2,2′‐Diamino‐6,6′‐diboryl‐1,1′‐binaphthyl: A Versatile Building Block for Temperature‐Dependent Dual Fluorescence and Switchable Circularly Polarized Luminescence

Temperature‐dependent dual fluorescence and switchable circularly polarized luminescence (CPL) are two highly pursued but challenging properties for small organic molecules (SOMs). We herein disclose a triarylborane π‐system based on a 2,2′‐diamino‐6,6′‐diboryl‐1,1′‐binaphthyl scaffold that can serve as a versatile building block for achieving these two properties by simply choosing different amino groups. BNMe₂‐BNaph with less bulky dimethylamino groups displays temperature‐dependent dual fluorescence, and can thus be used as a highly sensitive ratiometric fluorescence thermometer. On the other hand, BNPh₂‐BNaph with bulky diphenylamino groups exhibits intense fluorescence in both solution and in the solid state. A change of solvent from nonpolar cyclohexane to highly polar MeCN not only shifts the CPL position to much longer wavelength but also inverts the CPL sign. In addition, the complexation of BNPh₂‐BNaph with fluoride greatly enhances the CPL intensity.     

Boosting Electrochemical CO2 Reduction on Metal–Organic Frameworks via Ligand Doping

Electrochemical CO₂ reduction relies on the availability of highly efficient and selective catalysts. Herein, we report a general strategy to boost the activity of metal–organic frameworks (MOFs) towards CO₂ reduction via ligand doping. A strong electron‐donating molecule of 1,10‐phenanthroline was doped into Zn‐based MOFs of zeolitic imidazolate framework‐8 (ZIF‐8) as CO₂ reduction electrocatalyst. Experimental and theoretical evidences reveal that the electron‐donating nature of phenanthroline enables a charge transfer, which induces adjacent active sites at the sp² C atoms in the imidazole ligand possessing more electrons, and facilitates the generation of *COOH, hence leading to improved activity and Faradaic efficiency towards CO production.     

Thermally Activated Delayed Fluorescence in an Organic Cocrystal: Narrowing the Singlet–Triplet Energy Gap via Charge Transfer

Harvesting non‐emissive spin‐triplet charge‐transfer (CT) excitons of organic semiconductors is fundamentally important for increasing the operation efficiency of future devices. Here we observe thermally activated delayed fluorescence (TADF) in a 1:2 CT cocrystal of trans‐1,2‐diphenylethylene (TSB) and 1,2,4,5‐tetracyanobenzene (TCNB). This cocrystal system is characterized by absorption spectroscopy, variable‐temperature steady‐state and time‐resolved photoluminescence spectroscopy, single‐crystal X‐ray diffraction, and first‐principles calculations. These data reveal that intermolecular CT in cocrystal narrows the singlet–triplet energy gap and therefore facilitates reverse intersystem crossing (RISC) for TADF. These findings open up a new way for the future design and development of novel TADF materials.     

Ladungstransfer durch die DNA: Vom Mechanismus zur Anwendung

DNA charge transfer chemistry has been subject of considerable interest with consequences in the formation of oxidative damage to the DNA which can result in mutagenesis or carcinogenesis. In this article, important examples of spectroscopical and biochemical assays are compared and discussed in terms of the effiencies, rates, and mechanisms. Coupled with the demonstration that such charge transfer can be modulated both negatively and positively by DNA‐binding proteins, these observations therefore suggest the intriguing possibility that DNA‐mediated charge transfer chemistry is biological relevant and may play a role in cellular processes. Additionally, charge transfer chemistry plays a growing role in the recent development of DNA chips detecting mutations or lesions of nucleic acids.