Self-assembly of two zinc complexes with flexible building block of 4-pyridylthioethylphosphonate

A new organophosphonate ligand containing sulfide group, 4-pyridylthioethylphosphonic acid hydrobromide (H₂pytep·HBr), is synthesized through a facile route. Two zinc complexes of Zn₂(pytepH₂)₂Br₄ (1) and Zn(pytep)]·H₂O (2) are obtained by reacting H₂pytep·HBr with zinc nitrate in solution and under hydrothermal condition, respectively. X-ray crystallographic studies reveal that 1 has a dinuclear structure in which the equivalent Zn atoms are doubly bridged by phosphonate groups. Compound 2 has a layer structure where ladder-like chains made up of corner-sharing {ZnNO₃} and {CPO₃} tetrahedra are linked by the organic groups of pytep. Photoluminescent properties are investigated. Different from complex 1 which shows no photoluminescence, complex 2 exhibits photoluminescence at 468 nm (λ_ex = 353 nm) in the solid state at room temperature.