| 1. |
- Albinsson, Bo, 1963, et al.
(författare)
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Functionalized DNA Nanostructures for Light Harvesting and Charge Separation
- 2012
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Ingår i: Coordination Chemistry Reviews. - : Elsevier BV. - 0010-8545. ; 256:21-22, s. 2399-2413
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Forskningsöversikt (refereegranskat)abstract
- Mimicking natural photosynthesis by covalently arranging antenna and charge separation units is a formidable task. Many such beautiful supramolecular complexes have been designed and synthesized with large efforts, some of which are presented in this special issue. The ability to predict relative position of and electronic coupling between the active components in covalent arrays is quite high but there are two obvious drawbacks with the covalent approach. Firstly, as the size grows the complexity of the organic synthesis increases and secondly, sensitivity to light-induced damage becomes a major issue if covalent bonds are broken. Self-assembly of the photoactive components should, in principle, provide a solution to both these issues but generally the ability to predict position and electronic coupling is too low to have the designed properties needed for a functional artificial photosynthetic complex. Here, we present an approach of using DNA as a template for arranging both charge separation units and antenna molecules that govern long-range energy transfer. Of particular interest is the ability of DNA to function as a scaffold for chromophores, either through covalent attachment, or through non-covalent association by means of intercalation or grove binding. Using controlled positioning of dyes, multichromophoric assemblies can be created, capable of long range communication through multi-step energy transfer. This facilitates creation of DNA-based photonic devices for both light harvesting and directed information transfer. The channeled excitation energy can be transformed site specifically to chemical energy by charge separation of DNA linked porphyrins. A two phase system is discussed, in which the DNA is located in buffered solution whereas the hydrophobic porphyrins, responsible for the charge separation reaction, are located in the lipid bilayer of liposomes or supported lipid bilayers.
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| 2. |
- Börjesson, Karl, 1982, et al.
(författare)
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A Bioinspired Self Assembled Dimeric Porphyrin Pocket that Binds Electron Accepting Ligands
- 2012
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X .- 1359-7345. ; 48:12, s. 1793-1795
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Tidskriftsartikel (refereegranskat)abstract
- A binding pocket consisting of two zinc porphyrins self assembled by Watson-Crick base pairing is presented. The porphyrin binding pocket is located in the confined environment of a lipid membrane whereas the DNA is located in the water phase. Bidentate electron accepting ligands are shown to coordinate in-between the two porphyrins.
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| 3. |
- Börjesson, Karl, 1982, et al.
(författare)
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Conjugated anthracene dendrimers with monomer-like fluorescence
- 2014
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:38, s. 19846-19850
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Tidskriftsartikel (refereegranskat)abstract
- Two generations of highly emissive conjugated anthracene dendrimers containing up to 9 anthracene units are presented. In these dendrimers, anthracene-like absorption and emission properties are preserved due to the relatively weak electronic coupling between the anthracene units, while evidence of fast crosstalk within the molecular framework is still observed.
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| 4. |
- Börjesson, Karl, 1982, et al.
(författare)
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Efficiency Limit of Molecular Solar Thermal Energy Collecting Devices
- 2013
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Ingår i: ACS Sustainable Chemistry & Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 1:6, s. 585-590
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Tidskriftsartikel (refereegranskat)abstract
- As a larger fraction of energy is based on solar energy an other renewable energy sources, technologies for energy storage and conversion is becoming, increasingly important Molecular solar thermal (MOST) is a concept for long-term storage of solar energy in molecules and release of the energy as heat with full regeneration of the initial materials The process is inherently closed cycle and emission free. No assessment of the fundamental efficiency limits of the technology has been made. In this report, I efficiency limits and fundamental factors for molecular design of molecular solar thermal systems are discussed. Maximum efficiencies and potential temperature gradients are estimated using a number of basic assumptions on desired storage lifetimes and energy losses. The predicted maximum solar energy conversion efficiency is 10.6% at a S-1-S-0 gap of 1.89 eV. At this S-1-S-0 gap, the stored energy is able to create temperature differences of similar to 300 degrees C. Several existing systems have an energy storage density in line with the predicted maximum one but do so at larger than optimal S-1-S-0 gaps.
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| 5. |
- Börjesson, Karl, 1982, et al.
