Silvery fullerene in Ag102 nanosaucer.

Abstract

Despite the discovery of a series of fullerenes and a handful of noncarbon clusters with the typical topology of I _h-C₆₀, the smallest fullerene with a large degree of curvature, C₂₀, and its other-element counterparts are difficult to isolate experimentally. In coinage metal nanoclusters (NCs), the first all-gold fullerene, Au₃₂, was discovered after a long-lasting pursuit, but the isolation of similar silvery fullerene structures is still challenging. Herein, we report a flying saucer-shaped 102-nuclei silver NC (Ag102) with a silvery fullerene kernel of Ag₃₂, which is embraced by a robust cyclic anionic passivation layer of (KPO₄)₁₀. This Ag₃₂ kernel can be viewed as a non-centered icosahedron Ag₁₂ encaged into a dodecahedron Ag₂₀, forming the silvery fullerene of Ag₁₂@Ag₂₀. The anionic layer (KPO₄)₁₀ is located at the interlayer between the Ag₃₂ kernel and Ag₇₀ shell, passivating the Ag₃₂ silvery fullerene and templating the Ag₇₀ shell. The ^t BuPhS^- and CF₃COO^- ligands on the silver shell show a regioselective arrangement with the 60 ^t BuPhS^- ligands as expanders covering the upper and lower of the flying saucer and 10 CF₃COO^- as terminators neatly encircling the edges of the structure. In addition, Ag102 shows excellent photothermal conversion efficiency (η) from the visible to near-infrared region (η = 67.1% ± 0.9% at 450 nm, 60.9% ± 0.9% at 660 nm and 50.2% ± 0.5% at 808 nm), rendering it a promising material for photothermal converters and potential application in remote laser ignition. This work not only captures silver kernels with the topology of the smallest fullerene C₂₀, but also provides a pathway for incorporating alkali metal (M) into coinage metal NCs via M-oxoanions.