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Master Thesis_Kexing Xiao.pdf (936.48 KB)

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Deprotonation Property of Polyoxometalates with Different Lacunary Metal Ions

Xiao, Kexing
http://rave.ohiolink.edu/etdc/view?acc_num=akron155534024745702

Abstract Details

2019, Master of Science, University of Akron, Polymer Science.
Some biomacromolecules own unique deprotonation property due to water ligands which coordinated with metals. Like biomacromolecules, several Keplerate-type polyoxometalates (POMs) were reported to behave as weak polyprotic acids in aqueous solutions due to partial deprotonation of water ligands that attached to the non-Mo metal centers. These macroions show connections to biomacromolecules in self-assembly, self-recognition, catalysis, etc. By changing deprotonation degree, the unique bio-mimic features can be accurately tuned. Therefore, studying the deprotonation property of molecules is important as it will provide a simple model for people to understand more complicated biomacromolecules. In this work, a series of niobium/tungsten mixed-addendum POMs with different lacunary metal ions are used to investigate the deprotonation property of nanoscale molecules. Acid-base titration and isothermal titration calorimetry (ITC) were applied to characterize two POM clusters whose water ligands coordinated with two different lacunary metals, Europium and Copper. The results show that the deprotonation only occurs with the addition of base into the solutions, and the deprotonation capacity of POMs with different metals is different. The POM cluster whose water ligands attached to the Eu metals releases more protons than the cluster whose water ligands attached to the non-lanthanide ions. In addition, there exist two deprotonation sites and two stages during the whole deprotonation process. It is assumed that protons are initially deprotonated from water ligands which are attached to lacunary metal ions with the addition of base, and then released from hydroxide groups linked with niobium. The deprotonation from the coordinated water ligands and the linker can be distinguished for the POMs with lacunary copper ions, which is attributed to the charges of each cluster currently. Overall, the deprotonation property varies for POMs with different metal ions. The acidity strength of these weak nanoacids also differs depending on disparate lacunary metal ions.
Tianbo Liu (Advisor)
Toshikazu Miyoshi (Committee Member)
47 p.
Chemistry; Physical Chemistry
Deprotonation; Polyoxometalates; Water ligands;

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Citations

  • Xiao, K. (2019). Deprotonation Property of Polyoxometalates with Different Lacunary Metal Ions [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron155534024745702

    APA Style (7th edition)

  • Xiao, Kexing. Deprotonation Property of Polyoxometalates with Different Lacunary Metal Ions . 2019. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron155534024745702.

    MLA Style (8th edition)

  • Xiao, Kexing. "Deprotonation Property of Polyoxometalates with Different Lacunary Metal Ions ." Master's thesis, University of Akron, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron155534024745702

    Chicago Manual of Style (17th edition)

akron155534024745702
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This open access ETD is published by University of Akron and OhioLINK.