Single-crystal-to-single-crystal metalation of organic ligands represents a novel method to prepare metal-organic complexes, but remains challenging. Herein, a hierarchical self-assembly {(H12L8)·([N(C2H5)4]+)3·(ClO4-)15·(H2O)32} (1) (L = tris(2-benzimidazolylmethyl) amine) consisting of π-stacked cubes which are assembled from eight partially protonated L ligands is obtained. By soaking the crystals of compound 1 in the aqueous solution of Co(SCN)2, the ligands coordinate with Co2+ ions stoichiometrically and ClO4- exchange with SCN- via single-crystal-to-single-crystal transformation, leading to {([CoSCNL]+)8·([NC8H20]+)3·(SCN)11·(H2O)13} (2).
Keywords: ion exchange; metalation; self-assembly; single-crystal-to-single-crystal transformation; π-stacked cube.