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Shunichi Fukuzumi - One of the best experts on this subject based on the ideXlab platform.
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macrocyclic Dyads based on c60 and perylenediimides connected by click chemistry
Asian Journal of Organic Chemistry, 2014Co-Authors: Sara Pla, Shunichi Fukuzumi, Kei Ohkubo, Luis Martingomis, Fernando Fernandezlazaro, Angela SastresantosAbstract:Two sets of perylenediimide-[60]fullerene Dyads PDI-C60 connected through 1,2,3-triazole units have been synthesized and characterized. The cyclic Dyad PDICl4-C60 has four chlorine atoms in the 1,6,7,12-PDI positions, whereas the cyclic Dyad PDIPip2-C60 has two piperidine units in the 1,7-PDI positions. On the other hand, PDICl4-C60 and PDIPip2-C60 Dyads were synthesized as linear counterparts with the same substitution pattern. Also, a C60-PDICl4-C60 triad has been prepared. A small interaction between C60 and PDI moieties in the ground state was detected by UV/vis and electrochemical measurements in both PDI-C60 cyclic systems. The occurrence of photoinduced energy-transfer processes between PDI and C60 units was confirmed by time-resolved emission and transient absorption techniques. Femtosecond laser flash photolysis showed energy transfer from 1PDI* to C60 followed by intersystem crossing from 1C60* to 3C60* in the case of the PDICl4-C60 systems. The energy transfer rate for PDICl4-C60 in the cyclic Dyad and the triad is one order of magnitude faster than that in PDICl4-C60 in the linear Dyad. The fast energy transfer rate together with the enhanced molar absorption coefficient by perylenediimide functionalization will be highly beneficial for applications as acceptors in polymer solar cells. On the other hand, no electron transfer from the donor PDIpip2 units to the acceptor C60 moiety was detected in the case of PDIPip2-C60 Dyads.
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exciplex mediated photoinduced electron transfer reactions of phthalocyanine fullerene Dyads
Journal of Physical Chemistry A, 2008Co-Authors: Marja Niemi, Shunichi Fukuzumi, Kei Ohkubo, Nikolai V Tkachenko, Alexander Efimov, Heli Lehtivuori, Helge LemmetyinenAbstract:Evidences of an intramolecular exciplex intermediate in a photoinduced electron transfer (ET) reaction of double-linked free-base and zinc phthalocyanine-C60 Dyads were found. This was the first time for a Dyad with phthalocyanine donor. Excitation of the phthalocyanine moiety of the Dyads results in rapid ET from phthalocyanine to fullerene via an exciplex state in both polar and nonpolar solvents. Relaxation of the charge-separated (CS) state Pc•+-C60•− in a polar solvent occurs directly to the ground state in 30−70 ps. In a nonpolar solvent, roughly 20% of the molecules undergo transition from the CS state to phthalocyanine triplet state 3Pc*-C60 before relaxation to the ground state. Formation of the CS state was confirmed with electron spin resonance measurements at low temperature in both polar and nonpolar solvent. Reaction schemes for the photoinduced ET reactions of the Dyads were completed with rate constants obtained from the time-resolved absorption and emission measurements and with state ene...
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intramolecular electron transfer within the substituted tetrathiafulvalene quinone Dyads facilitated by metal ion and photomodulation in the presence of spiropyran
Journal of the American Chemical Society, 2007Co-Authors: Deqing Zhang, Shunichi Fukuzumi, Kei Ohkubo, Chunxi Zhang, Shiwei Yin, Lanqun Mao, Zhigang Shuai, Daoben ZhuAbstract:Intramolecular electron transfer is observed for two new substituted tetrathiafulvalene (TTF)-quinone Dyads 1 and 2 in the presence of metal ions. On the basis of the electrochemical studies of reference compound 5 and the comparative studies with Dyad 3, it was proposed that the synergic coordination of the radical anion of quinone and the oligoethylene glycol chain with metal ions may be responsible for stabilizing the charge-separation state and thus facilitating the electron-transfer process. Most interestingly, the intramolecular electron-transfer processes within these two Dyads can be modulated by UV-vis light irradiation in the presence of spiropyran, by taking advantage of its unique properties.
