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Solid-State Structural Transformations and Photoreactivity of 1D-Ladder Coordination Polymers of PbII

Authors

  • Dr. Goutam Kumar Kole,

    1. Department of Chemistry, National University of Singapore, Science Drive 3, 117543 (Singapore), Fax: (+65) 67791691
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  • Dr. Abdul Malik Puthan Peedikakkal,

    1. Department of Chemistry, National University of Singapore, Science Drive 3, 117543 (Singapore), Fax: (+65) 67791691
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  • Belinda Mei Fang Toh,

    1. Department of Chemistry, National University of Singapore, Science Drive 3, 117543 (Singapore), Fax: (+65) 67791691
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  • Prof. Dr. Jagadese J. Vittal

    Corresponding author
    1. Department of Chemistry, National University of Singapore, Science Drive 3, 117543 (Singapore), Fax: (+65) 67791691
    • Department of Chemistry, National University of Singapore, Science Drive 3, 117543 (Singapore), Fax: (+65) 67791691
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Abstract

An attempt has been made to design double-stranded ladder-like coordination polymers (CPs) of hemidirected PbII. Four CPs, [Pb(μ-bpe)(O2C-C6H5)2]2H2O (1), [Pb2(μ-bpe)2(μ-O2C-C6H5)2(O2C-C6H5)2] (2), [Pb2(μ-bpe)2(μ-O2C-p-Tol)2(O2C-p-Tol)2] 1.5 H2O (3) and [Pb2(μ-bpe)2(μ-O2C-m-Tol)2(O2C-m-Tol)2] (4) (bpe=1,2-bis(4′-pyridyl)ethylene), have been synthesised and investigated for their solid-state photoreactivity. CPs 24, having a parallel orientation of bpe molecules in their ladder structures and being bridged by carboxylates, were found to be photoreactive, whereas CP 1 is a linear one-dimensional (1D) CP with guest water molecules aggregating to form a hydrogen-bonded 1D structure. The linear strands of 1 were found to pair up upon eliminating lattice water molecules by heating, which led to the solid-state structural transformation of photostable linear 1D CP 1 into photoreactive ladder CP 2. In the construction of the double-stranded ladder-like structures, the parallel alignment of C[DOUBLE BOND]C bonds in 24 is dictated by the chelating and μ221 bridging modes of the benzoate and toluate ligands. The role of solvents in the formation of such double-stranded ladder-like structures has also been investigated. A single-crystal-to-single-crystal transformation occurred when 4 was irradiated under UV light to form [Pb2(rctt-tpcb)(μ-O2C-m-Tol)2(O2C-m-Tol)2] (5).

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