S1

Supporting Information

Wet synthesis and quantification of ligand–free sub–nanometric Au

clusters in solid matrices.

Judit Oliver–Meseguer,a Irene Dominguez,b Rafael Gavara,b Antonio Doménech-

Carbó,c J. M. González–Calbet,d Antonio Leyva–Pérez,a* and Avelino Corma.a*

a Instituto de Tecnología Química. Universidad Politécnica de Valencia–Consejo Superior de Investigaciones Científicas. Avda. de los Naranjos s/n, 46022, Valencia, Spain.

b Packaging Lab, Instituto de Agroquímica y Tecnología de Alimentos, IATA-CSIC, Av.

Agustín Escardino 7, 46980 Paterna, València, Spain.

c Departament de Química Analítica. Universitat de Valencia. Dr. Moliner, 50, 46100 Burjassot (Valencia). Spain.

d Departamento de Química Inorgánica, Facultad de Químicas, Universidad Complutense

(UCM), CEI Moncloa, 28040-Madrid, Spain.

Corresponding author: anleyva@itq.upv.es, acorma@itq.upv.es

Phone: +34963877800; Fax: +349638 77809.

Table of Contents:

- Experimental section:

o General………………………..…………... S2

o Preparation of the catalysts………………...S3

o Reaction procedures and characterisation ...S4

- Figures ………………………………………….…...S6

- NMR copies………………………………………....S12

Electronic Supplementary Material (ESI) for ChemComm.This journal is © The Royal Society of Chemistry 2016

S2

General.

Glassware was dried in an oven at 175 ºC before use. Reactions were performed in 2.0

ml vials equipped with a magnetic stirrer and closed with a steel cap having a rubber

septum part to take samples out. Reagents and solvents were obtained from commercial

sources and were used without further purification otherwise indicated. The solid Au-

catalysts were purchased from Strem Chemicals Co. (Au-Al2O3, Au-ZnO, Au-TiO2) or

Johnson-Matthey Co (Au-Ce2O3, Au-C). The products of the reaction test were

characterised by GC–MS, 1H– and 13C–NMR, and DEPT, and compared with the given

literature. Gas chromatographic analyses were performed in an instrument equipped

with a 25 m capillary column of 5% phenylmethylsilicone. Dodecane was used as an

external standard. GC/MS analyses were performed on a spectrometer equipped with

the same column as the GC and operated under the same conditions. 1H, 13C and DEPT

measurements were recorded in a 300 MHz instrument using CDCl3 as a solvent,

containing TMS as an internal standard. The metal content of the solids and filtrates was

determined by X-Ray fluorescence or by inductively coupled plasma–atomic emission

spectroscopy (ICP–AES) by disaggregation of the solid in aqueous acid mixture or after

dilution of the filtrates in 1 ml of ether and extraction with 3 mL (x3 times) of aqua

regia.

X–ray photoelectron spectroscopy (XPS) measurements were performed on a

SPECS spectrometer equipped with a Phoibos 150 MCD–9 analyzer using non–

monochromatic Mg KR (1253.6 eV) X–ray source working at 50 W. As an internal

reference for the peak positions in the XPS spectra, the C1s peak has been set at 284.5

eV. The samples were prepared by dropping a solid water suspension onto a

molybdenum plate followed by air drying. High Resolution Transmission Electron

Microscopy measurements were performed in a 200 KeV Jeol microscope by

impregnating a copper–carbon filmed grid with a drop of the corresponding solid after

dispersing in dichloromethane and leaving evaporation for at least 5 hours. Absorption

spectra were recorded on a Cary 300 UV–Vis spectrophotometer (UV0811M209,

Varian). Fluorescence spectra were obtained with a LP S–220B (Photon Technology

International) equipped with 75 W Xe lamp. The photophysical measurements were

performed under air at room temperature in a quartz cell of 1.0 cm optical path length.

S3

Preparation of the Au catalysts.

Au–TiO2 (1.5 wt%, 4.3 nm average size) was prepared following a reported procedure

(see main text).

Au–nCeO2 was prepared by impregnating on 1 g of the support the corresponding

amount of Au chloride (1 wt%) and hydrogenating at 200–300 ºC under a flow of 100

ml per min. of N2:H2 (10:1) gas for 2–3 h. For comparison, another sample of Au–

nCeO2 was obtained after a stronger reduction treatment: 1 g of nanoceria impregnated

with Au chloride (1 wt%) treated with 5 ml of phenylethanol at 160 ºC for 1 h. This

solid was nearly avoided of Au clusters. A solution of Au clusters in DMF or NMP was

prepared by placing 10 mg of Au–nCeO2 (1 wt%) in a round–bottomed flask equipped

with a magnetic bar and heating in a magnetically stirred oil–bath at 135 ºC in the

corresponding solvent for a few minutes. Then, the supernatant was passed through a

syringe filter in hot and an aliquot was taken for analysis by ICP–AES, as indicated

above.

