| 1. |
- Hillers-Bendtsen, Andreas Erbs, et al.
(författare)
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Investigation of the Structural and Thermochemical Properties of [2.2.2]-Bicyclooctadiene Photoswitches
- 2021
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 125:48, s. 10330-10339
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Tidskriftsartikel (refereegranskat)abstract
- Molecular photoswitches can under certain conditions be used to store solar energy in the so-called molecular solar thermal storage systems, which is an interesting technology for renewable energy solutions. The current investigations focus on the performance of seven different density functional theory (DFT) methods (B3LYP, CAM-B3LYP, PBE0, M06-2X, ωB97X-D, B2PLYP, and PBE0DH) when predicting geometries and thermochemical properties of the [2.2.2]-bicyclooctadiene (BOD) photoswitch. We find that all of the investigated DFT methods provide geometries that are in good agreement with those obtained using coupled cluster singles and doubles (CCSD) calculations. The dependence on the employed basis set is not large when predicting geometries. With respect to the thermochemical properties, we find that the M06-2X, CAM-B3LYP, PBE0, and ωB97X-D functionals all predict thermochemical properties that are in good agreement with the results of the CCSD, the CCSD including perturbative triples (CCSD(T)), and the explicitly correlated CCSD-F12 and CCSD(T)-F12 models. Lastly, for energy calculations, we tested the newly developed fourth-order cluster perturbation theory singles and doubles CPS(D-4) model, which in this study provides energy differences that are of CCSD and sometimes also CCSD(T) quality at a relatively low cost. We find that the CPS(D-4) model is an excellent choice for further investigation of BOD derivatives because accurate energies can be obtained routinely using this methodology. From the results, we also note that the predicted storage energies and storage energy densities for the BOD photoswitch are very large compared to other molecular solar thermal storage systems and that these systems could be candidates for such applications.
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| 2. |
- Lennartsson, Anders, 1980, et al.
(författare)
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A Convenient Route to 2-Bromo-3-chloronorbornadiene and 2,3-Dibromonorbornadiene
- 2015
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Ingår i: Synlett. - : Georg Thieme Verlag KG. - 1437-2096 .- 0936-5214. ; 26:11, s. 1501-1504
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Tidskriftsartikel (refereegranskat)abstract
- Substituted norbornadienes are useful in a wide range of applications, including molecular solar-thermal (MOST) energy storage systems. An important precursor for 2,3-substituted norbornadienes is 2-bromo-3-chloronorbornadiene, where the two halogen atoms can be substituted selectively through two consecutive Suzuki cross-coupling reactions. Previous routes to 2-bromo-3-chloronorbornadiene have used 1,2-dibromoethane as a brominating agent, a substance known to be carcinogenic and the use of which is restricted in certain countries. Herein is reported a one-pot route to 2-bromo-3-chloronorbornadiene in 50% yield using p-toluenesulfonyl bromide as a bromine source. In addition, the procedure has been adapted to allow synthesis of 2,3-dibromonorbornadiene in 37% yield.
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| 3. |
- Orrego Hernandez, Jessica, 1987, et al.
(författare)
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Norbornadiene/Quadricyclane (NBD/QC) and conversion of solar energy
- 2022
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Ingår i: Molecular Photoswitches: Chemistry, Properties, and Applications, 2 Volume Set. - 9783527827619 ; 1-2, s. 351-378
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter presents the norbornadiene (NBD) molecule as a photoswitch. This bicyclic molecule is photoconverted to a high-energy metastable isomer quadricyclane (QC) via light-induced [2+2] cycloaddition reaction. NBD is widely used as a molecular photoswitch due to its easily tunable isomerization properties (e.g. isomerization quantum yield, onset of absorption, half-life of the quadricyclane, and energy-storage density) by the functionalization with different chromophoric substituents. The molecular solar thermal-energy-storage system (MOST) application and its design of heat-release devices based on the NBD/QC system have been strongly evolving in the last years. However, also several new applications start to develop, making this photoswitch a versatile compound.
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| 4. |
- Orrego Hernandez, Jessica, 1987, et al.
(författare)
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Scalable Synthesis of Norbornadienes via in situ Cracking of Dicyclopentadiene Using Continuous Flow Chemistry
- 2021
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Ingår i: European Journal of Organic Chemistry. - : Wiley. - 1099-0690 .- 1434-193X. ; 2021:38, s. 5337-5342
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Tidskriftsartikel (refereegranskat)abstract
- The norbornadiene (NBD)-quadricyclane (QC) photoswitch has recently attracted attention due to its use in molecular solar thermal energy systems (MOST). Normally for device testing, several grams are needed. One way of synthesizing NBDs efficiently is through the Diels-Alder reaction between alkynes and cyclopentadiene. However, scaling up the reaction can be troublesome in a research lab environment. Also, dicyclopentadiene needs cracking before utilization which is a time-consuming step. Here, we developed a method where we both scale up the synthesis in a single reaction step that involves both in situ cracking of dicyclopentadiene and the direct reaction of cyclopentadiene with acetylene derivatives using a tubular coiled stainless steel flow reactor. As a proof-of-concept, we synthesized six different NBD compounds and scaled the synthesis to produce 87 g of a novel NBD in 9 h. The NBD is further characterized, showing promising properties for MOST applications. Our new method shows that flow chemistry is an attractive technique for the fast and efficient synthesis of large quantities of NBDs, needed to develop future real-life devices and applications.
