Synthesis, Structures and Properties of Two Ln(III) Coordination Polymers based on Pyrimidine‐2‐carboxylic Acid and Sodium Dicyanamide

Assemblies of pyrimidine‐2‐carboxylic acid (Hpmc) and samarium nitrate or europium nitrate in the presence of sodium dicyanamide (Na‐dca) under ambient conditions yielded two new coordination polymers, namely [Ln(pmc)2(dca)(H2O)2]n (Ln=Sm (1), Eu (2)). The complexes were characterized by single‐crystal X‐ray diffraction analysis, elemental analysis, IR and fluorescence spectra. Structure analysis shows two complexes are isostructural with monoclinic (C2/c) symmetry. And each central metal atom is coordinated by three chelate pmc−, one terminal dca− and two water molecules to generate an infinite zigzag chain. Through Owater−H ⋅ ⋅ ⋅ Ocarboxylate, Owater−H ⋅ ⋅ ⋅ Npyrimidine hydrogen bonds, the chains are connected to a two‐dimensional net, which is furtherly extended to a three‐dimensional supramolecular structure by Owater−H ⋅ ⋅ ⋅ Ncyano hydrogen bonds. Luminescent measurement of complex 2 shows the characteristic fluorescence of Eu3+.