Ag-S Type Quantum Dots versus Superatom Nanocatalyst: A Single Sulfur Atom Modulated Decarboxylative Radical Cascade Reaction

The preparation of high-nuclearity silver nanoclusters in quantitative yield remains exclusive and their potential applications in the catalysis of organic reactions are still undeveloped. Here, we have synthesized a quantum dot (QD)-based catalyst, [Ag62S13(SBut)32](PF6)4 (denoted as Ag62S12-S) in excellent yield that enables the direct synthesis of pharmaceutically precious 3,4-dihydroquinolinone in 92% via a decarboxylative radical cascade reaction of cinnamamide with ?-oxocarboxylic acid under mild reaction conditions. In comparison, a superatom [Ag62S12(SBut)32](PF6)2 (denoted as Ag62S12) with identical surface anatomy and size, but without a central S2- atom in the core, gives an improved yield (95%) in a short time and exhibits higher reactivity. Multiple characterization techniques (single-crystal X-ray diffraction, nuclear magnetic resonance (1H and 31P), electrospray ionization mass spectrometry, energy dispersive X-ray spectroscopy, Brunauer-Emmett-Teller (BET), Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis) confirm the formation of Ag62S12-S. The BET results expose the total active surface area in supporting a single e- transfer reaction mechanism. Density functional theory reveals that leaving the central S atom of Ag62S12-S leads to higher charge transfer from Ag62S12 to the reactant, accelerates the decarboxylation process, and correlates the catalytic properties with the structure of the nanocatalyst. � 2023 American Chemical Society.

Keywords

Atoms, Carboxylation, Crystal atomic structure, Density functional theory, Electrodeposition, Electrospray ionization, Energy dispersive spectroscopy, Fourier transform infrared spectroscopy, High resolution transmission electron microscopy, Ligands, Mass spectrometry, Nanocatalysts, Nanocrystals, Nuclear magnetic resonance spectroscopy, Silver compounds, Single crystals, Sulfur, Thermogravimetric analysis, X ray photoelectron spectroscopy, Brunauer emmett tellers, Nano-catalyst, Nuclearity, Organic reaction, Quantitative yields, Radical cascade reactions, Silver nanoclusters, Sulphur atoms, Superatoms, Synthesised, Semiconductor quantum dots