Spectroscopic study of cyclen-based 19 F NMR probe for detection of hydrogen sulfide

A cyclen-based 19 F NMR probe (F-cyclen) for hydrogen sulfide (H 2 S) has been prepared and evaluated for its complex formation ability with Cu 2+ ions and responsivity to H 2 S. F-Cyclen was readily synthesized by reacting cyclen with 4-(trifluoromethyl)benzyl bromide. Visible absorption spectrophotometry showed that, same as the original cyclen, F-cyclen formed a 1:1 complex with Cu 2+ ions. The 19 F NMR signal of F-cyclen at 16.5 ppm gradually decreased in intensity with increasing CuCl 2 concentration, with trifluoromethane sulfonic acid sodium salt (TFMSNa) used as an internal standard (0 ppm). When the Cu 2+ –F-cyclen complex was subjected to an increasing concentration of Na 2 S (as H 2 S donor), its corresponding 19 F NMR signal of F-cyclen at 16.5 ppm gradually increased in intensity. The regression curve between the 19 F NMR signal intensity ratio of F-cyclen to TFMSNa and Na 2 S concentration showed good linearity ( r = 0.986) over the Na 2 S concentration range of 25–150 μM. Graphical abstract