posted on 2023-12-01, 15:09authored byYue Wang, Yongfang Shi, Jinyun Wang, Liting Li, Cun Wang, Xu Zhang
A large sterically hindered alkynyl-protected neutral
gold nanocluster
[Au22L14] (1) (L = 2,4,6-tri(isopropyl)-phenylacetylene)
has been prepared by self-assembly under reduction condition. Single-crystal
X-ray diffraction reveals that the molecular structure contains a
polyhedral Au18 kernel, which is made of two hexagonal
bipyramids and two triangular pyramids with Au atoms as vertices.
Four staple-like RCC–Au–CCR (R = 2,4,6-tri(isopropyl)-phenyl)
motifs are located around the Au18 core, which further
built an entire Au22 core structure of cluster 1. The Au22 core is stabilized by 14 acetylide ligands
with 42 bulky isopropyl groups. It has been observed that the solid-state
Au22 nanocluster is emissive in the near-infrared region
with an intensive emission centered at 967 nm, and computational studies
indicate that the phosphorescent emission is ascribed to the metal
cluster-centered transition, phenylacetylide-centered IL, and LMCT
state from phenylacetylide to metal centers. Large Stokes’
shifts with a long range of emissive lifetime indicate that the emission
likely originates from a triplet-state parentage. Interestingly, under
the stimuli of mechanical force, 1 exhibits a significant
luminescent blue-shift response.