Search

It is very challenging to obtain stable room‐temperature luminescent open‐shell singlet diradicals. Herein we report the first stable Müller's hydrocarbon TTM‐PhTTM with luminescent properties. Variable‐temperature electron paramagnetic resonance spectroscopy measurements and theoretical calculations show that TTM‐PhTTM has an open‐shell singlet ground state with a diradical character of 90 %. Because of a small singlet‐triplet energy gap, the open‐shell singlet ground state can be thermally excited to a triplet state. TTM‐PhTTM shows room‐temperature deep‐red emission in various solutions. Unusually high stability of TTM‐PhTTM was also observed owing to effective steric hindrance and spin delocalization. Our results are beneficial to the rational design and discovery of more stable luminescent diradical materials. [ABSTRACT FROM AUTHOR]

Triazole and phenanthroimidazole moieties are commonly used to construct efficient blue-emitting materials as acceptors and donors, respectively. Benefitting from the D–A coupling of the two moieties, two novel bipolar blue emitters, TAZ-PPI and 4NTAZ-PPI, were synthesized. They showed excellent thermal stability and high photoluminescence quantum yields (PLQYs). Non-doped blue organic light-emitting diodes (OLEDs) based on 4NTAZ-PPI and TAZ-PPI present maximum external quantum efficiencies of 7.3% and 5.9%, respectively, and exhibit negligible efficiency roll-off. The CIE coordinates are (0.149, 0.131) and (0.149, 0.130) at a luminance of 1000 cd m−2, respectively. Because the combination of electron donors and acceptors is a favorable method to balance the carrier injection and transport, 4NTAZ-PPI and TAZ-PPI exhibit excellent hole and electron transporting capabilities. [ABSTRACT FROM AUTHOR]

In this study, we reported two fluorescent triazole‐based molecules, NC‐TAZ and CC‐TAZ. Both possessed preferential detection of Fe3+ as a highly sensitive fluorimetric/colorimetric dual‐channel probe. As fluorimetric probe, the fluorescence quenched notably by adding Fe3+; as colorimetric probe, the obvious color change (colorless to yellow) could be observed during the detecting process. Moreover, the dual‐channel probe can exclude the interferences from other metal ions and various water samples. Owing to these outstanding merits, the probes could be used directly in the real water samples. Finally, the possible detection mechanism was studied and attributed to the formation of the complexes between NC‐TAZ/CC‐TAZ and Fe3+. [ABSTRACT FROM AUTHOR]

Luminescent radicals, whose emission comes from the doublet exited state, have potential application in the field of organic optoelectronics. However, few radicals show luminescence at room temperature. Herein, a new pure red-emissive biphenyl-type (N-pyrido[3,4-b]indolyl)bis(2,4,6-trichlorophenyl)methyl radical (PyID-BTM) is designed and synthesized, in which the carbazole moiety of CzBTM (a previously reported biphenylmethyl radical by our group) is successfully replaced by β-carboline. Its photophysical properties, including the ground and excited states, and the radiative and non-radiative processes are systematically investigated. The photoluminescence quantum efficiency (Φ = 19.5%) of PyID-BTM is ten times higher than that of CzBTM (Φ = 2.0%) in cyclohexane. The crystal structure, magnetic properties, photostability and electroluminescence performance of PyID-BTM are studied. An optimized OLED device using PyID-BTM as an emissive dopant showed pure red emission with CIE coordinates of (0.649,0.317) and a maximum EQE of 2.8%, and the formation ratio of doublet excitons was up to 70%. This study provides a new approach for designing high-performance luminescence biphenylmethyl radicals for applications in organic electroluminescence. [ABSTRACT FROM AUTHOR]

• Novel three-component conjugated polymers applied in DNT vapor detection. • P1 and P2 present almost instantaneous fluorescence quenching (<90%) to DNT vapor. • The sensors are promisingly applied for on-site and real-time detection to DNT. Two novel three-component conjugated polymers, P1 and P2 , composed of fluorene, carbazole and anthracene / pyrene units, were designed and synthesized. After optimizing the ratio of these three components, their spin-coating films were prepared and used to detect nitro explosives in vapor phase, which present almost instantaneous fluorescence quenching (<90%) and high selectivity to 2, 4-dinitrotoluene (DNT) vapor. Moreover, the films presented outstanding reusability and their simple filter paper sensors have been applied in the visualized detection of DNT, which indicate their promising on-site and real-time detection to DNT. [ABSTRACT FROM AUTHOR]

