Aneta Slodek

NCN-Coordinating Ligands based on Pyrene Structure with Potential Application in Organic Electronics

Five novel derivatives of pyrene, substituted at positions 1,3,6,8 with 4-(2,2-dimethylpropyloxy)pyridine (P1), 4-decyloxypyridine (P2), 4-pentylpyridine (P3), 1-decyl-1,2,3-triazole (P4), and 1-benzyl-1,2,3-triazole (P5), are obtained through a Suzuki-Miyaura cross-coupling reaction or CuI -catalyzed 1,3-dipolar cycloaddition reaction, respectively, and characterized thoroughly. TGA measurements reveal the high thermal stability of the compounds. Pyrene derivatives P1-P5 all show photoluminescence (PL) quantum yields (Φ) of approximately 75 % in solution. Solid-state photo- and electroluminescence characteristics of selected compounds as organic light-emitting diodes are tested. In the guest-host configuration, two matrixes, that is, poly(N-vinylcarbazole) (PVK) and a binary matrix consisting of PVK and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) (50:50 wt %), are applied. The diodes show red, green, or blue electroluminescence, depending on both the compound chemical structure and the actual device architecture. In addition, theoretical studies (DFT and TD-DFT) provide a deeper understanding of the experimental results.

Luminescent-Substituted Fluoranthenes-Synthesis, Structure, Electrochemistry, and Optical Properties

Six novel fluoranthene derivatives, namely, three terminally substituted and three bis(fluoranthene) units with fluorene, bithiophene, and carbazole spacers, were obtained through [2+2+2] cycloaddition and characterized completely. Based on the conducted studies, the obtained derivatives can be classified as donor-acceptor (D-A) and acceptor-donor-acceptor (A-D-A) systems, in which the fluoranthene unit acts as an electron-withdrawing unit. The optical results revealed that novel fluoranthene derivatives absorb light in the range λ=236-417 nm, which originates from a π→π* transition within the conjugated system. The compounds exhibit fluorescence that range from deep blue to green, which mainly arises from intramolecular charge transfer (ICT) states. High Stoke shifts and high quantum yields in solution (ϕ=0.22-0.57) and in the solid state (ϕ=0.18-0.44) have been observed for fluoranthene derivatives. All the derivatives display multistep oxidation processes at low potentials. The electronic structure of the presented compounds is additionally supported by time-dependent DFT computations.