Polyoxometalate condensation and transformation mediated by adaptive coordination-assembled molecular flasks

Area of Science:

• Supramolecular Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• Polyoxometalates (POMs) are versatile inorganic clusters with diverse applications.
• Molecular flasks offer a confined environment for controlling chemical reactions.
• Understanding POM transformations is key to designing new functional materials.

Purpose of the Study:

• To investigate POM condensation and transformation reactions within adaptive coordination-assembled molecular flasks.
• To explore the role of encapsulation in cavity-confined POM transformations.
• To develop a novel approach for synthesizing functional POM-cage composite materials.

Main Methods:

• Synthesis of host-guest complexes using molecular flasks.
• In situ generation and templation of POM clusters.
• Characterization using Nuclear Magnetic Resonance (NMR), Electrospray Ionization Time-of-Flight Mass Spectrometry (ESI-TOF-MS), and Single-Crystal X-ray Diffraction (SCXRD).

Main Results:

• A new host-guest complex, (SiMo12O40)⊂2·(NO3)8, was formed via in situ POM condensation, with the host transforming from cage 1 to isomeric bowl 2.
• The in situ condensation reaction was 27.5-fold faster than direct templation.
• Encapsulation within the molecular flask was crucial for cavity-confined POM transformations, influencing product distribution.

Conclusions:

• Demonstrated a unique inorganic-reaction-driven responsive supramolecular system.
• Established a new method for preparing functional POM-cage composite materials.
• Highlighted the significant impact of molecular encapsulation on POM reactivity and transformation pathways.