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Abstract:
Solvothermal reactions of "V"-shaped 3,5-di(4'-carboxyl-phenyl) benzene
acid (H(2)dpb), and Cd(II)/Zn(II) salts in the presence of four
ancillary bridging imidazole linkers afford four novel luminescent
coordination polymers (LCPs), namely, {[Cd(dpb)(2)(bimb)(2)]center dot
0.5H(2)O}(n) (1), [Cd(dpb)(tib)](n) (2), [Zn(Hdpb) 2(4,4'-bibp)](n) (3)
and [Cd(dpb)(1,3-bitl)](n) (4), (bimb = 1,4-bis(imidazol-1-ylmethyl)
benzene, tib = 1,3,5-tris(1-imidazolyl) benzene, 4,4'-bibp =
4,4'-bis(imidazol-1-yl) biphenyl and 1,3-bitl = 1,3-bis(1-imidazoly)
toluene). Then complexes 1-4 are characterized by elemental analysis, IR
spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric (TG)
analysis and single-crystal X-ray diffraction. Single-crystal X-ray
diffraction analysis shows that complex 1 shows an unprecedented 3-nodal
(2,2,4)-connected 2D + 2D -> 3D two-fold interpenetration framework with
the Schlafli symbol (12(5) . 16)(12)(2). Complexes 2 and 3 show a 2D
layer structure and 1D zigzag chain, which are further assembled into a
3D supramolecular structure by pi center dot center dot center dot pi
interactions and H-bonds, respectively. While complex 4 displays a
3-nodal (2,2,8)-connected network with a -ABAB- fashion. The luminescent
recognition properties of polymers 1-4 to metal cations and anions have
also been explored systematically. The results demonstrate that 2 and 3
display highly sensitive and selective luminescence sensing towards Fe3+
ions, and 4 displays highly sensitive and selective luminescence sensing
towards Cu2+ ions. 1-4 can work as highly sensitive sensors to Cr2O72-
by luminescence quenching. Moreover, the photocatalytic properties of
four Cd(II)/ Zn(II) compounds (complex 1-4) have also been investigated.
