Spontaneous Resolution of Racemic Salen-Type Ligand in the Construction of 3D Homochiral Lanthanide Frameworks

A series of three 3D homochiral lanthanide–organic frameworks {[Ln­(H2LSS)­(NO3)2Cl]·2CH2Cl2}n [Ln = La (1), Ce (2), and Nd (3)] with the unique diamond (dia) topology have been obtained by utilizing racemic salen-type ligand and mixed lanthanide salts. Complexes 1–3 are isostructural, crystallizing in the chiral tetragonal space group P43212 and adopting an individual dia network formed by lanthanide ions and bridging ligand trans-N,N′-bis­(salicylidene)-(1S,2S)-cyclohexanediamine (H2LSS). This “from racemate to homochiral” approach may point to a new avenue for the preparation of homochiral materials.