A photo-switchable molecular capsule: sequential photoinduced processes

Area of Science:

• Supramolecular Chemistry
• Photochemistry
• Materials Science

Background:

• Metastable trilacunary heteropolyoxomolybdate ({PMo9}) and diarylethene (DAE) are key components.
• Ligand replacement methodology facilitates self-assembly.
• Photo-active molecular capsules offer novel functionalities.

Purpose of the Study:

• To synthesize a photo-active molecular capsule via self-assembly.
• To investigate the photochemical behavior of diarylethene ligands within the capsule.
• To understand the electron transfer dynamics in the donor-acceptor system.

Main Methods:

• Ligand replacement methodology for self-assembly.
• Spectroscopic techniques (steady-state and time-resolved) for investigating electrocyclisation.
• Spectroelectrochemical analysis and computational studies.
• Quantum yield determination using a custom quantum yield determination setup (QYDS).

Main Results:

• Formation of the photo-active molecular capsule [(PMo9O31)2(DAE)3]6-.
• Exclusive ligation of the photo-active antiparallel rotamer to the polyoxometalate (POM).
• Discovery of a photochemical cascade involving sequential ring closure and electron transfer from DAE to POM.
• Determination of ring-closing quantum yields, showing the impact of POM coordination.

Conclusions:

• The self-assembled molecular capsule exhibits controlled photochemical behavior.
• A distinct photochemical cascade, including electron transfer, was observed.
• POM coordination influences the photochemical processes and quantum yields.