Dipyridylamide ligand dependent dimensionality in luminescent zinc 2,4-pyridinedicarboxylate coordination complexes

Zinc nitrate, 2,4-pyridinedicarboxylic acid (2,4-pdcH2), and a hydrogen-bonding capable dipyridylamide ligand were combined in aqueous solution and subjected to hydrothermal reaction conditions. Three new crystalline coordination complexes were generated; their dimensionality depends crucially on the dipyridylamide length and geometric disposition of the pyridyl nitrogen donors. The three new phases were structurally characterized via single-crystal X-ray diffraction. {[H23-pina][Zn(2,4-pdc)2(H2O)2]·H2O} (1, 3-pina = 3-pyridylisonicotinamide) is a salt with protonated dipyridylamide cations and coordination complex anions. {[Zn2(2,4-pdc)2(H2O)4(3-pna)]·3H2O}n (2, 3-pna = 3-pyridylnicotinamide) shows a system of two-fold interpenetrated ruffled (6,3) coordination polymer layers. {[Zn(2,4-pdc)(H2O)2(3-pmna)]n (3, 3-pmna = 3-pyridylmethylnicotinamide) manifests a simple 1D chain topology. Luminescence was observed for two of the zinc complexes; this behavior is attributed to π–π* or π–n molecular orbital transitions. Thermal decomposition properties of the new phases are also probed. Reaction of zinc nitrate, 2,4-pyridinedicarboxylic acid (2,4-pdcH2), and a dipyridylamide ligand afforded crystalline coordination complexes whose dimensionality depends crucially on the dipyridylamide length and nitrogen donor disposition. {[Zn2(2,4-pdc)2(H2O)4(3-pna)]·3H2O}n (3-pna = 3-pyridylnicotinamide) shows a system of two-fold interpenetrated ruffled (6,3) coordination polymer layers. [Display omitted] •Zinc coordination complexes with 2,4-pyridinedicarboxylate (2,4-pdc).•Derivative with 3-pina (3-pyridylisonicotinamide) is a simple salt.•2-fold parallel interpenetrated (6,3) nets with 3-pna (3-pyridylnicotinamide).•1D coordination polymer chain with 3-pmna (3-pyridylmethylnicotinamide).