Simple and efficient: Ethylene glycol isonitrile gold(I) chlorides for the formation and stabilization of gold nanoparticles

Article abstract of DOI:10.1002/ejic.201100324

Ethylene glycol isonitriles C≡N(CH₂CH₂O) _nCH₃ (5a, n = 1; 5b, n = 3; 5c, n = 4) with different chain lengths were prepared by using straightforward synthesis methodologies including the Gabriel synthesis and an Appel-type reaction protocol. Upon treatment with [AuCl(SMe)₂], compounds 5a-c gave the corresponding isocyanide gold(I) chlorides [AuCl{C≡N(CH₂CH₂O) _nCH₃}] (7a, n = 1; 7b, n = 3; 7c, n = 4). Single-crystal X-ray diffraction studies reveal a polymeric (7a) or dimeric (7c) structure with aurophilic interactions. Gold(I) complexes 7a-c were applied in the formation and stabilization of gold nanoparticles (AuNPs). The isonitriles with their ethylene glycol functionalities, which provide multiple donating capabilities, are able to stabilize the encapsulated gold colloids. The reduction of 7a-c by the addition of Na[BH₄] in tetrahydrofuran or methanol produces AuNPs without the further addition of any stabilizer, since metal-organic 7a-c combine the stabilizing component and gold source in one molecule. The dependency of different solvents, concentrations, and varying ethylene glycol chain lengths on the NP size and size distribution is reported. Characterization by TEM, UV/Vis spectroscopy, and XRPD revealed that AuNPs are formed with a size between 6.4(±1.4) to 9.5(±2.3) nm in methanol and 18.2(±2.3) to 27.2(±3.5) nm in tetrahydrofuran. Copyright

Full text of DOI:10.1002/ejic.201100324

FULL PAPER
DOI: 10.1002/ejic.201100324
Simple and Efficient: Ethylene Glycol Isonitrile Gold(I) Chlorides for the
Formation and Stabilization of Gold Nanoparticles
André Tuchscherer,[a] Dieter Schaarschmidt,[a] Steffen Schulze,[b][‡] Michael Hietschold,[b][‡]
and Heinrich Lang*[a]
Keywords: Nanoparticles / Gold / Isonitriles / Ethylene glycol / Redox chemistry
Ethylene glycol isonitriles CϵN(CH2CH2O)nCH3 (5a, n = 1;
5b, n = 3; 5c, n = 4) with different chain lengths were pre-
pared by using straightforward synthesis methodologies in-
cluding the Gabriel synthesis and an Appel-type reaction
protocol. Upon treatment with [AuCl(SMe)2], compounds 5a–
tiple donating capabilities, are able to stabilize the encapsu-
lated gold colloids. The reduction of 7a–c by the addition of
Na[BH4] in tetrahydrofuran or methanol produces AuNPs
without the further addition of any stabilizer, since metal-
organic 7a–c combine the stabilizing component and gold
source in one molecule. The dependency of different sol-
vents, concentrations, and varying ethylene glycol chain
lengths on the NP size and size distribution is reported. Char-
acterization by TEM, UV/Vis spectroscopy, and XRPD re-
vealed that AuNPs are formed with a size between 6.4(Ϯ1.4)
to 9.5(Ϯ2.3) nm in methanol and 18.2(Ϯ2.3) to 27.2(Ϯ3.5) nm
in tetrahydrofuran.
c
gave the corresponding isocyanide gold(I) chlorides
[AuCl{CϵN(CH2CH2O)nCH3}] (7a, n = 1; 7b, n = 3; 7c, n =
4). Single-crystal X-ray diffraction studies reveal a polymeric
(7a) or dimeric (7c) structure with aurophilic interactions.
Gold(I) complexes 7a–c were applied in the formation and
stabilization of gold nanoparticles (AuNPs). The isonitriles
with their ethylene glycol functionalities, which provide mul-
Introduction
Schiffrin method, in which chloroauric acid is reduced by
sodium borohydride in presence of an alkanethiol.[13]
Möller and co-workers generated AuNPs by using sodium
borohydride or hydrazine as reducing agent in micelles that
behave like “nanoreaction vessels”.[14] These procedures re-
quire the addition of stabilizing agents and the use of hycro-
scopic chloroauric acid, which is also light-sensitive. For the
synthesis of high-quality AuNPs, stabilizing agents that fea-
ture donating functionalities or atoms like N, O, P, and S
are required, which will attach to the particle surface and
hence prevent aggregation. (Poly)ethylene glycols,[15] poly-
mers/block copolymers,[16] dendrimers,[17] phosphanes,[18]
amines,[19] thioethers,[20] and surfactants[21] are typically
used as stabilizing components.
We report here on the synthesis of [AuCl{CϵN-
(CH2CH2O)nCH3}] (n = 1, 3, 4) and its use in the formation
of gold NPs by a bottom-up methodology. The addition of
any further stabilizing agent is not necessary because the
appropriate gold(I) complex combines the gold source and
the stabilizing component in one molecule. The influence of
the ethylene glycol chain length, the use of different organic
solvents, and the ethylene glycol isocyanide gold(I) chloride
concentration on the NP size and the size distribution is
discussed.
In recent decades, considerable efforts have been made to
synthesize and stabilize defined transition-metal nanopar-
ticles (NP). As these materials have discrete particle sizes
between 1 and 100 nm diameter, their unique physicochemi-
cal properties are affected by the particle size, shape, size
distribution, and particle-to-particle interaction.[1] In par-
ticular, group 11 metal NPs allow the design of new genera-
tions of nanodevices and smart materials[2] due to their
unique optic,[3] electric,[4] magnetic,[5] catalytic,[6] or bio-
logical[7] properties. Bottom-up and top-down methodolo-
gies are widely applied in NP formation. The bottom-up
method allows their selective synthesis (e.g., defined struc-
tures through chemical reduction of a gold source),[8] de-
composition of metal-organic compounds,[9] or electro-
chemical[10] and photochemical[11] methods. For the first
time, Turkevich et al. synthesized gold colloids in aqueous
media by reducing chloroauric acid with sodium citrate.[12]
Another synthesis methodology is the so-called Brust–
[a] Faculty of Natural Sciences, Department of Inorganic
Chemistry,
Chemnitz University of Technology,
Strasse der Nationen 62, 09111 Chemnitz, Germany
Fax: +49-0371-531-21219
E-mail: heinrich.lang@chemie.tu-chemnitz.de
[b] Faculty of Natural Sciences, Department of Solid Surfaces
Analysis,
Results and Discussion
Synthesis and Characterization
Chemnitz University of Technology,
Reichenhainer Strasse 70, 09126 Chemnitz, Germany
[‡] Responsible for the TEM studies.
Starting from ethylene glycol monomethyl ether, the ap-
propriate gold(I) complexes [AuCl{CϵN(CH2CH2O)n-
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201100324.
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H. Lang et al.
