Spontaneous Resolution and Structure Transformation of NiII Metal–Organic Frameworks from an Achiral Precursor

Metal-center-driven spontaneous resolution of a pair of chiral doubly interpenetrated metal–organic frameworks (MOFs), [Ni3(ptd)6]·15.5H2O (1), which was synthesized from achiral precursors [ptd = 3-(pyridin-3-yl)-1,2,4-triazine-5,6-diol], shows vertical interpenetrated 2D → 3D frameworks with 1D channels. Interestingly, proceeding with solvothermal recrystallization in methanol, 1, with a high-symmetry tetragonal I4 space group, gives another tilted interpenetrated MOF of [Ni3(ptd)6]·10H2O·3.5MeOH (2), with low-symmetry monoclinic C2 space group. Accompanied with the structure transformation, a red shift in circular dichroism (CD) spectrum and a magnetic response (weak ferromagnetic interactions in 1 to weak antiferromagnetic interactions in 2) can be observed. Strikingly, 1 and 2 feature heterogeneous catalytic activities for the Knoevenagel reaction.