Kawashima Yuki, Ohkubo Kei, Blas-Ferrando Vicente Manuel, Sakai Hayato, Font-Sanchis Enrique, Ortíz Javier, Fernández-Lázaro Fernando, Hasobe Taku, Sastre-Santos Ángela, Fukuzumi Shunichi
†Department of Material and Life Science, Graduate School of Engineering, Osaka University, and ALCA, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan.
‡Área de Química Orgánica, Instituto de Bioingeniería, Universidad Miguel Hernández, Edificio Vinalopó, Avda. Universidad s/n, Elche E-03202, Spain.
J Phys Chem B. 2015 Jun 18;119(24):7690-7. doi: 10.1021/jp5123163. Epub 2015 Feb 9.
Two phthalocyanines possessing carboxylate groups ((TBA)4H2Pc·1 and (TBA)4H2Pc·2) form 1:2 supramolecular complexes with lithium cation-encapsulated C60 (Li(+)@C60) [H2Pc·1(4-)/(Li(+)@C60)2 and H2Pc·2(4-)/(Li(+)@C60)2] in a polar mixed solvent. From the UV-vis spectral changes, the binding constants (K) were estimated as ca. 10(12) M(-2). Upon the photoexcitation of constructed supramolecular complexes, photoinduced electron transfer occurred to form the charge-separated (CS) state. The lifetime of the CS state was determined to be 1.2 ms for H2Pc·2(4-)/(Li(+)@C60)2, which is the longest CS lifetime among the porphyrinoid/fullerene supramolecular complexes. H2Pc·1(4-)/(Li(+)@C60)2 also afforded the long-lived CS state of 1.0 ms. The spin state of the long-lived CS states was determined to be a triplet, as indicated by the EPR signal at g = 4. The reorganization energy (λ) and the electronic coupling term were determined to be λ = 1.70 eV, V = 0.15 cm(-1) from the temperature dependence of the rate constant for the charge recombination of the CS state of H2Pc·1(4-)/(Li(+)@C60)2. The energy of the CS state (0.49 eV) is much smaller than the reorganization energy, indicating that the back-electron-transfer process is located in the Marcus normal region. The small electronic coupling term results from the spin-forbidden back electron transfer due to the triplet CS state. Supramolecular complexes of anionic zinc phthalocyanines with Li(+)@C60 were also prepared and investigated. The ZnPc·4(4-)/Li(+)@C60 supramolecular nanoclusters were assembled on the optically transparent electrode (OTE) of nanostructured SnO2 (OTE/SnO2) to construct the dye-sensitized solar cell. The IPCE (incident photon-to-photocurrent efficiency) values of OTE/SnO2/(ZnPc·4(4-)/Li(+)@C60)n were much higher than the sum of the two IPCE values of the individual systems OTE/SnO2/(Li(+)@C60)n and OTE/SnO2/(ZnPc·4(4-))n, covering the near-infrared region.
两种带有羧基的酞菁（(TBA)4H2Pc·1 和 (TBA)4H2Pc·2）在极性混合溶剂中与锂阳离子封装的 C60（Li(+)@C60）形成 1:2 的超分子配合物 [H2Pc·1(4-)/(Li(+)@C60)2 和 H2Pc·2(4-)/(Li(+)@C60)2]。根据紫外可见光谱变化，估算出结合常数（K）约为 10(12) M(-2)。在构建的超分子配合物发生光激发时，发生了光诱导电子转移，形成了电荷分离（CS）态。对于 H2Pc·2(4-)/(Li(+)@C60)2，CS 态的寿命测定为 1.2 毫秒，这是卟啉类/富勒烯超分子配合物中最长的 CS 寿命。H2Pc·1(4-)/(Li(+)@C60)2 也产生了 1.0 毫秒的长寿命 CS 态。如 g = 4 处的电子顺磁共振信号所示，长寿命 CS 态的自旋态被确定为三重态。根据 H2Pc·1(4-)/(Li(+)@C60)2 的 CS 态电荷复合速率常数的温度依赖性，确定重组能（λ）和电子耦合项分别为 λ = 1.70 eV，V = 0.15 cm(-1)。CS 态的能量（0.49 eV）远小于重组能，表明反向电子转移过程位于 Marcus 正常区域。较小的电子耦合项是由于三重态 CS 态导致的自旋禁阻反向电子转移。还制备并研究了阴离子锌酞菁与 Li(+)@C60 的超分子配合物。ZnPc·4(4-)/Li(+)@C60 超分子纳米团簇组装在纳米结构 SnO2 的光学透明电极（OTE）上（OTE/SnO2），以构建染料敏化太阳能电池。OTE/SnO2/(ZnPc·4(4-)/Li(+)@C60)n 的入射光子到光电流效率（IPCE）值远高于单个系统 OTE/SnO2/(Li(+)@C60)n 和 OTE/SnO2/(ZnPc·4(4-))n 的两个 IPCE 值之和，覆盖近红外区域。
