Coordination Polymers in Selective Separation of Cations and Anions: A Series of Rarely Observed All Helical Three-Dimensional Coordination Polymers Derived from Various Chiral Amino Acid Based Bis-pyridyl-bis-amide Ligands

A series of CuII coordination polymers [{Cu(μL1)2Br2}·2H2O]∞ CP1, [{Cu(μL2)2·H2O·Br}·Br·4H2O]∞ CP2, [{Cu(μL3)2Br2}·2H2O]∞ CP3, [{Cu(μL3)2Cl2}·2H2O]∞ CP4, derived from bis-pyridyl-bis-amide ligands having a natural l-amino acid backbone have been synthesized and characterized by single crystal X-ray diffraction. Environmentally relevant cations (CuII) and anions (Br–) have been separated selectively from complex mixtures of cations (CuII, CoII, and ZnII) and anions (Br–, NO3–, SO42–, ClO4– and BF4–) via an in situ crystallization technique in separate experiments, respectively. Such separation of cations by in situ crystallization of coordination polymers represents the first example in the literature.