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Synthesis and Photoinduced Intramolecular Processes of Light‐Harvesting Silicon Phthalocyanine–Naphthalenediimide–Fullerene Connected Systems
Author(s) -
ElKhouly Mohamed E.,
Kim Jung Hoon,
Kay KwangYol,
Choi Chan Soo,
Ito Osamu,
Fukuzumi Shunichi
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200900165
Subject(s) - photoexcitation , photochemistry , intramolecular force , chemistry , excited state , phthalocyanine , singlet state , ultrafast laser spectroscopy , quenching (fluorescence) , fullerene , photoinduced electron transfer , electron transfer , fluorescence , spectroscopy , stereochemistry , organic chemistry , atomic physics , quantum mechanics , physics
Fast moving : A new pentad (see figure) composed of silicon phthalocyanine (SiPc), as electron donor, that is connected with two units of naphthalenediimide (NDI) and fullerene C 60 , as electron acceptors, undergoes fast and efficient charge‐separation processes via the NDI and SiPc singlet excited states.Photoinduced intramolecular processes of a newly synthesized pentad composed of silicon phthalocyanine (SiPc) that is connected with two units of naphthalenediimide (NDI) and fullerene C 60 to form SiPc‐(NDI) 2 ‐(C 60 ) 2 have been studied and the results are compared with the reference compounds, namely, the SiPc‐(NDI) 2 triad and NDI‐C 60 dyad. Upon photoexcitation, the main quenching pathway in polar solvents involved electron transfer via the singlet excited states of SiPc‐(NDI) 2 ‐(C 60 ) 2 and SiPc‐(NDI) 2 , but not NDI‐C 60 for which the energy transfer is dominant. The occurrence of electron‐transfer processes of SiPc‐(NDI) 2 ‐(C 60 ) 2 and SiPc‐(NDI) 2 were studied by time‐resolved emission and transient absorption techniques and confirmed by redox measurements and molecular orbital calculations with ab initio B3 LYP/3–21G(*) methods. Fast and efficient charge‐separation processes via the singlet excited states of NDI and SiPc were monitored, followed by charge recombination to populate the C 60 and SiPc triplet states. The lifetimes of charge‐separated states were estimated as 1000 and 250 ps for SiPc‐(NDI) 2 ‐(C 60 ) 2 and SiPc‐(NDI) 2 , respectively.