Fullerene- and Pyromellitdiimide-Appended Tripodal Ligands Embedded in Light-Harvesting Porphyrin Macrorings
Fullerene- and Pyromellitdiimide-Appended Tripodal Ligands Embedded in Light-Harvesting Porphyrin Macrorings
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DOI：
10.1021/ic201250q
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发表时间：
2011-10-17
影响因子：
4.6
通讯作者：
Kobuke, Yoshiaki
中科院分区：
文献类型：
--
作者：
Kuramochi, Yusuke;Satake, Akiharu;Kobuke, Yoshiaki
合成了三个新的三吡啶基三脚架配体，分别命名为C-60-s-Tripod，C-60-l-Tripod和PI Tripod，并将其引入到卟啉大环N-（1-Zn）（3）（其中1-Zn =三孢卟啉锌（II））中。根据紫外-可见吸收和荧光滴定数据，C-60-s-Tripod、C-60-l-Tripod和PI-Tripod与N-（1-Zn）（3）在苯甲腈中的结合常数分别估计为3 × 10（8）、1 × 10（7）和2 × 10（7）M-1。这些大的结合常数表示配体与N-（1-Zn）（3）的多重相互作用。较长的配体（C-60-l-Tripod）和均苯四甲酸二酰亚胺配体（PI-Tripod）的结合常数与没有富勒烯或均苯四甲酸二酰亚胺基团的那些几乎相同，表明它们通过三个吡啶基与卟啉锌（II）配位相互作用。与此相反，在较短配体（C-60-s-Tripod）的情况下，较大的结合常数和几乎完全的荧光猝灭表明与N-（1-Zn）（3）的相互作用是通过两个吡啶基与卟啉锌（II）配位以及富勒烯与卟啉的π-π相互作用。C-60-l-Tripod可使N-（1-Zn）（3）的荧光猝灭80%。纳秒瞬态吸收光谱显示，在选择性激发下，富勒烯只有三重峰，表明在C-60-l-Tripod/N-（1-Zn）（3）复合物中发生了从N-（1-Zn）（3）基团到富勒烯基的能量转移。在PI-Tripod的情况下，N-（1-Zn）（3）的荧光被猝灭45%。荧光猝灭可能是由N-（1-Zn）（3）基团向均苯四甲酸二酰亚胺基团的电子转移引起的。
Three new tripyridyl tripodal ligands appended with either fullerene or pyromellitdiimide moieties, named C-60-s-Tripod, C-60-l-Tripod, and PI Tripod, were synthesized and introduced into a porphyrin macroring N-(1-Zn)(3) (where 1-Zn = trisporphyrinatozinc(II)). From UV-vis absorption and fluorescence titration data, the bindin constants of C-60-s-Tripod, C-60-l-Tripod, and PI-Tripod with N-(1-Zn)(3) in benzonitrile were estimated to be 3 X 10(8), 1 X 10(7), and 2 x 10(7) M-1, respectively. These large binding constants denote multiple interactions of the ligands to N-(1-Zn)(3). The binding constants of the longer ligand (C-60-l-Tripod) and the pyromellitdiimide ligand (PI-Tripod) are almost the same as those without the fullerene or pyromellitdiimide groups, indicating that they interact via three pyridyl groups to the porphyrinatozinc(II) coordination. In contrast, the larger binding constants and the almost complete fluorescence quenching in the case of the shorter ligand (C-60-s-Tripod) indicate that the interaction with N-(1-Zn)(3) is via two pyridyl groups to the porphyrinatozinc(II) coordination and a pi-pi interaction of the fullerene to the porphyrin(s). The fluorescence of N-(1-Zn)(3) was quenched by up to 80% by the interaction of C-60-l-Tripod. The nanosecond transient absorption spectra showed only the excited triplet peak of the fullerene on selective excitation of the macrocyclic porphyrins, indicating that energy transfer from the excited N-(1-Zn)(3) group to the fullerenyl moiety occurs in the C-60-l-Tripod/N-(1-Zn)(3) composite. In the case of PI-Tripod, the fluorescence of N-(1-Zn)(3) was quenched by 45%. It seems that the fluorescence quenching probably originates from electron transfer from the excited N-(1-Zn)(3) group to the pyromellitdiimide moiety.