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CH3}] (7a, n = 1; 7b, n = 3; 7c, n = 4) were available through
Metal-organic complexes 7a–c are stable to air and
a five-step synthesis procedure using Gabriel synthesis and moisture both in the solid state and in solution. All newly
an Appel analogue reaction procedure (Scheme 1). Subse- prepared compounds have been identified by elemental
quent treatment of ethylene glycol monomethyl ethers 1a (n analysis, IR, and NMR (1H, 13C{1H}) spectroscopy. Ad-
= 1), 1b (n = 3), or 1c (n = 4) with phthalimide, PPh3, and ditionally, high-resolution-ESI TOF mass spectrometry and
diisopropyl azodicarboxylate (DIAD) gave the correspond- single-crystal X-ray structure analysis (7a and 7c) were car-
ing ethylene glycol monomethyl ether substituted phthal- ried out. Advantages of the reaction of 3a–c with methyl
imides 2a–c in yields between 85 and 96% (see Exp. Sect.). formate to give 4a–c is that it can easily be monitored by
Treatment of 2a–c with hydrazine hydrate followed by ad- IR spectroscopy, since the NH-deformation (δNH = 1597–
dition of concentrated aqueous HCl produced amines 3a– 1600 cm–1) and -valence vibrations (νNH = 3360–3368 cm–1)
c (59–70%). Further reaction with methyl formate and p- are shifted bathochromically (δNH = 1530–1536 cm–1, νNH
toluenesulfonic acid monohydrate resulted in the formation = 3297–3318 cm–1) when going from 3a–c to 4a–c. Ad-
of formamides 4a–c (93–99%) (Scheme 1). The latter mole- ditionally, the typical formamide C=O valence vibration oc-
cules gave isonitriles 5a–c along with PPh3, NEt3, and CCl4. curs at approximately 1680 cm–1. Further conversion of 4a–
Isonitrile gold(I) chlorides 7a–c were accessible by treating c to isonitriles 5a–c can also be monitored by IR spec-
5a–c with [AuCl(SMe2)] (6) in virtually quantitative yield.
troscopy due to the disappearance of the N-amide and
C=O vibrations accompanied by the appearance of the iso-
cyanide CϵN absorption between 2151 and 2155 cm–1 (see
Exp. Sect.). Coordination of isonitriles 5a–c to [AuCl]
causes a hypsochromic shift of the CϵN bonds (2259–
2268 cm–1), which is typical in gold(I) isocyanide chemis-
try.[22]
Characteristic for formamides 4a–c in the 1H NMR spec-
tra is the appearance of a broad signal at δ ≈ 6.6 ppm for
the N-amide functionality. The CHO moiety gives rise to a
signal at δ ≈ 8.1 ppm. Very characteristic in the 13C{1H}
NMR spectra of 4a–c is the appearance of the carbonyl
carbon atom at δ ≈ 161.2 ppm, whereas transformation to
isonitriles 5a–c causes a high-field-shifted isocyanide car-
bon atom, which could be detected at δ ≈ 157.5 ppm with
typical coupling constants (see Exp. Sect.). These signals
Scheme 1. Synthesis of isocyanide gold(I) complexes 7a–c from
1a–c.
Figure 1. Left: ORTEP diagram (50% probability level) of 7a with the atom-numbering scheme of selected bond lengths [Å] and angles
[°]: Au1–Cl1 2.262(3), C1–Au1 1.949(11), N1–C1 1.119(12), C2–N1 1.429(13), C2–C3 1.508(13), C3–O1 1.425(11), O1–C4 1.433(10); Cl1–
Au1–C1 1177.7(2), Au1–C1–N1 178.9(9), C1–N1–C2 179.7(9), C3–O1–C4 109.8(7). Right: 1D chain of 7a setup by aurophilic interactions
[Au1–Au1A 3.4557(6), Au1–Au1B 3.7320(5) Å] (symmetry-generated atoms are indicated by the suffix A and B; symmetry codes: –x, 1 –
y, 1 – z and –x, 2 – y, 1 – z.).
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Ethylene Glycol Isonitrile Gold(I) Chlorides
Figure 2. Left: ORTEP diagram (50% probability level) of 7c with the atom-numbering scheme of selected bond lengths [Å] and angles
[°]: Au1–Cl1 2.2603(10), C1–Au1 1.943(4), N1–C1 1.135(5), N1–C2 1.447(5), C2–C3 1.493(7), C3–O1 1.422(5), O1–C4 1.423(5); Cl1–
Au1–C1 178.27(14), Au1–C1–N1 177.6(4), C1–N1–C2 176.8(5), C3–O1–C4 112.3(3). Right: aurophilic interaction between two anti-
periplanar-oriented molecules of 7c in the solid state with Au1–Au1A contacts [3.5317(2) Å] (symmetry-generated atoms are indicated
by the suffix A; symmetry code: 1 – x, –1 – y, 1 – z.).
are shifted to higher field in AuI complexes 7a–c (δ ≈ fraction analysis of the AuNPs showed the presence of a
135.3 ppm), which indicates the coordination of 5a–c to a face-centered cubic (fcc) lattice structure. The ring pattern
transition-metal atom.[22]
can be indexed as derived from (111), (200), (220), (222),
The structures of 7a (Figure 1) and 7c (Figure 2) in the and (311) lattice planes of gold. In addition, XRPD analy-
solid state were determined by single-crystal X-ray diffrac- ses of the synthesized Au colloids were carried out in meth-
tion analysis. Relevant crystallographic and structure re- anol solutions and show four characteristic reflexes at
finement data are summarized in the Exp. Sect. Selected 38.19, 44.37, 64.59, and 77.57° (ICDD C03–068–2870),
bond lengths [Å] and bond angles [°] are given in the cap- which correspond to Miller indices (111), (200), (220), and
tions of Figures 1 and 2.
(311), thereby confirm an fcc lattice structure.[25]
Metal-organic 7a crystallized in the triclinic space group
Optical characterization of the AuNP solutions was done
¯
P1 and 7c in the monoclinic space group P21/n. As ex- by UV/Vis spectroscopy (Figure 3). All UV/Vis spectra
pected, the Cl–Au–CϵN–CH2 building blocks are linear show a strong absorption in the range of 450–650 nm due
with bond angles between 177 and 180° and a maximum to the plasmon resonance caused by the interaction of elec-
deviation of 0.115(4) (7a, for Cl1) or 0.100(2) Å (7c, for tromagnetic radiation with the electron fluctuation of col-
Cl1). Weak aurophilic interactions are observed, thereby re- loidal gold (see the Supporting Information). The plasmon
sulting in the formation of a 1D chain with Au–Au separa- maximum of the AuNP was observed between 513 and
tions of 3.4557(6) and 3.7320(5) Å (Figure 1, right).[23] 518 nm in methanol (Table 1).[26] When tetrahydrofuran
Complex 7c forms an anti-periplanar-oriented dimer with was used as solvent, the absorption maximum was batho-
an Au–Au distance of 3.5317(2) Å in the solid state (Fig- chromic shifted (527–538 nm) (Figure 3, Table 1). This indi-
ure 2, right). Similar species have recently been published cates that larger AuNPs are formed in tetrahydrofuran than
{i.e., [AuX(CϵNR)] (X = Cl, NO3; R = C3H7, C6H11)} by in methanol. Most probably the coordinating (stabilizing)
Schmidbaur and co-workers. The bond angles of the X– behavior of tetrahydrofuran is lower than methanol, thus
Au–C moiety are almost in the same range; however, the leading to larger particles, which corresponds with observa-
Au–C bond lengths are enlarged in 7a and 7c, respec- tions described in the literature.[27] The different ethylene
tively.[24]
glycol chain lengths show only a little effect on the AuNP
Nanoparticle Formation and Characterization
For generation of gold nanoparticles, isocyanide gold(I)
chlorides 7a–c were dissolved in tetrahydrofuran or meth-
anol (1ϫ10–2 to 8ϫ10–4 m) and reduced by the addition of
Na[BH]4 to the appropriated gold(I) solutions. A change
from colorless to intensive purple was observed, thus indi-
cating the formation of zero-valent AuNPs stabilized by the
isocyanide ethylene glycol chains. For completion of the re-
ducing process, stirring for 5 min was required (see Exp.
