A liquid azobenzene derivative as a solvent-free solar thermal fuel

Masutani, Kouta; Morikawa, Masa Aki; Kimizuka, Nobuo

doi:10.1039/c4cc07713j

Cited by 131 publications

(118 citation statements)

References 40 publications

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“…Azobenzene is one of the oldest photoswitches known, but new derivatives thereof are still being developed27282930. The low energy state of azobenzene is the trans-isomer and the high energy is the cis-isomer, which spontaneously isomerizes back to the trans isomer at ambient temperatures.…”

Section: Resultsmentioning

confidence: 99%

Determining the Photoisomerization Quantum Yield of Photoswitchable Molecules in Solution and in the Solid State

Stranius

Börjesson

2017

Sci Rep

125

109

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Photoswitchable molecules are able to isomerize between two metastable forms through light stimuli. Originally being studied by photochemists, this type of molecule has now found a wide range of applications within physics, chemistry and biology. The extensive usage of photochromic molecules is due to the two isomers having fundamentally different physical and chemical properties. The most important attribute of a photoswitch is the photoisomerization quantum yield, which defines the efficiency of the photoisomerization event. Here we show how to determine the photoisomerization quantum yield in the solid state and in solution when taking thermal processes into account. The described method together with provided software allows for rapid and accurate determination of the isomerization process for this important class of molecules.

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Section: Resultsmentioning

confidence: 99%

Determining the Photoisomerization Quantum Yield of Photoswitchable Molecules in Solution and in the Solid State

Stranius

Börjesson

2017

Sci Rep

125

109

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“…Several photochromic motifs, such as tetracarbonyl‐fulvalene‐diruthenium compounds, azobenzenes, norbornadienes, and dihydroazulenes have been investigated, both in solution and neat forms, as well as appended to polymers or integrated onto solid supports . The focus of our group has been on assessing the potential of the norbornadiene (NBD)/quadricyclane (QC) couple, where light can be used to facilitate a [2+2π] intramolecular cyclization to form the high energy QC1 from NBD1 (Figure ).…”

Section: Figurementioning

confidence: 99%

Norbornadiene‐Based Photoswitches with Exceptional Combination of Solar Spectrum Match and Long‐Term Energy Storage

Jevric

Petersen

Mansø

et al. 2018

Chemistry A European J

114

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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 S landscape on the NBD side to the S 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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“…With the availability of accurate computational tools, new approaches have leveraged carbon nanostructures and insights into the steric interaction of STFs to increase energy density employing highly cyclable and modest energy density (60-70 Wh kg −1 ) azobenzene derivatives. More recently, it was possible to develop liquid azobenzene fuels at room temperature by attaching bulky ligands to the molecule, [ 11 ] and with several computational works detailing the possibility of increasing its energy density through functionalization of the benzene rings, [ 12 ] this platform holds much promise for future STF developments. More recently, it was possible to develop liquid azobenzene fuels at room temperature by attaching bulky ligands to the molecule, [ 11 ] and with several computational works detailing the possibility of increasing its energy density through functionalization of the benzene rings, [ 12 ] this platform holds much promise for future STF developments.…”

mentioning

confidence: 99%

Solid‐State Solar Thermal Fuels for Heat Release Applications

Zhitomirsky

Cho

Grossman

2015

Advanced Energy Materials

108

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56 Wh kg −1 ) employing ruthenium with higher cyclability have been developed, [5][6][7] but remain prohibitively expensive for wide adoption. With the availability of accurate computational tools, new approaches have leveraged carbon nanostructures and insights into the steric interaction of STFs to increase energy density employing highly cyclable and modest energy density (60-70 Wh kg −1 ) azobenzene derivatives. [ 8,9 ] While demonstrating a per-molecule increase in energy density via templating, [ 10 ] these approaches require complex multistep reactions, have low yields, and the resulting material has low solubility in most organic solvents (<1 g L −1 ). More recently, it was possible to develop liquid azobenzene fuels at room temperature by attaching bulky ligands to the molecule, [ 11 ] and with several computational works detailing the possibility of increasing its energy density through functionalization of the benzene rings, [ 12 ] this platform holds much promise for future STF developments. With such rapid progress in STF materials, it is perhaps surprising that the solid-state platform and related applications have remained largely unexplored, with only recent studies on semi-solid photoliquefi able ionic crystals reaching energy densities of 35 Wh kg −1 . [ 13 ] Transitioning fully to the solid-state offers the possibility of integrating STF materials into a multitude of existing solid-state devices such as coatings for deicing, or novel applications such as solar blankets and other consumer oriented heating equipment.We took the view that if properly engineered on the molecular level, STF materials could be controllably tailored within the solid-state, and that until now, there has not been an efficient method to accomplish this. For one, the most recent STF reports have relied on carbon scaffolds [ 10,14 ] that simultaneously increase synthesis complexity, cannot be deposited into uniform fi lms, contribute to the optical density without resulting in photocharging, and introduce uncontrollable morphological effects that may limit charging and reversible switching in the solid-state. [ 15 ] Similarly, single-molecule thin fi lms do not make homogenous layers, can often result in crystallization, and melt at low temperatures (≈70 °C for azobenzene) thus limiting their utility in the solid-state. Fortunately, a wealth of literature exists on azobenzene-based materials in solid-state applications for microswitches, microactuators, and sensors. [16][17][18][19][20][21] We postulated that the ideal material class to form solid-state STF coatings would need to (1) form smooth fi lms with controllable thickness, (2) be resilient at high temperatures, (3) preserve the heat release properties of Closed cycle systems offer an opportunity for solar energy harvesting and storage all within the same material. Photon energy is stored within the chemical conformations of molecules and is retrieved by a triggered release in the form of heat. Until now, such solar thermal fuels (STFs) have been largely unavailable...

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A liquid azobenzene derivative as a solvent-free solar thermal fuel

Cited by 131 publications

References 40 publications

Determining the Photoisomerization Quantum Yield of Photoswitchable Molecules in Solution and in the Solid State

Determining the Photoisomerization Quantum Yield of Photoswitchable Molecules in Solution and in the Solid State

Norbornadiene‐Based Photoswitches with Exceptional Combination of Solar Spectrum Match and Long‐Term Energy Storage

Solid‐State Solar Thermal Fuels for Heat Release Applications

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