Photoinduced relaxation processes in self-assembling complexes from CdSe/ZnS water-soluble nanocrystals and cationic porphyrins

Sagun, E. I.; Knyukshto, V. N.; Ivashin, N. V.; Shchupak, E. E.; Жавнерко, Г. К.; Karatai, N. V.; Agabekov, V. E.

doi:10.1134/s0030400x12060185

Cited by 8 publications

(10 citation statements)

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“…We suggest that the mechanism through which the enhanced oxygen singlet is produced lies upon an energy transfer between the E-SWCNT and the porphyrin molecule (Figure ). The energy could be transferred either by the photoinduced charge transfer (PCT) − or through Förster effect, − ,− or even through a photonic emission-absorption mechanism. Whenever the incident photon energy is higher than the electronic gap of the semiconducting E-SWCNT, an exciton would be created and the energy of its recombination, minus the energy of phonon scattering, would be transferred to the porphyrin via all the aforementioned mechanisms.…”

Section: Discussionmentioning

confidence: 99%

Enhanced Oxygen Singlet Production by Hybrid System of Porphyrin and Enriched (6,5) Single-Walled Carbon Nanotubes for Photodynamic Therapy

et al. 2015

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We demonstrate that hybrid systems of porphyrins and chirality enriched (6,5) single-walled carbon nanotubes (E-SWCNTs) are better candidates for photodynamic therapy (PDT) than their components alone. Surprisingly, the E-SWCNTs act as optical absorption enhancers to the porphyrins increasing the oxygen singlet production when illuminated by a light source with energy higher than the E-SWCNT gap plus the equivalent in energy of an E-SWCNT phonon. The phenomenon is explained based on energy transfer from the E-SWCNT to the porphyrin which finally transfers it to the oxygen molecule. The large optical absorption cross section of E-SWCNT and the resonance of the porphyrin to the oxygen singlet–triplet transition are responsible for the synergistic effect.

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Section: Discussionmentioning

confidence: 99%

Enhanced Oxygen Singlet Production by Hybrid System of Porphyrin and Enriched (6,5) Single-Walled Carbon Nanotubes for Photodynamic Therapy

et al. 2015

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“…According to the recommendations of [37], the molecular energy in the ground and redox states was calculated by the DFT/B3LYP method using the extended basis set 6 311++g(2d, 2p). This approach allowed us to find the E ox potentials of porphyrins and E red of O 2 in good agreement with experimental data, as well as in our previous works [38,39]. The geometry of molecules and the vectors of nor mal vibrations were visualized with Molekel 4.3 [40] and GaussView [41] programs.…”

Section: Methodsmentioning

confidence: 67%

The effect of the structure and conformational dynamics on quenching of triplet states of porphyrins and their chemical dimers by molecular oxygen and on singlet oxygen generation

2015

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Quantum chemical calculations are performed to analyze the factors affecting rate constant k T of quenching of the lowest triplet state by molecular oxygen and quantum yield γ Δ of singlet oxygen generation in chemical dimers of porphyrins bound by phenyl spacers at one of the meso positions (OEP) 2 Ph, (TPP) 2 , and their Zn complexes. It is established that, for both types of dimers, the triplet excitation is localized on one of the mac rocycles. The steric hindrance of macrocycles at the site of the phenyl ring of (OEP) 2 Ph, (ZnOEP) 2 Ph, and their monomeric analogues OEP Ph and ZnOEP Ph facilitates its rotation by 90° in the triplet state. The lowest triplet state energy in this (U) conformation is lower than 7800 cm -1 , which makes impossible elec tronic excitation energy transfer to molecular oxygen. The potential barrier of transformation to the U con formation is considerably lower for dimers than for monomers. Because of this, the rate of conformational transformations for dimers is higher and some of the (OEP) 2 Ph and (ZnOEP) 2 Ph molecules have time to transform into the new U conformation before diffusion collision with O 2 molecules in solution. This leads to a noticeable decrease in γ Δ in accordance with experimental data. It is shown that the behavior of k T in the series of the studied dimers, their monomeric analogues, and relative compounds corresponds to the model of dipole-dipole electronic excitation energy transfer 1 ( 3 M⋅⋅⋅ ) → 1 ( 1 M 0 ⋅⋅⋅ 1 Δ g ) in collisional complexes.

