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.
Fukuzumi
Shunichi
S
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
Ohkubo
Kei
K
Ortiz
Javier
J
Gutiérrez
Ana M
AM
Fernández-Lázaro
Fernando
F
Sastre-Santos
Angela
A
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