Metal-Ion Exchange, Small-Molecule Sensing, Selective Dye Adsorption, and Reversible Iodine Uptake of Three Coordination Polymers Constructed by a New Resorcin[4]arene-Based Tetracarboxylate

By using a new resorcin[4]arene-based tetracarboxylate, three functional coordination polymers (CPs)--namely, [(CH3)2NH2][Cd2NaL(HCOO)2(HCOOH)(H2O)]·H2O (1), [(CH3)2NH2]2[CdL]·CH3OH·4H2O (2), and [(CH3)2NH2][Zn2Na3L2(H2O)2]·H2O (3)--have been synthesized under solvothermal conditions (H4L = 2,8,14,20-tetra-pentyl-4,10,16,22-tetrakis((4-carboxybenzyl)oxy)-6,12,18,24-tetra-methoxy-resorcin[4]arene and DMF = N,N'-dimethylformamide). The structures of 1-3 have been confirmed by single-crystal X-ray diffraction analyses and further physically characterized. In 1, L and HCOO(-) link Cd(II) and Na(I) ions to yield an unusual three-dimensional (3D) 4-connected heterometallic framework with (4(2)·6(4))(4·8(3)·10·12) topology. In 2, L anions link Cd(II) ions to give a 3D binodal 4-connected framework with (4(2)·6(3)·8)2 topology. In 3, adjacent dodecanuclear heterometallic clusters are joined together by L anions, yielding a two-dimensional (2D) (3,8)-connected (3·4(2))(3(4)·4(6)·5(6)·6(8)·7(3)·8) network. Most strikingly, CPs 1 and 2 display unusual metal-ion exchange characters. CP 2 shows remarkable reversible adsoption of I2 molecules. In addition, CPs 1-3 can selectively adsorb organic dyes and exhibit highly luminescent sensing properties for small molecules.