Abstract
Molecular photoswitches are molecules that undergo reversible isomerization upon exposure to different wavelengths of light. Isomerization induces changes in the molecular structures and configurations, resulting in significant variations in physical and chemical properties, including polarity, absorption, energy state, phase, and solubility. Consequently, the materials incorporating novel molecular switches hold promise for a wide range of applications including energy storage, drug delivery, sensing, optical memory, and recovery of high-value chemicals, among others. This thesis focuses on functionalizing two categories of photoswitches: azo derivatives and hydrazones, to meticulously modify their properties for applications in molecular solar thermal energy storage and catalyst recovery. The first part of this thesis aims to develop ideal materials featuring condensed phase isomerization, long energy storage times, reversible visible light activation, large energy storage, and phase transition for solar thermal energy storage. Strategies for functionalizing the photoswitches are developed, and their optical and thermal properties are investigated. Inspired by the solid-liquid phase transition of photoswitches, which indicates significant variation in the polarity and interactions of molecules upon light absorption, I explore the optical control over the solubility of photoswitches in organic solvents. The second part of my thesis focuses on the integration of photoswitches in catalyst structures to adjust their solubility in solvents and facilitate their recovery after catalysis. This approach enables the reversible dissolution and precipitation of the catalysts upon light stimulation, which allows us to harness the high activity of homogenized catalysts and the easy recovery of precipitated catalysts. This thesis aims to provide a comprehensive view of molecular photoswitches’ properties in solution and solid state, as well as their applications in various areas of research.