Prof. Kei OHKUBO
Prof. Kei OHKUBO
Osaka University, Japan
Title: Supramolecular Electrochemical Cell of Lithium Ion Encapsulated Fullerene with Porphyrinoids
Extensive efforts have so far been devoted to design and synthesize electron donor-acceptor linked molecules to achieve efficient photoinduced charge separation. We have recently designed and synthesized simple electron donor-acceptor supramolecular complexes composed of lithium ion encapsulated fullerene (Li+@C60) with porphyrin and phthalocyanines and chlorin derivatives. Photoinduced electron-transfer dynamics were examined by femto- and nanosecond laser flash photolysis. The charge-separated states were detected as the transient absorption spectra, where Li+@C60 radical anion of charge-separated state has a specific absorption at 1035 nm. The lifetimes of charge-separated state were determined from the decay of the absorbance at 1035 nm. The lifetime was 230 s in the case of a supramolecule between anionic porphyrin and Li+@C60 in PhCN. The long-lived charge-separation was also confirmed by EPR spectroscopy . Photoelectrochemical measurements were performed using a standard two-electrode system consisting of a working electrode and a Pt wire gauze electrode in air-saturated MeCN containing LiI and I2. The maximum IPCE values in the case of OTE/SnO2/(ZnTPPS4–/ Li+@C60)n attained in these experiments was 77% at 450 nm . The photocurrent generation occurred via photoinduced electron transfer from ZnTPPS4– to Li+@C60 in the supramolecular nanoclusters.
Dr. Kei Ohkubo, Chemistry Doctor (Ph.D.-engineering), now is a Professor of Institute for Advanced Co-Creation Studies, Osaka University, Japan. He earned his Ph.D. degree from Graduate School of Engineering, Osaka University in 2001. He was working as a JSPS fellow and JST research fellow at Osaka University (2001-2005) and a designated associate professor in Osaka University (2005-2014). He was a specially appointed professor at Osaka University (2014-2017). He is now a distinguished professor of Osaka University.