Enhanced brightness and electron affinity of terrylenediimide with sulfone-bridged substituents on the bay region

A nine-ring fused terrylene diimide exhibits switching between red TADF and near-IR room temperature phosphorescence

Herein, we report the first example of a terrylene diimide derivative that switches emission between thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) in the red region. By design, the molecule TDI-cDBT boasts a symmetrical, consecutively fused nine-ring motif with a kite-like structure. The rigid core formed by the annulated dibenzothiophene moiety favoured efficient intersystem crossing and yielded a narrow-band emission with a full-width half maxima (FWHM) of 0.09 eV, along with high colour purity. A small ΔE S1-T1 of 0.04 eV facilitated thermally activated delayed fluorescence, enhancing the quantum yield to 88% in the red region. Additionally, it also prefers a direct triplet emission from the aggregated state. The room temperature phosphorescence observed from the aggregates has a longer emission lifetime of 1.8 ms, which is further prolonged to 8 ms at 77 K in the NIR region. Thus, the current strategy is successful in not only reducing ΔE S1-T1 to favour TADF but also serves as a novel platform that can switch emission from TADF to RTP depending upon the concentration.

Double [4]Helicene-like Naphthobisbenzothiophene Diimides and Their Thienyl-S,S-dioxidized Derivatives with Attractive Solid-State Fluorescence and High Electron Affinity

A series of double [4]helicene-like naphthobisbenzothiophene diimides and their thienyl-S,S-dioxidized derivatives are synthesized via MoCl₅-catalyzed cyclization and m-CPBA-mediated oxidation reactions. The functional five-membered ring diimides show a helicene-like geometry, strong solid-state fluorescence, and deep LUMO of -4.37 eV.

Photostable fluorescent probes based on multifunctional group substituted naphthalimide dyes for imaging of lipid droplets in live cells

We designed and synthesized multifunctional group substituted naphthalimide (MFGNI) dyes by introducing glycine ethyl ester and azetidine on 1,8-naphthalimide. With different azetidine substituents, the emission of the MFGNI dyes was shifted from blue to green. These MFGNI dyes exhibited high photoluminescence quantum yields (61% to 85%) and large Stokes shifts (67 nm). The amides and hydroxyl groups improved the photostability of the MFGNI dyes. Due to the small molecular weight and lipophilic properties, these MFGNI dyes specifically stained lipid droplets in living cells.

Fluorescent probes based on multifunctional encapsulated perylene diimide dyes for imaging of lipid droplets in live cells

A multifunctional encapsulation strategy confers perylene diimide dyes with high brightness, live-cell permeability, excellent anti-oxidation and lipid droplet-specific staining ability.