配体尺度对配合物结构及光催化降解活性的调节:从零维到一维的Cu(Ⅱ)配合物

合成了桥联吡啶类配体2,6-二(3′-吡啶乙炔基)-4-甲基苯胺(L1)和未见文献报道的尺度更短的桥联吡啶配体2,6-二(3′-吡啶基)-4-甲基苯胺(L2),在常温下分别将其与一水合醋酸铜(Cu(OAc)2·H2O,OAc-=CH3CO2-)进行配位反应获得零维的配位大环分子Cu2(L1)(OAc)4]2(1)和一维的配位聚合物{Cu2(L2)(OAc)4]·2CH2Cl2·CH3CN}n(2)。对获得的2个配合物进行了X射线单晶衍射、傅里叶红外光谱、元素分析等方面的结构表征。对比其结构可以发现,配合物1和2中均存在{Cu2(OAc)4}的二核铜簇,不同的是2个配合物中配体的配位取向不同:配位大环化合物1中的配体L1以U型构型与二核铜簇形成了“2+2”的平面配位大环结构,而化合物2中的配体L2则以Z型构型连接相邻的二核铜簇形成一维链状结构。2个化合物的结构差异是由于配体的尺度导致的,更短的尺度使得配位氮原子取向发生改变而产生不同的配位构型,这显示了结构调控中配体尺度的影响作用。通过测定配体与配合物在固态下的荧光发射性质,证实了铜的引入会猝灭配体自身的荧光发射;同时,采用亚甲基蓝(MB)为底物的光催化降解实验证明,大环配位分子的光催化降解活性明显优于一维配位聚合物,两者的催化活性均远远强于醋酸铜本身的催化活性。

Regulation of Ligand Scale on Structure and Photocatalytic Degradation Activity of Complex:from Zero-Dimensional to One-Dimensional Cu(Ⅱ) Complexes

Bridged pyridine ligand 4-methyl-2,6-bis(pyridin-3''-ylethynyl) aniline (L1) and an unreported ligand with smaller scale, 2,6-bis(3''-pyridyl)-4-methylaniline (L2) were synthesized. Two complexesCu₂(L1)(OAc)₄]₂ (1, OAc^-=CH₃CO₂^-) and {Cu₂(L2)(OAc)₄]·2CH₂Cl₂·CH₃CN}_n (2) were obtained using L1 or L2 and cupric acetate monohydrate (Cu(OAc)₂·H₂O) in mixed organic solvent at room temperature. The complexes 1 and 2 were characterized by X-ray single crystal diffraction, IR and elemental analysis. The structural research reveals that both the complexes 1 and 2 contain the dinuclear copper cluster of {Cu₂(OAc)₄}, but complex 1 has a "2+2" planar macrocycle structure in which L1 coordinated with the dinuclear copper clusters in a U-configuration and complex 2 has 1D chain structure where L2 connected the adjacent dinuclears in a Z-configuration. The structural difference between the two complexes is due to the different scale of the ligands L1 and L2, demonstrating the effect of the ligand scale in structural regulation. The fluorescence property of these two complexes were investigated, and it was confirmed that the introduction of copper quenched the fluorescence emission. The experiment of photocatalytic degradation of methylene blue (MB) proved that the macrocycle complex 1 has better catalytic activity than complex 2 with 1D chain structure and both of them are better than cupric acetate.