Structures and Photoluminescence of Two Coordination Polymers Based on 2-Hydroxypyrimidine-4,6-dicarboxylic Acid

Two IIB group metal complexes based on 2-hydroxypyrimidine-4,6-dicarboxylic acid (H 3 L), formulated as {[Zn 3 L 2 (H 2 O) 4 ]·2H 2 O} n ( 1 ) and {[Cd 3 L 2 (H 2 O) 6 ]·H 2 O} n ( 2 ), have been synthesized solvothermally. Structural studies reveal that 1 and 2 are two- and one-dimensional polymeric networks, respectively, both of which are expanded to three-dimensional supramolecular structures by hydrogen bonds. The L 3− ligand takes the same μ 4 κ 5 ligation mode in both complexes. The Zn(II) coordination polyhedron in 1 is either octahedral or square pyramidal, but the Cd(II) atoms in 2 adopt two different octahedral polyhedra. Both 1 and 2 display remarkably strengthened fluorescence compared to the free H 3 L, and 1 emits much stronger than 2 , consistent with the structural features. Graphical Zn(II) and Cd(II) coordination polymers of 2-hydroxypyrimidine-4,6-dicarboxylic acid with 2D and 1D dimensions respectively exhibit different photoluminescence behavior.