Design, Synthesis, and Characterization of Triphenylene and Imide Diazocines with Improved Properties toward Application in Smart Materials

This dissertation is dedicated to the development, investigation, and application of novel photoswitchable systems based on diazocines. The focus is on the synthesis and characterization of two structural classes of derivatives, previously unreported in the literature, namely tetrasubstituted triphenylene diazocines and disubstituted cyclic-imide diazocines. Introduction of functional groups is facile by late-stage derivatization of the diazocine. Both classes of compounds undergo a photoinduced, wing-flapping-like, and reversible Z ⇆ E isomerization associated with a large switching amplitude, which makes these systems particularly attractive for use as actuators in photo- and mechanoresponsive materials. Preliminary results from the incorporation of an unsaturated derivative into a liquid-crystalline elastomer film demonstrate photothermally driven macroscopic motion of the material. The triphenylene diazocines feature large annulated aromatic ring systems with a characteristic tub-shaped arrangement in the Z configuration. The possibility to incorporate four long-chain aliphatic substituents renders them promising candidates for application in photosensitive columnar liquid crystals, which is supported by X-ray crystal structures. The imide diazocines exhibit a novel substitution pattern that aligns almost exactly with the molecular stretching and bending vectors during photoisomerization, which is supported by theoretical modeling and X-ray crystal structures. This geometry is particularly well-suited for photoactuators and molecular tweezers in supramolecular host-guest systems. In total, four scientific articles were published, describing novel diazocines and precursors. Another scientific publication explores a silylation strategy for the fabrication of polymeric thin films using initiated chemical vapor deposition, which can be applied for the preparation of photoswitchable materials with hydrophilic diazocines.

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