Polymolybdate-Based Complexes Containing Flexible Metal-Organic Windmills with Pseudocapacitive Activity and...

Area of Science:

• Coordination Chemistry
• Materials Science
• Electrochemistry

Background:

• Development of novel polyoxometalate-metal-organic complexes (POMoOCs) is crucial for advanced applications.
• Pyrazole-based ligands offer unique structural and electronic properties for complex synthesis.
• Exploring diverse POMoOC architectures is key to unlocking new functionalities.

Purpose of the Study:

• To synthesize and characterize novel POMoOCs using semirigid bis(pyridine)-bis(amide) ligands with pyrazole linkers.
• To investigate the structural diversity and electrochemical properties of the synthesized complexes.
• To evaluate their potential for energy storage (supercapacitors) and electrochemical sensing.

Main Methods:

• Solvothermal synthesis of four POMoOCs using cobalt, polymolybdates, and novel pyrazole-linked ligands (3-Hdpap and 3-Hdpyp).
• Structural characterization via single-crystal X-ray diffraction, infrared spectroscopy, and powder X-ray diffraction.
• Electrochemical performance evaluation using cyclic voltammetry and galvanostatic charge-discharge on modified electrodes.

Main Results:

• Four POMoOCs with diverse architectures (2D network, 1D chains, 2D supramolecular network) were successfully synthesized.
• Complex 1-GCE exhibited high specific capacitance (1658.3 F·g⁻¹) and excellent capacitance retention (89% after 1000 cycles).
• Complex 1 demonstrated effective electrochemical sensing of Cr(VI) with a low detection limit.

Conclusions:

• Novel POMoOCs with tunable architectures were synthesized, demonstrating the versatility of pyrazole-based ligands.
• Complex 1 shows superior pseudocapacitive performance, outperforming many reported POM-based materials.
• The study highlights the potential of these POMoOCs for electrochemical energy storage and sensitive Cr(VI) detection.