  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 {\pi}-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.
