Optoelectronic properties of a self-assembling rigidly-linked BF2-curcuminoid bichromophore

Claire Tonnelé (1) , Manon Catherin (2) , Michel Giorgi (2) , Gabriel Canard (2) , David Casanova (1) , Frédéric Castet (3) , Elena Zaborova (2) , Frédéric Fages (2)

1 DIPC - Donostia International Physics Center
2 AMU - Aix Marseille Université
3 UB - Université de Bordeaux

We describe the synthesis and spectroscopic study of the bichromophoric molecule DA-meso consisting of two boron difluoride curcuminoid (BF 2-curcuminoid) units tethered by the rigid diacetylenic bridge. This structural feature imparts the quadrupolar-like DA-meso with a strong ability to self-assemble in solution, which induces a profound change in the optical properties. The UV-vis absorption spectrum of the aggregate is characterized by the appearance of a redshifted band at low energy and its fluorescence emission occurs in the near infrared ( max = 700 nm) with a low quantum yield (5 %). This is in contradiction with the strong emission expected for J-aggregates considering the Frenkel exciton model. From concentration-dependent UV-vis absorption spectroscopy we demonstrate the formation of a dimer composed of four BF 2-curcuminoid units. Single-crystal X-ray diffraction structure analysis and in-depth quantum chemical calculations based on density functional theory (DFT) and subsequent decomposition of the electronic excited states on a diabatic basis enable to discuss the geometry of the DA-meso dimer, and to establish the presence of excited states close in energy to that of the unperturbed monochromophore, which are not predicted by the classical Frenkel exciton model. Different dimer structures characterized by π-stacks of two and up to four chromophores are investigated, in which low-lying excited states with

Domaines: Chimie

Claire Tonnelé, Manon Catherin, Michel Giorgi, Gabriel Canard, David Casanova, et al.. Optoelectronic properties of a self-assembling rigidly-linked BF2-curcuminoid bichromophore. Dyes and Pigments, 2022, 207, pp.110677. ⟨10.1016/j.dyepig.2022.110677⟩. ⟨hal-03778198⟩