Two 2D metal–organic frameworks based on N-heterocyclic and polycarboxylates ligands: Syntheses, structures, and photoluminescent properties

Two novel complexes constructed from aromatic acid and N-heterocyclic ligands have been synthesized by hydrothermal reaction: {[Mn(dipt)(BDC)3⋅H2O]n (1) [dipt = 2-(2,4-dichlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, BDC = terephthalic acid] and [Pb(dnpt)(BDC)2]n (2) [dnpt = 2-(4-nitrophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline]. Complexes 1 and 2 were characterized by elemental analysis, IR, single crystal X-ray diffraction and thermogravimetric analysis (TGA). The results suggest that complexes 1–2 exhibit 1D chain structure. The intermolecular C–H⋯O and N–H⋯O interactions extend the complexes into 2D networks, and the existing H-bonds further stabilized the title complexes, which can be proved by TGA experiment. Furthermore, the solid-state fluorescence spectrum of complexes 1 and 2 were also investigated, as well as the ligands dipt and dnpt.

► Two complexes constructed from novel N-heterocyclic ligands have been synthesized and characterized.
► Weak interactions provide additional assembly forces.
► The fluorescence spectrum of the complexes and ligands are also investigated.