Chromophores and Macrocycles

Our researches are focused on three main axes: (1) near-infrared chromophores, (2) molecular sensors and (3) surface coating and engineering.

1. Near-infrared (NIR) chromophores

The access to highly conjugated chromophores exhibiting optical properties in low energies spectral regions (near-infrared, 750-3000 nm) is at the core of our activities since 2013. This domain is highly important, notably in bio-imaging, since it includes the biological transparency windows, which are choice spectral ranges to provide the best penetration depths and contrasts. In the field of molecular electronics, NIR dyes furthermore enable the elaboration of flexible, transparent photo-detectors used for the optical processing or treatment of signals, or incorporated in revolutionary devices mimicking the human eye.

However, chromophores possessing electronic transitions located in the NIR remain scarce. Their preparation often imply multiple synthetic steps yielding unsaturated compounds that are tedious to incorporate in devices or biological media, mainly due to limited solubility. Thus, our team develop original NIR dyes using relatively simple strategies (e.g. coordination and macrocyclic chemistries).

Most notably, we are investigating the synthesis of emerging quinoidal compounds such as the azacalixphyrins (Angew. Chem. Int. Ed., 2013, DOI : 10.1002/anie.201301217) and the benzoquinone diimine ligands (Chem. Commun. 2014, DOI : 10.1039/C4CC07353C ; Coord. Chem. Rev. 2017, DOI : 10.1016/j.ccr.2017.06.015), which present unprecedented pi-electrons distribution that can be controlled to adjust their reactivity or tune their electronical/optical properties depending on the target application (e.g. bio-imaging: Chem. Commun., 2018, DOI : 10.1039/C8CC05851B).

i) Azacalixarenes :

The calixarene skeleton is a popular macrocyclic platform used for the conception of simple to sophisticated supramolecular receptors because of its high flexibility. In contrast, the azacalix[4]arenes, incorporating bridging nitrogen atoms, were rarely used as hosts, since only two examples of supramolecular host-guest complexes were reported in the literature when we started these investigations. Such cavitants adopt a stable 1,3-alternate conformation both in solution and at the solid state, contributing to anions complexation (Chem. Eur. J., 2016, DOI : 10.1002/chem.201505089).

ii) Diamino-benzoquinone diimines:

The interest for these derivatives is expanding since their remarkable fundamental properties allow to envisage multiple perspectives in emerging technological fields. Indeed, diamino-benzoquinone diimines possess a 12-pi electrons system which is better described as constituted of two 6-pi electrons subunits which are chemically connected (C-C single bonds) but electronically independent. This exceptional distribution has been beneficial to trigger intramolecular reactions depending on the molecule’s environment. We demonstrated a unprecedented rearrangement of the quinones toward zwitterionic species, accompanied by a marked color change in solution and at the solid state (Mater. Chem. Front., 2018, DOI : 10.1039/C8QM00171E).