Grafting nitroxide radicals on nanodiamond surface using click chemistry

Area of Science:

• Materials Science
• Nanotechnology
• Organic Chemistry

Background:

• Nanodiamonds (NDs) possess unique properties suitable for various applications.
• Surface functionalization is crucial for tailoring nanomaterial properties.
• Nitroxide radicals are stable organic radicals with potential applications in areas like spin chemistry and quantum sensing.

Purpose of the Study:

• To demonstrate the successful grafting of nitroxide radicals onto the surface of nanodiamonds.
• To utilize click chemistry for robust covalent attachment of radicals.
• To characterize the functionalized nanodiamonds and quantify the radical density.

Main Methods:

• Functionalization of nanodiamond surfaces with azide groups.
• Covalent attachment of nitroxide radicals via copper(I)-catalyzed azide/alkyne click chemistry.
• Confirmation of the reaction using infrared (IR) spectroscopy.
• Verification and quantification of grafted nitroxides using electron paramagnetic resonance (EPR) spectroscopy.

Main Results:

• Successful covalent bonding of nitroxide radicals to azide-functionalized nanodiamonds was achieved.
• Infrared spectroscopy confirmed the successful click chemistry reaction.
• Electron paramagnetic resonance (EPR) spectroscopy verified the presence of grafted nitroxides.
• EPR analysis estimated the grafting density, indicating hundreds of radicals on 100 nm NDs and tens on 25 nm NDs.

Conclusions:

• Nitroxide radicals can be effectively grafted onto nanodiamond surfaces using click chemistry.
• The developed method provides a reliable route for creating functionalized nanodiamonds with controlled radical attachment.
• The results open possibilities for utilizing these functionalized nanodiamonds in advanced material applications.