[tel-00958354] Molecular Flexibility of Self-Assembled Systems: Effects of Building Block Polarity

The self-assembly of molecules is considered as one of the most promising approach to conceive sophisticated and dynamic materials with a molecular-level control of structure, morphology and property. However, recent advancements highlight the need to ameliorate the understanding of molecular flexibility within supramolecules. Rod-shaped molecules were selected for this study. Composition of molecules were varied according to the number and location of dipoles. Three groups of building blocks were chosen: nonpolar one with no strong dipole, monofunctional one containing one dipole at one end, and bifunctional one composed of one dipole at each end. Self-assembly processes of these molecules were then carefully investigated and compared. The absence of strong dipoles within molecules was found to confer structural flexibility to the final supramolecules. Within aggregates, molecules are highly mobile and able to undergo several structural reconfigurations. In contrast, more stable supramolecules are prepared when molecules contain one or more polar extremities. Despite this constrained environment, molecular segments can locally move, thus revealing a ubiquitous degree of freedom for molecular motions. This research work aims at highlighting the flexibility of self-assembled systems, and also bring to light the potential of local molecular motions as an encouraging way to functionalize constrained supramolecules.



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