Au@EVOH. Pellets (2 mm diameter, 3 mm long) of EVOH with ethylene molar

contents of 26 (EVOH26), 29 (EVOH29), 32 (EVOH32) and 44 (EVOH44) were gently

supplied by The Nippon Chemical Company (Osaka, Japan). 13 g of EVOH29 were

initially dissolved in 100 mL of a 1:1 (v:v) 1–propanol: distilled water mixture heated at

75 ˚C under reflux. Once the copolymer was completely dissolved the mixture was left

to cool to room temperature, then HAuCl4x3H2O were added in order to obtain a metal

loading of 0.031 mmolAu/ g dry polymer. The resultant suspension was spread on a

Teflon coated glass plate by using a 200 µm spiral bar coater. By using a digital

Mitutoyo micrometer (Metrotec, San Sebastian, Spain) film thickness was determined,

obtaining an average value of 0.012± 0.003 mm.

To evaluate the influence of film thickness, ethylene molar percentage of EVOH as well

as the influence of UV radiation of the film in formation of Au clusters different

materials were obtained. To obtain thicker films, a 100 µm spiral bar coater was also

used providing films with 0.022 ± 0.004 mm of thickness. To check the effect of

copolymer composition, films based on three EVOH precursors (EVOH26, EVOH32

and EVOH44) were also prepared by the same procedure. To check for the effect of

S4

radiation on cluster formation in the films, Au@EVOH films were exposed to the

radiation of a Heraeus NIQ 80/36U lamp at 5 cm distance during 15 min.

Re-dispersion of Au-supported catalyst. 500 mg of Au-Al2O3, Au-TiO2, Au-ZnO and

Au-C were dispersed in a solution of 50 mg of I2 in water, 1,2-dichloromethane or 1,2-

dichloroethane. The reaction mixture was heated at 60 ºC during 24 hours. After cooling

to rt, the solids were filtered and washed with water and acetone. The solids were

analysed by X-Ray Fluorescence and UV-vis to confirm the formation of clusters and

the quantity of gold supported.

Reaction procedures and characterisation.

Reaction test. The Au supported catalyst (0.01 mol%), heptanoyl chloride 1 (1 mmol)

and propargylic alcohol 2 (10 mmol) were placed in a 2 ml vial equipped with a

magnetic stir bar. The vial was sealed and the resulting mixture was magnetically stirred

for 30 min at 25 ºC. Then, water (1 mmol) was added and the mixture was stirred and

aliquots of 25 μl were periodically taken, diluted in n-hexane, and analyzed by GC in

order to follow the reaction, using dodecane as an external standard. Product 2-methyl-

3-oxobutan-2-yl heptanoate 4 was isolated and characterization agrees that previously

reported (see references in main text). GC-MS (m/z, relative intensity): 215 (M+H, 1),

171 (17), 130, (1), 113 (100), 85 (29), 57 (9), 43 (23). IR (υ, cm-1): 2939 (m), 2863 (l),

1733 (vi), 1724 (vi), 1150 (i), 1120 (i). 1H NMR (δ, ppm; J,Hz): 2.26 (COCH, 2H, dd,

J= 9.6, 9.6), 2.04 (COCH3, 3H, s), 1.61-1.51 (aliphatic CH2, 2H, mult), 1.39 (CH3, 6H,

s), 1.24 (aliphatic CH, 6H, mult), 0.84-0.80 (aliphatic CH3, 3H, m). 13C NMR (δ, ppm):

206.7 (ketone, C), 173.0 (ester, C), 83.3 (aliphatic, C), 34.2 (aliphatic, CH2), 31.2

(aliphatic, CH2), 28.6 (aliphatic, CH2), 24.6 (aliphatic, CH2), 23.4 (methyl, 2CH3), 23.2

(methyl, COCH3), 22.3 (aliphatic, CH2), 13.8 (methyl, CH3). HRMS (ESI) [M+H+;

calculated for C12H23O3: 215.0899] found m/z 215.0895.

