Moving Beyond Boron-Based Substituents To Achieve Phosphorescence in Tellurophenes

Abstract

Previous research in our group showed that tellurophenes with pinacolboronate (BPin) units at the 2- and/or 5-positions displayed efficient phosphorescence in the solid state, both in the presence of oxygen and water. In this current study, we show that luminescence from a tellurophene is possible when various aryl-based substituents are present, thus greatly expanding the family of known (and potentially accessible) Te-based phosphors. Moreover, for the green phosphorescent perborylated tellurium heterocycle, 2,3,4,5-TeCBPin (4BTe), oxygen-mediated quenching of phosphorescence is an important contributor to the lack of emission in solution (when exposed to air); thus, this system displays aggregation-enhanced emission (AEE). These discoveries should facilitate the future design of color tunable tellurium-based luminogens.

Phosphorescence Through Hindered Motion of Pure Organic Emitters

“…More recently, Rivard and co‐workers expanded their scope by introducing fluorinated aromatic compounds, naphthalenes, and fluorene instead of pinacolboranate esters moieties leading to emission in the orange to red spectrum as well . Interestingly, only the tellurophenes containing trifluormethylated benzenes show satisfactory photophysical properties with an overall quantum yield of 9.5 %, a lifetime of 29.3 μs, and an emission at 595 nm, whereas the emission of the bare naphthalene‐ and fluorine‐substituted tellurophenes was significantly red‐shifted, but the QY turned out to be too low to be detected.…”

New Light on an Old Story: Breaking Kasha’s Rule in Phosphorescence Mechanism of Organic Boron Compounds and Molecule Design

“…In recent years, luminescent organoboron compounds have become the focus of investigations because of their promising luminescent properties [ 2 , 18 , 19 , 20 , 21 , 22 ]. In 2017, Yu et al [ 23 ] synthesized the (E)-3-(((4-nitrophenyl)imino)methyl)-2H-thiochroman-4-olate-BF2 compound (S-BF2; see Figure 1 b) based on the parent molecule (E)-2-(((4-nitrophenyl)imino)-methyl)-naphthalen-1-olate-BF2 (C-BF2; Figure 1 a), and explored the photoluminescence (PL) mechanism experimentally and theoretically.…”

Understanding the Role of Chalcogens in Ether‐Based Luminophores with Aggregation‐Induced Fluorescence and Phosphorescence

“…Rivard and co‐workers were the first group to describe the use of tellurium for purely organic phosphors . To this end, a series of tellurophenes were synthesized showing striking phosphorescence emission with lifetimes in the microsecond range . This first example of the higher chalcogens as efficient AI emitters showed that the influence on the emission of these elements is poorly understood and requires further investigation.…”