Reversible mechanical induction of optical activity in solutions of soft-matter nanophases.
Nanophases of J-aggregates of several achiral amphiphilic porphyrins, which have thin long acicular shapes (nanoribbons), show the immediate and reversible formation of a stationary mechano-chiral state in the solution by vortex stirring, as detected by their circular dichroic signals measured by 2-modulator generalized ellipsometry. The results suggest that when a macroscopic chiral force creates supramolecular chirality, it also creates an enantiomeric excess of screw distortions, which may be detected by their excitonic absorption. An explanation on the effect of the shear flow gradients is proposed on the basis of the orientation of the rotating particles in the vortex and the size, shape, and mechanical properties of the nanoparticles.
Department of Applied Physics and Optics Science, and Institut de Nanociència i Nanotecnologia (IN2UB), University of Barcelona, Martí i Franquès 1, 08028-Barcelona, Catalonia, Spain.
Oriol
O
Arteaga
Carlos
C
Escudero
Gerard
G
Oncins
Zoubir
Z
El-Hachemi
Joan
J
Llorens
Joaquim
J
Crusats
Adolf
A
Canillas
Josep M
JM
Ribó
D002942:Circular Dichroism; D055595:Mechanical Phenomena; D018625:Microscopy, Atomic Force; D049329:Nanostructures / Q000737:chemistry*; D009904:Optical Rotation; D011166:Porphyrins / Q000737:chemistry*; D012996:Solutions; D014867:Water / Q000737:chemistry
D011166:Porphyrins; D012996:Solutions; D014867:Water