Guest-induced photophysical property switching of artificial light-harvesting dendrimers.
An artificial light-harvesting multiporphyrin dendrimer (8P(Zn)P(FB)) composed of a focal freebase porphyrin (P(FB)) with eight zinc(II) porphyrin (P(Zn)) wings exhibited unique photophysical property switching in response to specific guest molecule binding. UV/Vis titration studies indicated stable 1:2 host-guest complex formation between 8P(Zn)P(FB) and meso-tetrakis(4-pyridyl)-porphyrin (TPyP) for which the first and second association constants were estimated to be >10(8) M(-1) and 3.0×10(7) M(-1), respectively. 8P(Zn)P(FB) originally shows 94% energy transfer efficiency from P(Zn) to the focal P(FB). By the formation of the host-guest complex (8P(Zn)P(FB)⋅2TPyP) the emission intensity of 8P(Zn)P(FB) is significantly decreased, and an ultrafast charge separation state is generated. The energy transfer process from P(Zn) wings to the P(FB) core in 8P(Zn)P(FB) is almost entirely switched to an electron transfer process by the formation of 8P(Zn)P(FB)⋅2TPyP.
Department of Chemistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea).
Young-Hwan
YH
Jeong
Minjung
M
Son
Hongsik
H
Yoon
Pyosang
P
Kim
Do-Hyung
DH
Lee
Dongho
D
Kim
Woo-Dong
WD
Jang
D001672:Biocompatible Materials / Q000737:chemistry*; D050091:Dendrimers / Q000737:chemistry*; D004579:Electron Transport; D004735:Energy Transfer; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D011166:Porphyrins / Q000737:chemistry
D001672:Biocompatible Materials; D050091:Dendrimers; D045342:Light-Harvesting Protein Complexes; D011166:Porphyrins
dendrimers; electron transfer; energy transfer; host-guest systems; porphyrin