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small reorganization energy of intramolecular electron transfer in fullerene based Dyads with short linkage
Journal of Physical Chemistry A, 2002Co-Authors: Kei Ohkubo, Hiroshi Imahori, Jianguo Shao, Karl M Kadish, Yihui Chen, Gang Zheng, Ravindra Pandey, Mamoru Fujitsuka, Osamu Ito, Shunichi FukuzumiAbstract:A bacteriochlorin-C60 Dyad (H2BCh-C60) and a zinc chlorin Dyad (ZnCh-C60) with the same short spacer have been synthesized. The rate constants for the charge-separation (CS) processes in these Dyads were determined by fluorescence lifetime measurements of the Dyads. The charge-recombination (CR) rate constants of the Dyads were determined using laser flash photolysis. The photoexcitation of the zinc chlorin-C60 Dyad results in formation of the long-lived radical ion pair, which has absorption maxima at 790 and 1000 nm due to the zinc chlorin radical cation and the C60 radical anion, respectively. Photoexcitation of the free-base bacteriochlorin-C60 Dyad with the same short linkage leads to formation of the radical ion pair, which decays quickly to the triplet excited state of the bacteriochlorin moiety. The driving force dependence of the electron-transfer rate constants of these Dyads with a short spacer affords a small reorganization energy (λ = 0.51 eV) as compared with the λ value (0.66 eV) of zinc po...
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photochemical and electrochemical properties of zinc chlorin c60 Dyad as compared to corresponding free base chlorin c60 free base porphyrin c60 and zinc porphyrin c60 Dyads
Journal of the American Chemical Society, 2001Co-Authors: Shunichi Fukuzumi, Hiroshi Imahori, Kei Ohkubo, Jianguo Shao, Yihui Chen, Gang Zheng, Ravindra Pandey, Mamoru Fujitsuka, Osamu Ito, Karl M KadishAbstract:The photochemical and electrochemical properties of four chlorin−C60 or porphyrin−C60 Dyads having the same short spacer between the macrocycle and the fullerene are examined. In contrast with all the previous results on porphyrin−fullerene Dyads, the photoexcitation of a zinc chlorin−C60 Dyad results in an unusually long-lived radical ion pair which decays via first-order kinetics with a decay rate constant of 9.1 × 103 s-1. This value is 2−6 orders of magnitude smaller than values reported for all other porphyrin or chlorin donor−acceptor of the molecule Dyad systems. The formation of radical cations of the donor part and the radical anion of the acceptor part was also confirmed by ESR measurements under photoirradiation at low temperature. The photoexcitation of other Dyads (free-base chlorin−C60, zinc porphyrin−C60, and free-base porphyrin−C60 Dyads) results in formation of the ion pairs which decay quickly to the triplet excited states of the chlorin or porphyrin moiety via the higher lying radical i...
Bo W Laursen - One of the best experts on this subject based on the ideXlab platform.
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rational design of bright long fluorescence lifetime Dyad fluorophores for single molecule imaging and detection
Journal of the American Chemical Society, 2021Co-Authors: Laura Kacenauskaite, Niels Bisballe, Rebecca Mucci, Marco Santella, Tonu Pullerits, Junsheng Chen, Tom Vosch, Bo W LaursenAbstract:Increasing demand for detecting single molecules in challenging environments has raised the bar for the fluorophores used. To achieve better resolution and/or contrast in fluorescence microscopy, it is now essential to use bright and stable dyes with tailored photophysical properties. While long fluorescence lifetime fluorophores offer many advantages in time-resolved imaging, their inherently lower molar absorption coefficient has limited applications in single molecule imaging. Here we propose a generic approach to prepare bright, long fluorescence lifetime Dyad fluorophores comprising an absorbing antenna chromophore with high absorption coefficient linked to an acceptor emitter with a long fluorescence lifetime. We introduce a Dyad consisting of a perylene antenna and a triangulenium emitter with 100% energy transfer from donor to acceptor. The Dyad retained the long fluorescence lifetime (∼17 ns) and high quantum yield (75%) of the triangulenium emitter, while the perylene antenna increased the molar absorption coefficient (up to 5 times) in comparison to the free triangulenium dye. These triangulenium based Dyads with significantly improved brightness can now be detected at the single molecule level and easily discriminated from bright autofluorescence by time-gated and other lifetime-based detection schemes.
