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 Cu^II/Co^II 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.