Synthesis of luminescent Cu9S5 nanoclusters from copper-2,5-dimercapto-1,3,4-thiadiazole coordination polymer as pH sensor

Cu9S5 nanoclusters (Cu9S5 NCs) with photoluminescence emission in the visible region have been synthesized via a simple treatment of copper-2, 5-dimercapto-1, 3, 4-thiadiazole (Cu(II)-DMTD) coordination polymer with ammonium hydroxide. This procedure involves a desulfurative C-N cross-coupling route, in which one mercapto group was replaced by amine, resulting in 2-mercapto-5-amine-1,3,4-thiadiazole (AMTD) as protecting agent for Cu9S5 NCs. The product exhibits a fluorescence emission at 567 nm with a quantum yield (Phi) 0.068. The as-prepared Cu9S5 NCs were employed as a broad-range pH sensor by virtue of the fluorescence intensity responding sensitively to pH fluctuating in a linear range of 3.0-10.0.