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rational design of bright long fluorescence lifetime Dyad fluorophores for single molecule imaging and detection
Journal of the American Chemical Society, 2021Co-Authors: Laura Kacenauskaite, Niels Bisballe, Rebecca Mucci, Marco Santella, Tonu Pullerits, Junsheng Chen, Tom Vosch, Bo W LaursenAbstract:Increasing demand for detecting single molecules in challenging environments has raised the bar for the fluorophores used. To achieve better resolution and/or contrast in fluorescence microscopy, it is now essential to use bright and stable dyes with tailored photophysical properties. While long fluorescence lifetime fluorophores offer many advantages in time-resolved imaging, their inherently lower molar absorption coefficient has limited applications in single molecule imaging. Here we propose a generic approach to prepare bright, long fluorescence lifetime Dyad fluorophores comprising an absorbing antenna chromophore with high absorption coefficient linked to an acceptor emitter with a long fluorescence lifetime. We introduce a Dyad consisting of a perylene antenna and a triangulenium emitter with 100% energy transfer from donor to acceptor. The Dyad retained the long fluorescence lifetime (17 ns) and high quantum yield (75%) of the triangulenium emitter, while the perylene antenna increased the molar absorption coefficient (up to 5 times) in comparison to the free triangulenium dye. These triangulenium based Dyads with significantly improved brightness can now be detected at the single molecule level and easily discriminated from bright autofluorescence by time-gated and other lifetime-based detection schemes. (Less)
Junsheng Chen - One of the best experts on this subject based on the ideXlab platform.
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rational design of bright long fluorescence lifetime Dyad fluorophores for single molecule imaging and detection
Journal of the American Chemical Society, 2021Co-Authors: Laura Kacenauskaite, Niels Bisballe, Rebecca Mucci, Marco Santella, Tonu Pullerits, Junsheng Chen, Tom Vosch, Bo W LaursenAbstract:Increasing demand for detecting single molecules in challenging environments has raised the bar for the fluorophores used. To achieve better resolution and/or contrast in fluorescence microscopy, it is now essential to use bright and stable dyes with tailored photophysical properties. While long fluorescence lifetime fluorophores offer many advantages in time-resolved imaging, their inherently lower molar absorption coefficient has limited applications in single molecule imaging. Here we propose a generic approach to prepare bright, long fluorescence lifetime Dyad fluorophores comprising an absorbing antenna chromophore with high absorption coefficient linked to an acceptor emitter with a long fluorescence lifetime. We introduce a Dyad consisting of a perylene antenna and a triangulenium emitter with 100% energy transfer from donor to acceptor. The Dyad retained the long fluorescence lifetime (∼17 ns) and high quantum yield (75%) of the triangulenium emitter, while the perylene antenna increased the molar absorption coefficient (up to 5 times) in comparison to the free triangulenium dye. These triangulenium based Dyads with significantly improved brightness can now be detected at the single molecule level and easily discriminated from bright autofluorescence by time-gated and other lifetime-based detection schemes.
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rational design of bright long fluorescence lifetime Dyad fluorophores for single molecule imaging and detection
Journal of the American Chemical Society, 2021Co-Authors: Laura Kacenauskaite, Niels Bisballe, Rebecca Mucci, Marco Santella, Tonu Pullerits, Junsheng Chen, Tom Vosch, Bo W LaursenAbstract:Increasing demand for detecting single molecules in challenging environments has raised the bar for the fluorophores used. To achieve better resolution and/or contrast in fluorescence microscopy, it is now essential to use bright and stable dyes with tailored photophysical properties. While long fluorescence lifetime fluorophores offer many advantages in time-resolved imaging, their inherently lower molar absorption coefficient has limited applications in single molecule imaging. Here we propose a generic approach to prepare bright, long fluorescence lifetime Dyad fluorophores comprising an absorbing antenna chromophore with high absorption coefficient linked to an acceptor emitter with a long fluorescence lifetime. We introduce a Dyad consisting of a perylene antenna and a triangulenium emitter with 100% energy transfer from donor to acceptor. The Dyad retained the long fluorescence lifetime (17 ns) and high quantum yield (75%) of the triangulenium emitter, while the perylene antenna increased the molar absorption coefficient (up to 5 times) in comparison to the free triangulenium dye. These triangulenium based Dyads with significantly improved brightness can now be detected at the single molecule level and easily discriminated from bright autofluorescence by time-gated and other lifetime-based detection schemes. (Less)
Kei Ohkubo - One of the best experts on this subject based on the ideXlab platform.