Sect.). Further addition of any stabilizing agents was not
necessary. The formation of gold NPs was proven by elec-
tron diffraction pattern and X-ray powder diffraction stud-
Figure 3. UV/Vis spectrum of 7c in methanol (dashed line) and
ies (XRPD) (see the Supporting Information). Electron dif- tetrahydrofuran (solid line) (T = 25 °C; c = 6.3ϫ10–3 m).
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H. Lang et al.
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size formation, as can be concluded from almost identical
UV/Vis spectra in tetrahydrofuran and methanol, respec-
tively.
Table 1. Comparison of the plasmon maxima and the AuNP size
depending on ethylene glycol chain lengths and solvent (see the
Supporting Information).
Solvent
UV/Vis [nm]
NP size [nm]
7a
7b
7c
methanol
methanol
methanol
515
513
518
8.2 (Ϯ2.0)
8.1 (Ϯ1.0)
8.3 (Ϯ1.5)
7a
7b
7c
tetrahydrofuran
tetrahydrofuran
tetrahydrofuran
538
533
527
27.2 (Ϯ4.1)
23.0 (Ϯ2.9)
24.3 (Ϯ3.5)
The particle size, size distribution, and shape of the
AuNPs were determined by tranmission electron micros-
copy (TEM) measurements to reveal an average size dia-
meter between 8.1(Ϯ1.1) and 8.3(Ϯ1.5) nm in methanol
(Figure 4). It can be seen that the ethylene glycol chain
length in methanol has no effect on the particle size. In
tetrahydrofuran, the AuNP size diameters are significant
larger 23.0(Ϯ3.3) to 27.2(Ϯ4.1) nm. An increase of the gold
particle size, effected by the shortest ethylene glycol chain,
occurs due to the lower number of donating functionalities
and hence the smaller organic matrix. Contrary to our ex-
pectations is that the obtained particle sizes of 7b and 7c
are nearly identical. This is most probably caused by the
small difference of only one additional CH2CH2O repeating
unit between 7a and 7b. The higher polarity of methanol
compared with tetrahydrofuran influences the formation of
smaller NPs. In addition to UV/Vis measurements (vide su-
pra), TEM studies were carried out to verify that different
chain lengths of appropriate isonitriles have only a small
influence on the NP size formation in both solvents (Fig-
ure 5; see also the Supporting Information).
Figure 5. TEM images and size distributions of AuNPs received
from 7a–c in tetrahydrofuran [T = 25 °C; c = 6.3ϫ10–3 m; (A) 7a,
(B) 7b, (C) 7c].
1.6ϫ10–2 m and 7.8ϫ10–4 m, respectively, were used. For
these studies, complex 7c was chosen, due to its highest do-
nation capacity and hence the largest organic stabilizing
framework.
To determine the nature of the plasmon band, the plas-
mon full width at half-maximum (FWHM) was determined
by deconvolution of the absorption spectra using four
Gaussian-shaped overlapping absorptions.[29] The fits are
good enough to allow an almost exact overlay of the sum
of the spectral components with the experimental data. The
increase of FWHM is caused by an increase in the concen-
tration (Table 2), which indicates a broader size distribution
of the AuNPs. This indicates an increase of the particle size.
TEM analyses are in agreement with the results of FWHM
and show a growth of the NP size from 18.2(Ϯ2.3) to
23.6(Ϯ3.5) nm for tetrahydrofuran and 6.4(Ϯ1.4) to
9.5(Ϯ2.3) nm for methanol solutions by increasing concen-
tration. In addition, the NP size distribution became
broader. The sharpest size distributions in tetrahydrofuran
Figure 4. TEM images and size distribution of AuNPs
(8.3Ϯ1.5 nm) generated from 7c upon addition of Na[BH4] in
methanol (ϑ = 25 °C; c = 6.3ϫ10–3 m).
It is well known that the stabilizing effect depends on the were obtained at low concentrations (7.8ϫ10–4 m) for 7c.
number of donating functionalities of the stabilizer as well In methanol, the sharpest size distribution is obtained by
as the solvent.[28] The narrowest NP size distributions were reducing 7c at concentrations of 6.3ϫ10–3 and 7.8ϫ10–4 m,
found for 7b and 7c, which feature the longest ethylene respectively. Higher concentrations lead to agglomeration
glycol chain length (n = 4) independent of the solvent used due to the higher probability of colliding (Table 2; see also
(vide supra).
the Supporting Information). The determination of the
Typical NP preparation was carried out in a concentra- polydispersity for NPs generated in methanol is between
tion of 6.3ϫ10–3 m. To study the influence of the concen- 12.4 and 24.4%, whereas for particles formed in tetra-
tration on particle size and shape concentrations of hydrofuran a polydispersity of 10.7–24.2% was found.
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Ethylene Glycol Isonitrile Gold(I) Chlorides
Table 2. Comparison of the AuNP size, plasmon maxima, and plas-
mon FWHM at different concentrations and solvents for 7c (see
the Supporting Information).
Conclusion
Ethylene glycol isonitriles with different chain lengths
CϵN(CH2CH2O)nCH3 (n = 1, 3, 4) were prepared by using
straightforward synthesis methodologies. Their coordina-
tion to gold(I) chloride gave the corresponding isocyanide
gold(I) chloride complexes [AuCl{CϵN(CH2CH2O)n-
CH3}]. These species show in relation to the chain length
in the solid state weak aurophilic interactions to give 1D
chains [AuCl{CϵN(CH2CH2O)CH3}] or anti-periplanar-
oriented dimers ([AuCl{CϵN(CH2CH2O)4CH3}]) with
Au–Au contacts between 3.4557(6) and 3.7320(5) Å. The
gold(I) complexes were used for the generation and stabili-
zation of gold NPs without any addition of a further stabi-
lizing agent. The oligo(ethylene glycol) isonitriles provide
multiple donating functionalities, which are essential for the
stabilization of gold colloids. Gold NPs are accessible
through an efficient reductive method, whereby the appro-
priate gold(I) precursor possesses stabilizer and gold source
in one molecule. These metal-organic complexes are able to
produce AuNPs that are reproducible through a reductive
method (the addition of Na[BH4]). The colloids were char-
acterized by TEM, UV/Vis, and XRPD experiments. The
relationship between different solvents, concentrations, and
variable ethylene glycol chain lengths and the AuNP size
and size distribution was studied. Gold NPs were formed
with a size of 8.1(Ϯ1.1) to 8.3(Ϯ1.5) nm (methanol) and
24.1(Ϯ2.9) to 27.2(Ϯ4.1) nm (tetrahydrofuran), respectively,
in relation to different ethylene glycol chain lengths. In
methanol, no influence on the average particle size diameter
was observed, whereas in tetrahydrofuran an increase in the
particle diameter for [AuCl{CϵN(CH2CH2O)CH3}] due to
the poor stabilizing effect of the isocyanide is characteristic.
