Substituted groups-directed assembly of Cd(II) coordination polymers based on 5-R-1,3-benzenedicarboxylate and 4,4′-bis(1-imidazolyl)bibenzene: syntheses, structures and photoluminescent properties

Hydrothermal reactions of CdCl2 center dot 2.5H(2)O with 4,4'-bis(1-imidazolyl)bibenzene (bimb) and 1,3-benzenedicarboxylate (1,3-H2BDC), 5-methyl-1,3-benzenedicarboxylate (5-Me-1,3-H2BDC), 5-amino-1,3-benzenedicarboxylate (5-NH2-1,3-H2BDC), 5-hydroxy-1,3-benzenedicarboxylate (5-HO-1,3-H2BDC), 5-nitro-1,3-benzenedicarboxylate (5-NO2-H(2)1,3-BDC), or 5-sulfo-1,3-benzenedicarboxylate (5-HSO3-1,3-H2BDC) resulted in the formation of six Cd(II) coordination polymers, [Cd(5-R-1,3-BDC)(bimb)](n) (R = H (1), R = Me (2), R = NH2 (3), R = OH (4)), {[Cd-2(H2O)(5-NO2-1,3-BDC)(2)(bimb)]center dot 2H(2)O}(n) (5) and [Cd(5-SO3-1,3-HBDC)(bimb)](n) (6). Compounds 1-6 were characterized by elemental analysis, IR, powder X-ray diffraction and single-crystal X-ray diffraction. 1-4 exhibit similar 3D frameworks in which 2D [Cd-4(5-R-1,3-BDC)(4)](n) (R = H, Me, NH2 and OH) layers are interlinked by bimb ligands. 5 has a two-fold interpenetrating 3D framework in which 1D [Cd-2(5-NO2-1,3-BDC)(2)](n) chains are interconnected by bimb ligands. 6 shows a 3D (3,5)-connected framework in which 2D [Cd-2(5-SO3-1,3-HBDC)(2)](n) networks are bridged by bimb ligands. The Schlafli symbols for these six 3D nets are (4.6(2))(4.6(6).8(3)) (1-4), (4(2).6)(4(2).6.10(2).12) (5) and (4.6.8)(4.6(5).8(3).10) (6). The solid state photoluminescent properties of 1-6 were also investigated.