Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The work presented in this thesis throws light on the supramolecular approach in exploration of
bi-porphyrin nanorods system wherein self-assembly plays an important role. Porphyrin based
nanorods were synthesized via self-assembly of meso-tetrakis (4-phenylsulfonicacid) porphyrin
dihydrochloride and Sn (IV) tetrakis (4-pyridyl) porphyrin. Understanding the sizes and growth
mechanism of the porphyrin nanorods by self-assembly and molecular recognition is essential for
their successful implementation in nanodevices. Spectroscopic and microscopic studies were
carried out to investigate the effect that time, concentration and solvents have on the fabrication
of the porphyrin nanorods by ionic self- assembly. This study demonstrated that aggregates of
the di- acid form of meso-tetrakis (4-phenylsulfonic acid) porphyrin dihydrochloride and Sn (IV)
tetrakis (4-pyridyl) porphyrin resulted in porphyrin nanorods with diameters between 20 nm and
60 nm, and μm in lengths. Enhanced optical properties illustrated the potential for slightly
modifying the method of synthesis to influence the physical and optical properties of porphyrin
nanorods. The porphyrin nanorods reflectance data demonstrated that these structures are good
absorbers of light and therefore could potentially be used to harvest light. The nonlinear optical
(NLO) properties of the porphyrin nanorods were investigated for the first time in this study by
second and third harmonic generation techniques. Such study was influenced by the fact that
porphyrins have great thermal stability and extended -conjugated macro cyclic ring which give
them large nonlinear optical effects. The NLO results showed that the porphyrin nanorods may
have many potential uses in photonic applications due to larger third order nonlinear
susceptibility. Single molecule spectroscopy was also used to investigate the dynamics of
intermolecular and intramolecular processes. Porphyrin nanorods were incorporated into polymer
matrices to achieve an arrangement where they can be directly used as a device. The assembly of
porphyrin nanorods on track-etched membranes was achieved through altering the surface charge
of the respective membranes. Porphyrin nanorods-polymer composites were produced using
latex technology and electrospinning techniques. The fibres were characterized with respect to
morphology and optical properties. / AFRIKAANSE OPSOMMING: Die werk wat in hierdie tesis beskryf word werp lig op die supramolekulêre benadering in die
ondersoek van bi-porfirien nano-silinders waarin self-versameling ‘n belangrike rol speel.
Porifirien nano-silinders was voorberei via self-versameling van meso-tetrakis(4-feniel
sulfoonsuur) porfirien dihidrochloried en Sn (IV) terakis (4-piridiel) porfirien. Dit is belangrik
om die meganismes wat verband hou met die groei en grootte van die nano-silinder struktuur te
ondersoek. Dit het ‘n invloed op die self-versameling asook die uiteindelike toepassing.
Spectroskopiese en mikroskopiese studies was uitgevoer om die effek van tyd, konsentrasie en
oplosmiddel op die selfversamelling te bestudeer. Die studie dui daarop dat bondels van die disuur
vorm van meso-tetrakis(4-feniel sulfoonsuur) porfirien dihidrochloried en Sn (IV) terakis
(4-piridiel) porfirien het gelei tot porfirien nano-silinders met lengtes tussen 20 nm en 60 nm
asook in die mikro meter skaal. Verhoogde optiese eienskappe het die potensiaal om effense
veranderinge in die metode om die nano-silinders voor te berei om sodoende ‘n groter invloed op
die fisiese en optiese einskappe te hê. Die reflektansie data wys dat hierdie strukture goeie
absorbsies van lig toon en daarom geskik sal wees om lig te stoor. Die nie-liniêre optisie (NLO)
eienskappe van die profirien nano-silinders was vir die eerste keer ondersoek deur middel van
tweed en derde hormoniese generasie tegnieke. Hierdie studie was beïnvloed deur die feit dat
porfiriene goeie stabiliteit by hoë temperatuur en ‘n verlengde -gekonjugeerde makro-sikliese
ring bevat wat dan groot nie-liniêre optiese effekte gee. Die NLO resultate wys dat die profirien
nano-silinders groot potensiaal het in die gebruik van fotoniese toepassings as gevolg van derde
orde nie-liniêre vatbaarheid. Enkel molekuul spektroskopie was ook gebruik om die dinamika
van intermolekulêre en intramolekulêre prosesse te ondersoek. Porfirien nano-silinders was
geïnkorporeer in polimeer matrikse om ‘n eweredige verspreiding te verkry en om direk as ‘n
toestel te gebruik. Die versameling van porfirien nano-silinders op baan-ingeëtse membrane was
bereik deur die verandering in oppervlak lading van die membrane. Porfirien nano-silinder /
polimeer samestellings was verkry deur lateks tegnologie en elektrospin tegnieke. Die vesels was
gekarakteriseer in terme van morfologie en optiese eienskappe.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/86772 |
| Date | 04 1900 |
| Creators | Mongwaketsi, Nametso Precious |
| Contributors | Maaza, Malik, Klumperman, Bert, Sparrow, Raymond, Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | xi, 88 pages : illustrations |
| Rights | Stellenbosch University |
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