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Λ-shaped photo-switches designed by employing the Tröger's base scaffold
thesisposted on 2022-03-28, 14:40 authored by Masoud Kazem-Rostami
This thesis introduces the first family of photo-responsive analogues of Tröger's base within three chapters, each incorporating one journal article. First, the availability of amino-carrying Tröger's base analogues was assessed following a review of the chemical literature and the most affordable one was chosen as the main building block in this thesis. Second, the syntheses were achieved by utilising standard diazotisation and azo-coupling procedures, which were optimised to improve the quality and quantity of the products. Therefore, various phenols were selected and coupled with a freshly produced bisdiazonium-carrying Tröger's base analogue to establish a new family of Λ-shaped molecular switches. The derivatisation of the selected compounds by Williamson's etherification reaction was also performed. Afterwards, the photo-isomerisation of the selected alkylated product was compared with the non-alkylated precursor to prove the photo-responsive nature of the obtained products. At the end, some issues including the racemisation of methano-strapped analogues, and the problematic production of the hydroxyl carrying ones, and various limitations imposed by the conventional synthesis procedures for Tröger's base analogues, were addressed. Furthermore, this thesis elaborates on the high yielding and economically viable preparation of various ethano-strapped Tröger's base analogues as versatile Λ-shaped building blocks. The introduced building blocks that carry triazenyl, sulfhydryl, hydroxyl ,carbamate and amino groups are the first of their kind. These smooth the way towards the formation of various novel molecules including non-racemisable and photo-switchable compounds. Based on the collected experimental results and comparing them with similar examples found in the literature, it can be concluded that these products have opened a new chapter into the design of molecular photo-switches, chiral liquid crystal dopants, photo-switchable molecular-recognition hosts, and chiral photo-alignment agents. The possible applications of the produced products are also elaborated on in the future directions section of the thesis.