From discrete metallacycle, cage to infinite chain: tuning the coordination frameworks by variation of the metal center or ligand functionality

Self-assembly of the angular dipyridyl-type ligand 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L1) with CuII(BF4)2 or CuI(ClO4) salt affords a bimetallic macrocyclic compound [Cu2(L1)2(H2O)6](BF4)4 · (H2O)3 · (CH3OH)0.5 (1) (similar to its CuII(ClO4)2 complex) or a novel trigonal–prismatic cage-shape species [(H2O) ⊂ Cu2(L1)3(CH3CN)2](ClO4)2 (2), respectively. However, substituting L1 with its analogous 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L2) to react with CuI(BF4) yields a 1-D infinite chain array {[Cu(L2)2(CH3CN)](BF4) · (H2O)1.5}n (3), being similar to its CuI(ClO4) compound. These results unequivocally suggest that the nature of the metal center and ligand functionality play the key role in formation of the coordination supramolecular frameworks of 1–3.