Viologen-based ditopic bis-pyridinyl-triazole bidentate ligands self-assemble in the presence of palladium ions into supramolecular polymers whose structure is imposed by the directed formation of coordination bonds. Light-irradiation of these electron-responsive supramolecular materials triggers a photo-induced electron transfer yielding isolated π-radicals and dimers of radicals. The photoreduction events and the associated dimerization steps trigger a large-scale reorganization occurring within the supramolecular network yielding aggregates or gels depending on the irradiation conditions (power, duration). Detailed electrochemical, spectro-electrochemical and photochemical analyses were conducted to understand the mechanisms at stakes in these light-induced aggregation and gelation.

Deep eutectic solvents are seen as a new class of green and cheap solvents in electrochemical processes. Many electrochemical deposition techniques have been reported in the literature mainly focusing on metal electrodeposition and electro-polymerization. Here, we report for the first time the efficient electro-grafting of aryl diazonium salts on carbon surfaces using ethaline as an example of a natural and biodegradable deep eutectic solvent. Three different aryl diazonium salts have been tested, namely the 4-iodophenyldiazonium ion, 4carboxymethylphenyl diazonium ion and 4-ethynylphenyldiazonium ion. Effect of concentration, deposition time and potential have been studied in relation to electrode blocking behavior toward redox probes in solution and deposited organic films thickness. Post-functionalization with redox active moieties is demonstrated on such electro-grafted organic layer to show their potential usefulness.

Redox-active conductive supramolecular gels involving highly ordered chiral assemblies of small organic molecules are very promising soft materials for many applications ranging from catalysis to electronics. However, combining all these properties in the same material has so far remained a difficult task. We now report the synthesis and detailed structural, rheological and electrical characterizations of supramolecular gels obtained by self-assembly of a dicationic low molecular weight gelator incorporating a redox-active 4,4’-bipyridinium unit. These molecules have been shown to self-assemble in pentanol to form chiral hollow core-shell cylinders eventually yielding dendritic clusters inducing gelation. We also showed that the optical, rheological and electrical properties of the gels can be tuned by addition of ionic additives. Careful control of the formation of charge-transfer complexes between viologens and iodides have led to a robust, transparent, conductive and chiral gel. The gelation process and the structure/properties of the gel have been thoroughly investigated by UV-Vis and ECD spectroscopy, rheology, bright-field microscopy, SAXS, AFM, electrochemical and impedance measurements.

Redox-active conductive supramolecular gels involving highly ordered chiral assemblies of small organic molecules are very promising soft materials for many applications ranging from catalysis to electronics. However, combining all these properties in the same material has so far remained a difficult task. We now report the synthesis and detailed structural, rheological and electrical characterizations of supramolecular gels obtained by self-assembly of a dicationic low molecular weight gelator incorporating a redox-active 4,4’-bipyridinium unit. These molecules have been shown to self-assemble in pentanol to form chiral hollow core-shell cylinders eventually yielding dendritic clusters inducing gelation. We also showed that the optical, rheological and electrical properties of the gels can be tuned by addition of ionic additives. Careful control of the formation of charge-transfer complexes between viologens and iodides have led to a robust, transparent, conductive and chiral gel. The gelation process and the structure/properties of the gel have been thoroughly investigated by UV-Vis and ECD spectroscopy, rheology, bright-field microscopy, SAXS, AFM, electrochemical and impedance measurements.

No abstract