In:
Journal of Materials Chemistry C, Royal Society of Chemistry (RSC), Vol. 9, No. 48 ( 2021), p. 17511-17517
Abstract:
A new pure organic donor–acceptor molecule, (4-chlorophenyl)(5 H -dibenzo[ b , f ]azepin-5-yl)methanone (IS-CBZ), was designed and synthesized, which demonstrates near ultraviolet (NUV) delayed fluorescence (DF) and dual emission of NUV DF and yellow room-temperature phosphorescence (RTP) in two crystals (B-crystal and Y-crystal), respectively. These two kinds of luminescence (DF and RTP) can be reversibly switched by external stimuli, such as grinding and heating/fuming, accompanied by reversible phase transition between two crystalline states. The experimental and theoretical studies reveal that this switchable luminescence between DF and RTP originates from a single-molecule conformational change in different molecular packings, mainly involving the twist angle ( θ ) between the donor and acceptor units. This θ fundamentally modulates the energy difference between the lowest singlet state (S 1 ) and the high-lying triplet state (T 2 ), Δ E S1–T2 , which determines the luminescence switching between DF and RTP. This work not only provides a new donor–acceptor architecture for pure organic multifunctional materials with mechanochromic luminescence (MCL) and mechanoluminescence (ML) properties, but also suggests a novel strategy to design stimuli-responsive materials with a unique luminescence switching between DF and RTP by tuning T 2 .
Type of Medium:
Online Resource
ISSN:
2050-7526
,
2050-7534
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2021
detail.hit.zdb_id:
2702245-6
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