Cadmium(II) and zinc(II) metal-organic frameworks with anthracene-based dicarboxylic ligands: solvothermal synthesis, crystal structures, and luminescent properties

Five new coordination polymers, namely, [Cd-4(L-1)(2)(DPP)(2)(DMF)(2)(SO4)(2)](infinity) (1), [Zn-2(L-1)(DPP)(2)Cl-2](infinity) (2), [Cd(L-2)(DPP)](infinity) (3), [Zn(L-2)(DPP)](infinity) (4) and {[Cd-2(L-2)Cl-4][(CH3)(2)NH2](2)}(infinity) (5), (DPP = 1,3-di(4-pyridyl) propane and DMF = N,N-dimethylformamide), were prepared by solvothermal reactions of anthracene-9,10-dicarboxylic acid (H2L1) or anthracene-1,5-dicarboxylic acid (H2L2) with Cd-II or Zn-II ions, and were structurally characterized by IR, elemental analysis, XRPD and single crystal X-ray diffraction. Complex 1 consists of a three-dimensional (3D) network with bcu (CsCl-type) topology assembled by pillar ligands L-1(2-), DPP and Cd-II ions and has one-dimensional (1D) channels running along the a-axis. In the case of complex 2, the Cd-II and SO42- ions are replaced by Zn-II and Cl-, resulting in a 1D ladder chain. Complexes 3 and 4 are made up of longer pillars, H2L2 instead of H2L1, and have similar 3D four-fold interpenetrating diamond frameworks. And complex 5 forms a two-dimensional (2D) (3(2).6(2).7(2)) kagome structure after taking out the longer pillar DPP. Moreover, the luminescence properties of all the complexes and the corresponding ligands in the solid state at room temperature have been investigated.