对位取代苯甲酸与2,2′-联吡啶配体构筑的两种二价铅配合物的合成、晶体结构及性质(英文)

Syntheses, Crystal Structures and Properties of Two Lead (Ⅱ) Complexes with Para-Substituted Benzoic Acid and 2,2′-Bipyridine Co-Ligand

水热条件下,合成了2个含对位取代苯甲酸和2,2′-联吡啶配体的二价铅配合物[Pb(4-HOBA)2(2,2′-bipy)]·H2O(4-HOBAH=4-hydroxybenzoicacid,2,2′-bipy=2,2′-bipyridine)(1)及[Pb(4-MBA)2(2,2′-bipy)](4-MBAH=4-methylbenzoicacid)(2),并通过X-射线单晶结构分析、元素分析、红外光谱、紫外光谱、荧光光谱以及热重分析等手段对配合物进行了表征与研究。X-射线单晶结构测定表明,2种晶体的不对称单元中,六配位的二价铅离子分别与来自1个2,2′-联吡啶的2个N原子和2个对位取代苯甲酸的4个O原子螯合。配合物1属单斜晶系,P21/c空间群,a=1.09483(4)nm,b=1.75194(6)nm,c=1.20479(4)nm,β=100.334(2)°,V=2.27339(14)nm3,Z=4,finalR1=0.0254,wR2=0.0674。广泛存在的分子间氢键和弱π…π堆积作用将配合物1组装成稳定的三维超分子结构。配合物2属三斜晶系,P1空间群,a=0.95510(11)nm,b=1.00805(12)nm,c=1.32483(15)nm,α=109.865(1)°,β=97.322(1)°,γ=90.643(1)°,V=1.1878(2)nm3,Z=2,finalR1=0.0284,wR2=0.0508。配合物2经由一对Pb…O(0.3185(2)nm)弱相互作用被组装成二聚体结构,弱的Pb…O相互作用及与配合物1中类似的π…π堆积作用共同构筑了配合物2的三维结构。在配合物1和2中,铅的6s孤电子均显示了立体化学活性,使配位键分布于半球型区域。同时,两种配合物固体均具有光致发光特性,并在蓝光区有较强发射。

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） nm^3, 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.