Synthesis, structures and luminescent properties of cadmium(ii) metal organic frameworks based on 3-pyrid-4-ylbenzoic acid, 4-pyrid-4-ylbenzoic acid ligands

Abstract

Two three-dimensional metal–organic frameworks, [Cd₃K(L₁)₆(H₂O)₃](OH)(DMF)₄ (1) (HL₁ = 3-pyrid-4-ylbenzoic acid) and [Cd(L₂)₂](DMF)(H₂O)_0.25 (2) (HL₂ = 4-pyrid-4-ylbenzoic acid), have been synthesized by using two ligands with different configuration and characterized by X-Ray diffraction and other techniques. Compound 1 shows a nanosize channel which is constructed by interlocked six-fold one-dimensional helical chains with the asymmetrical ligand HL₁. Compared with compound 1, compound 2 shows a larger size channel with the symmetrical ligand HL₂ in a single set of diamond cage. Nevertheless, the whole structure with the 4-fold interpenetrated diamondoid network leads to the absence of void space. The two compounds exhibit fascinating luminescence because of the interaction between Cd ions and organic ligands.