Three-Dimensional Supramolecular Architectures with CoII Ions Assembled from Hydrogen Bonding and π···π Stacking Interactions: Crystal Structures and Antiferromagnetic Properties

Five CoII complexes based on H3L1 and H3L2, namely, [Co3(L1)2­(4,4′-bipy)­(H2O)3]n (1), [Co3(L1)2­(4,4′-bipy)3­(H2O)4]n (2), {[Co2(L1)­(4,4′-bibp)­(μ3-OH)­(H2O)]­·H2O}n (3), {[Co3(L2)2­(dib)3]­·2H2O}n (4), and [Co3(L2)2­(4,4′-bibp)3]n (5) [(H3L1 = 4-[(3-carboxynaphthalen-2-yl)­oxy]­phthalic acid, H3L2 = 3-[(3-carboxynaphthalen-2-yl)­oxy]­phthalic acid, 4,4′-bipy = 4,4′-bipyridine, dib = 1,4-di­(1H-imidazol-1-yl) benzene, and 4,4′-bibp = 4,4′-bis­(imidazol)-biphenyl] have been synthesized by solvothermal reactions. Complex 1 displays a (4,4,6)-connected topology with a Schläfli symbol of (4.104.12)­(411.64)­(45.6)2, and the two-dimensional (2D) structure was assembled to form a three-dimensional (3D) framework by C–H···π interactions of internaphthalene rings, showing the dominant antiferromagnetic exchanges in a triangular {Co3} cluster. Complex 2 presents a 2D (3,4,4)-connected network with a Schläfli symbol of (5.62)2(52.63.7)2­(54.82) and weakly antiferromagnetic behavior. Complex 3 features a novel (4,4,8)-connected topology with a Schläfli symbol of (32.4.52.6)2­(32.42.52)2­(34.46.58.67.72.8). In addition, complex 3 based on a parallelogram-shaped [Co4(μ3-OH)2]6+ secondary building unit provides antiferromagnetic interactions mediated by μ3-OH and syn-syn-COO– groups. The driving forces in 3D supramolecular frameworks are C–H···O, C–H···π, and π···π stacking interactions for 2–3. Complexes 4–5 have an identical (4,4,5)-connected 2D network with a Schläfli symbol of (4.64.8)­(42.67.8)2­(44.62)2. Additionally, the C–H···O hydrogen bonds between naphthalene rings and uncoordinated carboxy oxygen atoms extend 2D networks into 3D supramolecular frameworks. Magnetic investigations reveal that 4 and 5 exhibit antiferromagnetic interactions in the linear {Co3} unit.