Solvent‐Mediated Transformation from Achiral to Chiral Nickel(II) Metal–Organic Frameworks and Reassembly in Solution

Reactions of 5‐nitroisophthalic acid (NO 2 ‐H 2 ip), 1,4‐bis(imidazol‐1′‐yl)butane (bimb), and Ni(NO 3 ) 2 ⋅ 6 H 2 O gave rise to four metal–organic frameworks (MOFs), [Ni 2 (NO 2 ‐ip) 2 (bimb) 1.5 ] n ( 1 ), [Ni 4 (NO 2 ‐ip) 3 (bimb) 2 (OH) 2 (H 2 O)] n ⋅ (CH 3 CH 2 OH) 0.5  n ( 2 ), [Ni(NO 2 ‐ip)(bimb) 1.5 (H 2 O)] n ⋅ (H 2 O) n ⋅ (CH 3 CH 2 OH) 0.5  n ( 3 ), and [Ni(NO 2 ‐ip) (bimb)(μ‐H 2 O)] n ⋅ (H 2 O) n ( 4 ). The metal/ligand ratio, pH value, and solvent exerted a subtle but crucial influence on the formation of complexes 1 – 4 , which possess different visual color and crystal structures. Complex 1 exhibits a twofold interpenetrating 3D pillared bilayer framework composed of binuclear and mononuclear Ni II units, whereas complex 2 is a 3D chiral network that consists of asymmetric tetranuclear Ni II units. Complexes 3 and 4 are 3D layer‐pillared frameworks that consist of mononuclear Ni II ions and a 3D six‐connected network of μ‐water‐bridged dinuclear Ni II units, respectively. Interestingly, achiral 4 can be transformed into chiral 2 by using a solvent‐mediated single‐crystal‐to‐single‐crystal process without any chiral auxiliary. Magnetic analyses of 2 and 4 show the occurrence of antiferromagnetic interactions. Complex 3 is difficult to obtain directly as a single solid phase, but it can be homogeneously formed by solvent‐mediated transformations from 1 , 2 , and 4 .