Theory of Chiral Electrodeposition by Chiral Micro-Nano-Vortices under a Vertical Magnetic Field -1: 2D Nucleation by Micro-Vortices

Abstract

Remarkable chiral activity is donated to a copper deposit surface by magneto-electrodeposition, whose exact mechanism has been clarified by the three-generation model. In copper deposition under a vertical magnetic field, a macroscopic tornado-like rotation called the vertical magnetohydrodynamic (MHD) flow (VMHDF) emerges on a disk electrode, inducing the precessional motions of various chiral microscopic MHD vortices: First, chiral two-dimensional (2D) nuclei develop on an electrode by micro-MHD vortices. Then, chiral three-dimensional (3D) nuclei grow on a chiral 2D nucleus by chiral nano-MHD vortices. Finally, chiral screw dislocations are created on a chiral 3D nucleus by chiral ultra-micro MHD vortices. These three processes constitute nesting boxes, leading to a limiting enantiomeric excess (ee) ratio of 0.125. This means that almost all chiral activity of copper electrodes made by this method cannot exceed 0.125. It also became obvious that chirality inversion by chloride additive arises from the change from unstable to stable nucleation by the specific adsorption of it.

Theory of Chiral Electrodeposition by Micro-Nano-Vortexes under a Vertical Magnetic Field-2: Chiral Three-Dimensional (3D) Nucleation by Nano-Vortexes

“…In an electrode reaction under a vertical magnetic field, a tornado-like macroscopic rotation called vertical magnetohydrodynamic (MHD) flow (VMHDF) appears on a disk electrode (vertical MHD electrode (VMHDE)). On the electrode surface under a VMHDF, numerous microscopic vortexes called micro-and nano-MHD flows are formed, accompanied by the rotations of microbubble clusters originating from ionic vacancies produced by electrode reactions [1][2][3].…”

“…This is experimentally validated because the natural lifetime of vacancy is about 1 s [6,7], which is extraordinarily long compared with the collis quency of solvent molecules of 10 −10 s. Therefore, a vacancy layer formed under a V is expected to have superfluidity similar to that of liquid helium. Copper electrodeposition under a vertical magnetic field gives rise to chira dislocations with remarkable chiral activity caused by a VMHDF [1]. However, formation of chiral screw dislocations of the order of 0.1 nm from a VMHDF with eter of 1 cm, size control over eight figures was directly required, which seemed i ble.…”

“…(a) (b) Copper electrodeposition under a vertical magnetic field gives rise to chiral screw dislocations with remarkable chiral activity caused by a VMHDF [1]. However, for the formation of chiral screw dislocations of the order of 0.1 nm from a VMHDF with a diameter of 1 cm, size control over eight figures was directly required, which seemed impossible.…”

“…However, for the formation of chiral screw dislocations of the order of 0.1 nm from a VMHDF with a diameter of 1 cm, size control over eight figures was directly required, which seemed impossible. To solve such a difficulty, the three-generation model of chiral screw dislocation was proposed in Part 1 [1]; chiral two-dimensional (2D) nuclei arise from chiral vortexes of micro-MHD flows (~0.1 mm) as the first generation, then chiral three-dimensional (3D) nuclei are formed by chiral vortexes of nano-MHD flows (~0.1 µm) as the second generation, and finally, chiral screw dislocations are created by chiral ultra-micro vortexes (~0.1 nm) as the third generation. As shown in Figure 2, all three steps constitute a nesting box structure.…”

“…As shown in Figure 2, all three steps constitute a nesting box structure. The validity of this model was proven by the fact that a measure of the chiral activity, i.e., the enantiomeric excess (ee) ratio, cannot exceed a limiting value of 0.125 [1].…”