Chiral Copper(I) Iodide Based Porous Coordination Frameworks with Asymmetrically Substituted Bridging N-Donor Ligands

The 2-dimensional coordination polymers 2 ∞ [{(CuI) 2 (Mepyz) 2 } · Mepyz] (1a), 2 ∞ [CuX(Mepyz)] (2a, X = Br; 2b, X = Cl) and 2 ∞ [(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 acetonitrile solution at 130 °C (2a/2b, 3a/3b) or without solvent at 20 °C (la). Mepyz ligands bridge (CuI) 2 rhomboid dimers in the chiral network of la, whose resulting 24-membered rings are large enough to accomodate an Mepyz guest molecule, la rapidly loses these guests to afford a crystalline powder (lb), that can reversibly imbibe benzonitrile molecules into its open channels. In contrast to la, the sheets of 2a/2b contain zigzag infinite CuX chains, those of 3a/3b staircase 1 ∞ [CuX] double chains as their characteristic substructures. Helical 3 ∞ [CuI] single chains in the 3-dimensional network of 3 ∞ [CuI Mepip)4 are bridged by R-2-methylpiperazine (Mepip) ligands in a second example of a chiral coordination polymer.