Two d10-metal-organic frameworks based on polydentate Schiff-base ligand derived from biphenyl dihydrazide: Synthesis, crystal structure and luminescent properties

Two two-dimensional d10-metal-organic frameworks {[CdL2(NO3)2]·(H2O)6}n (1) and {[Zn2L4(NCS)4]·(H2O)4·(CH3OH)}n (2) have been synthesized and characterized by IR, elemental analyses, XRPD, TG technique and complete X-ray single crystal structure analyses, where L is bis(pyridin-3-ylmethylene)biphenyl-2,2′-dicarbohydrazide. The two polymers display similar 2D layer network containing tetranuclear metallacyclic ring units [MII4L4] (M = Cd (1) and Zn (2)) in the chair conformation, in which each ligand L acts as a bidentate bridging ligand to bind two metal centers through two terminal pyridyl N-donors. The solvent molecules were filled into the macrometallacyclic ring units through multiform hydrogen bonds. In addition, the CH⋯π interactions are found in the 2D networks and also play an important role in stabilizing the networks. The luminescent properties of 1 and 2 were investigated in the solid state at room temperature.

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► Two d10-metal-organic frameworks have been synthesized.
► The polymers have been characterized by IR, XRPD, TG technique.
► The polymers display similar 2D network containing tetrametallic rings [MII4L4].
► The two polymers exhibit fluorescent emission in solid state, respectively.