Pillar-template strategy switching the redox activity and magnetic properties of trisphenylamine-based coordination polymers
It is an efficient approach to exploit the pillaring and templating strategy for creating varieties of functionalized coordination polymers (CPs). Four novel CPs incorporating single metal nodes and redox-active tris(4-(pyridine-3-yl)phenyl)amine ligand (m-NPy3) have been prepared by a hydrothermal method. Compounds 1-3, [M(m-NPy3)(NO3)2·CH3OH]n (M = Co for 1, Ni for 2, Zn for 3), are isomorphous two-dimensional (2D) layered CPs. Compound 4, [Co(m-NPy3)(TPA)0.5Cl·CH3OH]n (TPA = bidentate terephthalic acid), is a three-dimensional (3D) CP, which is pillared by linear bidentate terephthalic acid (TPA) linkers. Notably, with the existence of TPA, the layered compound 1 can be further assembled to the 3D pillared-layer architecture 4 by the single-crystal-to-single-crystal (SC-SC) transformation. All compounds were characterized and the redox activity of trisphenylamine is maintained in all four CPs proven by solid-state cyclic voltammetry. Compared with 1, the location of the first oxide peak in 4 shows a reduction of nearly 0.14 V vs Fc/Fc+. The magnetic study shows that the pillared-layer 4 exhibits the typical field-induced single-ion magnet property with a higher energy barrier (13.1 K) than 1 (5.1 K).