A high potential donor–acceptor dyad composed of zinc porphyrin bearing three
The effect of donor‐acceptor distance in controlling the rate of electron transfer in axially linked silicon phthalocyanine‐C60dyads has been investigated. For this, two C60‐SiPc‐C60dyads,
- NSF-PAR ID:
- 10237870
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemPhysChem
- Volume:
- 21
- Issue:
- 20
- ISSN:
- 1439-4235
- Page Range / eLocation ID:
- p. 2254-2262
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract meso ‐pentafluorophenyl substituents covalently linked to C60, as a novel dyad capable of generating charge‐separated states of high energy (potential) has been developed. The calculated energy of the charge‐separated state was found to be 1.70 eV, the highest reported for a covalently linked porphyrin–fullerene dyad. Intramolecular photoinduced electron transfer leading to charge‐separated states of appreciable lifetimes in polar and nonpolar solvents has been established from studies involving femto‐ to nanosecond transient absorption techniques. The high energy stored in the form of charge‐separated states along with its persistence of about 50–60 ns makes this dyad a potential electron‐transporting catalyst to carry out energy‐demanding photochemical reactions. This type of high‐energy harvesting dyad is expected to open new research in the areas of artificial photosynthesis especially producing energy (potential) demanding light‐to‐fuel products. -
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Abstract A panchromatic triad, consisting of benzothiazole (BTZ) and BF2‐chelated boron‐dipyrromethene (BODIPY) moieties covalently linked to a zinc porphyrin (ZnP) core, has been synthesized and systematically characterized by using1H NMR spectroscopy, ESI‐MS, UV‐visible, steady‐state fluorescence, electrochemical, and femtosecond transient absorption techniques. The absorption band of the triad, BTZ‐BODIPY‐ZnP, and dyads, BTZ‐BODIPY and BODIPY‐ZnP, along with the reference compounds BTZ‐OMe, BODIPY‐OMe, and ZnP‐OMe exhibited characteristic bands corresponding to individual chromophores. Electrochemical measurements on BTZ‐BODIPY‐ZnP exhibited redox behavior similar to that of the reference compounds. Upon selective excitation of BTZ (≈290 nm) in the BTZ‐BODIPY‐ZnP triad, the fluorescence of the BTZ moiety is quenched, due to photoinduced energy transfer (PEnT) from1BTZ*to the BODIPY moiety, followed by quenching of the BODIPY emission due to sequential PEnT from the1BODIPY* moiety to ZnP, resulting in the appearance of the ZnP emission, indicating the occurrence of a two‐step singlet–singlet energy transfer. Further, a supramolecular tetrad, BTZ‐BODIPY‐ZnP:ImC60, was formed by axially coordinating the triad with imidazole‐appended fulleropyrrolidine (ImC60), and parallel steady‐state measurements displayed the diminished emission of ZnP, which clearly indicated the occurrence of photoinduced electron transfer (PET) from1ZnP* to ImC60. Finally, femtosecond transient absorption spectral studies provided evidence for the sequential occurrence of PEnT and PET events, namely,1BTZ*‐BODIPY‐ZnP:ImC60→BTZ‐1BODIPY*‐ZnP:ImC60→BTZ‐BODIPY‐1ZnP*:ImC60→BTZ‐BODIPY‐ZnP.+:ImC60.−in the supramolecular tetrad. The evaluated rate of energy transfer,
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