Thermal and photochemical reactions of large metallaborane clusters and functionalizations of boron nitride nanosheets

<p>The thermal and photochemical pathways of several metallaborane compounds and the functionalization of boron nitride nanosheets have been investigated. The nanosheets have potential applications in Dye Sensitized Solar Cells.Chapters 1 and 3 describe the thermal and photochemical pathways for two metalladecaboranes, [nido -6-Mn(CO) ₃B ₉H ₁₃][NMe ₄] (1.1) and [6-C₅Me₅-nido-6-RhB₉H₁₃] (3.1). Isomerization or cage closure reactions were observed depending on the reaction conditions and the transition metal employed. Characterized products include the firstnido-5 metalladecaborane and ahypercloso-metalladecaborane containing a group 7 transitional metal, compound1.3 and1.4, respectively. Other findings include the facile acid catalyzed cyclic oxonium functionalization of complex1.1, the role of complex3.1 as the catalyst for the [2+2+2] cycloadditions of terminal alkynes, and the formation ofhypercloso-rhodadecaborane3.3 which is the firsthypercloso-metalladecaborane containing the metal rhodium.</p> <p>Chapter 2 describes investigations of the photochemical reactions between metallaboranes and unsaturated molecules. The complex 1.1was found to photoreact with both terminal and internal alkynes to afford the carborane with general formula [7-R-8-R'-7,8-nido-C₂B₉H₁₀][NMe₄] (2) in good yield. This represents a novel method for generating the substituted nido-C₂B₉ complex. Besides alkynes, the investigation of the photoreactions of other unsaturated species with the complex 1.1 were found to generate the [arachno-B₉H₁₄]- (2.4) and [nido-B₉H₁₂]- (2.5) anions in different relative ratios, depending on the nature of the unsaturated molecules. The complex1.1 was also found to act as an efficient catalyst for isocyanate cyclodimerization under photo-irradiation conditions, representing the first example of a metallaborane complex to catalyse the cyclodimerization of isocyanate.</p> <p>In Chapter 4, an effective and simple noncovalent functionalization and solubilization of boron nitride nanosheets (BNNSs) has been achieved by using polythiophene or polyvinylpyrrolidone as a functionalization polymer with BNNSs. The BNNSs form strong π-π stacking interactions with the polythiophenes and were found to act as a bandgap tuning tool for polythiophene derivatives. A BNNS-polythiophne-TiO₂ hybrid nanomaterial was achieved by the covalent binding between TiO₂ nanoparticle surfaces and the BNNS-polythiophene unit containing a carboxylic acid functional group. This nanomaterial was then further incorporated into a Dye Sensitized Solar Cells (DSSCs) and the observed enhancement of the performance of the cells is discussed.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Year

2013

Author dc:creator

• Ma, Pei

Contributors dc:contributor

• James T. Spencer

• Boron nitride nanosheets
• Carborane
• Crystal structures
• Functional derivatives
• Metallaborane
• Photochemistry
• Chemistry

Repository record dc:identifier

https://surface.syr.edu/etd/42

OAI identifier oai:identifier

oai:surface.syr.edu:etd-1040