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| 5. |
- Pettersson, Mariell, 1984, et al.
(författare)
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Design, Synthesis and Evaluation of 2,5-Diketopiperazines as Inhibitors of the MDM2-p53 Interaction
- 2015
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:10
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Tidskriftsartikel (refereegranskat)abstract
- The transcription factor p53 is the main tumour suppressor in cells and many cancer types have p53 mutations resulting in a loss of its function. In tumours that retain wild-type p53 function, p53 activity is down-regulated by MDM2 (human murine double minute 2) via a direct protein-protein interaction. We have designed and synthesised two series of 2,5-diketopiperazines as inhibitors of the MDM2-p53 interaction. The first set was designed to directly mimic the alpha-helical region of the p53 peptide, containing key residues in the i, i+4 and i+7 positions of a natural alpha-helix. Conformational analysis indicated that 1,3,6-trisubstituted 2,5-diketopiperazines were able to place substituents in the same spatial orientation as an alpha-helix template. The key step of the synthesis involved the cyclisation of substituted dipeptides. The other set of tetrasubstituted 2,5-diketopiperazines were designed based on structure-based docking studies and the Ugi multicomponent reaction was used for the synthesis. This latter set comprised the most potent inhibitors which displayed micromolar IC50 values in a biochemical fluorescence polarisation assay.
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| 6. |
- Quant, Maria, 1985
(författare)
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Design, Synthesis and Evaluation of Photoswitches for Molecular Solar Thermal Energy Storage Systems
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To meet the future energy demands and handle climate changes, new sustainable energy sources must be developed. Over the last decades, great scientific progress on harvesting solar energy has been made, but storing the energy is still a challenge. One way to store solar energy is in a compound that absorbs solar energy while being converted to a metastable isomer through a photoisomerization process, a technique referred to as molecular solar thermal energy storage (MOST). In this work, the norbornadiene/quadricyclane system, a promising candidate for MOST, was evaluated and new synthetic methods were developed to obtain a series of novel norbornadiene derivatives in an efficient way. Photophysical characterization of the series revealed a better solar spectrum match and high energy storage densities (114–124 kJ/mol) compared to previous series. Quantum yields for the photoisomerization processes were between 28–58% and the half-lives of the photoisomers in the range of hours to days. Solvent effects on the norbornadiene/quadricyclane system were studied, showing a pronounced effect on both the half-lives of the photoisomers and on the photoisomerization process when going from polar to non-polar solvents. Additionally, bicyclooctadiene derivatives were synthesized and for the first time evaluated as MOST candidates. The series exhibited very high storage densities (143–153 kJ/mol) compared to the corresponding norbornadiene derivatives (52–63 kJ/mol) and could switch back and forth for 645 cycles without significant degradation. The absorption profile and half-lives of the photoisomers need further improvement for MOST applications, but the molecular engineering concepts presented here can be used to develop future MOST systems based on the bicyclooctadiene/tetracyclooctane system. Altogether, this work illustrates the importance of detailed molecular design and the importance of the local environment of the photoswitches for obtaining desired MOST properties.
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| 7. |
- Quant, Maria, 1985, et al.
(författare)
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Low Molecular Weight Norbornadiene Derivatives for Molecular Solar-Thermal Energy Storage
- 2016
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Ingår i: Chemistry - A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 22:37, s. 13265-13274
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Tidskriftsartikel (refereegranskat)abstract
- Molecular solar-thermal energy storage systems are based on molecular switches that reversibly convert solar energy into chemical energy. Herein, we report the synthesis, characterization, and computational evaluation of a series of low molecular weight (193-260 g mol(-1)) norbornadiene-quadricyclane systems. The molecules feature cyano acceptor and ethynyl-substituted aromatic donor groups, leading to a good match with solar irradiation, quantitative photo-thermal conversion between the norbornadiene and quadricyclane, as well as high energy storage densities (396-629 kJ kg(-1)). The spectroscopic properties and energy storage capability have been further evaluated through density functional theory calculations, which indicate that the ethynyl moiety plays a critical role in obtaining the high oscillator strengths seen for these molecules.
