Photodissociation Rate Constants of New Light Sensitive Alkoxyamines

The photochemical properties of two new photocleavable alkoxyamines bearing a benzophenone‐derived chromophore were studied by electron spin resonance (ESR). The CO bond cleavage has been demonstrated and the photolysis rate constants (kd) determined over a large range of light intensity through the monitoring of the nitroxide concentration in aerated conditions. The obtained kinetic data highlight for the first time the linear dependence of kd on the light intensity for alkoxyamines: this should be a driving factor for nitroxide mediated radical photopolymerization (NMP2). The photodecomposition of two new photosensitive alkoxyamines bearing a benzophenone chromophore have been studied. ESR experiments highlight the CO bond cleavage under UV irradiation and allow to measure the photolysis rate constants kd of the alkoxyamines. It clearly appears that kd can be modulated by varying the light intensity and as a consequence, the nitroxide mediated photopolymerization (NMP2) behavior should be driven by the value of the light intensity.