Substituent effects in 4-connected zinc isophthalate coordination polymers with a pyridylnicotinamide ligand: From dimer-based layers to ribbons with embedded infinite water molecule chains

Abstract

The dimensionality and structure of divalent zinc coordination polymers containing the dipyridylamide ligand 3-pyridylnicotinamide (3-pna) can be adjusted by varying the 5-position substituent on an isopthalate moiety. Two new coordination polymer solids were obtained by hydrothermal self-assembly and structurally characterized via single-crystal X-ray diffraction. Using the unsubstituted isophthalate (ip) ligand, [Zn(ip)(3-pna)]n (1) was obtained. This material exhibits {Zn2(OCO)2} dimer-based [Zn(ip)]n chains linked into (426)(42678) 3,5L2 topology layers by anti conformation 3-pna ligands. By employing 5-methylisophthalate (mip), the coordination polymer {[Zn(mip)(3-pna)]·2H2O}n (2) was obtained; these feature syn conformation 3-pna ligands. Compound 2 shows a rarely encountered 4-connected 1-D ribbon motif with 33425 topology, encapsulating infinite single-file water molecule chains within incipient tubular channels. Thermal and luminescent properties of these materials are also discussed.