Increasing concentrations create an increase in the AuNP
size [methanol 6.4(Ϯ1.4) to 9.5(Ϯ2.3) nm, tetrahydrofuran
18.2(Ϯ2.3) to 24.3(Ϯ3.6) nm] due to higher probability of
colliding, which results in an agglomeration of the AuNPs.
Within this strategy, different particle sizes with small size
distribution could be obtained by changing the concentra-
tion or varying the chain length of the isocyanide. The low
influence of the ethylene glycol is caused by a too small
increase in the donating functionalities and hence the small
organic matrix. Further experiments with significantly more
repeating units (Ͼ30) should show a larger effect on the
AuNP size and size distribution. However, our methodol-
ogy to generate gold NPs at ambient temperature by using
a “two-in-one” molecule (which contains the gold source
and a stabilizer) results in the formation of small particles
with small size distributions.
Conc. [m]
Solvent
UV/Vis
[nm]
FWHM[a]
[cm–1]
NP size [nm]
1.6ϫ10–2
6.3ϫ10–3
7.8ϫ10–4
methanol
methanol
methanol
515
518
513
3257
3256
2815
9.5(Ϯ2.3)
8.3(Ϯ1.5)
6.4(Ϯ1.4)
1.6ϫ10–2
6.3ϫ10–3
7.8ϫ10–4
tetrahydrofuran
tetrahydrofuran
tetrahydrofuran
531
527
525
3596
2767
2664
23.6(Ϯ3.5)
24.3(Ϯ2.6)
18.2(Ϯ2.3)
[a] FWHM = plasmon full width at half-maximum.
Obtained TEM images and corresponding size distribu-
tions are given in Figure 6. It can be seen that a lower con-
centration causes smaller AuNPs and a sharper size distri-
bution, which is in agreement with the results of the
FWHM studies.
Figure 6. TEM images and size distribution of 7c in tetra-
hydrofuran [ϑ = 25 °C; (A) c = 1.6ϫ10–2 m; (B) c = 7.8ϫ10–4 m].
Experiments on the long-term stability showed that NPs
generated by precursor 7a are only stable for several hours.
In contrast, particles formed from 7b and 7c are stable for
weeks. In general, the stability of particles in methanol is
higher than in tetrahydrofuran due to the better stabiliza-
tion (vide supra). In agreement with literature that deals
with different low-molecular-mass colloid stabilizing agents
(e.g., oligo-ethers, sodium citrate, or low-generation dendri-
mers), the obtained particle size and size distributions are
in a similar range.[30] Particle sizes obtained in methanol as
solvent correspond well with those obtained by the Brust–
Schiffrin method. Particle sizes obtained in tetrahydrofuran
are similar to the ones from the Turkevich methodol-
ogy.[12,13,31] Please note that in our approach no additional
stabilizing component has to be added.
Experimental Section
Instruments and Materials: All synthetic procedures were per-
formed under an argon atmosphere with the solvents and reagents
degassed prior to use. 3,6,9-Trioxadecylamine[35] (3b), 1-isocyano-
2-methoxyethane[36] (5a), and [AuCl(SMe2)][37] (6) were prepared
according to literature procedures. All other chemicals were ob-
Currently, the performance of the thus-obtained well-de-
fined AuNPs as heterogeneous catalysts in hydrogenation
reactions of α,β-unsaturated aldehydes is being tested.[32–34] tained commercially and used without further purification.
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H. Lang et al.
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The H NMR spectra were recorded with a Bruker Avance III 500
1
colorless precipitate formed. After cooling to 25 °C, the solid was
filtered off and all volatiles were removed in an oil-pump vacuum.
spectrometer operating at 500.303 MHz in the Fourier transform
mode; the 13C{1H} NMR spectra were recorded at 125.800 MHz. The residue was dissolved in water (50 mL) and basified with
Chemical shifts are reported in δ [ppm] downfield from tetrameth-
NaOH (100 mL, 1 n). The obtained solution was extracted with
dichloromethane (12ϫ20 mL). The combined organic phases were
ylsilane with the solvent as reference (1H NMR: CHCl3, δ =
7.26 ppm; 13C{1H} NMR: CDCl3, δ = 77.00 ppm). The melting dried with MgSO4. After evaporation of the solvent, the residue
points of analytically pure samples (sealed off in nitrogen-purged
capillaries) were determined with a Gallenkamp MFB 595010M
melting-point apparatus. Microanalyses were performed with a
Thermo FLASHEA 1112 Series instrument. Infrared spectra were
recorded with an FT-Nicolet IR 200 spectrometer. UV/Vis absorp-
tion spectra were recorded with a Thermo Genesys 6 spectropho-
tometer. High-resolution mass spectra were recorded with a micrO-
TOF QII Bruker Daltonite workstation. Transmission electron mi-
croscopy (TEM) imaging was performed with a PHILIPS CM 20
instrument operating at 200 kV. X-ray powder diffraction (XRPD)
was carried out with a STOE-STAD IP device with Cu-Kα
(1.5404 Å) radiation.
was distilled under vacuum (0.1 Torr, 85 °C) to afford 3c as a color-
less oil (10.3 g, 0.049 mol, 65%, based on 2c). Analytical data agree
with the literature.[39]
N-{2-[2-(2-Methoxyethoxy)ethoxy]ethyl}formamide (4b): 3,6,9-
Trioxadecylamine (8.0 g, 0.05 mol) and p-toluenesulfonic acid
monohydrate (13 mg, 0.07 mmol) were dissolved in methyl formate
(50 mL) and heated at reflux for 24 h. After removing all volatiles
in an oil-pump vacuum, the residue was distilled (9 Torr, 145 °C)
to give colorless 4b (8.9 g, 0.046 mol, 93% based on 2b). Elemental
analysis, FTIR, and 1H NMR spectra are in agreement with the
data given in the literature.[40] 13C{1H} NMR (125 MHz, CDCl3):
δ = 37.76 (s, NHCH2), 58.93 (s, OCH3), 69.60 (s, CH2), 70.13 (s,
CH2), 7.42 (s, CH2), 70.46 (s, CH2), 70.54 (s, CH2), 71.86 (s, CH2),
161.41 (s, HCO) ppm. HRMS: m/z: calcd. for C8H18NO4: 192.1230;
found 192.1298 [M + H]+.
General Preparation Procedure for Gold Nanoparticles: The genera-
tion of gold NPs was carried out in solution. Therefore, AuI com-
plexes 7a–c were dissolved in tetrahydrofuran or methanol (c =
1.6ϫ10–2 m, 6.3ϫ10–3 m, 7.8ϫ10–4 m). The reaction solution
(20 mL) was stirred for 10 min at ambient temperature followed by
the addition of an equimolar amount of Na[BH4]. The color
changed immediately from colorless to purple by the addition of
Na[BH4]. The mixture was further aged for 5 min for completeness.
