Synthesis of merocyanine dye nanorods:: The importance of solvent, kinetic and thermodynamic control, and steric effects on self-assembly

Aggregation of dipolar merocyanine dyes into antiparallel dimers with high binding constant is an interesting binding motif for the construction of functional supramolecular architectures. This dipolar aggregation has been utilized for the formation of welldefined cylindrical nanorods. The self-assenibly of these nanorods is profoundly influenced by solvent polarity which determines nanorod growth under kinetic or thermodynamic control. A newly synthesized series of bis(merocyanine) dyes hearing alkyl substituents of different chain lengths and branching further reveals that small structural changes of the monomeric building blocks have a considerable impact on the stability and structure of the aggregates. The knowledge acquired by the present study should be helpful for the development of self-assembled nanomaterials.