Vortexes and Nanoscale Chirality

Emergence of Supramolecular Chirality by Flows

“…[18] 2) Although the J-aggregates of sulfonatophenyl diprotonated porphyrins showing irreversible and reversible effects belong to different compounds, H 4 TPPS 3 and H 4 TPPS 4 , respectively (see Supporting Information), there is no chemical reason for expecting different signs of the CD for the chiral exciton arising by folding or bending of the mesophases. However, the signs obtained by magnetic stirring in a small cylindrical flask for H 4 TPPS 3 (irreversible effect) [18] compared to those of H 4 TPPS 4 (reversible effect) [7,8,13] in a square section UV/Vis cuvette are opposite. To clarify this, we monitored the reversible effect in long J-aggregates of the diprotonated meso-tetrakis(4-sulfonatophenyl)porphyrin (H 4 TPPS 4 ; see Supporting Information) which shows a stationary state when stirred in a square section UV/Vis cuvette.…”

“…Notice that the reversible effect gives by time integration a stationary CD signal that disappears when stirring is stopped. Recent reports [4][5][6][7][8] suggest that the reversible emergence of a CD signal by the hydrodynamic forces of stirring, that is, the induction of a mechano-stationary chiral state in the solution of nanoparticles while stirring, occurs more often than the irreversible effect. In the reversible case the bending/ folding of the particles is still controversial.…”

“…To overcome these difficulties the use of non-conventional optical techniques to measure the CD is necessary. [8][9][10][11] Examples of the use of such techniques in solid samples [3,12] and in solution [7,13] are described elsewhere. The technique that we have extended to solutions is based on the determination of the complete Mueller matrix using two-modulator generalized ellipsometry [10] (2-MGE).…”

Stirring competes with chemical induction in chiral selection of soft matter aggregates

“…Discussions on the true nature of such an enantioselection in three-dimensional aggregates have raised some controversy [28][29][30][31][32][33] . Recently, d'Urso et al 34 have hinted at the possibility to exert enantioselective control on the supramolecular assembly of achiral components doped with a chiral complex by means of vortex flow. However, their system does not allow obtaining conclusive results, as a hypothetical genuine chiral effect cannot be decoupled from a transient fibre-alignment mechanism.…”

Supramolecular Principles of Self-Assembly of Pophyrin Nanotubes. 1. Models of SWPNTs Based on 5,10,15,20-Tetrakis(4’-sulfophenyl)porphine Zwitter-Ion

“…Each enantiomer has a definite signal in CD-spectra. [21] A peculiarity of SWPNT is the dependency of a particular enantiomer's yield on the direction of stirring of the solution.…”