear Pb-II units which are bridged through bpno ligands in novel modes to extend their topologies. Compound 1 exhibits a bilayered rhombus grid, while 2 displays a monolayered rhombus grid. The different excitations of solid samples of 1 and 2, at room temperature, produced intense emission bands which are almost the same in appearance with peak maxima at 616 nm and 617 nm, respectively. Both low-energy emissions were determined to be phosphorescence by their long decay lifetime at room temperature. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.