Is a Crystal Engineering Approach Useful in Designing Metallogels? A Case Study

A crystal engineering based design strategy for metallogels has been demonstrated in a series of mixed ligand based CuII/CoII coordination polymers derived from two bis-pyridyl-bis-amide ligands namely N,N′-bis-(3-pyridyl)isophthalamide (L1) and N,N′-bis-(3-pyridyl)terephthalamide (L2) and various dicarboxylates. These mixed ligand coordination polymers are shown to form gels as well as X-ray quality crystals under different conditions. The crystal structures of the gel fibers in the xerogels have been determined by using powder and single-crystal X-ray diffraction data. The results support the proof of the concept based on which the metallogels are designed.

本研究针对金属凝胶（metallogels）提出了一种基于晶体工程（crystal engineering）的设计策略，通过两类双吡啶双酰胺配体（bis-pyridyl-bis-amide ligands）——即N,N′-双(3-吡啶基)间苯二甲酰胺（L1）与N,N′-双(3-吡啶基)对苯二甲酰胺（L2）——以及多种二羧酸盐（dicarboxylates），构建了一系列混合配体铜(II)/钴(II)配位聚合物，验证了该策略的有效性。在不同实验条件下，此类混合配体配位聚合物既可形成凝胶体系，亦可获得适用于X射线衍射测试的高质量单晶。研究借助粉末X射线衍射与单晶X射线衍射数据，解析了干凝胶（xerogels）中凝胶纤维的晶体结构。所得实验结果佐证了该金属凝胶设计所依托的概念的正确性。