Colloidal gold solutions were used as obtained without further pu-
rification. Boric acid and sodium chloride that was formed by re-
duction of 7a–c with Na[BH4] did not influence the NP characteri-
zation due to their noncoordinating behavior.[38]
N-(2,5,8,11-Tetraoxatridecan-13-yl)formamide (4c): Compound 4c
was synthesized as described for 4b. Thus, 2,5,8,11-tetraoxatride-
can-13-amine (7.14 g, 0.034 mol) was treated with p-toluenesulfonic
acid monohydrate (10 mg, 0.05 mmol). Vacuum distillation
(0.1 Torr, 135 °C) gave 4c as a colorless oil (7.8 g, 0.033 mol, 98%
based on 2c). C10H21NO5 (235.28): calcd. C 51.05, H 9.00, N 5.95;
found C 50.90, H 8.77, N 6.16. FTIR (NaCl): ν = 3317 (s), 3051
˜
(m), 28.71 (s), 1697 (s), 1531 (s), 1456 (w), 1385 (w), 1245 (w), 1109
1
(m), 878 (m) cm–1. H NMR (500 MHz, CDCl3): δ = 3.31 (s, 3 H,
OCH3), 3.40 (m, 2 H, CH2), 3.50 (m, 4 H, CH2), 3.58 (m, 6 H,
CH2), 6.66 (br. s, 1 H, NH), 8.10 (s, 1 H, HCO) ppm. 13C{1H}
NMR (125 MHz, CDCl3): δ = 37.57 (s, NHCH2), 58.76 (s, OCH3),
69.40 (s, CH2), 69.91 (s, CH2), 70.20 (s, CH2), 70.24 (s, CH2), 71.71
(s, CH2), 161.34 (s, HCO) ppm. HRMS: m/z: calcd. for
C10H21KNO5: 274.1051; found 274.1052 [M + K]+.
2-(2,5,8,11-Tetraoxatridecan-13-yl)isoindoline-1,3-dione
(2c):
Phthalimide (21.48 g, 0.15 mol) and triphenylphosphane (37.8 g,
0.15 mol) were dissolved in tetrahydrofuran (400 mL). 2,5,8,11-Tet-
raoxatridecan-13-ol (25.00 g, 0.12 mol) was added dropwise to this
solution, and the mixture was stirred for an additional 15 min at
ambient temperature. DIAD (28.38 mL, 0.15 mol) was added drop-
wise to this mixture over a period of 30 min, and stirring was con-
tinued for an additional 12 h at ambient temperature and ethanol
(250 mL) was added. After evaporation of all volatiles in an oil-
pump vacuum, the residue was treated with a mixture of n-hexane/
ethyl acetate (100 mL, 1:1 v/v) and heated to 40 °C for 1 h. The
formed solid was filtered off and washed twice with n-hexane/ethyl
acetate (20 mL, 1:1 v/v). All volatiles were removed in an oil pump
vacuum and the crude product was subjected to chromatography
on silica (n-hexane/ethyl acetate, 1:4; column size 3ϫ40 cm) to af-
ford 2c (37.3 g, 0.102 mol, 85% based on 1c) as a colorless oil.
C17H23NO6 (337.37): calcd. C 60.52, H 6.87, N 4.15; found C
1-Isocyano-2-[2-(2-methoxyethoxy)ethoxy]ethane (5b): N-{2-[2-(2-
Methoxyethoxy)ethoxy]ethyl}formamide (4.0 g, 0.021 mol) was
dissolved in dichloromethane (50 mL) and treated with triethyl-
amine (2.12 g, 0.021 mol), triphenylphosphane (6.59 g, 0.025 mol),
and carbon tetrachloride (3.22 g, 0.021 mol) in this order. The reac-
tion mixture was heated at reflux for 3 h. After all volatiles had
been removed in an oil-pump vacuum the residue was extracted
with n-hexane (10ϫ10 mL). The combined extracts were dried with
MgSO4, and after removing the solvent in an oil-pump vacuum the
crude product was purified by distillation (9 Torr, 135 °C) to afford
5b as a colorless oil (3.1 g, 0.018 mol, 85% based on 4b).
C8H15NO3 (173.21): calcd. C 55.47, H 8.73, N 8.09; found C 55.73,
60.22, H 6.91, N 4.06. FTIR (NaCl): ν = 2873 (s), 1773 (s), 1711
˜
(s), 1429 (m), 1394 (s), 1109 (s), 1026 (m), 722 (s) cm–1. H NMR
1
H 8.98, N 8.28. FTIR (NaCl): ν = 2878 (s), 2151 (s), 1685 (w), 1458
˜
(s), 1451 (s), 1351 (w) 1248 (w), 1109 (s) cm–1. 1H NMR (500 MHz,
CDCl3): δ = 3.40 (s, 3 H, OCH3), 3.57 (m, 4 H, CH2) 3.68 (m, 4
H, CH2), 3.71 (m, 4 H, CH2) ppm. 13C{1H} NMR (125 MHz,
(500 MHz, CDCl3): δ = 3.34 (s, 3 H, OCH3), 3.50 (m, 2 H, CH2),
3
3.55 (m, 8 H, CH2), 3.62 (m, 2 H, CH2), 3.71 (t, JH,H = 5.87 Hz,
3
2 H, NCH2), 3.87 (t, JH,H = 5.87 Hz, 2 H, NCH2CH2), 7.68 (m,
2 H, CH), 7.82 (m, 2 H, CH) ppm. 13C{1H} NMR (125 MHz,
CDCl3): δ = 37.22 (s, NCH2), 58.94 (s, OCH3), 67.84 (s, CH2),
67.87 (s, CH2), 70.05 (s, CH2), 70.42 (s, CH2), 70.50 (s, CH2), 70.55
(s, CH2), 71.87 (s, CH2), 123.15 (s, CH), 132.11 (s, CHCCO), 133.84
(s, CH), 168.19 (s, CON) ppm. HRMS: m/z: calcd. for C17H24NO6:
338.1598; found 338.1601 [M + H]+.
1
CDCl3): δ = 41.71 (t, JN,C,N = 7.05 Hz, CNCCH2), 59.00 (s,
OCH3), 68.85 (s, CH2), 70.80 (s, CH2), 70.85 (s, CH2), 157.30 (t,
1JC,N
= 4.5 Hz, CNCCH2) ppm. HRMS: m/z: calcd. for
C8H15KNO3: 212.0684; found 212.0759 [M + K]+.
13-Isocyano-2,5,8,11-tetraoxatridecane (5c): Colorless 5c was iso-
lated as described for 5b. Thus N-(2,5,8,11-tetraoxatridecan-13-yl)-
formamide (6 g, 0.026 mol), triethylamine (2.5 g, 0.026 mol), tri-
phenylphosphane (8 g, 0.03 mol), and carbon tetrachloride (3.91 g,
0.26 mol) were reacted. Vacuum distillation gave colorless 5c as oil
(4.9 g, 0.022 mol, 87% based on 4c). C9H17NO4 (203.27): calcd. C
2,5,8,11-Tetraoxatridecan-13-amine (3c): 2-(2,5,8,11-Tetraoxatride-
can-13-yl)isoindoline-1,3-dione (26.00 g, 0.077 mol) was dissolved
in ethanol (250 mL) and treated with hydrazinemonohydrate
(5.3 mL, 0.1 mol). The mixture was heated to reflux for 12 h and a
4426
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 4421–4428

Ethylene Glycol Isonitrile Gold(I) Chlorides
55.28, H 8.81 N 6.41; found C 54.90, H 8.63, N 6.41. FTIR (NaCl):
non-hydrogen atoms were refined anisotropically and a riding
model was employed in the refinement of the hydrogen atom posi-
ν = 2875 (s), 2151 (s), 1734 (w), 1454 (s), 1350 (s), 1297 (w), 1247
˜
(m), 1199 (m), 1110 (s), 944 (m) cm–1. 1H NMR (500 MHz, tions.
