Metal and Proton Relay-Controlled Hierarchical Multistep Switching Cascade

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Molecular Machines

Background:

• Transition metals are crucial in biological processes like cellular regulation.
• Mimicking biological signaling with molecular machines is key for advanced applications.
• Controlling intermolecular communication is essential for developing solution-based molecular devices.

Purpose of the Study:

• To demonstrate a transition metal-based artificial multistep switching cascade.
• To achieve intrinsic hierarchical level control in molecular switching.
• To develop a controllable system for molecular machines.

Main Methods:

• Utilized a transition metal relay initiated by Zn(II) displacing Pd(II).
• Employed a macrocycle-encapsulated metal complex.
• Incorporated coordination-coupled deprotonation (CCD) and pH-sensitive hydrazone switches.

Main Results:

• Successfully demonstrated a multistep switching cascade with hierarchical control.
• Zn(II) initiated a metal relay, triggering a hydrazone switch via CCD.
• The generated proton induced E/Z isomerization in a second hydrazone switch.

Conclusions:

• The developed cascade offers a new paradigm for molecular switching.
• The system can be reset by removing Pd(II), enabling reversibility.
• This work advances the design of sophisticated, solution-based molecular machines.