Four congenetic zinc(II) MOFs from delicate solvent-regulated strategy: Structural diversities and fluorescent properties

Four new congenetic zinc(II) MOFs, namely [Zn5(bdcpp)3(DMF)(H2O)4]n·x(solvent) (1), [Zn2(bdcpp)(Hbdcpp)]n·y(solvent) (2), [Zn2(bdcpp)(DMF)(H2O)2]n (3), and [Zn2(bdcpp)(NMP)(H2O)2]n (4) (H4bdcpp = 2,6-bis(2′,4′-dicarboxylphenyl)pyridine, DMF = N,N'-dimethyl formamide, NMP = N-methyl-2-pyrrolidone), have been synthesized solvothermally with different solvent systems. Stabilized by Zn2(COO)4 paddle-wheel building blocks, the resulting MOFs 1–4 represent diverse structural features. Structurally, 1 is a rarely 3,4-c binodal 2D bilayered framework, 2 possesses a 4-c 2D (4,4) sql planar network accommodating two kinds of hetero chiral helix chains, 3 and 4 are isostructural 1D loop ladder chains except different solvent molecules occupying the axial terminals of Zn2(COO)4 paddle-wheels. This approach based on solvent-regulated strategy aiming to allow the structural fine-tuning provides a good role model in reticular chemistry. Complexes 1–3 display excellent solid-state photoluminescence stemming from the metal-to-ligand charge transfer or intraligand charge transmission.