CDCl3): δ = 3.33 (s, 3 H, OCH3), 3.51 (m, 4 H, CH2), 3.61 (m, 12
CCDC-815758 (for 7a) and -815757 (for 7c) contain the supple-
H, CH2) ppm. 13C{1H} NMR (125 MHz, CDCl3): δ = 41.60 (t,
1JN,C = 7.27 Hz, CNCCH2), 58.83 (s, OCH3, CN), 70.35 (s, CH2),
70.43 (s, CH2), 70.49 (s, CH2), 70.69 (s, CH2), 71.77 (s, CH2),
157.09 (t, 1JN,C = 5.45 Hz, CNCCH2) ppm. HRMS: m/z: calcd. for
C9H22NO4: 208.1543; found 208.1552 [M + H]+.
mentary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Crystal Data for 7a: C4H7AuClNO, Mr = 317.52 gmol–1, crystal
¯
dimensions 0.18ϫ0.12ϫ0.10 mm, T = 110 K, triclinic, P1, a =
(1-Isocyano-2-methoxyethane)gold(I) Chloride (7a): [AuCl(SMe2)]
(0.5 g, 1.7 mmol) was suspended in dichloromethane (50 mL) and
treated with 7a (0.145 g, 1.7 mmol) dissolved in dichloromethane
(5 mL). The suspension was stirred for 1 h at ambient temperature.
Evaporation of the solvent from the clear reaction solution gave
the title compound as a colorless solid (0.540 g, 1.7 mmol, 100%
based on 6). M.p. 60 °C. C4H7AuClNO (317.52): calcd. C 15.13, H
4.8467(4) Å, b = 6.3034(5) Å, c = 11.3673(9) Å, α = 96.738(7)°, β
= 94.318(7)°, γ = 96.026(7)°, V = 341.62(5) Å3, Z = 2, ρcalcd.
=
3.087 gcm–3, μ = 21.826 mm–1, θ range = 3.28–26.03°, reflections
collected: 2116, independent: 1329 (Rint = 0.0531), R1 = 0.0345,
wR2 = 0.0693 [IϾ2σ(I)].
Crystal Data for 7c: C10H19AuClNO4, Mr = 449.68 gmol–1, crystal
dimensions 0.30ϫ0.30ϫ0.05 mm, T = 110 K, monoclinic, P21/n,
a = 9.6493(2) Å, b = 13.8603(3) Å, c = 11.1234(3) Å, β =
101.214(2)°, V = 1459.27(6) Å3, Z = 4, ρcalcd. = 2.047 gcm–3, μ =
10.267 mm–1, θ range = 2.94–26.00°, reflections collected: 5693, in-
dependent: 2831 (Rint = 0.0235), R1 = 0.0243, wR2 = 0.0502
[IϾ2σ(I)].
2.22, N 4.41; found C 15.25, H 2.17, N 4.12. FTIR (KBr): ν =
˜
2922 (m), 2890 (m), 2830 (m), 2268 (s), 1462 (s), 1340 (s), 1196 (m),
1119 (s), 1083 (m), 1016 (s), 828 (s) cm–1. 1H NMR (500 MHz,
CDCl3): δ = 3.44 (s, 3 H, OCH3), 3.70 (m, 2 H, CH2), 3.82 (m, 2
H, CH2) ppm. 13C{1H} NMR (125 MHz, CDCl3): δ = 44.51 (t,
1JN,C = 7.27 Hz, CNCCH2), 59.16 (s, OCH3), 68.04 (s, CH2),
1
135.32 (t, JN,C = 25.43 Hz, CNCCH2) ppm. HRMS: m/z: calcd.
Supporting Information (see footnote on the first page of this arti-
cle): Electron diffraction pattern, XRPD, TEM images with size
distribution, UV/Vis and NMR (1H, 13C{1H}) data.
for C6H10AuN2O: 323.0412; found 323.0453 [C4H7AuNO
+
CH3CN]+
.
{1-Isocyano-2-[2-(2-methoxyethoxy)ethoxy]ethane}gold(I) Chloride
(7b): The title complex was prepared as described for 7a. Thus,
[AuCl(SMe2)] (0.25 g, 0.85 mmol) was treated with 1-isocyano-2-
[2-(2-methoxyethoxy)ethoxy]ethane (0.147 g, 0.85 mmol). After ap-
propriate workup, complex 7b was obtained as a colorless oil
(0.37 g, 0.85 mmol, 100% based on 6). C10H21AuClNO3 (435.70):
calcd. C 27.57, H 4.86, N 3.21; found C 27.12, H 4.53, N 3.46.
Acknowledgments
We gratefully acknowledge the Deutsche Forschungsgemeinschaft
(DFG) (IRTG, Materials and Concepts for Advanced Intercon-
nects, GRK 1215) and the Fonds der Chemischen Industrie for
generous financial support.
FTIR (NaCl): ν = 2875 (s), 2259 (s), 1679 (w), 1581 (m), 1453 (s),
˜
1351 (s), 1271 (w), 1107 (s), 1028 (m), 931 (w), 850 (m), 734 (s)
cm–1. H NMR (500 MHz, CDCl3): δ = 3.29 (s, 3 H, OCH3), 3.47
1
[1] a) J. Zhou, J. Ralstron, R. Sedev, D. A. Battie, J. Colloid Inter-
face Sci. 2009, 331, 251–262; b) S.-A. Dong, S.-P. Zhou, Mater.
Sci. Eng. B 2007, 140, 153; c) S. Park, K. Hamad-Schifferli,
Curr. Opin. Chem. Biol. 2010, 14, 616; d) M. Wang, M.
Thanou, Pharmacol. Res. 2010, 62, 90; e) A. Ethirajan, K.
Landfester, Chem. Eur. J. 2010, 16, 9398; f) R. Costi, A. E.
Saunders, U. Banin, Angew. Chem. Int. Ed. 2010, 49, 4878; g)
C. Marambio-Jones, E. M. V. Hoek, J. Nanopart. Res. 2010,
12, 1531.
[2] a) H. Wohltjen, A. W. Snow, Anal. Chem. 1998, 70, 2856; b)
A. G. Kanaras, F. S. Kamounah, K. Schaumburg, C. J. Kiely,
M. Brust, Chem. Commun. 2002, 2249; c) O. D. Velev, S.
Gupta, Adv. Mater. 2009, 21, 1897; d) M. Calderón, M. A.
Quadir, M. Strumia, R. Haag, Biochimie 2010, 92, 1242.
[3] a) D. Compton, L. Cornish, E. van der Lingen, Gold Bull.
2003, 36, 10; b) S. Link, A. Beeby, S. F. Gerald, M. A. El-
Sayed, T. G. Schaaff, R. L. Whetten, J. Phys. Chem. B 2002,
106, 3410; c) G. Palui, S. Ray, A. Banerjee, J. Mater. Chem.
2009, 19, 3457; d) S. Link, M. A. El-Sayed, Int. Rev. Phys.
Chem. 2000, 19, 409.
[4] a) D. L. Feldheim, C. D. Keating, Chem. Soc. Rev. 1998, 27, 1;
b) J. Zhu, S. Wei, L. Zhang, Y. Mao, J. Ryu, A. B. Karki, D. P.
