Ferrocenyl functionalized silver-chalcogenide nanoclusters

Effect of Specific Heavy Doping of Silver Atoms into the Icosahedral Au13 on Electronic Structure and Catalytic Performance

The exploration of specific heavy doping of silver atoms into icosahedral Au13 clusters and their electronic structures and properties has been somewhat limited. Herein, we report two heavily Ag doped nanoclusters, [Au7Ag6(C7H4NOS)4(Dppf)3Cl]0 and [Au7Ag6(C7H4NOS)3(Dppf)3Cl](SbF6) (Au7Ag6-0 and Au7Ag6-1, respectively) [C7H4NOSH = 2-mercaptobenzoxazole, and Dppf = 1,1'-bis(diphenylphosphino)ferrocene]. The electronic structures and superatomic orbitals of nanoclusters were determined by density functional theory (DFT) calculations, and the energy degeneracy of the superatomic orbitals of Au7Ag6-1 is higher than that of Au7Ag6-0. Transient absorption spectroscopy was performed, revealing that Au7Ag6-0 significantly extends the excited-state lifetime. Both nanoclusters were supported on activated carbon for the oxygen reduction reaction. DFT calculations confirm that the catalytic activities mainly stem from the carbon atom of ferrocene rather than the iron atom. This study not only sheds light on the preparation of icosahedral alloy clusters but also provides insights into the regulation of icosahedral superatomic structure and electrocatalytic properties.

Exploring the Emergent Redox Chemistry of Pd(II) Nodes with Pendant Ferrocenes: From Precursors, through Building Blocks, to Self-Assemblies

Energy-relevant small molecule activations and related processes are often multi-electron in nature. Ferrocene is iconic for its well-behaved one-electron chemistry, and it is often used to impart redox activity to self-assembled architectures. When multiple ferrocenes are present as pendant groups in a single structure, they often behave as isolated sites with no separation of their redox events. Herein, we study a suite of molecules culminating in a self-assembled palladium(II) truncated tetrahedron (TT) with six pendant ferrocene moieties using the iron(III/II) couple to inform about the electronic structure and, in some cases, subsequent reactivity. Notably, although known ferrocene-containing metallacycles and cages show simple reversible redox chemistry, this TT undergoes a complex multi-step electrochemical mechanism upon oxidation. The electrochemical behavior was observed by voltammetric and spectroelectrochemical techniques and suggests that the initial Fc-centered oxidation is coupled to a subsequent change in species solubility and deposition of a film onto the working electrode, which is followed by a second separable electrochemical oxidation event. The complicated electrochemical behavior of this self-assembly reveals emergent properties resulting from organizing multiple ferrocene subunits into a discrete structure. We anticipate that such structures may provide the basis for multiple charge separation events to drive important processes related to energy capture, storage, and use, especially as the electronic communication between sites is further tuned.

New atomically precise (M = Au/Ag) nanoclusters as excellent oxygen reduction reaction catalysts

By introducing 1,1'-bis-(diphenylphosphino)ferrocene (dppf) as an activating ligand, two novel nanoclusters, M1Ag21 (M = Au/Ag), have been controllably synthesized and structurally characterized. The atomically precise structures of the M1Ag21 nanoclusters were determined by SCXC and further confirmed by ESI-TOF-MS, TGA, XPS, DPV, and FT-IR measurements. The M1Ag21 nanoclusters supported on activated carbon (C) are exploited as efficient oxygen reduction reaction (ORR) catalysts in alkaline solutions. Density functional theory (DFT) calculations verify that the catalytic activities of the two cluster-based systems originate from the significant ensemble synergy effect between the M13 kernel and dppf ligand in M1Ag21. This work sheds lights on the preparation of cluster-based electrocatalysts and other catalysts that are activated and modified by peripheral ligands.

Ultrasonic-assisted fabrication of thin-film electrochemical detector of H2O2 based on ferrocene-functionalized silver cluster

A novel ferrocene-functionalized silver cluster (FcAgCs) has been designed and synthesized with the assistant of ultrasound treatment and fully characterized by single crystal spectroscopy, IR, UV-Vis, XRD, TGA, NMR, CV and elemental analyses. Ultrasound synthesis method facilitates and accelerates synthesis of this amazing structure and plays a vital role in the synthesis of this special cluster. Single-crystal X-ray analysis reveal that the cluster can be described as a cationic [(dppf)₂Ag₄(CC^tBu)₂(CH₃OH)₂]²⁺ (dppf = 1,1'-bis(diphenylphosphino)ferrocene) species consisted of four rhombic silver atom and two isolated BF₄^- counter anions. Thermal stability greater than 200 °C and solution CV results show that the title cluster is sufficiently stable and suitable for the fabricating of FcAgCs/ITO thin-films and exploring as electrochemical responding materials. Based on its properties, we use it to prepare thin-films on ITO substrate by spin coating method. Verification of synthesis, thickness, uniformity and stability of the fabricated FcAgCs/ITO thin-films were characterized and confirmed by UV, XRD, SEM and the scotch tape adhesion peel test. Moreover, we use this FcAgCs/ITO thin-film electrode as thin-film electrochemical detector which shows sensitive and quick response in the detection of H₂O₂.

