A colorimetric response to hydrogen sulfide

Two simple Cu(II) chromophores [Cu(acac)(dmp)](NO3) (1) and [Cu(acac)(dpph)](NO3) (2) (acac = acetylacetone, dmp = 2,9-dimethyl-1,10-phenanthroline and dpph = 4,7-diphenyl-1,10-phenanthroline) have been synthesised and immobilized into a highly permeable polymer matrix and subsequently used in the optical detection of low levels of hydrogen sulfide (10 ppm) over a 2 min period. The system is responsive to a concentration one-tenth that quoted as being immediately dangerous to life and health (IDLH) value (100 ppm) by the National Institute for Occupational Safety and Health (NIOSH). The UV–vis spectral change is a consequence of the hydrogen sulfide gas reducing the Cu(II) to Cu(I) in the polymer matrix. A crystal structure of [Cu(acac)(dpph)](NO3) (2) was obtained and will also be discussed.