Photoactive boron˗nitrogen˗carbon hybrids: from azo˗borazines to polymeric materials

Hamid Oubaha, Nicola Demitri, Joëlle Rault˗Berthelot, Philippe Dubois, Olivier Coulembier, Davide Bonifazi
J. Org. Chem. 2019, 84, 14, 9101-9116.
DOI: 10.1021/acs.joc.9b01046


In this paper, we describe synthetic routes for preparing a novel switchable BNC-based chromophore, composed of a borazine core peripherally functionalized with azobenzene moieties. Capitalizing on the Pd-catalyzed Suzuki cross-coupling reaction between a tris-triflate borazine and an organoboron azobenzene derivative, a photoswtichable azo-borazine derivative was successfully prepared. The molecule showed reversible E/Z photoisomerization upon irradiation at the maximum of the intense π–π* absorption feature (360 nm). X-ray crystallographic investigations revealed a nonplanar orientation of the three azobenzene moieties and the trans configuration of the −N═N– bonds. Building on the synthetic versatility of the borazine-azobenzene derivative, we used this photoactive scaffold to engineer soluble BN-doped polythiophene polymers. Photophysical characterization performed in solvents of different polarity suggested that the polymer undergoes intramolecular charge transfer (ICT).

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