Photophysical Properties of a Post-Self-Assembly Host/Guest Coordination Cage: Visible Light Driven Core-to-Cage Charge Transfer.
Supramolecular systems are capable of unique photophysical properties due to possible interactions between subcomponents, such as between an encapsulated molecule and its cage in a host/guest environment. Here, we report that the encapsulation of a chromophore by a metallacage dramatically enhances its photophysical properties. In the visible region, the encapsulated photosensitizer achieves a 6.5-fold enhancement to its absorptivity. The triplet lifetime of the encapsulated photosensitizer is three times longer than that of its free analogue. These enhancements are attributed to two key factors: (i) encapsulation-induced core-to-cage charge transfer (CCCT) generates new visible-light absorbing states, accounting for the enhanced absorption, and (ii) the microenvironment inside the metallacage inhibits nonradiative decay processes, resulting in prolonged triplet lifetime. The CCCT arises from the electrostatic interaction between the delocalized electrons of the guest coronene and the positive charge associated with the metallacage host. The work herein provides insight into the CCCT phenomenon.
†State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China.
Yang
Y
Yang
†State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China.|‡University of the Chinese Academy of Sciences, Beijing 100049, People's Republic of China.
Jun-Sheng
JS
Chen
†State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China.
Jian-Yong
JY
Liu
†State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China.
Guang-Jiu
GJ
Zhao
†State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China.
Lei
L
Liu
†State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China.
Ke-Li
KL
Han
§Department of Chemistry, University at Buffalo, Buffalo, New York 14260, United States.
Timothy R
TR
Cook
∥Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States.
Peter J
PJ
Stang
DFT/TDDFT; charge transfer; host/guest; post-self-assembly; time-resolved spectroscopy