Du Xiaodi, Gao Congli, Zhang Zhiqiang, Su Bing, Li Xi-Li
College of Chemistry and Chemical Engineering, Zhoukou Normal University, Zhoukou 466001, PR China.
Henan Provincial Key Laboratory of Surface and Interface Science, Zhengzhou University of Light Industry, Zhengzhou 450002, PR China.
Dalton Trans. 2023 Sep 26;52(37):13229-13234. doi: 10.1039/d3dt01923c.
By employing enantiomerically pure mono-bidentate N-donors (L/L) as chiral bridging ligands to react with Cu(ClO)(HO) in CHCN-DMF mixed solvent, respectively, a pair of ionic one-dimensional (1D) Cu(II) chain enantiomers formulated as {CuL(CHCN)(DMF)HO}/{CuL(CHCN)(DMF)HO} (D-1/L-1) were isolated and structurally characterized, where L/L = (-)/(+)-4,5-pinenepyridyl-2-pyrazine. They crystallize in the noncentrosymmetric (NCS) 222 space group of an orthorhombic system due to the introduction of chiral L/L, and the ClO groups as counteranions reside in crystal lattices, thus leading to charge separation with large dipole moments in their molecular structures. Based on crystal samples, investigation on their nonlinear optical (NLO) behaviors showed that D-1 and L-1 display simultaneously much larger second- and third-harmonic generation (SHG and THG) responses than their analogues based on the same chiral N-donors (L/L) and Cu(NO)(HO) with NO acting as the coordination group to bind Cu(II) ions. The SHG intensities of D-1/L-1 are 0.62/0.60 × KDP (KHPO), and THG intensities of D-1/L-1 are 238/228 × α-SiO. Our finding indicates that coordination polymers (CPs) with charge separation and NCS structures, , ionic CPs with NCS arrangements are the ideal NLO crystalline materials for the simultaneous observation of large SHG and THG responses, thus providing a new approach to obtain NLO-active CP crystalline materials with high-performance SHG and THG responses.
通过分别使用对映体纯的单齿双齿氮供体（L/L）作为手性桥联配体，使其在CHCN-DMF混合溶剂中与Cu(ClO)(HO)反应，分离得到了一对离子型一维（1D）铜（II）链对映体，其化学式为{CuL(CHCN)(DMF)HO}/{CuL(CHCN)(DMF)HO}（D-1/L-1），并对其进行了结构表征，其中L/L = (-)/(+)-4,5-蒎烯吡啶基-2-吡嗪。由于引入了手性L/L，它们结晶于正交晶系的非中心对称（NCS）222空间群中，并且作为抗衡阴离子的ClO基团存在于晶格中，从而导致其分子结构中具有大偶极矩的电荷分离。基于晶体样品，对其非线性光学（NLO）行为的研究表明，D-1和L-1同时表现出比基于相同手性氮供体（L/L）和以NO作为配位基团与铜（II）离子配位的Cu(NO)(HO)的类似物大得多的二次和三次谐波产生（SHG和THG）响应。D-1/L-1的SHG强度为0.62/0.60×KDP（KHPO），D-1/L-1的THG强度为238/228×α-SiO。我们的发现表明，具有电荷分离和NCS结构的配位聚合物（CPs），即具有NCS排列的离子型CPs是同时观察到大型SHG和THG响应的理想NLO晶体材料，从而为获得具有高性能SHG和THG响应的NLO活性CP晶体材料提供了一种新方法。
