Photoswitchable Pseudorotaxanes with Dual Chromism and Tunable Fluorescence for Multilevel Information Encryption

Area of Science:

• Supramolecular Chemistry
• Materials Science

Background:

• Mechanically interlocked molecules (MIMs) offer tunable properties for advanced applications.
• Developing stimuli-responsive MIMs is crucial for creating smart materials.

Purpose of the Study:

• To design and construct a photoswitchable pseudorotaxane system.
• To investigate its photochromic, vapochromic, and fluorescent properties.
• To develop a multilevel information encryption system.

Main Methods:

• Host-guest complexation between a vinyl-bipyridinium axle and cucurbit[7]uril (Q[7]).
• Photoisomerization induced by light irradiation (E→Z transition).
• Characterization of optical, vapor-sensing, and fluorescence properties.

Main Results:

• The system exhibits dual photochromic and vapochromic (NH3) activity in one state, and inertness in the other.
• Distinct solid-state fluorescence emissions were observed due to macrocyclic confinement.
• A multilevel information encryption system with three decryption states was successfully developed.

Conclusions:

• The developed pseudorotaxane system demonstrates integrated photoswitching, chromic, and fluorescent functionalities.
• This work provides a new paradigm for designing smart materials for security applications.
• The system enables programmable message display through color and fluorescence changes.