An eight-connected 3D lead(ii) metal–organic framework with octanuclear lead(ii) as a secondary building unit: synthesis, characterization and luminescent property

Abstract

A novel 3D lead(II) metal–organic framework {Pb₄(Bdc)₃(µ₄-O)(H₂O)}_n (1) (H₂Bdc = isophthalic acid) with octanuclear [Pb₈(Bdc)₆(µ₄-O)₂(H₂O)₂] as secondary building units (SBUs) has been obtained and fully characterized by single crystal X-ray diffraction, IR, elemental analysis, TG-DTA and fluorescent spectra. XRD results indicate octanuclear lead(II) SBU contains two inversely related [Pb₄(µ₄-O)] cores and is extended topologically into an infinite eight-connected bcu-type network via twelve Bdc ligands linking eight neighboring SBUs. At room temperature, 1 in the solid-state exhibits strong emission peak at 424 nm originated from the LMCT between delocalized π bonds of Bdc carboxylate groups and p orbitals of lead(II) centers.