Date of Award
Doctor of Philosophy (PhD)
Polyoxovanadate-alkoxide (POV-alkoxide) clusters are a new class of electroactive species with potential electrochemical applications in redox catalysis, energy storage, and optoelectronics. These clusters' redox properties can be tuned by the functionalization via heterometallic installation and changing alkoxide ligands. However, the formation mechanism of these POV-alkoxides in the solvothermal process is unknown, limiting the rational design to improve their electronic properties. This dissertation reports the speciation study of POV-alkoxide clusters, which is fundamental to controlling and manipulating the evolution of transient species during their nucleation and tuning the final product's properties. Chapter 2 and chapter 3 describe our computational study of nucleation pathways of two POV-alkoxide clusters in methanol, one with only vanadium centers, [(VV6-nVIVnO6)(O)(O-CH3)12](4-n)+ and another with heterometallic iron inserted in POV-alkoxides [(VV5-nVIVnO5)(O-CH3)12(O)(FeIIICl)] (3-n)+. Our investigations show how iron heterometal incorporates into POV-alkoxides, which have paved the way for installing other heterometallic centers (Ti, Zr, or Hf). Chapter 4 explores the formation of ring-type cyclic POV-alkoxide cluster [(VIVnOn(O-R)2n)] (n=5 and 6; R = -CH3, -C2H5, and -C3H7), which is an underdeveloped field. Our calculations show that anionic directing groups (F- and Cl-) and bridging alkoxides impact cyclic POV-alkoxide clusters' nucleation. Fluoride and chloride act as templating agents and stabilizers for cyclic pentamer [(VIV5O5(O-CH3)10)F]- and hexamer [(VIV6O6(O-CH3)12)Cl]- formation. Without halides, methoxide, ethoxide, and n-propoxide bridging ligands favor the formation of the cyclic hexamer [(VIV6O6(O-R)12)] (R = -CH3, -C2H5, and -C3H7), while isopropoxide favors the formation of cyclic pentamer [(VIV5O5(O-R)10)]. We predict the expansion of cyclic POV-alkoxide motifs by the possibility of isolating cyclic pentameric [(VIV5O5(O-CH3)12)F]- with fluoride template and cyclic pentameric [(VIV5O5(O-C3H7)12)] through isopropoxide ligand functionalization in future.
Cluster chemistry, Iron, Nucleation, Polyoxometalates, Polyoxovanadate-alkoxide, Vanadium
Number of Pages
University of South Dakota
Rabbani, S M Gulam, "COMPUTATIONAL STUDY ON THE NUCLEATION OF POLYOXOVANADATE-ALKOXIDE CLUSTERS" (2022). Dissertations and Theses. 65.
Available for download on Thursday, August 22, 2024