Kawashima Yuki, Ohkubo Kei, Okada Hiroshi, Matsuo Yutaka, Fukuzumi Shunichi
Department of Material and Life Science, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan), Fax: (+81) 6-6879-7370.
Chemphyschem. 2014 Dec 1;15(17):3782-90. doi: 10.1002/cphc.201402512. Epub 2014 Sep 11.
Lithium-ion-encapsulated [6,6]-phenyl-C61 -butyric acid methyl ester fullerene (Li(+) @PCBM) was utilized to construct supramolecules with sulfonated meso-tetraphenylporphyrins (MTPPS(4-) ; M=Zn, H2 ) in polar benzonitrile. The association constants were determined to be 1.8×10(5) M(-1) for ZnTPPS(4-) /Li(+) @PCBM and 6.2×10(4) M(-1) for H2 TPPS(4-) /Li(+) @PCBM. From the electrochemical analyses, the energies of the charge-separated (CS) states were estimated to be 0.69 eV for ZnTPPS(4-) /Li(+) @PCBM and 1.00 eV for H2 TPPS(4-) /Li(+) @PCBM. Upon photoexcitation of the porphyrin moieties of MTPPS(4-) /Li(+) @PCBM, photoinduced electron transfer occurred to produce the CS states. The lifetimes of the CS states were 560 μs for ZnTPPS(4-) /Li(+) @PCBM and 450 μs for H2 TPPS(4-) /Li(+) @PCBM. The spin states of the CS states were determined to be triplet by electron paramagnetic resonance spectroscopy measurements at 4 K. The reorganization energies (λ) and electronic coupling term (V) for back electron transfer (BET) were determined from the temperature dependence of kBET to be λ=0.36 eV and V=8.5×10(-3) cm(-1) for ZnTPPS(4-) /Li(+) @PCBM and λ=0.62 eV and V=7.9×10(-3) cm(-1) for H2 TPPS(4-) /Li(+) @PCBM based on the Marcus theory of nonadiabatic electron transfer. Such small V values are the result of a small orbital interaction between the MTPPS(4-) and Li(+) @PCBM moieties. These small V values and spin-forbidden charge recombination afford a long-lived CS state.
锂离子封装的[6,6]-苯基-C61-丁酸甲酯富勒烯（Li(+)@PCBM）用于在极性苯甲腈中与磺化中位四苯基卟啉（MTPPS(4-)；M = Zn，H2）构建超分子。测定ZnTPPS(4-)/Li(+)@PCBM的缔合常数为1.8×10(5) M(-1)，H2TPPS(4-)/Li(+)@PCBM的缔合常数为6.2×10(4) M(-1)。通过电化学分析，电荷分离（CS）态的能量估计对于ZnTPPS(4-)/Li(+)@PCBM为0.69 eV，对于H2TPPS(4-)/Li(+)@PCBM为1.00 eV。在MTPPS(4-)/Li(+)@PCBM的卟啉部分光激发后，发生光诱导电子转移以产生CS态。CS态的寿命对于ZnTPPS(4-)/Li(+)@PCBM为560 μs，对于H2TPPS(4-)/Li(+)@PCBM为450 μs。通过在4 K下的电子顺磁共振光谱测量确定CS态的自旋态为三重态。基于非绝热电子转移的马库斯理论，从kBET的温度依赖性确定反向电子转移（BET）的重组能（λ）和电子耦合项（V），对于ZnTPPS(4-)/Li(+)@PCBM，λ = 0.36 eV且V = 8.5×10(-3) cm(-1)，对于H2TPPS(4-)/Li(+)@PCBM，λ = 0.62 eV且V = 7.9×10(-3) cm(-1)。如此小的V值是MTPPS(4-)和Li(+)@PCBM部分之间小轨道相互作用的结果。这些小的V值和自旋禁阻的电荷复合产生了长寿命的CS态。