Synthesis of ester intermediate 3. The heptanoyl chloride 1 (13 mmol) was added to the

propargylic alcohol (130 mmol) and the mixture was stirred in a 25 ml round-bottom

flask equipped with a magnetic stir bar during 1 hour. The crude was purified by

column chromatography on basic alumina (20 % AcOEt in n-hexane) to achieve 2-

methylbut-3-yn-2-yl heptanoate 3 as a colourless oil (2.51 g, 13 mmol, 99 %).

Characterization agrees that previously reported (see references in main text). GC-MS

(m/z, relative intensity): 196 (M+·, 4), 113 (100), 98 (10), 85 (37), 83 (43), 67 (100), 55

S5

(29), 43 (43). IR (υ, cm-1): 3270 (l), 2927 (i), (1742 (vi), 1234 (m), 1131 (vi). 1H NMR

(δ, ppm; J,Hz): 2.43 (CH, 1H, s), 2.17 (COCH, 2H, dd, J= 7.5, 7.5), 1.57 (CH3, 6H, s),

1.52 (aliphatic CH, 2H, mult), 1.21 (aliphatic CH, 6H, mult), 0.79 (aliphatic CH3, 3H,

m). 13C NMR (δ, ppm): 171.8 (ester, C), 84.6 (alkyne, C), 72.0 (alkyne, CH), 71.1

(aliphatic, C), 34.7 (aliphatic, CH2), 31.3 (aliphatic, CH2), 28.7 (methyl, 2CH3), 28.5

(aliphatic, CH2), 24.6 (aliphatic, CH2), 22.3 (aliphatic, CH2), 13.8 (methyl, CH3).

Leaching studies. Two parallel reaction mixtures were followed by GC, taking aliquots

periodically, under typical reaction conditions and one of them was filtered at a

determined conversion through a 0.2 µm PTFE filter. The resulting filtrates were placed

under the same conditions (stirring and temperature) that the original reaction and also

followed by GC.

S6

Figures.

94 92 90 88 86 84 82 80 78 76

100

150

200

250

300

350

400

CPS

BE (eV)

Reduced under H2

Reduced with phenylethanol Au 0 Au 3+ Au+ Au Au+

Figure S1. XPS spectrum of a sample of Au-nCeO2 after hydrogenation of 1 g of Au chloride

on nceria at 200-300 ºC under a flow of 100 ml per min of N2:H2 (10:1) (black line). The

percentage of cationic Au in the reduced sample is 15% after deconvolution. For comparison, a

sample of Au-nCeO2 with a stronger reduction treatment –1 g of Au chloride on ceria with 5 ml

of phenylethanol at 160 ºC for 1 h (green line)– is also presented. The percentage of cationic Au

decreases significantly to 2%.

2200 2000

Abso

rban

ce

Wavenumber (cm-1)

Au/CeO2 (red. with H2 vs. phenylethanol)

2160 2130 2109AuoAuinterphase

Au+

IR-CO (-176 ºC)

Figure S2. CO–IR of the Au–CeO2 sample prepared by hydrogenation at 200 ºC. The presence of cationic Au not present in the interphase is clearly seen. For comparison, the sample of Au–CeO2 reduced with phenylethanol shows only cationic Au in the interphase.

Isolated atoms, cluster or NPs?

S7

0.0 -0.4 -0.8 -1.2

E (V vs. AgCl/Ag)

1 μA

a)

b)

Au+ + xe- Au(-x)+

Au(-x)+ + (-x)e- Au

Figure S3. Linear potential scan voltammograms at glassy carbon electrodes modified with films of: a) pristine Au–nCeO2; and b) Au–nCeO2 reduced at 200 ºC in H2/N2 atmosphere, immersed into air–saturated 0.1 M aqueous NaOH. The plotted curves were obtained after subtracting the corresponding voltammogram for nanoparticulated ceria. Potential scan rate 20 mV/s.

300 400 500 600 700

Refle

ctan

ce (a

. u.)

(nm)

Figure S4. Left: A typical HR-TEM image of Au-nCeO2 solids. Only nanometric Au particles

can be distinguish and not sub-nanometric particles or isolated Au cations. Right: Reflectance-

diffuse UV-vis spectrum of nCeO2, which avoids the detection of any absorption band of Au

clusters.

S8

Figure S5. Reaction test for the Au-nCeO2 sample reduced at 200 ºC under hydrogen, see main text for reaction conditions.

