Excited State Engineering in Ag<sub>29</sub> Nanocluster through Peripheral Modification with Silver(I) Complexes for Bright Near-Infrared Photoluminescence
Wataru Ishii, Yoshinori Okayasu, Yoichi Kobayashi, Rika Tanaka, Shohei Katao, Yoshiko Nishikawa, Tsuyoshi Kawai, Takuya Nakashima
Abstract
The optical property of an ionic metal nanocluster (NC) is affected by the ionic interaction with counter ions. Here, we report that the modification of trianionic [Ag 29 (BDT) 12 (TPP) 4 ] 3– NC (BDT: 1.3-benzenedithiol; TPP: triphenylphosphine) with silver(I) complexes led to the intense photoluminescence (PL) in the near-infrared (NIR) region. The binding of silver(I) complexes to the peripheral region of Ag 29 NC is confirmed by the single-crystal X-ray diffraction (SCXRD) measurement, which is further supported by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. The change of excited-state dynamics by the binding of silver(I) complexes is discussed based on the results of a transient absorption study as well as temperature-dependent PL spectra and PL lifetime measurements. The modification of Ag 29 NCs with cationic silver(I) complexes is considered to give rise to a triplet excited state responsible for the intense NIR PL. These findings also afford important insights into the origin of the PL mechanism as well as the possible light-driven motion in Ag 29 -based NCs.