Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry, 36:465–467, 2006
Copyright # 2006 Taylor & Francis Group, LLC
ISSN: 0094-5714 print/1532-2440 online
DOI: 10.1080/15533170600777903
Zintl Polyanions as Metal Nano Particle Precursors
S. M. Lake and J. J. Lagowski
Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas, USA
characteristic that is the basis for the production of metal nano-
Bismuth nanoparticles have been produced by the oxidation of particles.
the Zintl polyanion Bi242 in ethylenediamine solutions. TEM
images indicate that the crystalline nanoparticles produced in
the presence of polyethylene glycol are in the size range of
M
nꢀ þ ½OXꢁ
!
M
xðsÞ þ ½OXnꢀꢁ
We have chosen the well-characterized B242 polyanion[12]
for these initial experiments. The polyanion is produced from
the extration of a Na:Bi alloy by ethylenediamine.[12–13]
ꢀ20 nm. The oxidation of the polyanion by 2-octanol produce
larger nanoparticles of bismuth (ꢀ50 nm).
Keywords Bismuth, nanoparticles, metal anions, non-aqueous
solvents, synthesis
EXPERIMENTAL
All reactions were performed in an anaerobic environment
because H2O, O2, and CO2 can be reduced by metal anions.
Ethylenediamene was purified by the method of Dye.[14]
Bismuth-sodium alloys (1 : 1 molar ratio) were prepared in
vacuo by melting the appropriate quantities of the constituent
metals. The alloy was equilibrated with the dry ethylenedia-
mine solvent producing a red-brown colored solution,
aloquots of which were treated with an oxidant to yield the
desired nanoparticles. The products were characterized by
TEM and elemental analysis using X-ray fluorescence
techniques.
INTRODUCTION
Nanophase substances often exhibit different properties than
those of the same substance in the bulk crystalline phase. Many
of the new properties of nanophase materials (1–100 nm) arise
because the critical length scales of physical phenomena
become comparable or larger than the size of the nanoparti-
cles.[1] In general, the synthesis of nanophase substances
have involved the dispersion of bulk phases by physical pro-
cesses, or most commonly, the use of chemical processes that
start with conventional, molecular-sized species to produce
solids in a chemical environment that ensures the dispersion
of the desired products as nano-sized particles. By far, the
favored method of producing nanophase substances involves
the use of chemical processes that, as a group, possess a poten-
tial richness that allows for the possibilities of chemical
manipulation to produce nanophase substances with well-
defined properties.
RESULTS AND DISCUSSION
Two (2) different oxidizing environments were investi-
gated; (I) isopropyl alcohol in the presence of the surfactant,
polyethylene glycol (PEG), and (II) 2-octanol. Both environ-
ments produced particles of bismuth metal. The results of
these experiments follow.
I. A TEM photograph (Figure 1) of the product formed by
the oxidation of Bi242 in the presence of PEG consists of nano-
particles in the range of ꢀ20 nm. The crystalinity of the nano-
particles produced in environment I is established by the TEM
data shown in Figure 2, from which data we extracted a lattice
spacing of ꢀ0.33 nm.
We report here the results of preliminary experiments
designed to produce metal nanoparticles. The work reported
here is the latest manifestation of our long-time interest in
metal anions, a species that can be stabilized in non-aqueous
solvents such as amines and ethers.[2–11] Not surprisingly,
metal anions are highly reducing species, the chemical
II. In this environment, where 2-octanol is the oxidant, we
assume that the alcohol (or its anion) can also act as a surfac-
tant. The TEM of the product formed in this environment
(Figure 3) consists of nanoparticles of bismuth in the
ꢀ50 nm size. The larger sized nanoparticles produced in
environment II compared with those produced in environment
Received 23 February 2006; accepted 1 April 2006.
Address correspondence to J. J. Lagowski, Department of Chem-
istry and Biochemistry, The University of Texas at Austin, Austin, TX
78712, USA. E-mail: jjl@mail.utexas.edu
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