| Abstrakt: |
Two new two‐dimensional (2D) coordination polymers (CPs), namely, poly[diaqua[μ4‐2,2′‐(1,3,5,7‐tetraoxo‐1,2,3,5,6,7‐hexahydropyrrolo[3,4‐f]isoindole‐2,6‐diyl)diacetato‐κ4O:O′:O′′:O′′′]cadmium(II)], [Cd(C14H6N2O8)(H2O)2]n (1), and poly[[tetraaqua[μ4‐2,2′‐(1,3,5,7‐tetraoxo‐1,2,3,5,6,7‐hexahydropyrrolo[3,4‐f]isoindole‐2,6‐diyl)diacetato‐κ4O:O′:O′′:O′′′][μ2‐2,2′‐(1,3,5,7‐tetraoxo‐1,2,3,5,6,7‐hexahydropyrrolo[3,4‐f]isoindole‐2,6‐diyl)diacetato‐κ2O:O′]dizinc(II)] dihydrate], {[Zn(C14H6N2O8(H2O)2]·H2O}n (2), have been synthesized by the microwave‐irradiated reaction of Cd(CH3COO)2·2H2O and Zn(CH3COO)2·2H2O, respectively, with N,N′‐bis(glycinyl)pyromellitic diimide {BGPD, namely, 2,2′‐(1,3,5,7‐tetraoxo‐1,2,3,5,6,7‐hexahydropyrrolo[3,4‐f]isoindole‐2,6‐diyl)diacetic acid, H2L}. In the crystal structure of 1, the CdII ion is six‐coordinated by four carboxylate O atoms from four symmetry‐related L2− dianions and two coordinated water molecules, furnishing an octahedral coordination geometry. The bridging L2− dianion links four symmetry‐related CdII cations into a 2D layer‐like structure with a 3,4‐connected bex topology. In the crystal structure of 2, the ZnII ion is five‐coordinated by three carboxylate O atoms from three different L2− dianions and two coordination water molecules, furnishing a trigonal bipyramidal coordination geometry. Two crystallographically independent ligands serve as μ4‐ and μ2‐bridges, respectively, to connect the ZnII ions, thereby forming a 2D layer with a 3,3‐connected hcb topology. Crystal structure analysis reveals the presence of n→π* interactions between two carbonyl groups of the pyromellitic diimide moieties in 1 and 2. CP 1 exhibits an enhanced fluorescence emission compared with free H2L. The framework of 2 decomposes from 720 K, indicating its high thermal stability. A comparative analysis of a series of structures based on the BGPD ligand indicates that the metal‐ion size has a great influence on the connection modes of the metal ions due to different steric effects, which, in turn, affects the structures of the SBUs (secondary building units) and frameworks. [ABSTRACT FROM AUTHOR] |
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