Room-Temperature Reversible Control of Fluorescently Distinct Polymorphs Using Pressure and E-Field: Writing and...

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Organic Electronics

Background:

• Liquid crystals (LCs) exhibit unique optical and electronic properties.
• Polymorphism in organic materials can lead to distinct physical characteristics.
• Mechanochromism and electrochromism are stimuli-responsive phenomena with technological potential.

Purpose of the Study:

• To investigate the reversible polymorphic transformation of a hexacatenar liquid crystal (1).
• To explore the use of mechanical pressure and electric fields for inducing and controlling these transformations.
• To demonstrate potential applications in data storage and security features.

Main Methods:

• Synthesis of a hexacatenar liquid crystal molecule (1) with a pyrene core and triazole linkers.
• Induction of crystalline (1-B, blue emission) and liquid crystalline (1-G, green emission) polymorphs via controlled cooling.
• Application of mechanical pressure for 1-B to 1-G transformation (mechanochromism).
• Application of alternating current (AC) electric fields for 1-G to 1-B transformation (E-field-chromism).

Main Results:

• Room temperature reversible transformation between blue-emissive crystalline (1-B) and green-emissive liquid crystalline (1-G) polymorphs.
• Mechanical pressure induces 1-B to 1-G transition; AC electric field induces 1-G to 1-B transition.
• Successful recording and erasing of patterns using these stimuli, demonstrating proof-of-concept for applications.

Conclusions:

• The study reports the first instance of an electric field-induced polymorphic transformation in a liquid crystal.
• The reversible mechanochromic and E-field-chromic properties enable controllable optical switching.
• This material shows promise for applications in rewritable data storage, anticounterfeiting, and sensor technologies.