Monoarsine-protected icosahedral cluster [Au13(AsPh3)8Cl4]+: comparative studies on ligand effect and surface reactivity with its stibine analogue.

Ligand shells of gold nanoclusters play important roles in regulating their molecular and electronic structures. However, the similar but distinct impacts of the homologous analogues of the protecting ligands remain elusive. The C2v symmetric monoarsine-protected cluster [Au13(AsPh3)8Cl4]+ (Au13As8) was facilely prepared by direct reduction of (Ph3As)AuCl with NaBH4. This cluster is isostructural with its previously reported stibine analogue [Au13(SbPh3)8Cl4]+ (Au13Sb8), enabling a comparative study between them. Au13As8 exhibits a blue-shifted electronic absorption band, and this is probably related to the stronger π-back donation interactions between the Au13 core and AsPh3 ligands, which destabilize its superatomic 1P and 1D orbitals. In comparison to the thermodynamically less stable Au13Sb8, Au13As8 achieves a better trade-off between catalytic stability and activity, as demonstrated by its excellent catalytic performance towards the aldehyde-alkyne-amine (A3) coupling reaction. Moreover, the ligand exchange reactions between Au13As8 with phosphines, as exemplified by PPh3 and Ph2P(CH2)2PPh2, suggest that Au13As8 may be a good precursor cluster for further cluster preparation through the "cluster-to-cluster" route.

Ag22 Nanoclusters with Thermally Activated Delayed Fluorescence Protected by Ag/Cyanurate/Phosphine Metallamacrocyclic Monolayers through In-Situ Ligand Transesterification.

The composition of protection monolayer exerts great influence on the molecular and electronic structures of atomically precise monolayer protected metal nanoclusters. Four isostructural Ag/cyanurate/phosphine metallamacrocyclic monolayer protected Ag22 nanoclusters are synthesized by kinetically controlled in-situ ligand formation-driven strategy. These eight-electron superatomic silver nanoclusters feature an unprecedented interfacial bonding structure with diverse E-Ag (E=O/N/P/Ag) interactions between the Ag13 core and metallamacrocyclic monolayer, and displays thermally activated delayed fluorescence (TADF), benefiting from their distinct donor-acceptor type electronic structures. This work not only unmasks a new core-shell interface involving cyanurate ligand but also underlines the significance of high-electron-affinity N-heterocyclic ligand in synthesizing TADF metal nanoclusters. This is the first mixed valence Ag0/I nanocluster with TADF characteristic.

Electrocatalytic activity of salicylic acid on the platinum nanoparticles modified electrode by electrochemical deposition.

Platinum nanoparticles (PNP) were deposited on the Pt disk electrode by electrochemical deposition, it was found that salicylic acid (SA) had good electrocatalytic oxidation response at the prepared Pt nanoparticles modified Pt disk electrode (PNP/Pt). Then the modified electrode was used to detect SA in weak alkali condition, it was found that the response current was 9.2 times that of bare Pt disk electrode, and the linear range of detection was 2.0x10(-5) to 5.0x10(-4)M. After that, the electrode was adopted to detect the SA in Zuguangsan, one kind of Chinese medicine, the results showed that the PNP/Pt electrode has low detection limit, high repeatability and stability as SA sensor, could be applied in the detection of SA reliably.

Electrocatalytic oxidation of phytohormone salicylic acid at copper nanoparticles-modified gold electrode and its detection in oilseed rape infected with fungal pathogen Sclerotinia sclerotiorum.

Salicylic acid (SA) is a biological substance that acts as a phytohormone and plays an important role in signal transduction in plants. It is important to accurately and sensitively detect SA levels. A gold electrode modified with copper nanoparticles was used to assay the electrocatalytic oxidation of salicylic acid. It was found that the electrochemical behavior of salicylic acid was greatly improved at copper nanoparticles, indicating that anodic oxidation could be catalyzed at copper nanoparticles. And the pH had remarkable effect on the electrochemical process, a very well-defined oxidation peak appeared at pH 13.3 (0.2M NaOH). The kinetics parameters of this process were calculated and the heterogeneous electron transfer rate constant (k) was determined to be 1.34x10(-3)cms(-1), and (1-alpha)n(alpha) was 1.22. The gold electrode modified with copper nanoparticles could detect SA at a higher sensitivity than common electrodes. The electrode was used to detect the SA levels in oilseed rape infected with the fungal pathogen Sclerotinia sclerotiorum. The results showed that the SA concentration reached a maximum during the 10th-25th hours after infection. This result was very similar to that determined by HPLC, indicating that the gold electrodes modified with copper nanoparticles could be used as salicylic acid sensors.

Direct electrochemistry and electrocatalytic activity of hemoglobin at CdTe nanoparticle/nafion film-modified electrode.

Water-soluble CdTe nanoparticles and hemoglobin (Hb) were immobilized on a glassy carbon (GC) electrode with Nafion. The direct electrochemistry of Hb on this surface was studied. The results indicated that CdTe nanoparticles could effectively promote the direct electron transfer of Hb at the interface of a electrode. The average surface coverage of Hb on the surface could be calculated as 2.63 x 10(-9) mol/cm2, the heterogeneous electron transfer rate constant, k, was calculated as 0.068 s(-1) and the transfer coefficient, alpha, was 0.59, further study indicated that immobilized Hb still kept its catalytic activity to H2O2 reduction. The apparent Michaelis-Menten constant was calculated to be 17.7 microM. It was also found that the modified electrode could be used as a sensor for H2O2; the linear range of detection was 5.0 x 10(-6)-4.5 x 10(-5) M, with a detection limit of 8.4 x 10(-7) M. The sensor exhibited high sensitivity, reproducibility and stability.

Electrocatalysis of emodin at multi-wall nanotubes.

In this article, the electrochemical behavior of emodin at multi-wall carbon nanotube modified glassy carbon electrodes (MWNTs/GCE) was studied. The result showed that MWNTs/GCE had high electrocatalytic activity for emodin. And the electrocatalytic redox process was a two-charge-two-proton process. Diffusion coefficient (D(R)) of 8.403 x 10(-5) cm(2) s(-1) of emodin was obtained. Further experiments demonstrated that the oxidative peaks increased linearly with emodin concentrations in the range of 1.0 x 10(-6) to 1.0 x 10(-4) M with a limit of detection of 3.0 x 10(-7) M. This electrochemical method was accurate and reliable, therefore, it might provide a novel way for emodin detection.