Coordination Behavior of 5,6-Substituted 1,10-Phenanthroline Derivatives and Structural Diversities by Coligands in the Construction of Lead(II) Complexes

Eight new Pb(II) metal-organic coordination polymers, {[Pb(3-PDIP)(2)(1,4-bdc)]center dot 4H(2)O}(n) (1), [Pb(3-PDIP)(2)-(bpea)](n) (2), [Pb(HOIP)(pyc)(2)](2) (3), [Pb(HOIP)(1,3-bdc)](n) (4), {[Pb(4-PDIP)(glu)]center dot H2O}(n) (5), {[Pb(4-PDIP)(1,4-bdc)]center dot 2H2O}(n) (6), [Pb(4-PDIP)(1,3-bdc)](n) (7), and [Pb(4-PDIP)(4,4'-bpdc)](n) (8) (3-PDIP = 2-(3-pyridine) imidazo[4,5-f]1,10-phenanthroline, HOIP = 2-(4-hydroxylbenzene) imidazo[4,5-f]1,10-phenanthroline, 4-PDIP = 2-(4-pyridine) imidazo[4,5-f]1,10-phenanthroline, 1,4-H(2)bdc=benzene-1,4-dicarboxylic acid, H(2)bpea = biphenylethene-4,4'-dicarboxylic acid, Hpyc=pyridyl-2-carboxylic acid, 1,3-H(2)bdc = benzene-1,3-dicarboxylic acid, H(2)glu = glutaric acid, 4,4'-H(2)bpdc = biphenyl-4,4'-dicarboxylic acid), have been hydrothermally synthesized and structurally characterized. Complexes 1, 2, 4, and 6 possess one-dimensional (ID) chain structures. 3 is a mononuclear structure, and two separated molecules are connected by noncovalent interactions to generate an interesting double layer. 5 and 7 feature two-dimensional networks with (4,4) topology. Finally, complexes 1-7 are extended into three-dimensional (3D) supramolecular frameworks. 8 shows a 2-fold interpenetrating 3D framework with a rare self-penetrated topology. Three 5,6-substituted 1,10-phenanthroline derivatives exhibit two types of coordination modes and play important roles in the formation of supramolecular frameworks. The diverse structures of eight complexes may result from the different coordination behaviors of 1,10-phenanthroline derivatives, the coordination geometry of Pb(II) ion, and the coligands. Moreover, the fluorescence properties of complexes 5-8 have been investigated.