Although neutral luminescent radicals have arisen much attention recently, their applications in fluorescence imaging are rarely reported due to their insolubility in water and weak luminescence in polar solvents. Herein, we encapsulated a luminescent radical and its precursor into nanoparticles (NPs) by an amphiphilic polymer matrix, DSPE-PEG 2000 , to avoid aggregation-caused quenching and poor solubility in water to further achieve its application in cell-imaging. The obtained radical NPs exhibited strong red emission, excellent stability and remarkable biocompatibility under physiological conditions. The radical NPs were incubated with live HCT116 cells and showed good cellular uptake, thus making fluorescence imaging possible in vitro. The results confirm the feasibility of stable neutral luminescent radical as a promising candidate for the application in fluorescence imaging. [Display omitted] • Radical nanoparticles consist of the luminescent radical and its precursor were encapsulated together within an amphiphilic polymer matrix at an optimized proportion. • Radical nanoparticles exhibited bright red emission and excellent biocompatibility. • Radical nanoparticles can be internalized into HCT116 cells and become a promising tool in fluorescence imaging. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • New AIE materials applied in DNT vapor based on films: For rapid DNT vapor detection, new AIE molecules BTT and BPT were designed and synthesized. • Rapid response: Only in 5 s, the fluorescence of BTT and BPT is quenched 68% and 61%, respectively, which are remarkable compared with other reported works. • On-site test: The filter papers and spin-films of BTT and BPT were chose for simplicity and rapid on-site test of DNT. Abstract New aggregation-induced emission (AIE) materials 4 - (3, 5- bis (4′-(1, 2, 2-triphenylvinyl)-[1, 1′-biphenyl]-4-yl)-4 H -1, 2, 4-triazol-4-yl)- N , N -diphenylaniline (BTT) and 9-(4-(3, 5-bis(4′-(1, 2, 2-triphenylvinyl)-[1, 1′-biphenyl]-4-yl)- 4 H -1, 2, 4-triazol-4-yl) phenyl)-9H-carbazole (BPT) are designed and synthesized, which contain triazole, tetraphenylethylene and electron donating units. Further, their spin-coated films are used as fluorescent probes to detect 2, 4-dinitrotoluene (DNT) vapor with rapid fluorescence response, high sensitivity, high selectivity and reutilization. Moreover, by comparing BTT and BPT with other similar molecules without AIE properties, the extrusive sensing performances of BTT and BPT can be attributed to the introduction of AIE units. [ABSTRACT FROM AUTHOR]

Stable open-shell luminescent radicals have recently attracted much attention due to their unique luminescence properties. However, a radical molecule with both Kasha and anti-Kasha doublet emission properties has not been reported. Herein, we have successfully synthesized a stable chlorine-substituted Chichibabin's hydrocarbon, TTM-TTM, along with its mono-radical counterpart, TTM-HTTM. The emission of TTM-TTM follows Kasha's rule in the near infrared region. However, TTM-HTTM shows dual channel doublet emissions of Kasha and anti-Kasha. Remarkably, these two types of emission compete dynamically in both solution and condensed states. Our findings provide valuable insights into the rational design and discovery of stable radicals that possess distinctive luminescent properties, thus broadening the horizons of luminescent materials research., (© 2024 Wiley‐VCH GmbH.)

Organic light-emitting radicals have developed rapidly due to their unique doublet emission and great potential in display technology. Although some organic light-emitting diodes (OLEDs) exploiting small-molecular radicals as the emitters have been reported, there is no report about the polymer-radical-based OLEDs until now. Herein, a kind of polymer radical, PS-CzTTM, is adopted as the emitter to fabricate solution-processed OLEDs. A maximum external quantum efficiency of 3.0% is achieved for a deep-red device with an emissive layer of PS-CzTTM lightly doped in 2,2',2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1 H -benzimidazole) (TPBi). Temperature-dependent time-resolved photoluminescent spectra and transient electroluminescence of radical emitters and devices are first measured. The results demonstrate that the emission channels for both thin films and devices are from the transition of doublet excitons, indicating that the unique doublet emission mechanism of radicals is maintained in PS-CzTTM films and PS-CzTTM-based OLEDs.

A new luminescent radical, tris-2,4,6-trichlorophenylmethyl-1,5-diazarcarbazole (TTM-DACz), was synthesized and characterized. The photoluminescence quantum yield of TTM-DACz in solid 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene matrix film (5 wt %) is as high as 57.0%. Organic light-emitting diodes (OLEDs) employing TTM-DACz as the emitter were fabricated. By rational design of the device structure and host-guest doping system, external quantum efficiency (EQE) of up to 10.6% of the optimized device with a red CIE chromaticity of (0.62, 0.36) was obtained, which is among the highest values for red OLEDs using nonphosphorescent materials as the emitters. This work will accelerate the development of luminescent radical materials for high-performance OLEDs.