Multi-photochromic systems based on azobenzene units: towards 2D and 3D photoresponsive materials

The research activity focuses on the design, synthesis and characterization of photo-active organic compounds comprising azobenzenes as the photoswitchable unit. The molecules were conceived for the functionalization of graphite substrates to study the supramolecular self-assembly and to investigate changes in physicochemical properties upon irradiation with UV/Vis light. The present thesis is organized in four chapters. Chapter 1 gives an introduction to molecular switches and their potential applications in molecular devices. Azobenzenes and hexa-peri-hexabenzocoronenes are further detailed, focusing on their chemical and physical properties, synthetic methodologies towards their preparation and applications. Subsequently, the assembly of small organic molecules into 2D and 3D extended molecular architectures as promising materials for gas separation and storage, catalysis, drug delivery and semiconducting materials is described.
The main part, which is discussed in Chapter 2 and Chapter 4, deals with the design, synthesis and characterization of photochromic molecules containing switchable azobenzene moieties. The synthesized compounds were designed either for the functionalization of graphite surfaces aiming to the fabrication of novel optically triggered 2D self-assembled systems, or as photoactive building blocks in photo-responsive 3D metal-organic frameworks (MOFs) and covalent organic frameworks (COFs).