Emergence of Supramolecular Chirality by Flows

Hydrodynamic forces in stirred solution induce chirality in some supramolecular species of J-aggregates as detected at the level of the electronic transition However the mechanism that explains the phenomenon remains to be elucidated although basic effect of hydrodynamic gradients of the shear rate is most probably the folding or bending of the nanoparticles in solution Herein, we demonstrate a correlation between chiral flows in different regions of circular and square stirred cuvettes and the emergence of true circular dichroism (CD) The results show that chaotic flows lead to a racemic mixture of chiral shaped supramolecular species, and vortical flows to, scalemic mixtures In a magnetically stirred flask the descending an ascending flows are of different chiral sign and the CD reading depends on the weighting of these two flows of inverse chiral sign The effect of the gradient of shear rates of the flows leading to chiral shape objects depends on shape of the cuvette, which suggests that the flask shape and the controlled addition of reagents in defined regions of the stirred solutions may exert a Control in self-assembly processes