(författare)
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Exploring the Potential of Fulvalene Dimetals as Platforms for Molecular Solar Thermal Energy Storage: Computations, Syntheses, Structures, Kinetics, and Catalysis
- 2014
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Ingår i: Chemistry - A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 20:47, s. 15587-15604
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Tidskriftsartikel (refereegranskat)abstract
- A study of the scope and limitations of varying the ligand framework around the dinuclear core of FvRu(2) in its function as a molecular solar thermal energy storage framework is presented. It includes DFT calculations probing the effect of substituents, other metals, and CO exchange for other ligands on Delta H-storage. Experimentally, the system is shown to be robust in as much as it tolerates a number of variations, except for the identity of the metal and certain substitution patterns. Failures include 1,1',3,3'-tetra-tert-butyl (4), 1,2,2',3'-tetraphenyl (9), diiron (28), diosmium (24), mixed iron-ruthenium (27), dimolybdenum (29), and di-tungsten (30) derivatives. An extensive screen of potential catalysts for the thermal reversal identified AgNO3-SiO2 as a good candidate, although catalyst decomposition remains a challenge.
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| 6. |
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| 7. |
- Börjesson, Karl, 1982, et al.
(författare)
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Fluorinated fulvalene ruthenium compound for molecular solar thermal applications
- 2014
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Ingår i: Journal of Fluorine Chemistry. - : Elsevier BV. - 0022-1139. ; 161, s. 24-28
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Tidskriftsartikel (refereegranskat)abstract
- Molecular photoswitches, i.e. molecules capable of isomerizing between two states when submitted to light stimuli, has found applications in several areas such as molecular logic, molecular electronics, and, if the two isomers differ substantially in energy, molecular solar thermal (MOST) systems. In a MOST system the photoswitchable molecule absorbs a photon where after a photoinduced isomerisation to a high energy metastable photoisomer occurs. The photon energy is thus stored within the molecule. Fulvalenediruthenium compounds, has been suggested as a candidate in MOST systems thanks to the large difference in energy between the two isomers, its relative stability, and its ability to absorb sunlight. We here present a fluorinated fulvalene ruthenium derivative and show that its processing properties is remarkably different, while having retained photoisomerization efficiency, compared to its hydrocarbon analog. © 2014 The Authors.
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| 8. |
- Börjesson, Karl, 1982, et al.
(författare)
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Functionalized Nanostructures: Redox-Active Porphyrin Anchors for Supramolecular DNA Assemblies
- 2010
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 4:9, s. 5037-5046
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Tidskriftsartikel (refereegranskat)abstract
- We have synthesized and studied a supramolecular system comprising a 39-mer DNA with porphyrin-modified thymidine nucleosides anchored to the surface of large unilamellar vesicles (liposomes). Liposome porphyrin binding characteristics, such as orientation, strength, homogeneity, and binding site size, was determined, suggesting that the porphyrin is well suited as a photophysical and redox-active lipid anchor, in comparison to the inert cholesterol anchor commonly used today. Furthermore, the binding characteristics and hybridization capabilities were studied as a function of anchor size and number of anchoring points, properties that are of importance for our future plans to use the addressability of these redox-active nodes in larger DNA-based nanoconstructs. Electron transfer from photoexcited porphyrin to a lipophilic benzoquinone residing in the lipid membrane was characterized by steady-state and time-resolved fluorescence and verified by femtosecond transient absorption.
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| 9. |
- Börjesson, Karl, 1982, et al.
(författare)
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Photon up-conversion and molecular solar thermal energy storage: New materials and devices
- 2014
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Ingår i: 2014 IEEE Photonics Conference, IPC 2014. ; , s. 445-446
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Konferensbidrag (refereegranskat)abstract
- In a future society with limited access to fossil fuels, technologies for efficient on demand delivery of renewable energy are highly desirable. In this regard, methods that allow for solar energy storage and on demand solar driven energy generation are particularly relevant since the sun is the most abundant energy source.
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| 10. |
- Börjesson, Karl, 1982, et al.
(författare)
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Photon up-converting devices for solar fuels
- 2014
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Ingår i: SPIE Newsroom. - : SPIE-Intl Soc Optical Eng. - 1818-2259.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Employing a molecular solution capable of triplet-triplet annihilation in a layered microfluidic device enables the solar spectrum to be locally modified toward the UV, increasing solar energy system efficiency.
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