Supporting Information. A Method for Promoting Assembly of Metallic and Non-Metallic Nanoparticles into Interfacial Monolayer Films

Transcription

1 Supporting Information A Method for Promoting Assembly of Metallic and Non-Metallic Nanoparticles into Interfacial Monolayer Films Yikai Xu, Magdalena P. Konrad, Wendy W. Y. Lee, Ziwei Ye, Steven E. J. Bell * School of Chemistry and Chemical Engineering, Queen s University of Belfast, Stranmillis Road, Belfast BT9 5AG. s.bell@qub.ac.uk

2 Promoters Modifiers Coordinating Adsorbing 15-crown-5 (Na + ) complex TMPyP Pyridine 18-crown-6 (Na + ) complex [Fe(bpy) 3 ](PF 6 ) 2 1,10-phenanthroline 4-tertbutylcalix[4]arenetetramethylester [Ru(bpy) 3 ](PF 6 ) 2 1-pentanethiol (Na + ) complex 4-tertbutylcalix[4]arenetetraethylester(Na [Ru(bpy) 3 ]Cl 2 1-heptanethiol + ) complex TBANO 3 TOABr 1-dodecanethiol * [Cu(dmp) 2 ]BF 4 (with CRSC) [Cu(dmp) 2 ]BF 4 (with Benzene-thiol HRSC) * [Cu(dpp) 2 ]BF 4 (with CRSC) [Cu(dpp) 2 ]BF 4 (with TPAsNTF TPAsTPB TBATPB HRSC) TPAsCl TBABF 4 Table S1.Chemical compounds promoting MeLLF formation. The modifiers tune the surface hydrophobicity either by coordinating along with the initial surface species or by substituting them completely. The promoters on the other hand do not chemically modify the surface of the NPs. * marked promoters were initially reported as modifiers. Chemical compound abbreviations: dmp: 2,9-dimethyl-1,10-phenanthroline: dpp: 2,9-diphenyl-1,10- phenanthroline; TPAsNTF, tetraphenylarsoniumtrifluoromethylsulfonamide; TPB: tetraphenylborate; TMPyP: 5,10,15,20-tetrakis(1-,methyl-4-pyridyl)-21H,23H-porphine; bpy: 2,2 -bipyridine; TOA: tetraoctylammonium.

3 Samples Concentration of Cu + /10-7 M Control sample Control sample Control sample MeLLF sample MeLLF sample MeLLF sample Table S2. ICPOES measurements of promoter concentration in the bulk organic phase before and after MeLLFs formation. MeLLFs were prepared using [Cu(dmp) 2 ]BF 4 (dmp=2,9-dimethy-1,10-phenanthroline) as the promoter because the Cu ions can be detected without interference from the other components in the MeLLF. Control samples 1-3 represent three different samples all containing the same amount of promoters in the oil phase. MeLLF sample 1-3 represents the MeLLF made from each of their corresponding control samples respectively. It can be seen that ca. half the promoter was lost from the bulk organic phase after MeLLF formation.

4 Oil Miscibility with Water /mol/l 1,2 (25, 100 KPa) Successful MeLLF formation (CRSC + Oil + TBA + ) (Yes/No) hexadecane / Y cyclohexane Y hexane Y pentane Y toluene Y carbon tetrachloride Y trichloroethylene Y benzene Y methyl-t-butyl ether N chloroform Y 1,2-dichloroethane Y dichloromethane Y ethyl acetate N diethyl ether N n-butanol N Table S3. Summary of the oil phases tested throughout the research and their ability to act as liquid-liquid interfaces suitable for MeLLF formation. MeLLF formation is driven by a decrease in interfacial energy, thus the key property of the oil phase is to have a high energy interface with water. This could be further translated to the oil phase having a low miscibility with water. During this research it was found that MeLLFs do not form when the oil phase had a miscibility value with water higher than DCM. Interestingly, while methyl-tbutyl ether was much less miscible with water than DCM, here it could not act as a successful oil phase for MeLLFs formation. This was because the promoter TBA + was more soluble in water than in methyl-t-butyl ether.

5 Definitions for Symbols µ Chemical potential z R σ ε ε 0 L D x The number of nearest neighbouring NPs in a hexagonal array Particle radius Particle charge density Dielectric constant Permittivity of vacuum Debye length Side to side distance between two NPs in a hexagonal array y The fraction of available surface sites. y = (2R (x + 1) ) 2 e A γ γ l α Euler s number Hamaker constant Surface tension Line tension Fraction unit showing the extent to which the charge on a NP is reduced upon entering the organic phase Table S4. Definition of symbols in the terms of Figure 3e. Figure S1. Self-assembled 2-D arrays of negatively charged NPs at liquid-liquid interfaces. (a), (b) and (c) shows MeLLFs formed from hydroxylamine reduced silver colloid, borohydride reduced silver colloid and citrate reduced gold colloid respectively. Scale bars in all images represent 0.5µm. Optical photographs of the 2-D arrays corresponding to SEM images are shown on the top right corner.

6 Figure S2. Self-assembled 2-D arrays of positively charged NPs at the liquid-liquid interface. (a) Gold MeLLF in situ formed with positively charged gold NPs. (b-d) show MeLLFs formed from positively charged ca. 20 nm diameter spherical gold NPs, polygonal silver NPs, silver nano-boxes respectively. The NPs are packed more loosely due to the relatively low concentration caused by loss of NPs during centrifugation of the positively charged colloid. Scale bars in all images represent 1µm.

7 Figure S3. Self-assembled 2-D arrays of gold (silver)-silica composites. Self-assembled monolayer composites composed of silica and silver NPs (a-b), silica and gold NPs (c-d). Scale bars in all images represent 1µm. REFERENCES (1) Pubchem. The PubChem Project; 12/12/2015; (2) IUPAC. IUPAC-NIST Solubility Data Series Database, version 1.0 (opening page); 12/12/2015;