# Multidirectionally Controlled Arrangement via Ion‐Pairing Assembly of Amphiphilic Charged π‐Electronic Systems

## TL;DR

Researchers developed a method to control the assembly of charged π-electronic systems into liquid crystals by adjusting the positions of hydrophilic chains and using ion-pairing.

## Contribution

A controllable charge-by-charge strategy for designing π-electronic lyotropic chromonic liquid crystals with tunable structural and phase behaviors.

## Key findings

- Lamello-columnar phases form via amphiphilic iπ–iπ interactions and hydrophobic effects.
- Phase transitions to nematic and isotropic sheets occur with changes in water content and temperature.
- Monolayer sheet structures were identified as key components using scanning transmission electron microscopy.

## Abstract

Charged π‐electronic systems with hydrophilic substituents form lyotropic chromonic liquid crystals (LCLCs) through charge‐by‐charge assembly driven by
iπ–
iπ interactions and hydrophobic effects. In this study, the positions and numbers of triethylene glycol (TEG) chains in amphiphilic porphyrin AuIII complexes are tuned to control their assembly modes. In combination with the π‐electronic anion pentacyanocyclopentadienide (PCCp–), 5,15‐TEG‐aryl‐substituted porphyrin AuIII complex generates lamello‐columnar (Lamcol) phases via amphiphilic
iπ–
iπ interactions and proximal interactions at the unsubstituted sites. In the presence of water, the Lamcol phases, with lateral hydrophobic effects, exhibit transitions to nematic sheet (Nsheet) and isotropic sheet (Isosheet) phases depending on water content and temperature. The Lamcol phases align macroscopically under a magnetic field, and scanning transmission electron microscopy (STEM) reveals monolayer sheet structures as key components of the LCLCs. These findings demonstrate a controllable charge‐by‐charge strategy for designing π‐electronic LCLCs with tunable structural and phase behaviors.

Ion‐pairing lamello‐columnar lyotropic chromonic liquid crystals are formed from 2D sheet‐like structures via charge‐by‐charge assembly of partially hydrophilic‐aryl‐substituted porphyrin AuIII complex. The sheet‐like structures, arranged via amphiphilic
iπ–
iπ interactions and lateral hydrophobic effects, afford various phases, depending on water content and temperature.