Supramolecular Chiroptical Switches Based on Achiral Molecules

• Published in: Advanced materials (Weinheim) Vol. 20; no. 15; pp. 2908 - 2913
• Main Authors: Qiu, Yunfeng, Chen, Penglei, Guo, Peizhi, Li, Yuangang, Liu, Minghua
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 04-08-2008; WILEY‐VCH Verlag
• Subjects: achiral molecules; assembly; chiroptical switches; interfaces; supramolecular chirality
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.200801165

Chirality plays an important role in biological and material sciences. By introducing chiral elements into functional materials, new properties are created and an increase in information density can be achieved. Chiral properties of functional materials do not only rely on molecular structure, but also on supramolecular interaction between the building blocks. In contrast to the generally accepted opinion that chiral systems should include chiral molecules, this Research News introduces the role of achiral molecules in realizing chiral properties in films and gel‐like materials. Even a system that is entirely composed of achiral molecules can exhibit interesting chiroptical properties in supramolecular ultrathin films. This article demonstrates how achiral molecules can be assembled into supramolecular chiral films and organogels. It further shows how the incorporated achiral molecules can be used to switch the chiral properties of these supramolecular films and organogels.
Achiral phthalocyanine is assembled into optically active supramolecular films at the air/water interface. These films can be switched to show different chiralities upon exposure to HCl or NH3 gas. The chirality of the films can be switched reversibly for several tens of times.