Chiral copper(I) iodide based porous coordination frameworks with asymmetrically substituted bridging N-donor ligands

The 2-dimensional coordination polymers 2/infinity[{(CuI)(2)(Mepyz)(2)} . M epyz] (1a), 2/infinity[CuX(Mepyz)] (2a, X = Br; 2b, X = Cl) and 2/infinity[ (CuX)(2)(Mepyz)] (3a, X = I;3b, X = Br) may be prepared by reaction of the appropriate copper(I) halide with 2-methylpyrazine (Mepyz) either in aceton itrile solution at 130 degrees C (2a/2b, 3a/3b) or without solvent at 20 de grees C (1a). Mepyz ligands bridge (CuI)(2) rhomboid dimers in the chiral n etwork of 1a, whose resulting 24-membered rings are large enough to accomod ate an Mepyz guest molecule. 1a rapidly loses these guests to afford a crys talline powder (1b), that can reversibly imbibe benzonitrile molecules into its open channels. In contrast to in, the sheets of 2a/2b contain zigzag i nfinite CuX chains, those of 3a/3b staircase 1/infinity[CuX] double chains as their characteristic substructures. Helical 1/infinity[CuI] single chain s in the 3-dimensional network of 3/infinity[CuI(Mepip)]4 are bridged by R- 2-methylpiperazinne (Mepip) ligands in a second example of a chiral coordin ation polymer.