Trapping chlorine radicals via substituting nitro radicals in the gas phase

Although chlorine radicals are strong atmospheric oxidants, their direct spectroscopic detection in the environment (gas phase) using conventional analytical techniques has not been reported. Herein, chlorine radicals (Cl-center dot), generated by the YAG laser photolysis (lambda = 355 nm) of Cl-2 in the gas phase, were captured by using 2,2-diphenyl-1-picrylhydrazyl (DPPH center dot). The product was identified as DPPH, wherein NO2 was substituted by Cl-center dot at the ortho-carbon on the picryl aromatic ring, and was characterized using ion attachment ionization-quadrupolemass spectrometry. This reaction mechanism is a rare example of the detection and characterization of radical species, where radical spin densities on trapping reagents and frontier orbital interactions play important roles.