Macroscopic Spinning Chirality Memorized in Spin‐Coated Films of Spatially Designed Dendritic Zinc Porphyrin J‐Aggregates

Abstract

The breaking of chiral symmetry can occur under nonequilibrated conditions. [1][2][3][4] Such a spontaneous induction of optical activity from achiral entities has attracted much attention in relation to the origin of chirality in nature. Representative examples can be seen in growth processes of large electrostatic assemblies of achiral chromophoric compounds such as cyanine dyes and porphyrin derivatives in aqueous media. [5] In these cases, the assemblies are considered to adopt helical architectures, where either the P or M form is selected only accidentally at the initial stage of the self-organization event and develops predominantly in the subsequent stage. Hence, handedness of emerging chirality is unpredictable. Ribó et al.[5c] have discovered, through studies on electrostatic Jaggregation of a 4-sulfonatophenylporphyrin in aqueous media, that the sense of such an optical activity can be selected by the spinning direction of vortex stirring initially applied to the solutions. Herein we report an interesting finding that spin-coated films of dendritic zinc porphyrin Jaggregates chiroptically memorize the spinning directions. The optical activities of the spin-coated films are thermally stable and preserved up to the melting temperatures of the Jaggregates. In contrast with the previous examples, [5] the Jaggregates are optically inactive in solution.Porphyrin J-aggregates have attracted attention because of their potential application as nonlinear optical materials. [6] Although several examples of porphyrin J-aggregates have been reported, they are formed mostly in aqueous media; [5b, c] however, there are few examples of J-aggregation in organic media [7] which occur because of rather weak p-stacking interactions. We found that zinc porphyrins bearing carboxylic acid (-CO 2 H) functionalities at the opposite meso positions undergo supramolecular polymerization by dimerization of the -CO 2 H groups to give J-aggregates in organic media. The J-aggregation takes great advantage of a multi-[*] Dr.

π-Conjugated polymer-layered structures: synthesis and self-assembly

“…[3][4][5][6][7][8][9][10][11] Because π-conjugated compounds tend to aggregate by π-π stacking, the introduction of non-covalent interactions at appropriate positions increases their association constants and facilitates the formation of higher-ordered structures. 12,13 For example, supramolecular gels can be formed through intermolecular interactions such as hydrogen bonds, 14,15 and multiple long alkyl chains facilitate columnar stacking along the π-stacking direction of supramolecular assemblies [16][17][18][19] (Figure 1a).…”

Supramolecular polymer formed by reversible self-assembly of tetrakisporphyrin

“…Giant porphyrin arrays and large porphyrin wheels via metal coordination for modeling light-harvesting antenna have been reported by . Aida and coworkers have investigated self-assembled nanometric porphyrin arrays (27)(28)(29). There are limited examples of porphyrin self-assembly by subtle forces, such as van der Waals and CH/ interactions in organic media, despite the fact that porphyrin possesses a flat and electron-rich surface that creates van der Waals, stacking, and charge transfer interactions that play a significant role in its self-assembly (30,31).…”

Supramolecular Structure of Extrinsically Chiral Porphyrin Hetero‐Assemblies and Achiral Analogues

“…The last case is defined as "memory" effect. [11][12][13] The chiral memory phenomenon is of particular interest because, used in combination with the non-covalent strategy, permits to assembly supramolecular species able to perform predetermined functions coupled with chiral discrimination. [14,15] With these premises, it is clear that understanding the forces involved and the mechanism accompanying induction, modulation and memory of supramolecular chirality could allow for the rational design and assembly of chiral supramolecular systems.…”