Four new metal–organic frameworks based on bi-, tetra-, penta-, and hexa-nuclear clusters derived from 5-(phenyldiazenyl)isophthalic acid: syntheses, structures and properties

Abstract

Four new metal–organic frameworks (MOFs), namely, [Cu(PDIA)(DMA)]_n (JUC-126), [Mn₄(PDIA)₄(DMF)₆]_n·nDMF·2nH₂O (JUC-127), [Zn₂₃(PDIA)₁₈(μ₄-O)₂(μ₃-OH)₆DMA₆]_n·10nDMA·6nH₂O (JUC-128), [Co₃(PDIA)₂(HCOO)(μ₃-OH)(H₂O)(DMA)₂]_n·nDMA·nH₂O (JUC-129) (JUC = Jilin University, China), based on a new rigid ligand 5-(phenyldiazenyl)isophthalic acid (H₂PDIA) with azobenzene were synthesized under solvothermal conditions. The ligand is connected to different metals to form bi-, tetra-, penta- and hexa-nuclear cores with distinctive coordination modes to generate different structures. Moreover, π–π stacking interactions between arene cores of the ligands also exist to affect the structural assembly process. JUC-126 displays a three-dimensional (3D) NbO topology with the point symbol (6⁴·8²) based on Cu₂(COO)₄ as secondary building units (SBUs), JUC-127 shows a two-dimensional (2D) sql topology with the point symbol (4⁴·6²) based on Mn₂(COO)₄ as SBUs, JUC-128 has a new 3D topology with the point symbol (3³·4⁶·5⁶)₂(3⁶·4⁸·5¹⁰·6⁴)₃ based on Zn₄O(COO)₆ and Zn₅(μ₃-OH)₂(COO)₈ as SBUs and JUC-129 exhibits a 2D sql topology with the point symbol (4⁴·6²) based on Co₆(μ₃-OH)₂(COO)₁₀ as SBUs. In addition, JUC-126, JUC-128 and JUC-129 are achiral frameworks; however, JUC-127 shows a chiral framework from an achiral ligand. Furthermore, the luminescent property of JUC-128 and the magnetic properties of JUC-127 and JUC-129 have been studied and discussed.