Ligand effect on size, valence state and red/near infrared photoluminescence of bidentate thiol gold nanoclusters - Supporting information

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1 Electronic Supplementary Material (ESI) for Nanoscale. This journal is The Royal Society of Chemistry Reflector Spec #1 MC[BP = 277.1, 12167] Ligand effect on size, valence state and red/near infrared photoluminescence of bidentate thiol gold nanoclusters - Supporting information Wavenumber (cm-1) Fig. S1. Infrared spectrum of Zw between 7 and 37 cm -1. Characteristic peaks of Zw : =1654 cm -1 (s, (amide C=O)); =1544 cm -1 (m, (amide N-H)); =118 cm -1 (m, (sulfonate S=O)); =137 cm -1 (s, (aliphatic amine C-N)). % In t e n s it y Mass (m/z) Fig. S2. Maldi/Tof in reflective mode of Zw with the matrix α-cyano-4-hydroxycinnamic acid (CHCA) of Zw calculated for C 15 H 3 N 2 O 4 S 3 at [Zw+H] + found at

2 Fig. S3. 1 H NMR (D 2 O, 4MHz) of Zw. [ppm]: (m, 4H), (m, 4H), (m, 8H), (t, 2H J= 6Hz, (m, 1H), (m, 4H), (m, 1H), (m, 4H), (m, 2H). Table S1. Determination of the weight loss of AuZw samples prepared at different Au:Zw ratio. Weight loss between 3 C - 5 C (wt%) Weight loss at 8 C (wt%) Zw AuZw 1: AuZw 1: AuZw 1: AuZw 1: AuZw 1: AuZw 1: AuZw 1: AuZw 1:1 AuZw 1:3 AuZw 1:4 AuZw 1:3 Fig. S4. Transmission electron microscope (TEM) images of AuZw 1:1, AuZw 1:3 and AuZw 1:4. The sample AuZw 1:1 presents some polydispersity with particle size above 2 nm.

3 % Intensity AuZw 1: Mass (m/z) AuZw 1:4 % Intensity Mass (m/z) Fig. S5. MALDI/TOF in linear positive mode of AuZw 1: and AuZw 1:4 using CHCA as matrix. Measurements show the shift of the band corresponding to the Au NCs associated to the ligand to the high molecular weight. The high contribution of the organic moiety for AuZw 1:4 prevents the ionization of the fragmented AuNCs

4 Fig. S6. MALDI/TOF in linear positive mode of AuZw 1:3 using CHCA as matrix. The shift of mass m/z= 197 and m/z= 32 correspond to the fragmentation of thiol gold nanoclusters. 25kDa kda 1kDa 2kDa 1:1 1:2 1:3 1:5 1:1 1: 1:4 25kDa kda 1kDa 2kDa Fig. S7. PAGE electrophoresis of AuZw with Au:Zw = 1:1; 1:2; 1:3; 1:5; 1:1; 1: and 1:4. AuZw with ratio Au:R (R< 5) do not fluoresce in the visible range. S(+VI) S ox S-H Au ox. Au() S-Au (c) normalized intensity [a.u.] (b) normalized intensity [a.u.] (a) binding energy [ev] binding energy [ev] 8 Fig. S8. XPS spectra of S 2p (left side) and Au 4f (right side) of AuZw 1:1 (a), AuZw 1:3 (b), and AuZw 1: (c). Au4f 7/2 can be deconvoluted in two distinct bands: one located at 84. ev corresponding to Au() and the second one at 84.7 ev, which can be attributed to partially-oxidized gold atoms. The binding energies of S 2p 3/2 at 162. ev, ev, 165. ev and 168. ev are assigned to metal-ligand, sulfur bound to hydrogen/carbon,

5 partially oxidized sulfur (with a degree IV) and fully oxidized sulfur, respectively. Spectra of S 2p enable to see the increase of the peak at ev related to S-H (purple line) when the ratio Au:Zw increases from 1:1 to 1:. Absorbance ratio 1:1 ratio 1:2 ratio 1:3 ratio 1:5 ratio 1:1 ratio 1: ratio 1: Fig. S9. Absorbance spectra of AuZw solutions at different ratio Au:Zw. (Gold concentration = 5 g/ml). Arrows indicate the weak absorption bands observed at 51 nm (2.43 ev), 59 nm (2.1 ev), 7 nm (1.77 ev) and 8 nm (1.51 ev).

