Metallic coordination selectivity effect in thetrinuclear M3(RCOO)6 secondary building units ofthree layer metal–carboxylate frameworks
Metallic coordination selectivity effect in thetrinuclear M3(RCOO)6 secondary building units ofthree layer metal–carboxylate frameworks
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三层金属-羧酸盐骨架三核M3(RCOO)6二级结构单元中的金属配位选择性效应
DOI：
10.1039/c6ra00213g
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Xin Han
中科院分区：
文献类型：
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作者：
Xiao-Feng Wang;Hongqing Wang;Shuhong Wang;Jun Li;Shenbiao Li;Kang-Cheng Zheng;Xin Han
以吡啶为碱，DMF为溶剂，M（NO3）2和H2 BDC反应，合成了3种二维金属羧酸盐骨架（MCFs）：Zn 3（BDC）3（py）2·2DMF（1），Mn 3（BDC）3（DMF）4（2）和Co 3（BDC）3（DMF）2（py）2（3）[H2 BDC = 1，4-苯二甲酸，py =吡啶，DMF = N，N′-二甲基甲酰胺]，在微波辅助溶剂热条件下。用单晶X射线衍射仪对三种MCFs进行了表征，并测定了它们的荧光和磁性。结构分析表明，配合物1-3是由不同的羧酸根桥联的线性M3（RCOO）6（LT）2/4簇合物构成，其中1中的配位末端配体（LT）为py，2中的配位末端配体（LT）为DMF，3中的配位末端配体（LT）为py/DMF.结果表明，在每个SBU的两侧，不同的金属离子倾向于与各自选择的LT配位。含时密度泛函理论（TDDFT）计算表明，1的发射峰在423-428 nm之间，（实验值为425 nm）可能来自配体-配体电荷转移（LLCT）上的能量跃迁，其中电子密度位于π-BDC 2 −的成键轨道转移到吡啶的π*-反键轨道。变温磁化率的研究表明存在反铁磁交换耦合内的M3-单位2和3。
Three two-dimensional metal–carboxylate frameworks (MCFs), namely Zn3(BDC)3(py)2·2DMF (1), Mn3(BDC)3(DMF)4 (2) and Co3(BDC)3(DMF)2(py)2 (3) [H2BDC = 1,4-benzene dicarboxylic acid, py = pyridine, DMF = N,N′-dimethylformamide], have been synthesized by reaction of the M(NO3)2 and H2BDC with py as base and DMF as solvent, under the microwave-assisted solvo-thermal conditions. Three MCFs were characterized by single crystal X-ray diffraction and mensurated its fluorescent or magnetic behaviors. The structural analyses reveal that 1–3 are constructed of the slightly dissimilar carboxylate bridged linear M3(RCOO)6(LT)2/4 clusters where the coordination terminal ligand (LT) are py in 1, DMF in 2 and py/DMF in 3, respectively. The results demonstrated the different metal ions in two side of every SBU inclined to coordinate their respectively selected LT. The time-dependent density functional theory (TDDFT) calculations of 1 show that the emission peak of 423–428 nm (the experimental value is 425 nm) might be derived from the energy transition on the ligand-to-ligand charge transfer (LLCT) where electron densities residing on the π-bonding orbital of BDC2− are transferred to the π*-anti-bonding orbital of pyridine. Variable-temperature magnetic susceptibility studies indicate the presence of antiferromagnetic exchange coupling within the M3-units of 2 and 3.