Abstract
Reactions of Pb(CH3COO)(2)center dot 3H(2)O, MNO3 (M = K, Rb, and Cs) with m-H2BDC (1,3-H2BDC = 1,3-benzenedicarboxylic acid) in a mixed-solvent of DMF and methanol (v/v = 2/1) resulted in the formation of novel metal-organic frameworks [(Me)(4)N](2)[Pb6M6(m-BDC)(9)(OH)(2)]center dot H2O (1: M = K; 2: M = Rb; 3: M = Cs). With H(2)SDBA (H(2)SDBA = 4,4 '-sulfonyldibenzoic acid), two new lead(II) coordination polymers, [K2Pb(SDBA)(2)(mu(3)-H2O)]center dot 3H(2)O (4) and [Cs2Pb2(SDBA)(3)(DMF)] DMF (5), were isolated. These complexes have been fully characterized by elemental analysis, PXRD, FTIR, TGA and single crystal X-ray diffraction. Compounds 1-3 are 3-D coordination frameworks built by a novel 12-metal heterometallic Pb-6-M-6 cage that extends topologically into an eight-connected hex network via isophthalic acid ligands. Compounds 4 and 5 are new 3-D lead(II) MOFs constructed by ladder-like Pb(II)/K(I)/SDBA(2-) and rod-shaped Pb(II)/Cs(I)/SDBA(2-) motifs, respectively. The Pb(II) ions in these complexes show different coordination geometries with various coordination numbers (5, 7 and 9). In addition, an ideal T-shaped mu(3)-H2O is observed in 4. The SDBA(2-) ligands in 4 and 5 display three types of new coordination modes that have not been observed before. At room temperature, 1-3 exhibit strong emissions in the solid-state which can be attributed to ligand-to-metal charge transfer between the delocalized pi bonds of carboxylate groups and p orbitals of lead(II) centers.