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| 8. |
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| 9. |
- Quant, Maria, 1985
(författare)
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Norbornadienes for molecular solar thermal energy storage
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Over the last decade, there has been great scientific progress in terms of harvesting solar energy but the area of storing energy is still facing challenges. One approach to store solar energy is via photoinduced isomerization of chemical bonds, referred to as molecular solar thermal energy storage (MOST). Norbornadiene is a promising candidate molecule for this purpose, since upon irradiation isomerization occurs to form the metastable quadricyclane. The reaction is reversible and back conversion can be triggered to release the energy as heat. In this work, a new synthetic approach was developed to obtain 2-bromo-3-chloronorbornadiene that serves as an important starting material for further functionalization of norbornadienes. Through the developed procedure, a series of norbornadienes, decorated with electron donating and accepting substituents were synthesized. Photophysical characterization revealed that norbornadienes with cyano acceptor groups and ethynyl-substituted aromatic donor groups show a good solar spectrum match and high energy storage densities (296 – 545 kJ/kg). The obtained quantum yields for the photoisomerization processes were between 28 – 58% and the half-lives of the corresponding quadricyclanes in the range of 5 – 22 hours for the compounds with an ethynyl linker, and 55 days for the quadricyclane with similar substituents but without the ethynyl linker. The synthesized compounds illustrate the challenge in optimizing all parameters for an efficient MOST system in a single molecule system. For a deeper understanding of the relation between the structure and the properties, more variations of norbornadienes have to be synthesized and evaluated in future research.
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| 10. |
- Quant, Maria, 1985, et al.
(författare)
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Solvent effects on the absorption profile, kinetic stability, and photoisomerization process of the norbornadiene-quadricyclanes system
- 2019
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 123:12, s. 7081-7087
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Tidskriftsartikel (refereegranskat)abstract
- Molecular photoswitches based on the norbornadiene-quadricyclane (NBD-QC) couple can be used to store solar energy and to release the stored energy as heat on demand. In this context, the energy storage time as well as the quantum yield of the energy storing reaction are important parameters. Here, we explore for the first time solvent effects on these processes for a series of four NBD-QC compounds in four different solvents with different polarity (acetonitrile, tetrahydrofuran, toluene, and hexane). We show that the energy storage time of the QC forms can vary by up to a factor of 2 when going from the most to the least polar solvent. Moreover, we show that for the norbornadiene derivatives with an asymmetric 1,2 substitution pattern, the quantum yield of conversion is highly solvent dependent, whereas this is not the case for the symmetrically substituted compounds. The spectroscopic observations are further rationalized using classical molecular dynamics (MD) simulations and time-dependent density functional theory (TDDFT) calculations. These demonstrate the importance of vibrational and rotational excitations for obtaining broad-band absorption, which is a prerequisite for capturing a wide range of the solar spectrum.
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| 11. |
- Quant, Maria, 1985, et al.
(författare)
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Synthesis, characterization and computational evaluation of bicyclooctadienes towards molecular solar thermal energy storage
- 2022
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Ingår i: Chemical Science. - : Royal Society of Chemistry (RSC). - 2041-6539 .- 2041-6520. ; 13:3, s. 834-841
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Tidskriftsartikel (refereegranskat)abstract
- Molecular solar-thermal energy storage (MOST) systems are based on photoswitches that reversibly convert solar energy into chemical energy. In this context, bicyclooctadienes (BODs) undergo a photoinduced transformation to the corresponding higher energy tetracyclooctanes (TCOs), but the photoswitch system has not until now been evaluated for MOST application, due to the short half-life of the TCO form and limited available synthetic methods. The BOD system degrades at higher temperature via a retro-Diels-Alder reaction, which complicates the synthesis of the compounds. We here report a cross-coupling reaction strategy that enables an efficient synthesis of a series of 4 new BOD compounds. We show that the BODs were able to switch to the corresponding tetracyclooctanes (TCOs) in a reversible way and can be cycled 645 times with only 0.01% degradation. Half-lives of the TCOs were measured, and we illustrate how the half-life could be engineered from seconds to minutes by molecular structure design. A density functional theory (DFT) based modelling framework was developed to access absorption spectra, thermal half-lives, and storage energies which were calculated to be 143-153 kJ mol(-1) (0.47-0.51 MJ kg(-1)), up to 76% higher than for the corresponding norbornadiene. The combined computational and experimental findings provide a reliable way of designing future BOD/TCO systems with tailored properties.
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| 12. |
- Wang, Zhihang, 1989, et al.
(författare)
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Macroscopic heat release in a molecular solar thermal energy storage system
- 2019
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Ingår i: Energy and Environmental Sciences. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 12:1, s. 187-193
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Tidskriftsartikel (refereegranskat)abstract
- The development of solar energy can potentially meet the growing requirements for a global energy system beyond fossil fuels, but necessitates new scalable technologies for solar energy storage. One approach is the development of energy storage systems based on molecular photoswitches, so-called molecular solar thermal energy storage (MOST). Here we present a novel norbornadiene derivative for this purpose, with a good solar spectral match, high robustness and an energy density of 0.4 MJ kg-1. By the use of heterogeneous catalyst cobalt phthalocyanine on a carbon support, we demonstrate a record high macroscopic heat release in a flow system using a fixed bed catalytic reactor, leading to a temperature increase of up to 63.4 °C (83.2 °C measured temperature). Successful outdoor testing shows proof of concept and illustrates that future implementation is feasible. The mechanism of the catalytic back reaction is modelled using density functional theory (DFT) calculations rationalizing the experimental observations.
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