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| 2. |
- Glasbey, JC, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 3. |
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| 4. |
- Jevric, Martyn, 1973, et al.
(författare)
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Norbornadiene-Based Photoswitches with Exceptional Combination of Solar Spectrum Match and Long-Term Energy Storage
- 2018
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Ingår i: Chemistry - A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 24:49, s. 12767-12772
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Tidskriftsartikel (refereegranskat)abstract
- Norbornadiene-quadricyclane (NBD-QC) photoswitches are candidates for applications in solar thermal energy storage. Functionally, they rely on an intramolecular [2+2] cycloaddition reaction, which couples the S0 landscape on the NBD side to the S1 landscape on the QC side of the reaction and vice-versa. This commonly results in an unfavourable correlation between the first absorption maximum and the barrier for thermal back-conversion. This work demonstrates that this correlation can be counteracted by using steric repulsion to hamper the rotational motion of the side groups along the back-conversion path. It is shown that this modification reduces the correlation between the effective back-conversion barrier and the first absorption maximum and also increases the back-conversion entropy. The resulting molecules exhibit exceptionally long half-lives for their metastable forms without significantly affecting other properties, most notably solar spectrum match and storage density.
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| 5. |
- Jevric, Martyn, 1973, et al.
(författare)
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Tuning Molecular Solar Thermal Properties by Modification of a Promising Norbornadiene Photoswitch
- 2019
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Ingår i: European Journal of Organic Chemistry. - : Wiley. - 1099-0690 .- 1434-193X. ; 2019:13, s. 2354-2361
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Tidskriftsartikel (refereegranskat)abstract
- Carefully targeted modifications to the norbornadiene-quadricyclane couple should give molecules with great potential for solar energy storage. Here we report the synthesis of derivatives of a well-studied compound, 2-cyano-3-anisyl norbornadiene (NBD5). The conjugation was extended by conversion of the nitrile into acrylonitrile and acrylate derivatives over two steps. Despite red-shifting the absorbance properties, the metastable quadricyclanes exhibited extremely short lifetimes. Meanwhile, treatment of NBD5 with acetyl halides in the presence of aluminum trihalides led to the formation of 7-acetyl norbornenes through a Wagner–Meerwein rearrangement. Subsequent transformations made it possible to synthesise norbornadienes with varying degrees of steric bulk at the 7-position of the molecular scaffold. It was found that the bulkier this group was, the more stable the quadricyclane form. This reaction sequence allows for the synthesis of norbornadiene derivatives which are more suited to molecular solar thermal applications in domestic heating despite providing a slightly lower energy density.
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| 6. |
- Lissau, Jonas Sandby, et al.
(författare)
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Conformational Impact on Energy Storage Efficiency of Subphthalocyanine-Fullerene Hybrids
- 2018
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 122:33, s. 6683-6692
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid molecules involving subphthalocyanine and Buckminsterfullerene derivatives are interesting candidates as heavy metal free triplet sensitizers. Subphthalocyanine efficiently absorbs visible photons and transfer the singlet excited state energy to the Buckminsterfullerene where intersystem crossing produces triplet states in high yield. Thus, far the efficiency of the triplet-generating photophysics in these systems has been hampered by back energy transfer to the subphthalocyanine triplet state resulting in loss of excitation energy. Herein an efficient strategy is realized to avoid loss of triplet energy by back energy transfer. A hybrid molecule based on subphthalocyanine and Buckminsterfullerene is presented in which dispersion-induced π-π interactions result in a molecular geometry where highly efficient through-space singlet excited state energy transfer takes place in one direction, whereas energy flow in the opposite direction via the triplet manifold is blocked by lack of orbital overlap. The approach opens for a new class of heavy-metal-free triplet sensitizers of particular relevance to the fields of photodynamic therapy and noncoherent photon upconversion.
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