Figure S6. Left: TOF0 (h-1) values in the reaction test for different Au-nCeO2 samples after

different reductive treatments, including a commercial sample reduced at 200 ºC under

hydrogen and nCeO2 impregnated with 15% neat Au3-7 clusters in aqueous solution. See main

text for reaction conditions. Right: Linear correlation for the different Au-nCeO2 solids between

TOF values in the reaction test and amount of cationic Au found by quantitative XPS

measurements.

Au-nCeO2 red. with phenylethanol

Au-nCeO2 red. at 500ºC

Au-nCeO2 red. at 200ºC

Au-nCeO2 comercial

Au clusters-CeO2

S9

0

20

40

60

80

100

0 5 10 15 20

Yiel

d of

4(%

)

Time (h)

D)

0

20

40

60

80

100

0 5 10 15 20

Yiel

d of

4 (%

)

Time (h)

C)

Figure S7. Leaching during the reaction test for Au-nCeO2 reduced at 200 ºC under hydrogen (left) and Au-Al2O3 (right).

OHCl

O+

O

O

O

O

O

5

A)

B)

Au@EVOH(0.01 mol%)

iPrOH:H2O (2:1)25 ºC

2 ( 2 eq)1

3

or

5

5

4

0 5 10 15 20 25

0

20

40

60

80

Con

vers

ion

(%)

Time (h)

Figure S8. Kinetic plot for the reaction test catalyzed by Au@EVOH, either starting from acyl

chloride 1 and propargylic alcohol 2 (squares) or from propargylic ester intermediate 3 (circles).

S10

200 300 400 500 600 700 800-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Abs

orba

nce

(a. u

.)

(nm)

Figure S9. Top: Zetasizer measurement for Au@EVOH. Bottom: UV-vis Au@EVOH after

disaggregation

0

5

10

15

20

25

30

0 5 10 15

Prob

abili

ty <

1 nm

(%)

Average particle size measured by TEM (nm)

Transition metaloxide

Rare earth metaloxides

Carbonaceous

Aluminosilicates

0

5

10

15

20

25

30

35

0 5 10 15

Prob

abili

ty <

1 nm

(%)

Average particle size measured by TEM (nm)

Transition metaloxide

Rare earth metaloxides

Carbonaceous

Aluminosilicates

Figure S10. Normal (left) and lognormal (right) distributions for 30 different Au-supported

catalysts described in the literature (see main text) as a function of the average particle size

found by TEM.

S11

05

101520

2 3 4 5 >6

nº n

anop

artic

les

diameter (nm)

Figure S11. Transmission Electron Microscopy (TEM) image (left) and histogram of different samples (right) for Au–TiO2.

0 5 10 15 20 25-10

0

10

20

30

40

50

60

70

80

Au-Al2O3 Commercial DCM H2O

Conv

ersio

n (%

)

Time (h)

0 5 10 15 20 25

0

10

20

30

40

50

Au-TiO2 Commercial DCM H2O

Conv

ersio

n (%

)

Time (h)

0 5 10 15 20 25

0

20

40

60

80

Au-ZnO Commercial DCM H2O

Conv

ersio

n (%

)

Time (h)

Au loading: 1.5 wt%.

Average nanoparticle size: 4.3 nm.

Figure S12. Reaction test starting from compound 3 for Au-Al2O3, Au-TiO2 and Au-ZnO catalysts after being treated with I2 solutions in water.

S12

NMR copies.

0.10.30.50.70.91.11.31.51.71.92.12.32.52.72.93.13.3ppm

3.00

6.13

2.046.04

2.06

1.00

0.79

1.20

1.521.57

2.17

2.43

102030405060708090100110120130140150160170180190200210ppm

13.8

22.2

24.6

28.5

28.7

31.2

34.7

71.1

72.0

84.6

171.8

1H-RMN

13C-RMN

O

O3

O

O3

S13

2030405060708090100110120130140150160170180190200ppm

13.8

22.3

24.6

28.5

28.7

31.3

34.7

72.0

84.6

0.80.91.01.11.21.31.41.51.61.71.81.92.02.12.22.32.42.52.62.72.82.93.03.1ppm

3.25

6.14

6.03

2.11

2.92

2.00

0.82

1.24

1.39

1.56

2.04

2.26

DEPT

1H-RMN

O

O3

O

O

O

4

S14

2030405060708090100110120130140150160170180190200210ppm

13.8

22.3

23.2

23.4

24.6

28.6

31.3

34.2

34.2

83.3

173.0

206.7

102030405060708090100110120130140150160170180190200210ppm

13.8

24.6

28.6

31.2

34.2

13C-RMN

DEPT

O

O

O

4

O

O

O

4