Singlet—singlet intramolecular energy and electron transfer in covalently-linked porphyrin—phthalocyanine heterodimers

Tian, Hongjian; Qing, Zhou; Shu‐Yin, Shen; Xu, Huijun

doi:10.1016/1010-6030(93)85023-2

Cited by 32 publications

(1 citation statement)

References 6 publications

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“…A substantial number of covalently linked and axially bound P−Pc systems have been reported. ,− However, only a few of them exhibit energy- and charge-transfer characteristics. ,,,,,, Lindsey et al reported a series of mixed P−Pc arrays which are efficient light harvesters, but electron transfer was not detected in these systems. ,, Tran-Thi et al. carried out a detailed study of the competing intramolecular electron and energy transfer processes in a covalently linked P−Pc heterodimer, in which the fluorescence of Pc was quenched and a fast decaying component of Pc emission appeared.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Solvent Polarity and Metalation on Energy and Electron Transfer in Porphyrin−Phthalocyanine Heterotrimers

et al. 2007

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Heteroporphyrin and -phthalocyanine arrays represent an attractive class of light harvesters and charge-separation systems exhibiting an easy route of synthesis and high chemical stability. In the present work, we report the results of photophysical investigations of two novel non-sandwich-type porphyrin-phthalocyanine heterotriads, in which two meso-tetraphenylporphyrin rings (H2TPP or ZnTPP) are linked to the central silicon atom of a silicon(IV) phthalocyanine core. It was found that the photophysical properties of the triads (H2Tr and ZnTr) in N,N-dimethylformamide (DMF) and toluene are strongly affected by two different types of interaction between the porphyrin (P) and the phthalocyanine (Pc) parts, namely excitation energy transfer (EET) and photoinduced charge transfer. The first process results in appearance of the Pc fluorescence when the P-part is initially excited, and plays a dominant role in fast depopulation of the first excited singlet state of the P moiety. If the first excited singlet state of the Pc-part is populated (either directly or via EET), it undergoes fast depopulation by hole transfer (HT) to the charge-separated (CS) state. In polar DMF, the CS state is the lowest excited state, and the charge recombination occurs directly to the ground state. Using transient absorption spectroscopy, the lifetime of the CS state was estimated to be 30 and 20 ps for H2Tr and ZnTr, respectively. In nonpolar toluene, the energy gap between the first excited singlet state of the Pc-part and the CS state is very small, and back HT occurs in both triads, resulting in appearance of "delayed fluorescence" of the Pc-part with a decay time similar to the lifetime of the CS state (190 and 280 ps for H2Tr and ZnTr, respectively). Since the energy of the CS state of ZnTr in toluene is lower than that of H2Tr, the probability of back HT for ZnTr is lower. This was clearly proved by decay-associated fluorescence spectral measurements.

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Section: Introductionmentioning

confidence: 99%

The Influence of Solvent Polarity and Metalation on Energy and Electron Transfer in Porphyrin−Phthalocyanine Heterotrimers

et al. 2007

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Axial‐Bonding Heterotrimers Based on Tetrapyrrolic Rings: Synthesis, Characterization, and Redox and Photophysical Properties

Giribabu¹,

Kumar²,

Reddy³

2007

Chemistry An Asian Journal

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We prepared two heterooligomeric arrays based on free base/metalloporphyrins at axial positions and a metalloid phthalocyanine as a basal scaffolding unit by using the axial-bonding capabilities as well as the known oxophilicity of dihydroxytin(IV) phthalocyanine. Both heterotrimers were completely characterized by elemental analysis, MALDI-TOF MS, and 1H NMR (one- and two-dimensional), UV/Vis, and fluorescence spectroscopy as well as cyclic voltammetry. The ground-state properties indicate that there is minimal pi-pi interaction between the macrocyclic units. The excited-state properties show that there is electronic energy transfer competing with photoinduced electron transfer from the singlet state of the axial porphyrin to the central metalloid phthalocyanine and a photoinduced electron transfer from the ground state of the axial porphyrin to the singlet state of the central metalloid phthalocyanine.

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Porphyrin‐Appended Europium(III) Bis(phthalocyaninato) Complexes: Synthesis, Characterization, and Photophysical Properties

Bian

Chen

Wang

et al. 2007

Chemistry A European J

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Mixed cyclization of 3-mono-, 4-mono-, or 4,5-di(porphyrinated) phthalonitrile compounds 2, 3, or 6 and unsubstituted phthalonitrile with the half-sandwich complex [EuIII(acac)(Pc)] (Pc=phthalocyaninate, acac=acetylacetonate) as the template in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in n-pentanol afforded novel porphyrin-appended europium(III) bis(phthalocyaninato) complexes 7-9 in 30-40% yield. These mixed tetrapyrrole triads and tetrad were spectroscopically and electrochemically characterized and their photophysical properties were also investigated with steady-state and transient spectroscopic methods. It has been found that the fluorescence of the porphyrin moiety is quenched effectively by the double-decker unit through an intramolecular photoinduced electron-transfer process, which takes place in several hundred femtoseconds, while the recombination of the charge-separated state occurs in several picoseconds. By using different phthalocyanines containing different numbers of porphyrin substituents at the peripheral or nonperipheral position(s) of the ligand, while the other unsubstituted phthalocyanine remains unchanged in these double-deckers, the effects of the number and the position of the porphyrin substituents on these photophysical processes were also examined.

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Singlet—singlet intramolecular energy and electron transfer in covalently-linked porphyrin—phthalocyanine heterodimers

Cited by 32 publications

References 6 publications

The Influence of Solvent Polarity and Metalation on Energy and Electron Transfer in Porphyrin−Phthalocyanine Heterotrimers

The Influence of Solvent Polarity and Metalation on Energy and Electron Transfer in Porphyrin−Phthalocyanine Heterotrimers

Axial‐Bonding Heterotrimers Based on Tetrapyrrolic Rings: Synthesis, Characterization, and Redox and Photophysical Properties

Porphyrin‐Appended Europium(III) Bis(phthalocyaninato) Complexes: Synthesis, Characterization, and Photophysical Properties

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