Modeling Electron-Transfer Degradation of Organic Light-Emitting Devices.

The operational lifetime of organic light-emitting devices (OLEDs) is governed primarily by the intrinsic degradation of the materials. Therefore, a chemical model capable of predicting the operational stability is highly important. Here, a degradation model for OLEDs that exhibit thermally activated delayed fluorescence (TADF) is constructed and validated.

Benzothiazole Synthesis: Mechanistic Investigation of an In Situ-Generated Photosensitizing Disulfide.

The use of a visible light absorbing intermediate as a photosensitizer makes a chemical process simple and sustainable, obviating the need for the use of chemical additives. Herein, the formation of a photosensitizing disulfide in benzothiazole synthesis from 2-aminothiophenol and aldehydes was proposed and confirmed through in-depth mechanistic studies. A series of photophysical and electrochemical investigations revealed that an in situ-generated disulfide photosensitizes molecular oxygen to generate the key oxidants, singlet oxygen and superoxide anion, for the dehydrogenation step.

Conformation-dependent degradation of thermally activated delayed fluorescence materials bearing cycloamino donors.

Organic light-emitting devices (OLEDs) containing organic molecules that exhibit thermally activated delayed fluorescence (TADF) produce high efficiencies. One challenge to the commercialization of the TADF OLEDs that remains to be addressed is their operational stability. Here we investigate the molecular factors that govern the stability of various archetypal TADF molecules based on a cycloamino donor-acceptor platform.

Visible-Light-Induced Trifluoromethylation of Unactivated Alkenes with Tri(9-anthryl)borane as an Organophotocatalyst.

Tri(9-anthryl)borane was successfully applied as an organophotocatalyst for the visible-light-induced trifluoromethylation of unactivated alkenes with CFI. The mild reaction conditions tolerated a variety of functional groups, and the reaction could be extended to perfluoroalkylations with CFI and CFI. Mechanistic studies revealed that the photoredox catalysis involves an oxidative quenching pathway.

Generation of N-Centered Radicals via a Photocatalytic Energy Transfer: Remote Double Functionalization of Arenes Facilitated by Singlet Oxygen.

An unprecedented approach to the generation of an N-centered radical via a photocatalytic energy-transfer process from readily available heterocyclic precursors is reported, which is distinctive of the previous electron transfer approaches. In combination with singlet oxygen, the in-situ-generated nitrogen radical from the oxadiazoline substrate in the presence of fac-Ir(ppy) undergoes a selective ipso addition to arenes to furnish remotely double-functionalized spiro-azalactam products. The mechanistic studies provide compelling evidence that the catalytic cycle selects the energy-transfer pathway.

Visible light-driven photogeneration of hydrogen sulfide.

The combined use of a singlet oxygen photosensitizer and 1,3-diarylisobenzothiophene enables efficient generation of hydrogen sulfide under visible light illumination.

Low-Affinity Zinc Sensor Showing Fluorescence Responses with Minimal Artifacts.

The study of the zinc biology requires molecular probes with proper zinc affinity. We developed a low-affinity zinc probe (HBO-ACR) based on an azacrown ether (ACR) and an 2-(2-hydroxyphenyl)benzoxazole (HBO) fluorophore. This probe design imposed positive charge in the vicinity of a zinc coordination center, which enabled fluorescence turn-on responses to high levels of zinc without being affected by the pH and the presence of other transition-metal ions.