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“…We have also analyzed PL excitation (PLE) spectra of the samples presented in Figure , in order to estimate the efficiency of FRET, which confirms QD/Ce6 nanostructure formation in solution. ,,,, …”

Section: Resultsmentioning

confidence: 99%

“…We have also analyzed PL excitation (PLE) spectra of the samples presented in Figure 6, in order to estimate the efficiency of FRET, which confirms QD/Ce6 nanostructure formation in solution. 11,12,16,28,30 The FRET model 55 for QDs-based hybrid nanostructures was used to estimate energy transfer efficiency in the samples. The analysis of PL properties of the QDs/Ce6 hybrid nanostructures, i.e.…”

Section: ■ Resultsmentioning

confidence: 99%

“…Recent progress in the area of hybrid nanomaterials indicates their excellent prospects. − However, during the development of hybrid nanomaterials, a number of difficulties and challenges arise. For instance, it has been reported that the formation of hybrid nanostructures based on colloidal semiconductor quantum dots (QDs) and PSs may be accompanied by the appearance of nonradiative channels that deactivate the excited states of the QDs and/or PSs. − In turn, this can lead to a decrease in the photoluminescent properties of PSs and their ability to generate singlet oxygen. Other common difficulties are associated with the aggregation of components of PS-based hybrid nanostructures.…”

Section: Introductionmentioning

confidence: 99%

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Circular Dichroism Spectroscopy as a Powerful Tool for Unraveling Assembly of Chiral Nonluminescent Aggregates of Photosensitizer Molecules on Nanoparticle Surfaces

et al. 2019

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Recent developments in nanoscience and nanotechnology significantly help improve the properties of traditional materials. A striking example of this is the formation of hybrid nanostructures based on nanoparticles and photosensitizer molecules, the potential range of applications of which extends from photovoltaics to biomedicine. However, the creation of new and effective hybrid nanomaterials of this form inevitably entails new challenges, one of which is a common and critical problem of aggregation of both nanoparticles and photosensitizer molecules. Therefore, a fundamental challenge is to determine the presence of these aggregates, which will produce a significant step toward creating a new generation of materials and devices of broad-spectrum applicability. Here we report on the key role of circular dichroism spectroscopy as a tool to detect the formation of nonluminescent aggregates of chlorin e6, a second-generation photosensitizer, in a hybrid nanostructure with ZnS:Mn quantum dots. These aggregates are active acceptors of photoexcitation energy from quantum dots and limit the photophysical properties of the whole nanostructure. It has been established that circular dichroism spectroscopy reveals the presence of nonluminescent molecule aggregates at chlorin e6 concentrations of ∼10 −6 mol/L, which compares very favorably to absorption spectroscopy which does not show any direct indications of aggregation up to ∼10 −5 mol/L. This result demonstrates the promise and importance of using circular dichroism spectroscopy in the study of organic/inorganic hybrid nanostructures.

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Photoinduced relaxation processes in self-assembling complexes from CdSe/ZnS water-soluble nanocrystals and cationic porphyrins

Cited by 8 publications

References 57 publications

Enhanced Oxygen Singlet Production by Hybrid System of Porphyrin and Enriched (6,5) Single-Walled Carbon Nanotubes for Photodynamic Therapy

Enhanced Oxygen Singlet Production by Hybrid System of Porphyrin and Enriched (6,5) Single-Walled Carbon Nanotubes for Photodynamic Therapy

The effect of the structure and conformational dynamics on quenching of triplet states of porphyrins and their chemical dimers by molecular oxygen and on singlet oxygen generation

Circular Dichroism Spectroscopy as a Powerful Tool for Unraveling Assembly of Chiral Nonluminescent Aggregates of Photosensitizer Molecules on Nanoparticle Surfaces

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