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Use of the N,N-dialkyl-N’-benzoyl(thio)selenoureas as single source precursors for the synthesis of semiconducting quantum dots
Thesis (PhD (Chemistry and Polymer Science))--Stellenbosch University, 2008.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2008
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| _version_ | 1867614117542494208 |
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| access_status_str | Open Access |
| author | Bruce, Jocelyn Catherine |
| author2 | Koch, Klaus R. |
| author_browse | Bruce, Jocelyn Catherine Koch, Klaus R. |
| author_facet | Koch, Klaus R. Bruce, Jocelyn Catherine |
| author_sort | Bruce, Jocelyn Catherine |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD (Chemistry and Polymer Science))--Stellenbosch University, 2008. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/1205 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:46:56.603Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2008 |
| publishDateRange | 2008 |
| publishDateSort | 2008 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/1205 Use of the N,N-dialkyl-N’-benzoyl(thio)selenoureas as single source precursors for the synthesis of semiconducting quantum dots Bruce, Jocelyn Catherine Koch, Klaus R. Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. Nanoparticles N,N-dialkyl-N'-aryl(thio)selenoureas Single source precursors Chemical vapour deposition Dissertations -- Chemistry Theses -- Chemistry Thesis (PhD (Chemistry and Polymer Science))--Stellenbosch University, 2008. The successful preparation and structural characterization of a number of N,N-dialkyl-N’-benzoyl(thio)selenourea ligands is described; where the intermolecular interactions are characterized by the presence of Resonance Assisted Hydrogen Bonding (RAHB), π- π interactions between neighbouring benzene residues only being evident amongst the longer alkyl chain derivatives. The first structural characterization of an asymmetrically substituted N,N-dialkyl- N’-benzoylselenourea ligand reveals an increased stability of the Z isomer in the solid state, this being reflected by the sulfur analogue. Attempts to synthesise N,N-dicyclohexyl-N’-benzoylselenourea led to the isolation and structural characterization of a novel 1,3,5-oxaselenazine salt and dicyclohexylaminobenzoate. The first structural characterization of a “bipodal” N,N-dialkyl-N’-benzoylselenourea ligand, 3,3,3’,3’-tetrabutyl-1,1’- isophthaloylbis(selenourea), reveals RAHB in the crystal lattice similar to that exhibited by the “monopodal” analogue, N,N-dibutyl-N’-benzoylselenourea. The successful complexation of the N,N-dialkyl-N’-benzoyl(thio)selenourea ligands to a number of different transition metal ions is reported allowing the preparation of several potential single source precursors. Coordination through the O and Se/S donor atoms to Pd(II) results in the formation of square planar metal complexes, with a cis conformation, several of which could be structurally characterized. In particular, the first structural elucidation of an asymmetrically substituted N,N-dialkyl-N’-benzoylselenourea metal complex, cis-bis(N-benzyl-N-methyl-N’- benzoylselenoureato)palladium(II) indicates the increased stability of the EZ isomer in the solid state. Structural elucidation of the novel (N,N-diphenyl-N’-benzoylselenoureato)cadmium(II) reveals a bimetallic complex in the solid state, where the expected 2:1 ligand : metal ratio is maintained, and the two Cd(II) centres are 5 and 6 coordinated, with O and Se donor atoms. Multinuclear Nuclear Magnetic Resonance (NMR) Spectroscopy has been employed in the thorough characterisation of the potential single source precursors, 77Se NMR spectroscopy indicating a decreased shielding of the 77Se nucleus as the “hardness” of the central metal ion increases i.e. Pd(II) > Zn(II) > Cd(II). Use of 113Cd NMR spectroscopy indicates the preferential binding of N,N-diethyl-N’- benzoylselenourea to Cd(II) over that of its sulfur analogue, and initial studies suggest a form of chelate metathesis taking place in solution. 