posted on 2024-03-15, 17:36authored byYe Tao, Ni Luan, Chunyun Yang, Jiayu Sun, Kai Li, Xing Dai, Hailong Zhang, Zhifang Chai, Shuao Wang, Yaxing Wang
We present the first example of an 99TcO4– anion entrapped within the cavity of a
silver
cluster, revealing an unprecedented photoinduced charge transfer phenomenon.
[Ag24(CCtBu)20(99TcO4)]·(BF4)3 (denoted as 99TcO4–@Ag24) was successfully synthesized and structurally characterized.
Single-crystal X-ray diffraction and Raman spectroscopy reveal that
the tetrahedral structure of the 99TcO4– anion sustains significant symmetry breaking with
weakened Tc–O bond strength under confinement within the Ag24(CCtBu)204+ cluster. Notably, 99TcO4–@Ag24 exhibits a broadband electronic absorption
spectrum in the visible region, which was absent for the other 99TcO4–-containing compounds.
Density functional theory calculations elucidate that host–guest
electrostatic interactions result in an electron polarization effect
between the 99TcO4– anion
core and the Ag24 cationic shell. The emergence of an absorption
band in 99TcO4–@Ag24 is rationalized by intermolecular charge transfer from the Ag24 electronic states to the lowest unoccupied molecular orbitals
of 99TcO4– instead of the
intramolecular electron transition observed in other 99TcO4–-containing compounds.