Younge, Z. Guo, J. Mater. Chem. 2011, 21, 342; c) V. D. Nithya,
R. K. Selvan, Phys. B 2011, 406, 24; d) A. K. Singh, Adv. Pow-
der Technol. 2010, 21, 609.
[5] a) S. Laurent, D. Forge, M. Port, A. Roch, C. Robic, L. V. Elst,
R. N. Muller, Chem. Rev. 2008, 108, 2064; b) Q. Ge, J. Su, T.-
S. Chung, G. Amy, Ind. Eng. Chem. Res. 2011, 50, 382; c) B.
Zhang, B. Chen, Y. Wanga, F. Guo, Z. Li, D. Shi, J. Colloid
Interface Sci. 2011, 353, 426; d) Z.-A. Lin, J.-N. Zheng, F. Lin,
L. Zhang, Z. Caic, G.-N. Chen, J. Mater. Chem. 2011, 21, 518.
(m, 2 H, CH2), 3.60 (m, 4 H, CH2), 3.62 (m, 2 H, CH2), 3.75 (m,
2 H, CH2), 3.61 (m, 2 H, CH2) ppm. 13C{1H} NMR (125 MHz,
CDCl3): δ = 44.64 (t, 1JN,C = 6.36 Hz, CNCCH2), 58.72 (s, OCH3),
66.69 (s, CH2), 70.17 (s, CH2), 70.20 (s, CH2), 70.49 (s, CH2), 71.53
(s, CH2), 134.37 (t, 1JN,C = 25.43 Hz, CNCCH2) ppm. HRMS: m/z:
calcd. for C10H22AuNO3: 201.0666; found 201.0710 [M + H]+.
(13-Isocyano-2,5,8,11-tetraoxatridecane)gold(I) Chloride (7c): Com-
pound 7c was prepared as described for 7a. Thus, [AuCl(SMe2)]
(0.5 g, 1.70 mmol) was treated with 13-isocyano-2,5,8,11-tetra-
oxatridecane (0.37 g, 1.70 mmol). After appropriate workup, 7c was
isolated as a colorless solid (0.81 g, 1.70 mmol, 100% based on 6).
M.p. 45 °C. C12H25AuClNO4 (479.75): calcd. C 30.04, H 5.25, N
2.92; found C 29.86, H 5.05 N 3.06. FTIR (KBr): ν = 2872 (s),
˜
2266 (s), 1474 (m), 1343 (s), 1281 (m), 1245 (w), 1102 (s), 950 (m),
860 (m) cm–1. 1H NMR (500 MHz, CDCl3): δ = 3.37 (s, 3 H,
OCH3), 3.55 (m, 2 H, CH2), 3.65 (m, 8 H, CH2), 3.70 (m, 2 H,
CH2), 3.83 (m, 4 H, CH2) ppm. 13C{1H} NMR (125 MHz, CDCl3):
1
δ = 44.66 (t, JN,C = 7.26 Hz, CNCCH2), 58.92 (s, OCH3), 70.39
(s, CH2), 70.47 (s, CH2), 70.53 (s, CH2), 70.55 (s, CH2), 70.87 (s,
1
CH2), 134.99 (t, JN,C = 26.34 Hz, CNCCH2) ppm. HRMS: m/z:
calcd. for C10H19AuNO4: 414.0974; found 414.0957 [M]+.
Single-Crystal X-ray Diffraction Analysis: Single crystals of 7a and
7c suitable for X-ray diffraction analysis were obtained by crystalli-
zation from diethyl ether at –30 °C. Data were collected with an
Oxford Gemini S diffractometer at 110 K using Mo-Kα (λ =
0.71073 Å) radiation. The structures were solved by direct methods
and refined by full-matrix least-squares procedures on F2.[41] All
Eur. J. Inorg. Chem. 2011, 4421–4428
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4427

H. Lang et al.
FULL PAPER
[6] a) M. Haruta, M. Daté, Appl. Catal. A 2001, 222, 427; b) A.
Villa, G. M. Veith, L. Prait, Angew. Chem. Int. Ed. 2010, 49,
4499–4502; c) R. Narayanan, M. A. El-Sayed, J. Phys. Chem.
B 2005, 109, 12663; d) G. Kyriakou, S. K. Beaumont, S. M.
Humphrey, C. Antonetti, R. M. Lambert, ChemCatChem
2010, 2, 1444; e) V. Calò, A. Nacci, A. Monopoli, P. Cotugno,
Chem. Eur. J. 2009, 15, 1272; f) V. Calò, A. Nacci, A. Mono-
poli, J. Mol. Catal. A 2004, 214, 45.
[19]
[20]
a) Y. G. Kim, S.-K. Oh, R. M. Crooks, Chem. Mater. 2004, 16,
167; b) Y. Chen, Y.-M. Zhang, Y. Liu, Chem. Commun. 2010,
5622.
a) A. G. Kanaras, F. S. Kamounah, K. Schaumburg, C. J.
Kiely, M. Brust, Chem. Commun. 2002, 2294; b) T. Peterle, P.
Ringler, M. Mayor, Adv. Funct. Mater. 2009, 19, 3497; c) T.
Peterle, A. Leifert, J. Timper, A. Sologubenko, U. Simon, M.
Mayor, Chem. Commun. 2008, 3438.
[7] a) M.-C. Daniel, D. Astruc, Chem. Rev. 2004, 104, 293–346; b)
S.-E. Stiriba, H. Frey, R. Haag, Angew. Chem. Int. Ed. 2002,
41, 1329; c) N. L. Rosi, C. A. Mirkin, Chem. Rev. 2005, 105,
1547; d) X. Huang, S. Neretina, M. A. El-Sayed, Adv. Mater.
2009, 21, 4880.
[21]
[22]
a) H. Hiramatsu, F. E. Osterloh, Chem. Mater. 2004, 16, 2509;
b) M. Y. Han, C. H. Quek, Langmuir 2000, 16, 362.
R.-Y. Liaua, T. Mathiesona, A. Schiera, R. J. F. Bergera, N.
Runebergb, H. Schmidbaur, Z. Naturforsch., Teil B 2002, 57,
881.
[8] a) E. Gaffet, M. Tachikart, O. E. Kedim, R. Rahouadj, Mater.
Charact. 1996, 36, 185; b) G. M. Whitesides, J. C. Love, Sci.
Am. 2001, 39; c) S. Eustis, A. El-Sayed, Chem. Soc. Rev. 2006,
35, 209; d) N. N. Kariuki, J. Luo, M. M. Maye, S. A. Hassan,
T. Menard, H. R. Naslund, Y. H. Lin, C. M. Wang, M. H. En-
gelhard, C. J. Zhong, Langmuir 2004, 20, 11240; e) N. R. Jana,
L. Gearheart, C. J. Murphy, Chem. Mater. 2001, 13, 2313; f)
K. R. Brown, D. G. Walter, M. J. Natan, Chem. Mater. 2000,
12, 306.
[9] a) M. Steffan, A. Jakob, P. Claus, H. Lang, Catal. Commun.
2009, 10, 437; b) S. F. Jahn, T. Blaudeck, A. Jakob, P. Ecorch-
ard, T. Rüffer, H. Lang, R. R. Baumann, Chem. Mater. 2010,
22, 3067; c) A. Tuchscherer, D. Schaarschmidt, S. Schulze, M.
Hietschold, H. Lang, Inorg. Chem. Commun. 2011, 14, 676.
