Hot gels get turned off: Gelation of the title molecules facilitate transfer of excitation energy exclusively from the self-assembled nanostructures (see scheme path a) to Rhodamine B and not from the single molecules (path b), thereby establishing the role of self-assembled gel nanostructures in light harvesting. The emission from the dye can be shut off in a thermoreversible fashion since the self-assembly breaks to form molecular, dissolved oligo(phenylenevinylene)s above the gel melting temperature (T<sub>gel</sub>)
