Electronic Supplementary Material (ESI) for Journal of Materials Chemistry C. This journal is The Royal Society of Chemistry 2018 Electronic supplementary information (ESI): Towards atomically precise luminescent Ag 2 S clusters separable by thin layer chromatography C. K. Manju, Jyoti Sarita Mohanty, Depanjan Sarkar, Sudhakar Chennu and Thalappil Pradeep a * DST Unit of Nanoscience (DST UNS) and Thematic Unit of Excellence, Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India. Table of contents No Description Page No S1 Full range MALDI MS of clusters synthesized at different 2 temperature S2 MALDI MS of solvent dependent cluster synthesis 3 S3 MALDI MS of Ag 2 S-70 and TLC separated Ag 2 S-70 4 S4 ESI MS of Ag 2 S-60 and TLC separated clusters 5 S5 TEM images of TLC separated Ag 2 S-60 6 S6 TG data of Ag 2 S-80 7 S7 EDS spectrum of Ag 2 S-80 cluster 8 S8 Jacobian Correction 8 S9 Cluster assignment 9
Supporting information 1 60 C 70 C 80 C 90 C Intensity 90 C 80 C 70 C 60 C 20000 40000 60000 80000 100000 Fig. S1. Full range MALDI MS spectra of Ag 2 S clusters synthesized at different temperature.
Supporting information 2 ODE Toluene OA Intensity 20000 40000 60000 80000 100000 Fig. S2 MALDI MS of solvent dependent Ag 2 S cluster formation. Octadecene (ODE) is only one species. Use of toluene gives multiple population and oleylamine (OA) resulted in bigger quantum dots.
Supporting information 3 Ag 2 S 70 Intensity Band two Band one 30000 60000 90000 Fig. S3 MALDI MS of parent Ag 2 S-70 and TLC separated bands.
Supporting information 4 A) B) Band one Band two Parent Band one Band two Parent 2650 2660 2670 2680 2690 2700 3800 3840 3880 3920 500 1000 1500 2000 2500 3000 3500 4000 2800 3200 3600 4000 Fig. S4 ESI MS of Ag 2 S-60 and TLC separated clusters. Cesium acetate was used as an ionization enhancer as the cluster was not having any charge. (A) Shows full range mass spectra were cesium clusters are seen in the lower range (below 2000 ). (B) MS shows cluster fragments in the positive mode. Specific regions are expanded in the inset.
Supporting information 5 A B Counts 0 10 20 30 40 50 60 70 1.0 1.3 1.6 1.9 2.2 2.5 2.8 Particle size (nm) C D Counts 0 10 20 30 40 50 60 70 1.3 1.6 1.9 2.2 2.5 2.8 3.1 Particle size (nm) 20 nm Fig. S5 TEM images of TLC separated Ag 2 S-60 clusters. (A) and (B) Band two and (C) and (D) band one, at different magnifications.
Supporting information 6 100 Weight loss % 90 80 23% 70 0 200 400 600 Temperature ( C) Fig. S6 TG data of Ag 2 S-80 showing 23% weight loss due to the protecting BBSH group.
Supporting information 7 Element Wt% At% C K 27.21 68.96 S K 7.06 6.70 Cu K 29.41 14.09 Ag L 36.32 10.25 Totals 100.00 Energy (kv) Fig S7. EDS spectrum of purified Ag 2 S-80 cluster. Ag:S ratio of 1:0.65. Supporting information 8 Jacobian correction: This uses the equations E=hc/λ f(e) de = f(λ) d(λ) f(e) = f(λ) (de/dλ) = f(λ) (d/de)(hc/e) = f(λ) (hc/e 2 )
The factor (hc/e 2 ), known as the Jacobian factor, is used to scale the signal values along with wavelength conversion [wavelength (in nm) = 1239.8/(energy (ev)]. Normally, it is plotted by multiplying the absorbance value with the factor 1/W 2, where W is the value in electronvolts corresponding to the wavelength in nanometers Supporting information 9 Cluster assignment: MALDI MS peak for Ag 2 S-80 = 25450 Da TG showed 23% weight loss. This weight loss is due to organic ligand. 23% of 25450 = (23*25450)/100 = 5854 = Total ligand mass Mass of one SBB ligand = 179.41 No of ligands = 5854/179.41 ~ 32 Cluster core mass is calculated by subtracting the total ligand mass from cluster mass This is = 25450-5854 = 19596 Da This cluster core mass can contain 79 Ag 2 S units Mass of Ag 2 S = 248 19596/248 79 From this, the cluster core can be assigned as Ag 158 S 79. Hence the total molecular formula may be given as (Ag 158 S 79 )SBB 32. This is in agreement with the Ag:S ratio of 1:0.65 obtained from EDS measurement.