Structures and Conformations of Alkanedithiols on Gold and Silver Nanoparticles in Water

Abstract

Organodithiols with two distal thiols have been used extensively in gold and silver nanoparticle (AuNP and AgNP) applications. However, understanding the structures and conformations of organodithiols on these nanoparticles is challenging. Reported in this work is a combined surface enhanced Raman spectroscopy (SERS), transmission electron microscope (TEM), inductively-coupled plasma mass-spectrometry (ICP-MS), and localized surface plasmonic resonance (LSPR) study of alkyldithiol (ADT, (HS-(CH 2 ) n -SH, n= 2, 4, and 6) interactions with AuNPs and AgNPs in water. These complementary techniques revealed a series of new insights that would not be possible using individual methods. A large-fraction of ADTs lies flat on AuNP surfaces. The upright ADTs are dimerized horizontally through disulfide-bond, or remain as monothiolates on the AuNP surfaces. Possibility of significant amount of vertically disulfide-linked organodithiol on the surface is excluded on the basis of ICP-MS and AuNP LSPR experiments. ADTs induced significant AgNP disintegrations in which ADTs are predominantly in dithiolate forms. This work highlights the extraordinary complexity of organodithiol interactions with plasmonic nanoparticles. The insights provided in this work will be important for enhancing fundamental understanding of the structure and properties of organothiol-functionalized AgNPs and AuNPs.

Dynamic Au-Thiolate Interaction Induced Rapid Self-Healing Nanocomposite Hydrogels with Remarkable Mechanical Behaviors

“…20 Gold NPs wrapped by polymer chains cannot be eliminated from GNP-15 directly because of their exceptional chemical stability. As far as we know, similar interaction between gold NPs and thiolate molecules has been reported for silver NPs, 32 and novel NC hydrogels can be prepared by replacing gold NPs with silver NPs through a photochemical reaction, providing GNP hydrogels with a similar polymer network. To obtain a uniform network without the introduction of gold NPs, we found that silver NPs wrapped in the network could be eliminated by ammonium persulfate, producing a uniform structure but with larger pores ( Figures S9A and S9B), and the same gel network as GNP-15 was obtained and defined as GNP-0 (etching).…”

Ion Pairing as the Main Pathway for Reducing Electrostatic Repulsion among Organothiolate Self-assembled on Gold Nanoparticles in Water

“…Besides the pH measurement data, another critical supporting evidence that organothiol binds to AuNPs through deprotonation pathway is the comparison of the SERS spectra of BuT and DBDS (Figure ). The S–H stretching Raman peak (∼2600 cm –1 ) in neat BuT (Figure a) is absent in BuT in 1 M NaOH (Figure b), suggesting that BuT is in thiolate form in 1 M NaOH. − BuT adsorption onto AuNP is evident from the absence of the S–H stretching Raman peak (∼2600 cm –1 ) in the BuT SERS spectra (Figure c), − while DBDS adsorption onto AuNP is experimentally confirmed by the disappearance of disulfide (S–S) stretching Raman feature in the ∼500 cm –1 region (Figure e) compared to neat DBDS in Figure f. , These results indicate that the S–H peak in BuT and the S–S peak in DBDS are both cleaved upon their binding to AuNPs (Figure c,e). However, the SERS spectrum of the BuT in water is much more similar to the SERS spectrum of BuT dissolved in 1 M NaOH (Figure c,d), but different from the SERS spectrum of DBDS adsorbed onto AuNP in water (Figure e), particularly for the spectral feature from 1000 to 1500 cm –1 region.…”

Pillar[5]arene‐stabilized Plasmonic Nanoparticles as Selective SERS Sensors

“…Covalent interactions are often restricted to analytes that present a functional moiety such as thiol or amine functionalities. [15][16] On the other hand, electrostatic interactions are restricted to charged analytes interacting with an opposite charged plasmonic substrate. [17] Unfortunately, most analytes do not present such affinity towards the plasmonic substrate.…”