Luminescent zinc terephthalate coordination polymers with pyridylnicotinamide ligands: Effect of added base and nitrogen donor disposition on topology

Abstract

Hydrothermal reaction of zinc nitrate, potassium terephthalate (K2tere), and 3-pyridylnicotinamide (3-pna) or 4-pyridylnicotinamide (4-pna) afforded coordination polymers with different dimensionality depending on nitrogen donor disposition and the initial pH of the reaction mixture. {[Zn(tere)(3-pna)2(H2O)2]⋅2H2O}n (1) was prepared in the presence of aqueous NaOH, and manifests 1-D coordination polymer chains with monodentate 3-pna ligands. A mixture of {[Zn(tere)(3-pna)]⋅3H2O}n (2) and {[Zn4(tere)3(OH)2(3-pna)2]⋅2H2O}n (3) was prepared by performing a similar reaction in the absence of extra base. Compound 2 shows a 2-D (6,3) hexagonal grid topology with very tight interdigitation, while 3 has a 2-fold interpenetrated 3-D pcu network built from {Zn4(OCO)2(OH)2} centrosymmetric tetrameric nodes. {[Zn(tere)(4-pna)]⋅H2O}n (4) has parallel 2-fold interpenetrated sawtooth layer motifs. Luminescent and thermal decomposition properties are also discussed.