Molecular Quadripod as a Noncovalent Interfacial Coupling Reagent for Forming Immobilized Coordination Assemblies

Area of Science:

• Materials Science
• Electrochemistry
• Supramolecular Chemistry

Background:

• Immobilization of coordination assemblies on electrode surfaces is crucial for advanced functional materials.
• Existing covalent functionalization methods can be complex and harsh.
• Development of robust, noncovalent strategies for surface modification is highly desirable.

Purpose of the Study:

• To introduce a pyrene-cored molecular quadripod, TAPyr, as an effective noncovalent interfacial coupling reagent.
• To demonstrate the facile immobilization of coordination assemblies onto electrode surfaces using TAPyr.
• To evaluate the stability and properties of the resulting functionalized thin films.

Main Methods:

• Synthesis and characterization of the pyrene-cored molecular quadripod (TAPyr).
• Noncovalent immobilization of TAPyr onto indium tin oxide (ITO) electrode surfaces via a dipping procedure.
• Grafting of pyridine-terminated ruthenium complexes onto the TAPyr-modified surface using a palladium metallolinker.
• Electrochemical, absorption spectral, atomic force microscopy (AFM), and scanning tunneling microscopy (STM) analyses to probe immobilization and film properties.

Main Results:

• TAPyr is readily available, bench-stable, and forms firmly immobilized, upright monolayers on electrode surfaces.
• Ruthenium complexes were successfully grafted onto the ITO/TAPyr surface, forming stable thin films.
• The resulting films exhibited electrochemical stability comparable or superior to state-of-the-art covalent methods.
• Appealing electrochromism was observed in the thin films of ruthenium complexes.

Conclusions:

• TAPyr serves as an efficient noncovalent reagent for the robust immobilization of coordination assemblies on electrode surfaces.
• This approach provides a simple, ambient condition method for creating stable, functional thin films.
• The demonstrated electrochromism highlights the potential of TAPyr-modified surfaces in electrochromic devices.