Very sensitive probes for quantitative and organoleptic detection of oxygen based on conformer-induced room-temperature phosphorescence enhancement of the derivative of triazatruxene and phenothiazine

Organic materials which show room-temperature phosphorescence (RTP) are of interest for many applications including chemical qubits which are the core units of a quantum information systems, organic light emitting diodes, chemical sensors. In contrast to triplet emitters based on noble metals (e.g. Ir, Rh), quantum yields of RTP of noble-atom-free organic emitters are much lower than unity. In this work, we report on a new approach to conformer-induced RTP enhancement of organic triplet emitters. The synthesis, thermal, photophysical, charge-transporting and oxygen sensing properties of the derivative of phenothiazine and triazatriazatruxene in which phenothiazine moieties are linked to nitrogen atoms of triazatriazatruxene via C-2 positions are presented. This compound exhibit stable RTP with a quantum yield of 54% which is more than six times higher than that of a reference material. For 1% solid solution of the compound in Zeonex, the ratio of intensity of RTP observed under vacuum and fluorescence intensity recorded in air reached the value of 19 which allows quantitative detection of oxygen with the high Stern-Volmer quenching constant of 7.83×10 -3 ppm -1 . The observed change of emission colour depending on the oxygen concentration can be used for the simple detection of oxygen by human eye. • A new approach to conformer-induced room-temperature phosphorescence enhancement for materials without noble metal complexes • Noble-atom-free compound with stable room-temperature phosphorescence with a quantum yield of 54% • High ratio of intensities of room-temperature phosphorescence versus fluorescence recorded in air reaching 19 • Among state-of-art value of Stern-Volmer quenching constant for oxygen probes of optical sensors of 7.83×10 -3 ppm.