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(mu L1)(2)Br-2}center dot 2H(2)O](infinity) CP1, [{Cu(mu L2)(2)center dot H2O center dot Br} center dot Br center dot 4H(2)O](infinity) CP2, [{Cu(mu L3)(2)Br-2} center dot 2H(2)O](infinity) CP3, [{Cu(mu L3)(2)Cl-2} center dot 2H(2)O](infinity) 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 (Cu-II) and anions (Br- have been separated selectively from complex mixtures of cations (Cu-II, Co-II, and Zn-II) 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.