Naujų pirimidino - fenoksazino TADF spinduolių sintezė ir tyrimas /

Thermally activated delayed fluorescence (TADF) is an attractive way to achieve 100% internal fluorescence quantum yield without involving any expensive heavy atoms by converting all excitations to singlet ones by thermal activation. Usually, this is achieved by constructing TADF molecules with electron-donating and –accepting fragments, decreasing the spatial overlap of electron density distribution in highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbitals (LUMO). This results in narrowing the singlet-triplet energy gap (ΔEST) up to values, comparable to thermal energy at room temperature. Recently, compounds containing pyrimidine heterocycle as an acceptor unit have been demonstrated to be efficient TADF materials for OLED application. Seeing the potential of phenoxazine-pyrimidine pair for achieving efficient TADF, the aim of the present work was design, synthesis and photophysical characterization of some novel phenoxazine-pyrimidine conjugates bearing methyl group in the 5th position of pyrimidine ring and different substituents in the 2nd position of pyrimidine ring, and with or without methyl groups in a phenyl spacer. Synthesis of the target compounds and some intermediates was carried out starting from an easily accessible 4,6-diodo-5-methyl-2-methylthiopyrimidine by a combination of Buchwald-Hartwig, Suzuki-Miyaura and Liebeskind-Srogl palladium-catalyzed cross-coupling reactions. Synthesis protocol and convenient methods of synthesis of 4,6-di[4-(10-phenoxazinyl)phenyl]-5-methyl-2-methyltiopyrimidines were elaborated. Eleven new compounds were synthesized and characterized. Their structures were confirmed by 1H-, 13C-NMR and HRMS spectroscopies. Optical properties of the synthesized materials were assessed by DFT calculations and investigated by absorption, fluorescence and phosphorescence spectroscopies in toluene solutions, in solid state and in air, and oxygen-free conditions, Fluorescence quantum yield, ΔEST of the synthesized pyrimidine-phenoxazine conjugates were determined. It was shown that the investigated materials are TADF emoitters. Their fluorescence wavelengths depend on substituents at the 2nd position of pyrimidine ring and in phenyl spacer, what allows to expect that modifying emitter structure it is possible to create TADF emitters of various colours for application in OLED technology.

Grantor dc:publisher

Institutional Repository of Vilnius University

Year dc:date

2021

Author dc:creator

• Šapalaitė, Toma,

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

lit

Repository record dc:identifier

https://repository.vu.lt/VU:ELABAETD193234458&prefLang=en_US

OAI identifier oai:identifier

oai:vu.lt:elaba:193234458