Molecular designs merging circularly polarized luminescence (CPL) and thermally activated delayed fluorescence (CP-TADF) using the concept of chiral perturbation appeared recently as a cornerstone for the development of efficient CP-organic light emitting diodes (CP-OLED). Such devices could strongly increase the energy efficiency and performances of conventional OLED displays, in which 50% of the emitted light is often lost due to the use of antiglare filters. In this context, herein, ten couples of enantiomers derived from novel chiral emitter designs are reported, exhibiting CPL, TADF, and aggregation induced enhancement emission properties (AIEE). Representing the first structure properties relationship investigation for CP-TADF materials, this thorough experimental and theoretical work highlights crucial findings on the key structural and electronic parameters (isomerism, nature of the carbazole substituents) governing the synergy between CPL and TADF properties. To conclude this study, the first top emission CP-OLED is elaborated as a new approach of generating CP light in comparison with classical bottom-emission CP-OLED architecture. Indeed, the top-emission configuration represents the only relevant device architecture for future microdisplay applications. Thereby, in addition to offer molecular guidelines to combine efficiently TADF and CPL properties, this study opens new avenues toward practical applications for CP-OLEDs.
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A novel Zr‐chain based MOF, namely MIL‐163, was designed and successfully synthesized using a bis‐1,2,3‐trioxobenzene ligand. Endowed with large square‐shaped channels of 12 Å width, it shows remarkable water uptake (ca. 0.6 cm3 g−1 at saturating vapor pressure) and a remarkable stability in simulated physiological media, where archetypical Zr carboxylate MOFs readily degrade.
Countless people have been affected by the COVID‐19 pandemic on a global scale. Favipiravir, has shown potential as an effective drug for SARS‐CoV‐2, attracting scientists’ attention. However, overuse of Favipiravir easily leads to serious side effects, requiring real‐time monitoring in body fluids. Given this, a new lanthanide metal‐organic framework (MOF) was prepared under solvothermal conditions from either Eu (Eu‐MOF or (1)) or Tb (Tb‐MOF or (2)) using the highly delocalized imidazoledicarboxylic acid linker H2L (H2L=5‐(4‐(imidazol‐1‐yl) phenyl) isophthalic acid) and could be successfully applied to selective optical detection of Favipiravir. In this MOF framework, the organic linker H2L provides a high excitation energy transfer efficiency that can sensitize luminescence in lanthanides. In addition, through deliberate tuning of Eu/Tb molar ratio and reaction concentration in the lanthanide framework, ratiometric recyclable luminescent EuxTb1‐x‐MOF nanoparticles with open metal sites have been constructed, which present a high detection sensitivity (Ksv=1×107 [M−1], detection limit is 4.63 nM) for Favipiravir. The detection mechanism is discussed with the help of Density Functional Theory (DFT) calculations that sheds light over the selective sensing of Favipiravir over other related COVID‐19 drug candidates. Finally, to explore the practical application of Favipiravir sensing, MOF based thin films have been used for visual detection of Favipiravir and recycled 5 times.
A new
donor–acceptor dyad composed of a BODIPY (4,4′-difluoro-4-bora-3a,4a-diaza-s-indacene) donor and a fullerene C60 acceptor
has been synthesized and characterized. This derivative has been prepared
using a clickable fullerene building block that bears an alkyne moiety
and a maleimide unit. The post-functionalization of the maleimide
group by a BODIPY thiol leads to a BODIPY-C60 dyad, leaving
the alkyne moiety for further functional arrangement. On the basis
of the combination of semi-empirical and density functional theory
(DFT) calculations, spectroelectrochemical experiments, and steady-state
and time-resolved spectroscopies, the photophysical properties of
this new BODIPY-C60 dyad were thoroughly studied. By using
semi-empirical calculations, the equilibrium of three conformations
of the BODIPY-C60 dyad has been deduced, and their molecular
orbital structures have been analyzed using DFT calculations. Two
short fluorescence lifetimes were attributed to two extended conformers
displaying variable donor–acceptor distances (17.5 and 20.0
Å). Additionally, the driving force for photoinduced electron
transfer from the singlet excited state of BODIPY to the C60 moiety was calculated using redox potentials determined with electrochemical
studies. Spectroelectrochemical measurements were also carried out
to investigate the absorption profiles of radicals in the BODIPY-C60 dyad in order to assign the transient species in pump–probe
experiments. Under selective photoexcitation of the BODIPY moiety,
occurrences of both energy and electron transfers were demonstrated
for the dyad by femtosecond and nanosecond transient absorption spectroscopies.
Photoinduced electron transfer occurs in the folded conformer, while
energy transfer is observed in extended conformers.
A facile efficient synthetic tool, Buchwald-Hartwig cross-coupling reaction, for the functionalization of 1,2,4,5-tetrazines is presented. Important factors affecting the Buchwald-Hartwig cross-coupling reaction have been optimized. Seven new donor-acceptor tetrazine molecules (TA1-TA7) were conveniently prepared in good to high yields (61%-72%). They have been subsequently engaged in inverse Electron Demand Diels-Alder (iEDDA) reaction with cyclooctyne. The photophysical and electrochemical properties of the new pyridazines have been studied. Some are fluorescent acting as turn-on probes. More importantly two pyridazines (DA3 and DA6) exhibit room temperature phosphorescence (RTP) properties.
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