Synthethic pathways to multiple surface functionalization of polyhedral boranes
Abstract
[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] The chemistry of dodecahydro--closo--dodecaborate(2-), closo-[B12H12]2-, and decahydro-closo-decaborate(2-), [B10H10]2-, with different organic substituents was investigated in this research. The previously reported sequential synthesis of closo-[B12H12]2- hydroxyl derivatives were irreproducible. Through close monitoring of time and temperature mono-, di-, and tri- substituted hydroxyl, [B12H12-y(OH)y]2-, was synthesized in a controlled manner at 0.5 g, 5 g, and 10 g scales with significantly improved yields, >86%, 68%, >95%, respectively. Each of the hydroxylated species were exhaustively chlorinated in yields exceeding 95%. Oxidizing the perchlorinated hydroxylated products to the neutral species allows for their solubility in organic solvents, thus, open to easier manipulation in various organic settings and more accessible to perform organic chemistry. The more organic behavior of the cage allows us to synthesize hydroxyl derivatives. closo-[B12H10(SH)2]2- was synthesized from reduction of the inner-sulfonium salt of closo-[B12H10(SMe2)2] to make a suitable candidate for single molecular electronic conductors. An alternative synthetic route was proposed using ethylenediamine and n-propylamine as a great substitute for methylamine in the reaction for the formation of dithiol derivative from 1. A yield of 70% - 75% of the bis-(1,12-thiol)-closo-dodecaborate(2-) and 75% - 83% of bis-(1,7-thiol)-closo-dodecaborate(2-) was reported using this method. Recently, we reported a new class of organic-inorganic hybrid nanomolecular ions designated as polyarylboranes. These polyarylboranes are synthesized from the direct reaction between closo-[B12H12]2-or closo-[B10H10]2- and various aromatic hydrocarbons. The highly fluorescent characteristics of the product ions in solution results in high fluorescent quantum yields (0.3 to 0.6), high molar absorptivity, and large Stokes shifts (>200 nm). All of the newly synthesized compounds have been characterized by FT-IR, multi-nuclei NMR, and high-resolution mass spectrometry. In addition, the absorption, fluorescence excitation and emission properties for many of these materials have been measured.
Degree
Ph. D.
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