AUTHOR=Wang Zhe , Li Xuefeng , Chen Shengli , Dong Jinfeng 

TITLE=Fabrication of Soft-Oxometalates {Mo132} Clusters With Novel Azobenzene Surfactants: Size Control by Micelles and Light

JOURNAL=Frontiers in Chemistry

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2021.625077

DOI=10.3389/fchem.2021.625077

ISSN=2296-2646

ABSTRACT=<p>Soft-oxometalates (SOMs) are colloid suspensions of superstructured assemblies of polyoxometalates (POMs) and are found to be very effective photo-catalysts in a number of chemical reactions. The stabilization of SOMs generally requires legends or stabilizers, e.g., polymers and surfactants. In this paper, a light responsive azobenzene surfactant, C<sub>10</sub>AZOC<sub>2</sub>N<sub>3</sub>, was developed and used to stable {Mo<sub>132</sub>} SOMs. Various techniques such as Dynamic light scattering, TEM, UV-Vis spectra and cyclic voltammetry were employed to characterize the experimental results. The outstanding structure-directing effect of surfactant self-assembly micelles in solution on inorganic counter-anions was demonstrated. Different amount of cyclohexane was solubilized into C<sub>10</sub>AZOC<sub>2</sub>N<sub>3</sub> micelles to successfully control the size of {Mo<sub>132</sub>} SOMs cluster. Furthermore, the clusters exposed to UV light for a certain time can be served as a second trigger to control the size of SOMs due to the <italic>trans</italic>-cis conformation transition of surfactant molecules. The redox potentials of C<sub>10</sub>AZOC<sub>2</sub>N<sub>3</sub>-{Mo<sub>132</sub>} SOMs were investigated as the cluster size varied. Interestingly, the redox potential of {Mo<sub>132</sub>} was not affected by the cluster size, indicating that the presence of surfactant did not change the main function of {Mo<sub>132</sub>} as an electrochemical catalyst, but merely assisted in the size control of SOM aggregation.</p>