A-Azo: Tuning storage in MOST systems using intra- and intermol- ecular interactions with Azobenzenes

分子太阳能热能储存（MOST）系统的成功与所使用的光可切换分子实体（mostophore）不可或缺。有多个因素控制的性质，这直接关系到它的MOST功能。除其他外，关键参数是能量储存密度、半衰期或与太阳光谱的匹配。本文以偶氮苯为例，探讨了解决MOST分子固有参数的一般策略：（1）在一个分子中组合多个MOST基团;（2）通过后续反应稳定存储状态;（3）通过非共价相互作用控制开关过程。在（1）中，不仅多个偶氮苯将被连接，而且MOST研究组内研究的其他mostophore也将被连接。在这里，氮杂硼杂环是特别令人感兴趣的候选者，因为它们可以取代偶氮苯内的一个（或两个）苯基单元，潜在地导致存储能量的急剧增加，同时将氮杂硼杂环的吸收有利地转移到可见光范围内。根据应用，需要不同的储存时间。长期储存是一个特殊的挑战。如果将MOST系统的能量加载过程与一个后续反应连接起来，使MOST系统保持在储存状态，则能量可以保持无限长的时间。理想地，后续反应也被光化学促进。这一概念将在（2）部分得到体现。附加基团的连接以改变MOST性质主要导致由于增加的分子量而降低的存储密度。因此，在第（2）部分中，探索非共价相互作用以优化能量储存和释放过程的不同阶段的MOST性质。该项目的主要部分包括MOST组件的设计、合成和分析。流动化学发挥着不可或缺的作用，允许大规模的合成测试，但也在高通量分析。所有部分都将与研究小组内的其他项目很好地结合在一起，例如化合物的交流，合成知识（A-BN，A-Nor，B-Cat），分析（B-Spec，B-Surf），计算设计和机制的阐明（D-Ground，D-Photo），以及概念验证设备（D-Dev）的测试。所获得的见解将为有机光化学提供新的基本见解，包括合成，分析和机械理解。作为该研究小组的整体获得的这些知识将使我们能够将MOST技术推向一个新的水平，并为实际应用铺平道路。

The success of Molecular Solar Thermal Energy Storage (MOST) systems is indispensably connected to the light-switchable molecular entity (mostophore) utilized. There are multiple factors controlling the properties, which directly correlate to its MOST function. Critical parameters are inter alia the energy storage density, the half-life, or the match with the solar spectrum. In this proposal, general strategies to tackle the MOST-molecule inherent parameters for an optimized candidate will be explored with the example of azobenzenes: (1) Combination of multiple mostophores in one molecule; (2) Stabilization of the storage state by follow-up reaction; (3) Control of switching process by non-covalent interactions. In (1) not only multiple azobenzenes will be connected, but also other mostophores investigated within the Research Group FOR MOST. Here, the azaborines are especially interesting candidates, as they can replace one (or two) of the phenyl-units within the azobenzene, potentially leading to a drastic increase in storage energy while shifting the absorption of the azaborine favorably into the visible range. Depending on the application different storage times are desirable. Long-term storage poses a special challenge. If the energy loading process of the mostophore is connected to a follow-up reaction fixing the MOST-system in the storage state, the energy could be kept for an infinitive time. Ideally, the follow-up reaction is also promoted photochemically. This concept will be brought to life in the (2) part. The attachment of additional groups to alter the MOST properties leads mostly to a reduced storage density due to the increased molecular weight. Therefore, in part (2) non-covalent interactions are explored to optimize the MOST properties at different stages of the energy storage and release process. The main part of this project consists of the design, synthesis, and analysis of MOST components. Flow chemistry is playing an integral role, allowing large scale synthesis for testing, but also in high-throughput analysis. All parts will be well integrated with the other projects within the Research Group, e.g. exchange of compounds, knowledge in synthesis (A-BN, A-Nor, B-Cat), analysis (B-Spec, B-Surf), computational design, and elucidation of mechanisms (D-Ground, D-Photo), as well as testing in proof-of-concept devices (D-Dev). The insights gained will provide new fundamental insights into organic photochemistry, ranging from synthesis, analysis, and mechanistic understanding. This knowledge gained as an ensemble of this Research Group will allow us to push the MOST technology to a new level and pave the way to practical applications.