Structure and dynamics in solvent-polarity-induced aggregates from a c60 fullerene-based dyad.

A novel methanofullerene dyad based on a hydrophobic (acceptor C60 moiety)-hydrophilic (bridge with benzene and ester functionalities)-hydrophobic (donor didodecyloxybenzene) network is designed and synthesized. Electronic absorption spectral features revealed the molecule to exhibit a strong tendency to self-aggregate in binary solvent mixtures at room temperature, where the dielectric constant exceeds a critical value, approximately 30. The dynamic structure factors of these spherical aggregates revealed stretched exponential decay with sizes varying between 110 and 250 nm with an increasing concentration, estimated from the dynamic light scattering experiments. However, a loss of shape selectivity of these aggregates was noted at lower water volume fractions in the binary solvent mixtures. The water-extracted spherical clusters were identified to be fractals with a dimension of 1.85, leading to diffusion-limited cluster aggregation as the mechanistic route for clusterization.