Syntheses, structures and properties of two zinc(II) coordination complexes based on two bis(pyridyl)-bis(amide) ligands and 1,2-phenylenediacetic acid

Two new zinc(II) coordination complexes [Zn(pda)(3-bpcd)_0.5] (<b>1</b>) and [Zn(pda)(3-bpoa)]·H₂O (<b>2</b>) have been synthesized by self-assembly of 1,2-phenylenediacetic acid (H₂pda), semi-rigid/or flexible bis(pyridyl)-bis(amide) ligands [3-bpcd = N,N′-bis(pyridin-3-yl)cyclohexane-1,4-dicarboxamide, 3-bpoa = N,N'-bis(3-pyridyl)octandiamide] and zinc nitrate. Complex <b>1</b> is a 2 D layered framework derived from the 1 D [Zn(pda)]_2n ribbon-like chain and the bidentate 3-bpcd, which is a (3,4)-connected (4²·6³·8)(4²·6) topology, then the adjacent layers are linked by hydrogen bonds to build a 3 D supramolecular network. Complex <b>2</b> displays a 3 D framework based on the 1 D [Zn(pda)]_2n ribbon-like chains and the 1 D [Zn(3-bpoa)]_n chains, which represents a (3,5)-connected (4².6⁵.8³)(4².6) topology. Two bis(pyridyl)-bis(amide) ligands with different flexibilities play an important role in constructing final topological structures for title complexes. Moreover, the fluorescent properties of two zinc(II) complexes and their fluorescent sensing properties toward small solvent molecules have been studied. Additionally, the photocatalytic properties of complexes <b>1 </b>−<b> 2</b> toward the degradation of dyes have been investigated.