A new pyrene-based tert-butylnitroxide radical “off-on” fluorescent probe for H2S detection in living cells

Abstract A new pyrene-based tert -butylnitroxide radical 1- tert -butyl(pyrenyl)nitroxide ( TBPNO ) has been designed and synthesized with medium yield by two steps using 1-bromopyrene as the starting material, which has been fully characterized by the means of mass spectrum, single X-ray diffraction analysis, elemental analysis and electron spin resonance. In addition, the magnetic property of the title compound has been measured, which also confirms the single electron nature of radical. The photochemical properties of compound TBPNO have been investigated in detail under different pH environments and various biologically-related species. The results show that compound TBPNO displays excellent selectivity, sensitivity and quick response time for the detection of H 2 S in aqueous solution, as well as living cells by showing a significant ‘‘off–on’’ fluorescence change with the detection limit of 17.9 nM. The study on the recognition mechanism indicates that the detection of compound TBPNO for H 2 S can be attributed to the transformation of compound TBPNO to N - tert -butyl-1-pyrenylamine ( Py-NH ). This is the first H 2 S probe based on the nitroxide radical recognition site.