scholarly journals The Emission Mechanism of Gold Nanoclusters Capped with 11-Mercaptoundecanoic Acid, and the Detection of Methanol in Adulterated Wine Model

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6342
Author(s):  
Ming Wei ◽  
Ye Tian ◽  
Lijun Wang ◽  
Yuankai Hong ◽  
Dan Luo ◽  
...  

The absorption and emission mechanisms of gold nanoclusters (AuNCs) have yet to be understood. In this article, 11-Mercaptoundecanoic acid (MUA) capped AuNCs (AuNC@MUA) were synthesized using the chemical etching method. Compared with MUA, AuNC@MUA had three obvious absorption peaks at 280 nm, 360 nm, and 390 nm; its photoluminescence excitation (PLE) peak and photoluminescence (PL) peak were located at 285 nm and 600 nm, respectively. The AuNC@MUA was hardly emissive when 360 nm and 390 nm were chosen as excitation wavelengths. The extremely large stokes-shift (>300 nm), and the mismatch between the excitation peaks and absorption peaks of AuNC@MUA, make it a particularly suitable model for studying the emission mechanism. When the ligands were partially removed by a small amount of sodium hypochlorite (NaClO) solution, the absorption peak showed a remarkable rise at 288 nm and declines at 360 nm and 390 nm. These experimental results illustrated that the absorption peak at 288 nm was mainly from metal-to-metal charge transfer (MMCT), while the absorption peaks at 360 nm and 390 nm were mainly from ligand-to-metal charge transfer (LMCT). The PLE peak coincided with the former absorption peak, which implied that the emission of the AuNC@MUA was originally from MMCT. It was also interesting that the emission mechanism could be switched to LMCT from MMCT by decreasing the size of the nanoclusters using 16-mercaptohexadecanoic acid (MHA), which possesses a stronger etching ability. Moreover, due to the different PL intensities of AuNC@MUA in methanol, ethanol, and water, it has been successfully applied in detecting methanol in adulterated wine models (methanol-ethanol-water mixtures).

2021 ◽  
Author(s):  
Arunavo Chatterjee ◽  
Pradipta Purkayastha

The ligand-to-metal charge transfer in gold nanoclusters gets influenced by the interacting lipid that regulates photoinduced electron transfer in the aqueous medium.


2021 ◽  
Author(s):  
Qing-Dou Xu ◽  
Chen Zeng ◽  
Shao-Dong Su ◽  
Yu-Ying Yang ◽  
Sheng-Min Hu ◽  
...  

This work shows that the energy of MMCT in cyanidometal-bridged complexes can be tuned systematically by changing the auxiliary ligand of the cyanidometal bridge.


2017 ◽  
Vol 46 (38) ◽  
pp. 12964-12970 ◽  
Author(s):  
Jishi Chen ◽  
Yanze Pan ◽  
Zonghua Wang ◽  
Peng Zhao

A series of tiara like structural Pdn(SR)2n (5 ≤ n ≤ 20) nanoclusters exhibit emission at 620 nm with excitation at around 268 nm. Their emission is due to ligand to metal charge transfer.


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