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macrocyclic Dyads based on c60 and perylenediimides connected by click chemistry
Asian Journal of Organic Chemistry, 2014Co-Authors: Sara Pla, Shunichi Fukuzumi, Kei Ohkubo, Luis Martingomis, Fernando Fernandezlazaro, Angela SastresantosAbstract:Two sets of perylenediimide-[60]fullerene Dyads PDI-C60 connected through 1,2,3-triazole units have been synthesized and characterized. The cyclic Dyad PDICl4-C60 has four chlorine atoms in the 1,6,7,12-PDI positions, whereas the cyclic Dyad PDIPip2-C60 has two piperidine units in the 1,7-PDI positions. On the other hand, PDICl4-C60 and PDIPip2-C60 Dyads were synthesized as linear counterparts with the same substitution pattern. Also, a C60-PDICl4-C60 triad has been prepared. A small interaction between C60 and PDI moieties in the ground state was detected by UV/vis and electrochemical measurements in both PDI-C60 cyclic systems. The occurrence of photoinduced energy-transfer processes between PDI and C60 units was confirmed by time-resolved emission and transient absorption techniques. Femtosecond laser flash photolysis showed energy transfer from 1PDI* to C60 followed by intersystem crossing from 1C60* to 3C60* in the case of the PDICl4-C60 systems. The energy transfer rate for PDICl4-C60 in the cyclic Dyad and the triad is one order of magnitude faster than that in PDICl4-C60 in the linear Dyad. The fast energy transfer rate together with the enhanced molar absorption coefficient by perylenediimide functionalization will be highly beneficial for applications as acceptors in polymer solar cells. On the other hand, no electron transfer from the donor PDIpip2 units to the acceptor C60 moiety was detected in the case of PDIPip2-C60 Dyads.
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exciplex mediated photoinduced electron transfer reactions of phthalocyanine fullerene Dyads
Journal of Physical Chemistry A, 2008Co-Authors: Marja Niemi, Shunichi Fukuzumi, Kei Ohkubo, Nikolai V Tkachenko, Alexander Efimov, Heli Lehtivuori, Helge LemmetyinenAbstract:Evidences of an intramolecular exciplex intermediate in a photoinduced electron transfer (ET) reaction of double-linked free-base and zinc phthalocyanine-C60 Dyads were found. This was the first time for a Dyad with phthalocyanine donor. Excitation of the phthalocyanine moiety of the Dyads results in rapid ET from phthalocyanine to fullerene via an exciplex state in both polar and nonpolar solvents. Relaxation of the charge-separated (CS) state Pc•+-C60•− in a polar solvent occurs directly to the ground state in 30−70 ps. In a nonpolar solvent, roughly 20% of the molecules undergo transition from the CS state to phthalocyanine triplet state 3Pc*-C60 before relaxation to the ground state. Formation of the CS state was confirmed with electron spin resonance measurements at low temperature in both polar and nonpolar solvent. Reaction schemes for the photoinduced ET reactions of the Dyads were completed with rate constants obtained from the time-resolved absorption and emission measurements and with state ene...
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intramolecular electron transfer within the substituted tetrathiafulvalene quinone Dyads facilitated by metal ion and photomodulation in the presence of spiropyran
Journal of the American Chemical Society, 2007Co-Authors: Deqing Zhang, Shunichi Fukuzumi, Kei Ohkubo, Chunxi Zhang, Shiwei Yin, Lanqun Mao, Zhigang Shuai, Daoben ZhuAbstract:Intramolecular electron transfer is observed for two new substituted tetrathiafulvalene (TTF)-quinone Dyads 1 and 2 in the presence of metal ions. On the basis of the electrochemical studies of reference compound 5 and the comparative studies with Dyad 3, it was proposed that the synergic coordination of the radical anion of quinone and the oligoethylene glycol chain with metal ions may be responsible for stabilizing the charge-separation state and thus facilitating the electron-transfer process. Most interestingly, the intramolecular electron-transfer processes within these two Dyads can be modulated by UV-vis light irradiation in the presence of spiropyran, by taking advantage of its unique properties.
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small reorganization energy of intramolecular electron transfer in fullerene based Dyads with short linkage
Journal of Physical Chemistry A, 2002Co-Authors: Kei Ohkubo, Hiroshi Imahori, Jianguo Shao, Karl M Kadish, Yihui Chen, Gang Zheng, Ravindra Pandey, Mamoru Fujitsuka, Osamu Ito, Shunichi FukuzumiAbstract:A bacteriochlorin-C60 Dyad (H2BCh-C60) and a zinc chlorin Dyad (ZnCh-C60) with the same short spacer have been synthesized. The rate constants for the charge-separation (CS) processes in these Dyads were determined by fluorescence lifetime measurements of the Dyads. The charge-recombination (CR) rate constants of the Dyads were determined using laser flash photolysis. The photoexcitation of the zinc chlorin-C60 Dyad results in formation of the long-lived radical ion pair, which has absorption maxima at 790 and 1000 nm due to the zinc chlorin radical cation and the C60 radical anion, respectively. Photoexcitation of the free-base bacteriochlorin-C60 Dyad with the same short linkage leads to formation of the radical ion pair, which decays quickly to the triplet excited state of the bacteriochlorin moiety. The driving force dependence of the electron-transfer rate constants of these Dyads with a short spacer affords a small reorganization energy (λ = 0.51 eV) as compared with the λ value (0.66 eV) of zinc po...
