Uno Takuma, Koga Masafumi, Sotome Hikaru, Miyasaka Hiroshi, Tamai Naoto, Kobayashi Yoichi
Department of Applied Chemistry, College of Life Sciences , Ritsumeikan University , 1-1-1 Noji-higashi , Kusatsu , Shiga 525-8577 , Japan.
Division of Frontier Materials Science and Center for Promotion of Advanced Interdisciplinary Research, Graduate School of Engineering Science , Osaka University , Toyonaka , Osaka 560-8531 , Japan.
J Phys Chem Lett. 2018 Dec 20;9(24):7098-7104. doi: 10.1021/acs.jpclett.8b03106. Epub 2018 Dec 7.
There has been an increasing amount of interest in stepwise two-photon-absorption (2PA)-induced photochemical reactions because of their extremely lower power thresholds compared to that of the simultaneous process and drastic reaction enhancements in some cases. However, stepwise 2PA-induced photochemical reactions were reported only in single chromophores and covalently bound bichromophores and there are few reports on these reactions in noncovalently bound systems because of weak electronic interactions among chromophores. This study demonstrated the stepwise 2PA-induced electron transfer from higher excited states in noncovalently bound protoporphyrin IX·CdS/ZnS core/shell nanocrystals (NCs). The electron transfer from higher excited states of porphyrin to CdS NCs successfully overcomes the activation barrier associated with the wide bandgap ZnS shell, indicating that a high reduction potential can be obtained with the stepwise 2PA process. The concept presented in this study can be applied to various noncovalently bound multichromophore systems to explore nonlinear photoresponses.
