Linear Momentum of a Microfluid Realizes an Anisotropic Reaction at the Ends of a Supramolecular Nanofiber

Abstract

Abstract The anisotropic properties of one-dimensional (1D) supramolecules have generally been the sole way to input molecular information along a structure of high density. Although the chain reaction of a synthetic polymer (e.g., in radical polymerization) does realize anisotropic polymer elongation, it has remained challenging to induce such properties in artificial 1D self-assembling systems. Herein, by employing J-aggregate nanofibers of TPPS — a sort of self-assembling porphyrin — as a model, we describe a system in which linear momentum of laminar flow facilitates directional supramolecular elongation of the flowing nanofibers. In situ fluorescence and linear dichroism (LD) measurements revealed that the elongation of the J-aggregate nanofibers could be accelerated only when they were oriented in the flow direction. Moreover, linear transport of the oriented nanofibers along the stream disrupted the isotropic reactivity at their two termini; one terminus could be activated selectively, resulting in directional nanofiber elongation. The shear rate gradient of the laminar flow induced collisions of the TPPS monomer units at the end of one terminus of the nanofibers. This strategy should be applicable more generally to supramolecular 1D elongation (supramolecular polymerization) of various functional molecules, regardless of their chemical properties, thereby extending the frontiers of supramolecular chemistry.