First 3D heterotrimetallic Mn(II)–Cu(II)–K(I) polymer and three 3D Cu(II)/Mn(II) open network based on pyridine-2,3,5,6-tetracarboxylic acid

Four novel 3D coordination polymers, {[K3Cu2(H0.5pdtc)2 (H2O)6]·(H2O)2}n (1), {[trans-K2Mn3(pdtc)2 (H2O)11]·H2O}n (2), {[trans-K2Mn3(pdtc)2 (H2O)10]·H2O}n (3) and {[cis-K2Cu2Mn(pdtc)2 (H2O)10]·H2O}n (4), were synthesized by the self-assembly of potassium pyridine-2,3,5,6-tetracarboxylate (K4pdtc) with metal salts. All of them contain infinite 1D stepwise chain. Notably, 2–4 have 2D network structures depending on the trans- and cis- hexacoordinated Mn(II) acting as connecters between the chains. Then, they further assemble into 3D or twin-plane structures by K(I) ions. 4 is the first Cu/Mn/K heterotrimetallic complex with H4pdtc. The (H2O)6 clusters in 1 arranged stepwise along the complex chains owing to the host chainsʹ template effect. The variable–temperature magnetic measurements reveal that weak antiferromagnetic interactions exist in complexes 1 and 4.