| Abstract: Two mononuclear Lead(Ⅱ) complexes [Pb(4-HOBA)2(2,2′-bipy)]·H2O (1) and [Pb(4-MBA)2(2,2′-bipy)] (2) were isolated from the hydrothermal reaction of 4-hydroxybenzoic acid (4-HOBAH), 4-methylbenzoic acid (4-MBAH), 2,2′-bipyridine (2,2′-bipy) and Pb(CH3COO)2·3H2O, and characterized by elemental analysis, IR, UV, TG and single-crystal X-ray structure analysis. In these two complexes, Pb(Ⅱ) ions are six-coordinated and chelated by two N atoms from one 2,2′-bipy ligand and four O atoms from two para-benzonate ligands. Complex 1 crystallizes in the monoclinic system, space group P21/c with a=1.094 83(4) nm, b=1.751 94(6) nm, c=1.204 79(4) nm, β=100.334(2)°, V=2.273 39(14) nm3, Z=4, final R1=0.025 4, wR2=0.067 4. The extensive hydrogen bonds and weak π…π stacking effects assemble and stabilize the 3D supramolecular structure. Complex 2 crystallizes in the triclinic system, space group P1 with a=0.955 10(11) nm, b=1.008 05(12) nm, c=1.324 83(15) nm, α=109.865(1)°, β=97.322(1)°, γ=90.643(1)°, V=1.187 8(2) nm3, Z=2, final R1=0.028 4, wR2=0.050 8. The complex 2 molecules related by inversion center are organized into dimeric units via a pair of Pb…O interactions of 0.318 5(2) nm. The weak Pb…O interactions and similar π…π stacks with complex 1, construct the complex 2 into a stable three-dimensional supramolecular structure. In both complexes 1 and 2, the 6s lone pair of electrons of PbⅡ atom has a stereochemistry activity resulting the distribution of the bonds in a hemisphere. The photoluminescence properties of these two complexes in the solid state were also studied at room temperature and strong blue emissions were observed. CCDC: 765050, 1; 767116, 2. |
