Femtosecond time-resolved energy transfer from CdSe nanoparticles to phthalocyanines

Dayal, Smita; Krolicki, Robert; Lou, Yongbing; Qiu, Xiaoqing; Berlin, Jeffrey C.; Kenney, Malcolm E.; Burda, Clemens

doi:10.1007/s00340-006-2293-z

Cited by 57 publications

(37 citation statements)

References 25 publications

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“…1) and the process is also exergonic in nature. However, energy transfer from QDs to adjacent dye molecules would be expected to result in fluorescence enhancement of the dye (FRET) 58,59 as has been 50 observed for related systems namely; from CdTe QDs in the presence of metal phthalocyanines. 60,61 No fluorescence from ZnTMPyP4 is observed in our experiments and thus this mechanism is discounted as the likely origin of the phenomena observed.…”

Section: Picosecond Transient Absorptionmentioning

confidence: 94%

Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin

et al. 2012

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The photophysical properties of 2.3 nm thioglycolic acid (TGA) coated CdTe quantum dots (QDs) prepared by a reflux method have been studied in the presence of a cationic meso-tetrakis(4-N-methylpyridyl) zinc porphyrin (ZnTMPyP4). Addition of the CdTe QDs to porphyrin in H 2 O results in a marked red-shift and hypochromism in the porphyrin absorption spectrum, indicative of a non-covalent binding interaction with the QD surface. Low equivalents of the quantum dot were required for complete quenching of the porphyrin fluorescence revealing that one quantum dot 10 may quench more than one porphyrin. Similarly addition of porphyrin to the quantum dot provided evidence for very efficient quenching of the CdTe photoluminescence, suggesting the formation of CdTe-porphyrin aggregates. Definitive evidence for such aggregates was gathered using small angle X-ray spectroscopy (SAXS). Ultrafast transient absorption data are consistent with very rapid photoinduced electron transfer (1.3 ps) and the resultant formation of a long-lived porphyrin species.

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Section: Picosecond Transient Absorptionmentioning

confidence: 94%

Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin

et al. 2012

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“…Although the increased contribution to the very short-lived TA decay appears to be outside the expectation of a FRET mechanism, a recent study has demonstrated bleach dynamics effects on a similar time scale (~30-50 ps) for the interaction of pthalocyanines (Pcs) with CdSe QDs. 40,43 One might postulate that the effects seen in the short time regime of the TA experiment is associated with the surface trapped carriers that give rise to the weak broad luminescence band at ~750 nm, which is quenched by low concentrations (100 μM) of 1. Similar effects are seen for added 2 and 3, despite failure by the latter to quench the band edge emission band.…”

Section: Transient Absorbance Experimentsmentioning

confidence: 99%

Quantum Dot Fluorescence Quenching Pathways with Cr(III) Complexes. Photosensitized NO Production from trans-Cr(cyclam)(ONO)₂⁺

et al. 2007

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Described is the photoluminescence (PL) of water soluble CdSe/ZnS core/shell quantum dots (QDs) as perturbed by salts of the chromium(III) complexes trans-Cr(cyclam)Cl 2 + (1), trans-Cr(cyclam) (ONO) 2 + (2), and trans-Cr(cyclam)(CN) 2 + (3) (cyclam = 1,4,8,11-tetraazacyclo-tetradecane). The purpose is to probe the characteristics of such QDs as antennae for photosensitized release of bioactive agents (in the present case, the bioregulatory molecule NO) from transition metal centers. Addition of 1 or 2 to a QD solution results in concentration dependent quenching of the band edge emission, but 3 has a minimal effect. Added KCl strongly attenuates the quenching by 1, and this suggests that the Cr(III) cations and the QDs form electrostatic assemblies via ion pairing on the negatively charged QD surfaces. Quenching by 2, a known photochemical NO precursor, was accompanied by photosensitized NO release. All three, however, do quench the broad red emission (~650-850 nm) attributed to radiative decay of surface trapped carriers. The effect of various concentrations of 1 on time-resolved PL and absorbance were explored using ultra-fast spectroscopic methods. These observations are interpreted in terms of the Förster resonance energy transfer mechanism for quenching of the band edge PL by multiple units of 1 or 2 at the QD surface, while quenching of the low energy trap emission occurs via a charge transfer pathway.

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“…The 1 O 2 agent can be effectively generated using self-assembled aggregates of tetrapyrrole dyes and small (3-10 nm) QDs covered by ligands [25]. The commonly used tetrapyrrole dyes include phtalocyanin [26] and porphyrin [27][28][29][30]. QDs are used for the following reasons: (i) they store excitation energy and distribute it to many dye molecules, which reside on the QD surface and produce singlet oxygen; (ii) QDs are efficient photon harvesters, since their absorption spectrum is broader than the spectra of typical organic dyes used in PDT; and (iii) the photon absorption of QDs can be tuned to the spectral transparency window of human skin.…”

Section: E-mail Address: Prezhdo@uwashingtonedu (Ov Prezhdo)mentioning

confidence: 99%

Ab initio study of exciton transfer dynamics from a core–shell semiconductor quantum dot to a porphyrin-sensitizer

Kilin

Tsemekhman

Prezhdo

et al. 2007

Journal of Photochemistry and Photobiology A: Chemistry

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The observed resonance energy transfer in nanoassemblies of CdSe/ZnS quantum dots and pyridyl-substituted free-base porphyrin molecules [Zenkevich et al., J. Phys. Chem. B 109 (2005) 8679] is studied computationally by ab initio electronic structure and quantum dynamics approaches. The system harvests light in a broad energy range and can transfer the excitation from the dot through the porphyrin to oxygen, generating singlet oxygen for medical applications. The geometric structure, electronic energies, and transition dipole moments are derived by density functional theory and are utilized for calculating the Förster coupling between the excitons residing on the quantum dot and the porphyrin. The direction and rate of the irreversible exciton transfer is determined by the initial photoexcitation of the dot, the dot-porphyrin coupling and the interaction to the electronic subsystem with the vibrational environment. The simulated electronic structure and dynamics are in good agreement with the experimental data and provide real-time atomistic details of the energy transfer mechanism.

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Femtosecond time-resolved energy transfer from CdSe nanoparticles to phthalocyanines

Cited by 57 publications

References 25 publications

Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin

Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin

Quantum Dot Fluorescence Quenching Pathways with Cr(III) Complexes. Photosensitized NO Production from trans-Cr(cyclam)(ONO)₂⁺

Ab initio study of exciton transfer dynamics from a core–shell semiconductor quantum dot to a porphyrin-sensitizer

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Femtosecond time-resolved energy transfer from CdSe nanoparticles to phthalocyanines

Cited by 57 publications

References 25 publications

Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin

Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin

Quantum Dot Fluorescence Quenching Pathways with Cr(III) Complexes. Photosensitized NO Production from trans-Cr(cyclam)(ONO)2+

Ab initio study of exciton transfer dynamics from a core–shell semiconductor quantum dot to a porphyrin-sensitizer

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Quantum Dot Fluorescence Quenching Pathways with Cr(III) Complexes. Photosensitized NO Production from trans-Cr(cyclam)(ONO)₂⁺