Layer Sliding-Induced Fluorescence Changes in a Flexible Hydrogen-Bonded Organic Framework.

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Organic Chemistry

Background:

• Flexible hydrogen-bonded organic frameworks (HOFs) show promise for dynamic fluorescence applications.
• Established design strategies for controlling HOF fluorescence upon structural changes are lacking.
• Tuning emission properties of HOFs is crucial for advanced functional materials.

Purpose of the Study:

• To demonstrate that sliding of 2D layers in HOFs can induce dynamic emission color changes.
• To establish a new design strategy for constructing functional fluorescent porous materials based on layer sliding.
• To investigate the photobehavior of HOFs undergoing structural transformation.

Main Methods:

• Synthesis and characterization of layered HOFs (CP-tBPy-1 and CP-tBPy-2) from a tert-butylpyrene derivative.
• Single-crystal X-ray diffraction to analyze structural changes and pyrene core arrangements.
• Fluorescence spectroscopy and microscopy to study photobehavior and emission color shifts.

Main Results:

• Layered HOF CP-tBPy-1 transformed to CP-tBPy-2 upon guest solvent release.
• Single-crystal X-ray diffraction revealed layer sliding, altering pyrene cores from monomeric to dimeric species.
• Fluorescence color changed dynamically from blue to green, correlating with structural transformation.

Conclusions:

• Layer sliding in HOFs is a viable mechanism for inducing dynamic fluorescence color changes.
• This study presents the first example of fluorescence changes driven by the sliding of hydrogen-bonded 2D network layers in HOFs.
• A novel design strategy for functional fluorescent porous materials based on layer sliding is proposed.