TY - JOUR
T1 - An extremely long-lived charge-separated state of zinc tetraphenylporphyrin coordinated with pyridylnaphthalene-diimide
AU - Saito, Kenji
AU - Kashiwagi, Yukiyasu
AU - Ohkubo, Kei
AU - Fukuzumi, Shunichi
N1 - Funding Information:
This work was supported by a Grant-in-Aid (No. 17750039) from the Ministry of Education, Culture, Sports, Science and Technology, Japan. We thank Dr. Yasuyuki Araki and Prof. Osamu Ito for fluorescence lifetime measurements. K. S. and Y. K. express their special thanks for the center of excellence (21COE) program “Creation of Integrated EcoChemistry of Osaka University”.
PY - 2006
Y1 - 2006
N2 - The nitrogen of pyridylnaphthalenediimide (PyNIm) coordinates to the metal center of zinc tetraphenylporphyrin (ZnTPP) to form a donor-acceptor complex: ZnTPP-PyNIm. Formation of the ZnTPP-PyNIm complex was probed by UV-vis, fluorescence and NMR spectra. The fluorescence of ZnTPP is strongly quenched and the fluorescence lifetime is shortened significantly in the complex. The transient absorption spectrum of the charge-separated state (ZnTPP •+-PyNIm•-) is successfully detected by laser flash photolysis measurements of the ZnTPP-PyNIm system in benzonitrile. The charge-separated state of the complex produced by the photoinduced electron transfer has the longest lifetime, (450 μs) at 288 K, ever reported for donor-acceptor systems linked covalently or non-covalently in solution. However, when benzonitrile is replaced by benzene, the triplet excited state ( 3ZnTPP*), rather than the charge-separated state, is formed upon laser excitation of the ZnTPP-PyNIm complex, due to the lower energy of 3ZnTPP* compared to the charge-separated state in benzene.
AB - The nitrogen of pyridylnaphthalenediimide (PyNIm) coordinates to the metal center of zinc tetraphenylporphyrin (ZnTPP) to form a donor-acceptor complex: ZnTPP-PyNIm. Formation of the ZnTPP-PyNIm complex was probed by UV-vis, fluorescence and NMR spectra. The fluorescence of ZnTPP is strongly quenched and the fluorescence lifetime is shortened significantly in the complex. The transient absorption spectrum of the charge-separated state (ZnTPP •+-PyNIm•-) is successfully detected by laser flash photolysis measurements of the ZnTPP-PyNIm system in benzonitrile. The charge-separated state of the complex produced by the photoinduced electron transfer has the longest lifetime, (450 μs) at 288 K, ever reported for donor-acceptor systems linked covalently or non-covalently in solution. However, when benzonitrile is replaced by benzene, the triplet excited state ( 3ZnTPP*), rather than the charge-separated state, is formed upon laser excitation of the ZnTPP-PyNIm complex, due to the lower energy of 3ZnTPP* compared to the charge-separated state in benzene.
KW - Charge separation
KW - Donor-acceptor complex
KW - Photoinduced electron transfer
KW - Zinc porphyrin
UR - http://www.scopus.com/inward/record.url?scp=33847344828&partnerID=8YFLogxK
U2 - 10.1142/S1088424606000740
DO - 10.1142/S1088424606000740
M3 - Article
AN - SCOPUS:33847344828
SN - 1088-4246
VL - 10
SP - 1371
EP - 1379
JO - Journal of Porphyrins and Phthalocyanines
JF - Journal of Porphyrins and Phthalocyanines
IS - 12
ER -