31P NMR spectroscopy is used to gain insight into the formation of cis-bis(N,N-diethyl-N’- benzoylselenoureato)Pt(II). Thermolysis of (N,N-diethyl-N’-benzoylselenoureato)cadmium(II) and its sulfur analogue led to the successful synthesis of CdSe and CdS quantum dots respectively, where thermolysis over a range of temperatures allows a degree of size control over the resulting nanoparticles. The effect of precursor alkyl chain length on nanoparticle morphology was investigated for both the N,N-dialkyl-N’-benzoylthio- and –selenoureas. A correlation between the two for the (N,N-dialkyl-N’-benzoylselenoureato)Cd(II) complexes is described and possible growth mechanisms are discussed. Preliminary investigations into the use of other N,N-dialkyl-N’-benzoyl(thio)selenourea metal complexes as single source precursors reveal that both (N,N-diethyl-N’-benzoylselenoureato)Zn(II) and its sulfur analogue show potential as single source precursors for the formation of ZnO and ZnS nanoparticles respectively. Initial studies into the use of N,N-dialkyl-N’-benzoyl(thio)selenourea metal complexes as single source precursors for the synthesis of core-shell nanoparticles is briefly described. The Aerosol Assisted Chemical Vapour Deposition (AACVD) of several N,N-dialkyl-N’-benzoyl(thio)selenourea metal complexes is reported, where both (N,N-diethyl-N’-benzoylselenoureato)Cd(II) and its sulfur analogue allow the deposition of crystalline CdSe and CdS respectively. The AACVD of (N,N-diethyl-N’- benzoylselenoureato)Zn(II) leads to the deposition of crystalline ZnSe, ZnS being deposited by (N,N-diethyl-N’-benzoylthioureato)Zn(II). The deposition of heazelwoodite (Ni3S2) with varying morphologies results from the AACVD of cis-bis(N,N-diethyl-N’-benzoylthioureato)Ni(II). Thermal annealing of the amorphous material deposited by the AACVD of cis-bis(N,N-diethyl-N’-benzoylthioureato)Pd(II), allows the formation of highly crystalline palladium. The deposition of metallic platinum using cis-bis(N,N-diethyl-N’-benzoylthioureato)Pt(II) is described as well as the deposition of crystalline Pd17Se15 from cis-bis(N,N-diethyl-N’-benzoylselenoureato)Pd(II). This, to the best of our knowledge, is the first time that AACVD has been performed, using the N,N-dialkyl-N’- benzoyl(thio)selenourea metal complexes as single source precursors, in addition, we believe it to be the first time that palladium selenide has been deposited using the AACVD technique. Doctoral 2008-11-14T14:26:37Z 2010-06-01T08:15:00Z 2008-11-14T14:26:37Z 2010-06-01T08:15:00Z 2008-12 Thesis http://hdl.handle.net/10019.1/1205 en_ZA Stellenbosch University application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Nanoparticles N,N-dialkyl-N'-aryl(thio)selenoureas Single source precursors Chemical vapour deposition Dissertations -- Chemistry Theses -- Chemistry Bruce, Jocelyn Catherine Use of the N,N-dialkyl-N’-benzoyl(thio)selenoureas as single source precursors for the synthesis of semiconducting quantum dots |
| title | Use of the N,N-dialkyl-N’-benzoyl(thio)selenoureas as single source precursors for the synthesis of semiconducting quantum dots |
| title_full | Use of the N,N-dialkyl-N’-benzoyl(thio)selenoureas as single source precursors for the synthesis of semiconducting quantum dots |
| title_fullStr | Use of the N,N-dialkyl-N’-benzoyl(thio)selenoureas as single source precursors for the synthesis of semiconducting quantum dots |
| title_full_unstemmed | Use of the N,N-dialkyl-N’-benzoyl(thio)selenoureas as single source precursors for the synthesis of semiconducting quantum dots |
| title_short | Use of the N,N-dialkyl-N’-benzoyl(thio)selenoureas as single source precursors for the synthesis of semiconducting quantum dots |
| title_sort | use of the n n dialkyl n benzoyl thio selenoureas as single source precursors for the synthesis of semiconducting quantum dots |
| topic | Nanoparticles N,N-dialkyl-N'-aryl(thio)selenoureas Single source precursors Chemical vapour deposition Dissertations -- Chemistry Theses -- Chemistry |
| url | http://hdl.handle.net/10019.1/1205 |
| work_keys_str_mv | AT brucejocelyncatherine useofthenndialkylnbenzoylthioselenoureasassinglesourceprecursorsforthesynthesisofsemiconductingquantumdots |