Control of photoinduced electron transfer in zinc phthalocyanine-perylenediimide dyad and triad by the magnesium ion.
Photoexcitation of a zinc phthalocyanine-perylenediimide (ZnPc-PDI) dyad and a bis(zinc phthalocyanine)-perylenediimide [(ZnPc) 2-PDI] triad results in formation of the triplet excited state of the PDI moiety without the fluorescence emission, whereas addition of Mg (2+) ions to the dyad and triad results in formation of long-lived charge-separated (CS) states (ZnPc (*+)-PDI (*-)/Mg (2+) and (ZnPc) 2 (*+)-PDI (*-)/Mg (2+)) in which PDI (*-) forms a complex with Mg (2+). Formation of the CS states in the presence of Mg (2+) was confirmed by appearance of the absorption bands due to ZnPc (*+) and PDI (*-)/Mg (2+) complex in the time-resolved transient absorption spectra of the dyad and triad. The one-electron reduction potential ( E red) of the PDI moiety in the presence of a metal ion is shifted to a positive direction due to the binding of Mg (2+) to PDI (*-), whereas the one-electron oxidation potential of the ZnPc moiety remains the same. The binding of Mg (2+) to PDI (*-) was confirmed by the ESR spectrum, which is different from that of PDI (*-) without Mg (2+). The energy of the CS state (ZnPc (*+)-PDI (*-)/Mg (2+)) is determined to be 0.79 eV, which becomes lower that of the triplet excited state (ZnPc- (3)PDI*: 1.07 eV). This is the reason why the long-lived CS states were attained in the presence of Mg (2+) instead of the triplet excited state of the PDI moiety.
Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan. fukuzumi@chem.eng.osaka-u.ac.jp
Shunichi
S
Fukuzumi
Kei
K
Ohkubo
Javier
J
Ortiz
Ana M
AM
Gutiérrez
Fernando
F
Fernández-Lázaro
Angela
A
Sastre-Santos
D003198:Computer Simulation; D004583:Electrons; D007094:Imides / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D054833:Isoindoles; D007834:Lasers; D008274:Magnesium / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry; D010777:Photochemistry; D010782:Photolysis; D013997:Time Factors; D017967:Zinc Compounds
D007094:Imides; D007211:Indoles; D007477:Ions; D054833:Isoindoles; D009942:Organometallic Compounds; D017967:Zinc Compounds; C521332:perylenediimide; C052159:Zn(II)-phthalocyanine; D010569:Perylene; D008274:Magnesium