Efficient Purely Organic Room-Temperature Phosphorescence from Selenium-Containing Conjugated Polymers for Signal-Amplified Oxygen Detection

Abstract

Purely organic room-temperature phosphorescent (RTP) polymers with good processability and flexibility over small molecular crystals are highly attractive. Although many non-conjugated polymers (non-CPs) with efficient RTP emission have been reported, the development of metal-free RTP CPs remains a formidable challenge. Herein, CPs with clear RTP emission in both doped and neat films are readily prepared by introducing a selenium-containing phenoselenazine unit into conjugated backbones. The resulting RTP CPs can achieve phosphorescence lifetimes ranging from microseconds to milliseconds and phosphorescence quantum yields of up to 17.2% in film states, representing the highest value for metal-free CPs. Moreover, these RTP polymer films can be used for ratiometric oxygen detection due to their sensitive RTP emission to oxygen. Remarkably, for the first time, these metal-free CPs demonstrate significant phosphorescent signal amplification with a Stern–Volmer quenching constant (K SV) value of up to 5.54 × 10–3 ppm–1, which is 250 times higher than that of their molecule counterpart.

Synthesis of Two Isomers of pyrido/benzo[b][1,4]selenazines: A Selective Catalyst‐Dependent Formation of C−N and C‐Se Bonds

“…Since the best reaction condition has been stablished, we turned our attention to explore the scope of the reaction using different diselenides 1 a-d and several 1,3-dicarbonyl compounds 2 a-q, leading to a series of novel pyrido/benzo [1,4] e)) groups were attached to the benzene ring, the selenazine products were isolated in similar yields. A slightly decrease in the product yield was observed when the strongly electron-withdrawing trifluoromethyl group was present, giving 3 f in 61% yield.…”

“…The synthesis of selenium-functionalized heterocycles is of growing interest due to their widespread applications as synthetic intermediates, [1] optoelectronic devices, [2] and pharmacologically active compounds. [3] Among them, benzo[1,4]selenazine derivatives, bearing a selenium and a nitrogen atom organized in a six-membered ring fused to a benzene unit, found synthetically usefulness in the preparation of functional organic materials, [4] and have also received special attention in medicinal chemistry as antitubercular agent, [5] and multi-targeting drug to treat Alzheimer's disease [6] and microbial infections. [7] Despite the synthetic and pharmacological importance of these compounds, efforts to obtain them are still scarce.…”

“…In 2006, Xu and Zhang depicted the synthesis of 2H-1,4-benzoselenazin-3(4H)-ketoximes promoted by SmI 2 from bis(o-nitrophenyl) diselenide and βnitroethylenes (Scheme 1a). [8] Later on, Viglianisi (2012) [9a] and Menichetti (2016) [9b] reported the access to benzo[b] [1,4]selenazines via a Cu(OTf) 2 -catalyzed [4 + 2] cycloaddition reaction of 2-N-sulfonylamino diselenides with electron rich alkenes (Scheme 1b). More recently, our research group demonstrated a simple and efficient way to synthesize diverse bis(2pyridyl) diselenides.…”

“…[11] The low cost, ability to vary its oxidation state, and environmental sustainability, may represent attractive aspects involved in the application of iodine as a useful alternative to transition-metal catalysts. [12] In this context, we report the first access to two different pyrido/benzo [1,4]selenazine isomers on a catalyst-dependent selective reaction. To achieve this goal, bis(3-amino-2-pyridyl/2-aminophenyl) diselenides and readily available 1,3-dicarbonyl compounds were employed as reagents (Scheme 1d).…”

Recent Advances of Pure Organic Room Temperature Phosphorescence Based on Functional Polymers

“…(f) Molecular design of P­(PSeZ-Ph), P­(PseZ-DMPh), and P­(PSeZ-TMPh) toward efficient RTP. Reproduced with permission from ref . Copyright 2023 American Chemical Society.…”