[10] a) C. Fu, H. Zhou, D. Xie, L. Sun, Y. Yin, J. Chen, Y. Kuang,
Colloid Polym. Sci. 2010, 288, 1097; b) B. Nikoobakht, Z. L.
Wang, M. A. El-Sayed, J. Phys. Chem. B 2000, 104, 8635; c)
Y. Y. Yu, S. S. Chang, C. L. Lee, C. R. C. Wang, J. Phys. Chem.
B 1997, 34, 6661.
[11] E. I. Isaeva, M. Y. Kim, V. V. Gorbunova, T. B. Boitsova, Russ.
J. Gen. Chem. 2007, 77, 812.
[12] J. Turkevitch, P. C. Stevenson, J. Hillier, Discuss. Faraday Soc.
1951, 11, 55–75.
[13] M. Brust, M. Walker, D. Bethell, D. Schiffrin, R. Whyman, J.
Chem. Soc., Chem. Commun. 1994, 801–802.
[14] a) G. Schmid, B. Corain, Eur. J. Inorg. Chem. 2003, 3081–3098;
b) J. P. Spatz, S. Möβmer, M. Möller, Chem. Eur. J. 1996, 12,
1552; c) J. P. Spatz, A. Roescher, M. Möller, Adv. Mater. 1996,
8, 337; d) M. Möller, J. P. Spatz, Curr. Opin. Colloid Interf. Sci.
1997, 2, 177.
[15] a) V. Delmas, S. Grugeon, R. Herrera Urbina, P.-Y. Silvert, K.
Tekaia-Elhsissen, Nanostruct. Mater. 1999, 11, 1277; b) C.-H.
Wang, C.-J. Liu, C.-L. Wang, T.-E. Hua, J. M. Obliosca, K. H.
Lee, Y. Hwu, C.-S. Yang, R.-S. Liu, H.-M. Lin, J.-H. Je, G.
Margaritondo, J. Phys. D 2008, 41, 1; c) M. Maccarini, G. Bri-
ganti, S. Rucareanu, X.-D. Lui, R. Sinibaldi, M. Sztucki, R. B.
Lennox, J. Phys. Chem. C 2010, 114, 693.
[16] a) G. A. Nimola, K. Pandian, Colloids Surf. A 2006, 290, 138;
b) G. V. Ramesh, S. Porel, T. P. Radhakrishnan, Chem. Soc.
Rev. 2009, 38, 2646; c) R. M. Stoltenberg, C. Liu, Z. Bao,
Langmuir 2010, 27, 445.
[17] a) E. Boisselier, A. K. Diallo, L. Salmon, C. Ornelas, J. Ruiz,
D. Astruc, J. Am. Chem. Soc. 2010, 132, 2729; b) F. Gröhn,
B. J. Bauer, Y. A. Akpalu, C. L. Jackson, E. J. Amis, Macromol-
ecules 2000, 33, 6042; c) K. Esumi, Colloid Chemistry II, Top.
Curr. Chem. 2003, 227, 31; d) R. Haag, F. Vögtle, Angew.
Chem. Int. Ed. 2004, 43, 272; e) S. Dietrich, S. Schulze, M.
Hietschold, H. Lang, J. Colloid Interface Sci. 2011, 359, 454.
[18] a) H. D. Jin, A. Garrison, T. Tseng, B. K. Paul, C.-H. Chang,
Nanotechnology 2010, 21, 1; b) S. K. Mallissery, D. Gudat, Dal-
ton Trans. 2010, 39, 4280.
[23]
a) H. Schmidbaur, A. Schier, Chem. Soc. Rev. 2008, 37, 1931;
b) D. Schneider, O. Schuster, H. Schmidbaur, Organometallics
2005, 24, 3547.
J. D. E. T. Wilton-Ely, H. Ehlich, A. Schier, H. Schmidbaur,
Helv. Chim. Acta 2001, 84, 3217.
S. Tajammul Hussain, M. Iqbal, M. Mazhar, J. Nanopart. Res.
2009, 11, 1383.
P. K. Khanna, R. Gokhale, V. V. V. S. Subbarao, A. K. Vish-
wanath, B. K. Das, C. V. V. Satyanarayana, Mater. Chem. Phys.
2005, 92, 229.
W. Haiss, N. T. K. Thanh, J. Aveyard, D. G. Fernig, Anal.
Chem. 2007, 79, 4215.
E. Boisselier, A. K. Diallo, L. Salmon, J. Ruiz, D. Astruc,
Chem. Commun. 2008, 4819–4821.
a) A. Hildebrandt, D. Schaarschmidt, H. Lang, Organometal-
lics 2011, 30, 556; b) M. Lohan, P. Ecorchard, T. Rüffer, F.
Justaud, C. Lapinte, H. Lang, Organometallics 2009, 28, 1878;
c) M. E. Moro, M. M. Velázquez Rodríguez, J. Pharm. Biomed.
Anal. 1988, 6, 1013.
a) S. Link, Z. L. Wang, M. A. El-Sayed, J. Phys. Chem. B 1999,
103, 3529; b) K. Esumi, H. Houdatsu, T. Yoshimura, Langmuir
2004, 20, 2536; c) J. Zhou, J. Ralston, R. Sedev, D. A. Beattie,
J. Colloid Interface Sci. 2009, 331, 251.
[24]
[25]
[26]
[27]
[28]
[29]
[30]
[31] A. Manna, P. Chen, H. Akiyama, T. Wei, K. Tamada, W.
Knoll, Chem. Mater. 2003, 15, 20–28.
[32] M. Bron, A. Knop-Gericke, D. Teschner, A. Scheybal, M.
Hävecker, R. Födisch, D. Hönicke, R. Schlögl, P. Claus, J. Ca-
tal. 2005, 234, 37.
[33] P. Claus, Appl. Catal. A 2005, 291, 222.
[34] M. Steffan, A. Jakob, P. Claus, H. Lang, Catal. Commun. 2009,
10, 437.
[35] a) O. A. Sherman, G. B. W. L. Lighthart, H. Ohkawa, R. P.
Sijbesma, E. W. Meijer, Proc. Natl. Acad. Sci. USA 2006, 203,
11850; b) K. L. Dombi, N. Griesang, C. Richter, Synthesis
2002, 6, 816–824.
[36] T. Kercher, C. Rao, J. R. Bencsik, J. A. Josey, J. Comb. Chem.
2007, 9, 1177.
[37] S. Ahmad, A. A. Isab, H. P. Perzanowski, M. S. Hussain, M. N.
Akhtar, Trans.-Met. Chem. 2002, 27, 177.
[38] J. Lu, D. B. Dreisinger, W. C. Cooper, Hydrometallurgy 1997,
45, 305–322.
[39] R. Voicu, R. Boukherroub, V. Bartzoka, T. Ward, J. T. C.
Wojtyk, D. D. M. Wayner, Langmuir 2004, 20, 11713.
[40] M. Schmidt, R. Amstub, G. Crass, D. Seebach, Chem. Ber.
1980, 113, 1691.
[41] a) G. M. Sheldrick, Acta Crystallogr., Sect. A 1990, 46, 467; b)
G. M. Sheldrick, SHELXL-97, Program for Crystal Structure
Refinement, University of Göttingen, Germany, 1997.
Received: March 28, 2011
Published Online: August 11, 2011
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