Recent advances in the self-assembly of polynuclear metal–selenium and –tellurium compounds from 14–16 reagents

The use of reagents containing bonds between group 14 elements and Se or Te for the self-assembly of polynuclear metal–chalcogen compounds is covered. Background material is briefly reviewed and examples from the literature are highlighted from the period 2007–2017. Emphasis is placed on the different classes of 14–16 precursors and their application in the targeted synthesis of metal–chalcogen compounds. The unique properties arising from the combination of specific 14–16 precursors, metal atoms, and ancillary ligands are also described. Selected examples are chosen to underline the progress in (i) controlled synthesis of heterometallic (ternary) chalcogen clusters, (ii) chalcogen clusters with organic functionalized surfaces, and (iii) crystalline open-framework metal chalcogenides.

Antioxidant and hepatoprotective role of selenium against silver nanoparticles

Silver nanoparticles (AgNPs) have attracted the most interest in terms of their potential biomedical and industrial applications. However, these nanoparticles have shown their toxic behavior toward environment, living tissues, and organisms. Selenium (Se), an essential trace element, is necessary for various metabolic processes, including protection against oxidative stress and immune function. The present study was undertaken to evaluate the effect of Se against AgNP-induced hepatic oxidative stress. AgNPs were synthesized and then prepared nanoparticles were characterized using various analytical techniques such as UV-visible spectroscopy, X-ray diffraction, and transmission electron microscopy. Rats were administered AgNPs intraperitoneally (5 mg/kg/day) and Se (0.2 mg/kg) was given by gavage. AgNP administration induced hepatic damage as indicated by the serum marker enzymes with reduction in levels of glutathione, and decrease in activities of SOD, CAT, and GSH-peroxidase (P<0.05). Decrease in levels of total antioxidant capacity (TAC) and increase in level of C-reactive protein (CRP) was also observed in AgNP-treated group compared to control group. However, Se markedly attenuated AgNP-induced biochemical alterations, levels of TAC, CRP, and serum transaminases (AST, ALT) (P<0.05). Taken together, these findings suggest that administration of AgNPs produces hepatotoxicity in rats, whereas Se supplementation attenuates these effects.

Charge-Transfer Effects in Ligand Exchange Reactions of Au25 Monolayer-Protected Clusters

Reported here are second-order rate constants of associative ligand exchanges of Au25L18 nanoparticles (L = phenylethanethiolate) of various charge states, measured by proton nuclear magnetic resonance at room temperature and below. Differences in second-order rate constants (M(-1) s(-1)) of ligand exchange (positive clusters ∼1.9 × 10(-5) versus negative ones ∼1.2 × 10(-4)) show that electron depletion retards ligand exchange. The ordering of rate constants between the ligands benzeneselenol > 4-bromobenzene thiol > benzenethiol reveals that exchange is accelerated by higher acidity and/or electron donation capability of the incoming ligand. Together, these observations indicate that partial charge transfer occurs between the nanoparticle and ligand during the exchange and that this is a rate-determining effect in the process.

Stepwise assembly of a semiconducting coordination polymer [Cd8S(SPh)14(DMF)(bpy)]n and its photodegradation of organic dyes

A semiconducting coordination polymer with 1D helical structure was constructed by stepwise assembly of chalcogenolate clusters and organic linkers.

Organotin-oxido cluster-based multiferrocenyl complexes obtained by hydrolysis of ferrocenyl-functionalized organotin chlorides

Three organotin-oxido clusters were formed by hydrolysis of ferrocenyl-functionalized organotin chloride precursors in the presence of NaEPh (E=S, Se). [R(Fc) SnCl3 ⋅HCl] (C; R(Fc) = CMe2 CH2 C(Me)=N-N=C(Me)Fc) and [SnCl6 ](2-) formed {(R(Fc) SnCl2 )3 [Sn(OH)6 ]}[SnCl3 ] (3 a) and {(R(Fc) SnCl2 )3 [Sn(OH)6 ]}[PhSeO3 ] (3 b), bearing an unprecedented [Sn4 O6 ] unit, in a one-pot synthesis or stepwise through [(R(Fc) SnCl2 )2 Se] (1) plus [(R(Fc) SnCl2 )SePh] (2). A one-pot reaction starting out from FcSnCl3 gave [(FcSn)9 (OH)6 O8 Cl5 ] (4), which represents the largest Fc-decorated Sn/O cluster reported to date.

Synthesis, crystal structure, and photoluminescence studies of a ruthenocenyl-decorated Sn/S cluster

Recently, we reported on ferrocenyl-decorated Sn/S clusters; herein, we present the extension of our investigations by attachment of ruthenocenyl units to an according cluster skeleton. The latter was realized upon improvement of the synthesis of acetylruthenocene, its conversion to a hydrazone derivative, and the subsequent reaction with a keto-functionalized Sn/S precursor complex. The report comprises the crystal structures of acetylruthenocene and the ruthenocenyl-terminated Sn/S cluster [(R(Rc)Sn)4Sn2S10] (R(Rc) = CMe2CH2C(Me)═N-N═C(Me)Rc), as well as the discussion of the electrochemical properties of the latter and its behavior during time-resolved photoluminescence investigations.

Towards the installation of transition metal ions on donor ligand decorated tin sulfide clusters

Decoration of tetrelchalcogenide T-E clusters with chelating donor ligands was achieved to capture transition metal ions on their surfaces. We demonstrate that by covalent linking of bispyridyl ligands to an Sn-S complex, [ZnX](+) units can be trapped and incorporated into the cluster framework. Intermediates that were identified using spectroscopy and/or X-ray diffraction gave insight into the formation processes.