Tris‐benzo[<i>cd</i>]indole Cyanine Enables the NIR‐photosensitized Radical and Thiol‐ene Polymerizations at 940 nm
Christine Elian, Benjamin Mourot, Camil Benbouziyane, Jean‐Pierre Malval, Sonia Lajnef, Fabienne Peyrot, Florian Massuyeau, Olivier Siri, Denis Jacquemin, Simon Pascal, Davy‐Louis Versace
Abstract
Abstract A near‐infrared‐absorbing heptamethine ( HM + ) incorporating three bulky benzo[ cd ]indole heterocycles was designed to efficiently prevent self‐aggregation of the dye, which results in a strong enhancement of its photoinitiating reactivity as compared to a parent bis‐benzo[ cd ]indole heptamethine ( HMCl + ) used as a reference system. In this context, we highlight an efficient free‐radical NIR‐polymerization up to a 100 % acrylates C=C bonds conversion even under air conditions. Such an important initiating performance was obtained by incorporating our NIR‐sensitizer into a three‐component system leading to its self‐regeneration. This original photoredox cycle was thoroughly investigated through the identification of each intermediary species using EPR spectroscopy.