| 1. |
- Jevric, Martyn, 1973, et al.
(author)
-
Norbornadiene-Based Photoswitches with Exceptional Combination of Solar Spectrum Match and Long-Term Energy Storage
- 2018
-
In: Chemistry - A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 24:49, s. 12767-12772
-
Journal article (peer-reviewed)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.
|
|
| 2. |
- Jevric, Martyn, 1973, et al.
(author)
-
Tuning Molecular Solar Thermal Properties by Modification of a Promising Norbornadiene Photoswitch
- 2019
-
In: European Journal of Organic Chemistry. - : Wiley. - 1099-0690 .- 1434-193X. ; 2019:13, s. 2354-2361
-
Journal article (peer-reviewed)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.
|
|
| 3. |
- Mony, Jürgen, et al.
(author)
-
Photoisomerization Efficiency of a Solar Thermal Fuel in the Strong Coupling Regime
- 2021
-
In: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 31:21
-
Journal article (peer-reviewed)abstract
- Strong exciton-photon coupling is achieved when the interaction between molecules and an electromagnetic field is increased to a level where they cannot be treated as separate systems. This leads to the formation of polaritonic states and an effective rearrangement of the potential energy surfaces, which opens the possibility to modify photochemical reactions. This work investigates how the strong coupling regime is affecting the photoisomerization efficiency and thermal backconversion of a norbornadiene-quadricyclane molecular photoswitch. The quantum yield of photoisomerization shows both an excitation wavelength and exciton/photon constitution dependence. The polariton-induced decay and energy transfer processes are discussed to be the reason for this finding. Furthermore, the thermal back conversion of the system is unperturbed and the lower polariton effectively shifts the absorption onset to lower energies. The reason for the unperturbed thermal backconversion is that it occurs on the ground state, which is unaffected. This work demonstrates how strong coupling can change material properties towards higher efficiencies in applications. Importantly, the experiments illustrate that strong coupling can be used to optimize the absorption onset of the molecular photoswitch norbonadiene without affecting the back reaction from the uncoupled quadricyclane.
|
|
| 4. |
- Petersen, Anne, 1986, et al.
(author)
-
Triazole-Functionalized Norbornadiene-Quadricyclane Photoswitches for Solar Energy Storage
- 2018
-
In: European Journal of Organic Chemistry. - : Wiley. - 1099-0690 .- 1434-193X. ; 2018:32, s. 4465-4474
-
Journal article (peer-reviewed)abstract
- Herein work on 2,3-substituted norbornadiene-quadricyclane molecular photoswitches designed for solar energy storage purposes is presented. A series of six new systems bearing 1,4- or 1,5-alkyl triazoles as the acceptor unit combined with various aryl donor groups, as well as four functional intermediates, were synthesized and fully characterized. The new photoswitches were evaluated by measuring optical absorption profiles, activation energies for the thermal conversion of quadricyclanes to norbornadienes, as well as the storage energy densities. These triazoles featured a molar energy storage of 81.2–101 kJ mol–1corresponding to energy densities of 215–267 kJ kg–1. The optical absorption profiles exhibited absorption onsets up to 382 nm and a study of the thermally activated conversion from high-energy quadricyclanes to norbornadienes revealed energy storage half lives of up to 402 days at 25 °C. The modular nature of the “click chemistry” synthesis concept used herein enables access to a large range of compounds with tailored properties such as solubility, thermal half-life, and solar spectrum match.
|
|
| 5. |
- Schuschke, Christian, et al.
(author)
-
Solar energy storage at an atomically defined organic-oxide hybrid interface
- 2019
-
In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 10:1
-
Journal article (peer-reviewed)abstract
- Molecular photoswitches provide an extremely simple solution for solar energy conversion and storage. To convert stored energy to electricity, however, the photoswitch has to be coupled to a semiconducting electrode. In this work, we report on the assembly of an operational solar-energy-storing organic-oxide hybrid interface, which consists of a tailor-made molecular photoswitch and an atomically-defined semiconducting oxide film. The synthesized norbornadiene derivative 2-cyano-3-(4-carboxyphenyl)norbornadiene (CNBD) was anchored to a well-ordered Co3O4(111) surface by physical vapor deposition in ultrahigh vacuum. Using a photochemical infrared reflection absorption spectroscopy experiment, we demonstrate that the anchored CNBD monolayer remains operational, i.e., can be photo-converted to its energy-rich counterpart 2-cyano-3-(4-carboxyphenyl)quadricyclane (CQC). We show that the activation barrier for energy release remains unaffected by the anchoring reaction and the anchored photoswitch can be charged and discharged with high reversibility. Our atomically-defined solar-energy-storing model interface enables detailed studies of energy conversion processes at organic/oxide hybrid interfaces.
|
|
