Exploring the Syntheses, Structures, and Properties of Two 3D Porous Metal–Organic Frameworks Based on Aromatic Polyacid Ligands

Two porous coordination polymers, {[Zn8(L)2(H2O)11]·6DMF·5H2O}n (Zn-1) and {[Co2(H4L)(H2O)4]·4DMA}n (Co-2), have been successfully constructed by using elongated and aromatic-rich ligand methanetetrayl(biphenyl-3,5-dicarboxylic acid) (H8L) and Zn(NO3)2·6H2O or Co(NO3)2·6H2O. Single-crystal X-ray diffraction results reveal that polymer Zn-1 has a three-dimensional skeleton, in which the two different dual core paddle-wheels [Zn2(COO)4] and [Zn2(COO)3] are linked by eight-connected node L8– anions, assembling into a (3, 4, 8)-connected 3D metal organic framework with irregular channels. The complex Zn-1 exhibits excellent recognition ability for dopamine through the luminescence quenching mechanism with high KSV (4.61 × 103 M–1) and limit of detection (9.24 × 10–5 M). Moreover, it also shows excellent anti-interference properties in different amino acid solutions. In Co-2, the dual core secondary building units [Co2(COO)4(H2O)] and four connected nodes H4L4– interconnected and assembled into a (4, 4)-connected 3D framework containing rectangular channels with the size of 12.2 × 9.6 Å2 along the [001] direction. In addition, Co-2 exhibits excellent selective adsorption properties for cationic organic dyes, rhodamine B (RB+) and methylene blue (MB+). It also exhibits a good separation effect of cationic and anionic dyes MB+/MO–.