Room temperature phosphorescence lifetime and spectrum tuning of substituted thianthrenes

Piotr Pander,Agnieszka Swist,Jadwiga Soloducho,Fernando B Dias

doi:10.1016/j.dyepig.2017.03.049

Abstract

A group of thianthrene derivatives has been studied to investigate the effect of different substituents and substitution positions on their photophysical behavior. Strong room temperature phosphorescence (RTP) and dual fluorescence-phosphorescence at room temperature (RT-DFP) have been observed. Compounds with efficient (Φ ≈ 0.4) yellow and long-lived (τ = 88 ± 6 ms) green phosphorescence have been characterized. The involvement of nπ* and ππ* states was evaluated to explain their high triplet formation yield and phosphorescent properties. To give an insight into electron properties of studied molecules cyclic voltammetry and DFT calculations have been performed.

Highlights

Thianthrene is a heterocyclic analog of anthracene but with two sulfur atoms substituting carbon atoms at the 9,10-positions
In this study we present a group of thianthrene derivatives (Scheme 1) examining the effect of both the substitution positions and the type of substituent on their room temperature phosphorescent properties
Our results enabled us to understand the structure-property relationships in the room temperature phosphorescence (RTP) and RT-DFP systems based on thianthrene to further optimize the efficiency and performance of these emitters in future applications

Summary

Introduction

Thianthrene is a heterocyclic analog of anthracene but with two sulfur atoms substituting carbon atoms at the 9,10-positions. This structure leads to a bent, non-aromatic geometry of the central thianthrene ring [1e3]. Thianthrenes are commonly known due to their interesting electrochemical properties [3e7] and quite well studied chemistry [2,3,6,8]. Phosphorescent properties of thianthrene crystals have already been demonstrated [1], but no study has been performed on its derivatives. Of particular interest are the room temperature phosphorescent (RTP) properties of thianthrene, which suggests this group can be used to promote dual fluorescence-phosphorescence at room temperature in its derivatives, which brings additional interest on thianthrene based compounds. The observation of dual luminescence [14] e.g. dual fluorescence-phosphorescence emissions at room temperature, (RT-DFP), enhances the possibility to achieve tunable luminescent characteristics under external stimuli, which expands the potential of these compounds in photonic and optoelectronic applications

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Results