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This project received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreements No. 716139 and No. 677023), the Swiss National Science Foundation (SNSF, PP00P2_170534, PP00P2_198900), Project PGC2018-101181-B-I00 funded by MCIN/AEI/ 10.13039/501100011033 FEDER "Una manera de hacer Europa", grant A-FQM-230-UGR20 funded by FEDER/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades and the German Academic Exchange Service (DAAD, postdoc fellowship to D. G.). Open access funding provided by the University of Zurich., We present the concept of combining circularly polarized luminescence (CPL) and excited-state intramolecular proton transfer (ESIPT) features into a single molecule as a strategy to generate high-performance ESIPT-based CPL materials. For this purpose, a [6]helicene bearing two ESIPT structural units was synthesized using a double Suzuki-Miyaura reaction and a double C(sp(2))-H hydroxylation approach. The photophysical properties of the doubly hydroxylated [6]helicene were studied in parallel with a non-hydroxylated [6]helicene control compound, revealing that the presence of a chiral [6]helicene unit results in a strong CPL response and the presence of the ESIPT units in a considerable red shift. The red-shifted emission along with the outstanding g(lum) (approximate to 10(-2)) and a large Stokes shift makes the doubly hydroxylated [6]helicene a promising candidate for use in optoelectronics., European Research Council (ERC) 716139 677023, Swiss National Science Foundation (SNSF) PP00P2_170534 PP00P2_198900, Deutscher Akademischer Austausch Dienst (DAAD), University of Zurich, MCIN/AEI FEDER "Una manera de hacer Europa" PGC2018-101181-B-I00, FEDER/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades A-FQM-230-UGR20

Within this thesis, novel, purely organic luminophores were synthesized and investigated towards their photophysical properties. The luminescence originates from an intramolecular proton transfer in the energetically excited state, which is referred to as “Excited-State Intramolecular Proton Transfer“ (ESIPT). The incorporation of the central phenolic hydroxy group was realized by the development of a mild late-stage hydroxylation method. The directed ortho C(sp2)–H magnesiation on 2-aryloxazolines and subsequent oxidation using molecular oxygen or air was highly efficient. In addition to the high regio- and chemoselectivity, an ample range of functional groups were tolerated under the mild reaction conditions. The efficiency of this method was highlighted by the use of sustainable oxygen sources as oxidants and the implementation at ambient temperature. The isolated phenols strongly differ in their emission properties depending on the substitution pattern and the size of the π-system. In order to give a general statement towards emission tendencies, a panoply of luminophores were investigated in both solution and the solid state. In particular, minimalistic benzene-based fluorophores bearing nitrile substituents showed extremely high emission efficiencies. Quantum yields of up to 87.3 % in the solid state and strong π-π-interactions were found. In addition, ESIPT-based luminophores bearing electron-donating or -withdrawing groups were investigated towards their emission potency. As a consequence, electron poor aromatic compounds exhibited a greater emission potential. Another priority was the modification of fluorenes with π-expanded proton acceptors. The tuning of the emission color was easily achieved through chalcogen atom insertion into the benzazolebased proton acceptors. Additionally, a mild and regioselective ortho-functionalization method of fluorenes was developed, which enabled the covalent linkage of these chromophores on superior structures.

The direct hydroxylation of 2-aryloxazolines via a deprotonative magnesiation using TMPMgCl·LiCl and subsequent oxidation with molecular oxygen or air as a green oxidant is reported. This method proceeds under mild conditions at room temperature with high regioselectivity and chemoselectivity. The obtained phenols exhibit tunable luminescence properties, induced by excited-state intramolecular proton transfer. This method opens a new opportunity for the sustainable synthesis of luminescent organic molecules.