University of Zagreb. Faculty of Science. Department of Chemistry.
Abstract
U okviru ove doktorske disertacije provedena je sinteza novih derivata ftalimida i istraživanje fotokemijske reaktivnosti tih spojeva. Novopripravljene molekule su ftalimidni derivati adamantanskih aminokiselina, pri čemu je istražen utjecaj udaljenosti između ftalimidnog kromofora (akceptor elektrona) i karboksilne skupine (donor elektrona) na učinkovitost fotoinduciranog prijenosa elektrona (PET) i dekarboksilacije. Udaljenost tih skupina ima značajan utjecaj na učinkovitost dekarboksilacije istraživanih spojeva, a intramolekulski PET je najsporiji stupanj cijelog procesa. Nadalje, istražen je i utjecaj različitih supstituenata vezanih na položaju 4 ftalimidnog kromofora na fotofizička svojstva i fotokemijsku reaktivnost. Ftalimide s elektron-donorskim supstituentom općenito karakterizira reaktivnost i iz singletnog i iz tripletnog pobuđenog stanja. Fluorescencija tih spojeva je u kompeticiji s PET-om, a populacija tripletnog pobuđenog stanja u odsutnosti senzibilizatora je neučinkovita. S druge strane, ftalimidi s elektron-akceptorskim supstituentom reagiraju uglavnom iz tripletnog pobuđenog stanja. Međutim, nitro-derivat je drukčiji budući da ima reaktivnost karakterističnu za nitrobenzenski kromofor. Istraživan je i utjecaj supramolekulske kontrole s ciklodekstrinima (CD) na [3 + 2] cikloadiciju alkena i fotogeneriranih azometin-ilida iz odabranih ftalimida. Kompleksiranjem adamantilftalimidnog derivata s β-CD povećava se iskorištenje adukata.In this PhD thesis synthesis of new phthalimide derivatives and study of their photochemical reactivity are described. Newly synthesized molecules are phthalimide derivatives of adamantane amino acids, where an influence of the distance between the phthalimide (electron acceptor) and the carboxylate (electron donor) on photoinduced electron transfer (PET) and decarboxylation efficiency was investigated. The distance between these groups in the investigated compounds has a significant influence on the decarboxylation efficiency, while PET is the rate-determining step of the whole process. Moreover, study of the influence of different substituents attached to the position 4 of the phthalimide chromophore on the photophysical properties and photochemical reactivity was conducted. The phthalimides bearing electron-donating substituents are generally characterized by reactivity from both singlet and triplet excited states. The fluorescence from these compounds is in competition with PET, and triplet excited state population in the absence of a sensitizer is inefficient. On the contrary, phthalimides bearing electron-withdrawing substituents react mostly from the triplet excited state. However, the nitro derivative is different since it exhibits typical reactivity of the nitrobenzene chromophore. The effect of supramolecular control with cyclodextrins (CD) on [3 + 2] cycloaddition of alkenes and photogenerated azomethine ylides from selected phthalimides was described. Complexation of adamantylphthalimide derivative with β-CD increased the yield of adducts
