Three polymers based on pyridine-2,3,5,6-tetracarboxylic acid: Syntheses, crystal structures and luminescent properties

Three novel coordination polymers, {[cis-K2Zn2Mn(μ7-pdtc)2(H2O)10]·H2O}n (1), {[cis-K2Zn3(μ7-pdtc)2(H2O)10]·0.5H2O}n (2) and [trans-K2Zn3(μ5-pdtc)2(H2O)12]n (3), were synthesized by the self-assembly of potassium pyridine-2,3,5,6-tetracarboxylate (K4pdtc) with metal salts. 1 is the first Zn/Mn/K heterotrimetallic complex with H4pdtc. 1 and 2 have 3D network structures, while 3 is a 2D coordination polymer, which are due to the different bonding modes of H4pdtc with K(I) and metal(II) ions. The fluorescence spectroscopy measurements reveal that strong photo-luminescent characteristics exhibit in 1–3 in aqueous solution at room temperature.