6 5 AuZw 1:2 1 AuZw ph 3 ph 4 ph 6 ph 7 ph9 ph ph 3 ph 4 ph 6 ph 7 ph 9 ph AuZw 1:5 25 AuZw 1: ph 3 ph 4 ph 6 ph 7 ph 9 ph ph 3 ph 4 ph 6 ph 7 ph 9 ph AuZw 1: ph 4 ph 6 ph 7 ph 9 ph Fig. S1. Fluorescence emission of AuZw at different ph between 3 and 11. Excitation at exc. = 45 nm. Fluorescence measurements of AuZw 1:1 were not performed at different ph due to weak signal intensities.

7 3 25 AuZw 1:5 5deg 1deg 15deg deg 37deg 5deg 4 35 AuZw 1: 5deg 15deg 1deg deg deg 5deg Fig. S11. 8 Fluorescence emission of AuZw samples at 7 5deg 1deg different temperature between 5 and 5 C. 6 15deg deg Excitation at = 45 nm. 37deg 5deg 5 4 AuZw 1:4 3 Table S2. PL quantum yields of AuZw at different ratios determined by comparative method 1 using Rhodamine 6G (QY=.95 in EtOH) with O.D. = (%) AuZw 1:1.8 AuZw 1:2 1.1 AuZw 1:3 1.2 AuZw 1:5 5.5 AuZw 1:1 5.8 AuZw 1: 7.9 AuZw 1:4 15.1

8 25 AuZw 1:6 8 AuZw 1: no NaBH4 with 25uL NaBH4 (.1M) with 5uL NaBH4 (.1M) no NaBH4 with 25uL NaBH4 (.1M) with 5uL NaBH4 (.1M) AuZw 1:3 no NaBH4 Fig. S12. PL emission 6 spectra (* exc. = 45 nm) of AuZw 1:6, Au:Zw 1:4 and AuZw with 25 ul NaBH4 (.1M) 1:3 after two cycles of etching process with 5uL NaBH4 (.1M) Figure S13. PL decay curves of AuZw 1:5 at different emission wavelengths using the same excitation wavelength of 45 nm. The red/nir decay curves (at 64 nm and 8 nm) show significantly longer (1 to 3 orders of magnitude) decays than the visible decay curve (45 nm)..

9 a b Fig. S14. PL decay curves for (a) AuZw 1:5 and (b) AuZw 1:4 recorded at o C (black) and 4 o C (red). exc. = 45 nm, em. = 8 nm. Table S3. PL decaytimes 1 and 2 and their amplitudes A 1 and A 2 (fractions a 1 and a 2 in paraphrases) and intensity and amplitude averaged decay times ( int =(A A 2 22 )/(A 1 1 +A 2 2 ) and amp =(A 1 1 +A 2 2 )/(A 1 +A 2 )) of AuZw 1:5 and 1:4 at different temperatures and emission wavelengths using 45 nm as excitation wavelength. nm] T ( o C) 1 [µs] A 1 2 [µs] A 2 int [µs] amp [µs] 64 nm (38%).2 16 (62%) (38%).2 91 (62%) (32%) (68%) (27%) (73%) nm (45%) (55%) (45%) (55%) (42%) (58%) nm] 37 T ( o C) 1 [µs] A 1 2 [µs] A 2 int [µs] amp [µs] (36%) (64%) nm (53%) (46%) (47%) (54%) (48%) (46%) (52%) (54%) (45%) (39%) (55%) (61%) (41%) (36%) (59%) (64%) nm nm AuZw 1: (52%) (48%) (53%) (47%) (46%).2 18 (54%) (42%) (58%) (57%).3 78 (43%) (55%).3 7 (45%) (48%).3 98 (52%) (45%) (55%) 1.1.7

10 Error on the fluorescence lifetimes:.1 s AuZw 1:4