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photochemical and electrochemical properties of zinc chlorin c60 Dyad as compared to corresponding free base chlorin c60 free base porphyrin c60 and zinc porphyrin c60 Dyads
Journal of the American Chemical Society, 2001Co-Authors: Shunichi Fukuzumi, Hiroshi Imahori, Kei Ohkubo, Jianguo Shao, Yihui Chen, Gang Zheng, Ravindra Pandey, Mamoru Fujitsuka, Osamu Ito, Karl M KadishAbstract:The photochemical and electrochemical properties of four chlorin−C60 or porphyrin−C60 Dyads having the same short spacer between the macrocycle and the fullerene are examined. In contrast with all the previous results on porphyrin−fullerene Dyads, the photoexcitation of a zinc chlorin−C60 Dyad results in an unusually long-lived radical ion pair which decays via first-order kinetics with a decay rate constant of 9.1 × 103 s-1. This value is 2−6 orders of magnitude smaller than values reported for all other porphyrin or chlorin donor−acceptor of the molecule Dyad systems. The formation of radical cations of the donor part and the radical anion of the acceptor part was also confirmed by ESR measurements under photoirradiation at low temperature. The photoexcitation of other Dyads (free-base chlorin−C60, zinc porphyrin−C60, and free-base porphyrin−C60 Dyads) results in formation of the ion pairs which decay quickly to the triplet excited states of the chlorin or porphyrin moiety via the higher lying radical i...
Kerstin Tham - One of the best experts on this subject based on the ideXlab platform.
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combined life satisfaction of persons with stroke and their caregivers associations with caregiver burden and the impact of stroke
Health and Quality of Life Outcomes, 2011Co-Authors: Aileen Bergstrom, Gunilla Eriksson, Lena Von Koch, Kerstin ThamAbstract:Little is known about the life satisfaction of the person with stroke combined with their caregiver, i.e. the Dyad, despite the fact that life satisfaction is an important rehabilitation outcome. The aim of this study was to describe the Dyads combined life satisfaction and to understand this in relationship to the perceived impact of stroke in everyday life and caregiver burden. In this cross-sectional study, the life satisfaction of persons and their informal caregivers was measured in 81 Dyads one year post stroke. Their global life satisfaction, measured with LiSat-11, was combined to a Dyad score and the Dyads were then categorized as satisfied, dissatisfied or discordant. The groups were compared and analyzed regarding levels of caregiver burden, measured with the Caregiver Burden scale, and the perceived impact of stroke in everyday life, measured with the Stroke Impact Scale (SIS). The satisfied Dyads comprised 40%, dissatisfied 26% and those that were discordant 34%. The satisfied Dyads reported a significantly lower impact of the stroke in everyday life compared with the Dyads that were not satisfied. As expected, Dyads that were not satisfied reported a significantly greater caregiver burden compared with the satisfied Dyads. The discordant group was further broken down into a group of dissatisfied and satisfied caregivers. The caregivers that were not satisfied in the discordant group perceived a significantly greater level of caregiver burden compared with the satisfied group. Even caregivers who were satisfied with life but whose care recipients were not satisfied reported caregiver burden. Measuring combined life satisfaction provides a unique focus and appears to be a feasible way of attaining the Dyads' perspective. The findings suggest that those Dyads with a discordant life satisfaction could be vulnerable because of the caregivers' reported caregiver burden. These findings support the importance of a Dyadic perspective and add to the understanding of the reciprocal influences between the caregiver and recipient. This knowledge has clinical implications and contributes to the identification of possible vulnerable Dyads in need of tailored support.
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combined life satisfaction of persons with stroke and their caregivers associations with caregiver burden and the impact of stroke
Health and Quality of Life Outcomes, 2011Co-Authors: Aileen Bergstrom, Gunilla Eriksson, Lena Von Koch, Kerstin ThamAbstract:Background Little is known about the life satisfaction of the person with stroke combined with their caregiver, i.e. the Dyad, despite the fact that life satisfaction is an important rehabilitation outcome. The aim of this study was to describe the Dyads combined life satisfaction and to understand this in relationship to the perceived impact of stroke in everyday life and caregiver burden.
