A series of transition metal-organic frameworks based on a bipyridinium carboxylate ligand: Syntheses, structures and photoluminescent properties

Abstract

Based on a bipyridinium carboxylate ligand 1-(3,5-dicarboxy)-benzyl-1,2-di(pyridine-4-yl)ethylene chloride (H2L+Cl−), eight transition metal coordination polymers, namely, {[Zn(L)Cl]⋅4H2O}n (1), {[Zn(L)H2O]⋅NO3⋅2H2O}n (2), {[Zn(L) (H2O)]⋅(NO3)0.5⋅(Cl)0.5⋅2H2O}n (3), {[Cd(L)(H2O)(NO3)]⋅2H2O}n (4), {[Cd1.5(L) (Cl)2]⋅2H2O}n (5), {[Cu(L)(H2O)]⋅NO3⋅H2O}n (6), {[Cu(HL)2(H2O)2]·Cl2·6H2O}n (7) and {[Ni(L)(H2O)Cl]⋅4H2O}n (8) have been synthesized and characterized by single-crystal X-ray diffraction analyses. Complexes 1 and 8 display 2D wave-like layer structures with a 3-connected 63 topology. Complexes 2 and 6 demonstrate 3D 2-fold interpenetrating frameworks with uninodal, 3-connected (10,3)-d utp-topology. Another pair of 3D 2-fold interpenetrating frameworks 3 and 4 possess 3-connected, uninodal 103ThSi2 (ths)-topology. Complex 5 shows a 2D layer structure based on the extending of trinuclear Cd(II) subunits. Complex 7 presents 1D double-chain structure, in which the central Cu(II) ions are connected by the partially deprotonated ligand HL. Additionally, powder X-ray diffractions (PXRD) and thermogravimetric analyses of complexes 1–8, as well as the solid-state luminescent properties of d10 metal complexes 1–4 at room temperature have also been discussed.