Synthesis of DI- and trialkylthiourea complexes of Cd, Mn and Ni as precursors for phosphonoacetic acid (PAA)-capped metal sulphide nanoparticles
Date
2010-08-03
Authors
Mlambo, Mbuso
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Abstract
Many studies on thiourea and its derivatives in different metal (II) complexes have confirmed
that coordination is through the sulphur atom. The bonding of substituted thioureas to
different metals was confirmed with a combination of spectroscopic studies such as IR and
NMR spectroscopy and elemental analysis. A series of metal (II) di- and trialkylthioureas
complexes have been synthesized and characterized. Their bonding through sulphur atoms
rendered these complexes good precursors for the preparation of metal sulphide
nanoparticles. Thermogravimetric analysis on the complexes was undertaken to check their
suitability as precursors for the synthesis of nanoparticles and their potential as precursors for
metal sulphide thin films using the chemical vapour deposition (CVD) technique and their
general chemical and thermal stability.
All the complexes reported in this work were used as single source molecular precursors for
the synthesis of cadmium, manganese and nickel sulphide nanoparticles. In this study the
investigation on the influence of capping agent and temperature on the size and morphology
of nanoparticles was undertaken. Nanoparticles obtained by thermolysis of precursors in
phosphonoacetic acid (PAA) were bigger in size and rod-shaped compared to smaller rods
obtained in hexadecylamine (HDA). CdS nanoparticles prepared using PAA as a capping
agent showed a huge blue-shift of the band edge from the bulk of 515 nm, compared to CdS
nanoparticles obtained using HDA as a capping agent. When PAA was mixed with
trioctylphosphine oxide (TOPO), a blue shift of band edges in all the bulk materials of
different metal sulphides prepared was observed and the rod-shaped nanoparticles changed to
spherical particles.