Divergent topologies in luminescent and nitrobenzene-detecting zinc diphenate coordination polymers with flexible dipyridylamide ligands

Abstract

Hydrothermal reaction of zinc nitrate, diphenic acid (H2dip), and one of the dipyridylamide ligands N,N′-(hexane-1,6-diyl)diisonicotinamide (hdin), N,N′-(pentane-1,5-diyl)diisonicotinamide (pedin), N,N′-(butane-1,4-diyl)diisonicotinamide (bdin), or N,N′-(ethane--1,2-diyl)diisonicotinamide (edin) resulted in coordination polymers whose dimensionalities depend on the aliphatic tether length within the coligand and the amount of base used in the synthesis. The five new phases were characterized by single crystal X-ray diffraction. {[Zn(dip)(hdin)]·2.5H2O}n (1) and {[Zn(dip)(pedin)]·2.5H2O}n (2) both possess undulating 2D coordination polymer layers with [Zn(dip)]n chains spanned by looped dipyridylamine ligands into a 2,4-connected self-penetrated (6)(648.10) topology. [Zn(dipH)2(bdin)]n (3) manifests a 1-D zig-zag chain topology, while {[Zn3(dip)3(bdin)3]·13H2O}n (4) and {[Zn(dip)(edin)]·3H2O}n (5) manifest helical substructures linked into a rare two-fold interpenetrated 6482nbo topology. Thermal and luminescent properties were also probed; compounds 1–5 showed ability to detect nitrobenzene in ethanol suspension with the 3D derivatives 4 and 5 manifesting the best “turn-off” luminescence quenching behavior.