Synthesis, X-ray structures and luminescence properties of three multidimensional metal–organic frameworks incorporating the versatile 5-(pyrimidyl)tetrazolato bridging ligand

The hydrated sodium salt of the novel and versatile 5-(pyrimidyl)tetrazolato ligand (pmtz-), Na(pmtz)*H2O (1), has been prepared in very mild conditions from 2-cyanopyrimidine and NaN3. Two coordination polymers [Cd(pmtz)2]n (2) and [Cd(pmtz)(mu-Cl)0.5(mu-N3)0.5(H2O)]n (3), have been synthesized from (1) under conventional or hydrothermal conditions, respectively, and fully characterized by single-crystal or powder X-ray diffraction methods. Compounds 1 and 3 consist of mono-dimensional polymeric chains, further stabilized by interchain pi-pi stacking and hydrogen bond interactions. Compound 2, containing octacoordinated Cd ions of crystallographic D-2 symmetry, exhibits neutral (4, 4) layers formed by square units of the metallacalix[4]arene type in 1,3-alternate conformation. Species 1, 2 and 3 display intense, room temperature, photoluminescence in the solid state.