Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Two new potentially biodegradable aminopolycarboxylic acid ligands, iminodiglutaric
acid tetra sodium salt (IDG-4Na) and iminoglutaricsuccinic acid tetra sodium salt (IGS-
4Na), were synthesized in reasonably good yield and purity. The commercially
unavailable precursor for the two ligands, ethyl p-aminoglutarate, was synthesised in high
yield and purity, and together with the two ligands were fully characterized by means of
melting point measurements and various spectrometric techniques CH-NMR, 13C-NMR,
MS and IR).
For the first time, an electrochemical study has been conducted on the complexes of these
ligands with selected transition metal ions (Zn2+, Cu2+ and Cd2+). An electrochemical
technique, cyclic voltammetry (CV), was utilized on the study of the complexing ability
of the ligands to the selected metal ions. An electrochemical cell comprising three
electrodes was employed: thin film mercury coated carbon microelectrode was used as
the working electrode, a Platinum wire as the auxiliary electrode, and a Ag/AgCI as the
reference electrode.
CV has been used and proven to offer a convenient route towards the determination of
metal-ligand complex stability constants in aqueous media". The values of the logarithms
of the metal-ligand formation constants obtained by this technique, when compared with
other widely used aminopolycarboxylic acids (APCAs), show better complexing ability
of the ligands with the transition metal ions. When the two ligands are compared, IGS
showed greater affinity towards the selected transition metal ions. This is due to the fact
that, in aqueous media, as the side chain ligators decrease, the stabilization energy of the
complex increases. The formation stability constants were determined by plotting the
change in the reduction potential (ΔE) against solution pH. A process making use of a
modification of lingane equation was used. / AFRIKAANSE OPSOMMING: Twee nuwe potensieel bio-afbreekbare amienpolikarboksielsuurligande,
iminobiglutaarsuur -tetranatriumsout (IBG-4Na) en iminoglutaarsuksiensuurtetranatriumsout
(IGS-4Na), was vervaardig met redelike goeie opbrengs en suiwerheid.
Die kommersïeel onverkrygbare voorloper van die twee ligande, etiel-B-aminoglutaraat,
was berei met hoë obrengs en suiwerheid, en was saam met die twee ligande ten volle
geïdentifiseer deur middel van smeltpunt bepalings en verskeie spektrometriese tegnieke
CH-KMR, 13C-KMR, MS en IR.).
Vir die eerste keer is 'n elektrochemiese studie uitgevoer op die komplekse van hierdie
ligande met selektiewe oorgangsmetaalione (Zn2+, Cu2+, en Cd2+). 'n Elektrochemiese
tegniek, sikliese voltametrie (SV), is gebruik om die komplekseringsvermoë van die
ligande ten opsigte van die geselekteeerdr metaalione te bestudeer. 'n Elektrochemiese
sel wat bestaan uit drie elektrodes is gebruik: 'n Dunlaag kwikelektrode bedek met
koolstof is gebruik as die werkselektrode, 'n platinumdraad as die bykomende elektrode
en 'n Ag/AgCI elektrode as die verwysingselektrode.
SV is voorheen gebruik en bewys as 'n gerieflike metode vir die bepaling van
metaalligandkompleksstabiliteitskonstantes in waterige media'. Die waardes van die
logaritmes van die metaalligandvormingskonstantes wat verkry word deur hierdie
tegniek, soos vergelyk met ander algemeen gebruikte amienpolikarboksielsure (APKSe),
vertoon beter komplekseringsvermoë met die ligande deur middel van die
oorgangsmetaalione. Wanneer die twee ligande met mekaar vergelyk word, het IGS-4Na
groter affiniteit gehad vir die oorgangsmetaalione. Dit is as gevolg van die feit dat die
stabiliteitsenergie van die kompleks in waterige media verminder word soos wat die
sykettings van die ligande toeneem. Die vormingstabilitietskonstantes was bepaal deur 'n
varandering in reduksie potensiaal (ΔE) teenoor die pH van die oplossings te plot. Die
grafieke is verkry deur 'n aanpassing van die Lingnane-vergelyking te gebruik.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/50112 |
| Date | 12 1900 |
| Creators | Yohannes Desta, Yonas |
| Contributors | Crouch, A. M., Bredenkamp, M. W., Stellenbosch University. Faculty of Science. Dept. of Chemistry & Polymer Science. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 87 p. : ill. |
| Rights | Stellenbosch University |
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