Abstract: Using 2-mercaptoisonicotinic acid (H₂mna)， Cu⁺ and Zn²⁺ as raw materials, a  novel heterometallic complex {\Cu₆Zn₃(mna)₆(en)₃H₂O\].solvent}_n(1)  was prepared by solvothermal  synthesis using a one-pot  method. Its structure and thermal stability were characterized by single crystal  X-ray diffraction,  infrared spectroscopy and thermogravimetric analysis. The experimental results show that the  interactions of Cu⁺  and (mna)^2-₆ in compound 1 form  two anionic \[Cu₆(mna)₆\]^6-  metal ligands through coordination bonds,  both containing pseudo\|hexagonal prismatical Cu₆S₆ clusters,  and Cu₆S₆ clusters are connected to  Zn²⁺  to form a three-dimensional network structure.  Compound 1 exhibits distinct red light emission in the solid state with a maximum emission wavelength of 664 nm. Compound 1 shows a sensitive fluorescence quenching response to 2-nitrotoluene,  with quenching constant (K_SV) and detection limit of  2.33×10³ (mol/L)^-1 and 1.20×10^-5 mol/L,  respectively. The quenching effect of 2-nitrotoluene is primarily due to photoinduced electron transfer.

Key words: Cu₆S₆ cluster,  , one-pot method,  , heterometallic complex,  , fluorescence sensing