Singlet oxygen generated from the decomposition of peroxymonocarbonate and its observation with chemiluminescence method

The decomposition of peroxymonocarbonate (HCO4−) has been investigated by flow-injection chemiluminescence (CL) method. An ultraweak CL was observed during mixing the bicarbonate and hydrogen peroxide solution in organic cosolvent. An appropriate amount of fluorescent organic compounds, such as dichlorofluorescein (DCF), was added to the HCO4− solution, a strong CL was recorded. Based on studies of the spectrum of fluorescence, CL and UV–vis spectra, electron spin trapping (ESR) technique, mass spectra (MS) and comparison with H2O2/hypochlorite (ClO−) and H2O2/molybdate (MoO4−) systems, the CL mechanism was proposed. The reaction is initiated by unimolecular homolysis of the peroxo OO bond in HOOCOO− molecule. It was suggested that the bond rearrangement within radicals yield superoxide ion (O2−). The interaction of superoxide ion with perhydroxyl radical produces singlet oxygen (1O2). The energy transfers from singlet oxygen to DCF forming an excited energy acceptor (DCF*). Luminescence (λmax = 509 nm) was emitted during the relaxation of the energy acceptor to the ground state.