Three unique MOFs constructed by 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene and dicarboxylates: From rhombic tetrameric zinc(II) 2D layer to 2D + 2D → 3D polycatenated frameworks

Abstract Three metal–organic networks, namely, [Zn 2 (Hnip)(4-bpdb)(nip) 2 ( μ 3 -OH)] (1), {[Zn(tbip)(4-bpdb) 1.5 ]·CH 3 OH} n (2), and {[Ni(1,3-bdc)(4-bpdb)]·2H 2 O} n (3) (4-bpdb = 1.4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, H 2 nip = 5-nitroisophthalic acid, H 2 tbip = 5- tert -butylisophthalic acid, and 1,3-H 2 bdc = 1,3-benzenedicarboxylic acid) are synthesized under hydrothermal conditions. The structure of 1 is built around uncommon rhombic {Zn 4 } clusters with double T d and double O h Zn(II) geometries, which extend into a 2D network by the rigid deprotonated H 2 nip and 4-bpdb bridges. Meanwhile, 2 presents a novel 2D → 3D parallel polycatenated framework assembled from 2D bilayers with cuboids as the fundamental building units. Compound 3 features an interesting 2D → 3D inclined polycatenated network based on 4 4 -sql subunits. Moreover, the thermal stabilities, photoluminescence, and magnetic properties of the compounds are also discussed.