Realization of a "lockable" molecular switch via pH- and redox-modulated cyclization

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Molecular Switches

Background:

• Development of molecular systems with multiple controllable states is crucial for advanced applications.
• pH and redox stimuli offer orthogonal control mechanisms for molecular devices.

Purpose of the Study:

• To design and characterize a novel switchable organic system with four interconvertible states.
• To investigate the use of pH and redox chemistry for controlling molecular states.

Main Methods:

• Synthesis of phenanthridine-based heterocycles: 1-isobutyl-1,2,3,12b-tetrahydroimidazo[1,2-f]phenanthridine (TIP) and 5-[2-(isobutylamino)ethyl]phenanthridinium (AEP).
• In situ structure determination using UV and 1H NMR spectroscopy in a biphasic DCM/water solution.
• Application of pH and redox stimuli to induce state interconversions.

Main Results:

• Successfully developed a four-state switchable organic system.
• Demonstrated reversible interconversion between TIP and AEP states via pH control.
• Achieved conversion to pH-inert states (DIP and AEDP) through oxidation or reduction.
• Confirmed quantitative and repeatable pH-modulated cyclization and phase-transfer processes.
• Showcased the ability to lock states against acid-base changes using redox manipulation.

Conclusions:

• The developed system offers robust and repeatable control over molecular states using orthogonal pH and redox stimuli.
• The ability to lock states provides a mechanism for memory in molecular systems.
• This work lays the foundation for designing sophisticated molecular machines and responsive materials.