Sequential Isomerization of a Macrocyclic Polyoxometalate Archetype.

Area of Science:

• Inorganic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Polyoxotungstates (POTs) are versatile inorganic clusters with diverse structures and applications.
• The macrocyclic {P₈W₄₈O₁₈₄}^40- archetype serves as a platform for constructing complex POT architectures.
• Isomerization of POT building blocks is crucial for tuning their properties and functionalities.

Purpose of the Study:

• To investigate the controlled isomerization of {α-P₂W₁₂O₄₈} units within the {P₈W₄₈O₁₈₄}^40- framework.
• To explore the role of site-specific copper(II) coordination in directing these isomerizations.
• To synthesize and characterize novel isomers of the {P₈W₄₈O₁₈₄}^40- cluster.

Main Methods:

• Reaction of the classical {αααα-P₈W₄₈O₁₈₄}^40- with CuCl₂ in a sodium acetate buffer (pH 5.2).
• Isolation and characterization of the resulting POT derivatives using solid-state and solution-state techniques.
• Electrocatalysis assessments of the synthesized compounds.

Main Results:

• Formation of three distinct POT derivatives: [αγαγ-P₈W₄₈O₁₈₄{Cu(H₂O)}₂]^36- (1), [γγγγ-P₈W₄₈O₁₈₄{Cu(H₂O)_0.5}₄]^32- (2), and [αγγγ-P₈W₄₈O₁₈₄{Cu(H₂O)}₃]^34- (3).
• Discovery of the previously unknown {γγγγ-P₈W₄₈} and {αγγγ-P₈W₄₈} isomers.
• Demonstration that site-specific Cu^II coordination controls the isomerization of {α-P₂W₁₂O₄₈} building blocks.

Conclusions:

• Site-specific copper(II) coordination is a powerful strategy for inducing controlled isomerization in macrocyclic polyoxotungstates.
• The study expands the library of known {P₈W₄₈O₁₈₄}^40- isomers, including novel {γγγγ} and {αγγγ} forms.
• The characterized POT derivatives show potential for applications, including electrocatalysis.