Reversibly Switchable Fluorescent Molecular Systems Based on Metallacarborane-Perylenediimide Conjugates

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Electrochemistry

Background:

• Icosahedral metallacarboranes, specifically cobaltabisdicarbollide [Co(C2B9H11)2]-, exhibit unique redox properties due to their structure and charge.
• These metallacarboranes are attractive for electron-transfer applications.
• Perylenediimide dyes are known for their photophysical properties.

Purpose of the Study:

• To synthesize and characterize novel switchable luminescent molecules and materials based on metallacarboranes.
• To investigate the electrochemical control of luminescence in these new systems.
• To explore the self-assembly behavior and supramolecular structures of these conjugates.

Main Methods:

• Covalent tethering of cobaltabisdicarbollide ([Co(C2B9H11)2]-) to perylenediimide dyes.
• Electrochemical studies to analyze redox processes and their effect on luminescence.
• Solvent-induced gelation experiments to investigate self-assembly.
• Spectroscopic techniques to characterize the luminescent properties.

Main Results:

• Successful synthesis of the first metallacarborane-based switchable luminescent molecules and materials.
• Demonstration of reversible modulation of fluorescence via redox stimuli, acting as electrochemically-controlled fluorescent switches.
• Comparison showing superior performance over ferrocene-perylenediimide systems.
• Formation of self-assembled 1D nanostructures and luminescent gels from the conjugates.
• Preservation of luminescence in the gel state for one compound.

Conclusions:

• Cobaltabisdicarbollide-perylenediimide conjugates represent a new class of switchable luminescent materials.
• Redox stimuli effectively control luminescence, enabling applications as molecular switches.
• Self-assembly leads to the formation of functional supramolecular materials, including luminescent gels.