A new cobalt-catalyzed coupling of aryl halides with thiophenols and alkanethiols is reported. A variety of aryl sulfides can be prepared in excellent yields under mild reaction conditions using 1-2 mol % of CoI2(dppe) and Zn. This new cobalt-catalyzed coupling represents an interesting addition to previously known methods to synthesize thioethers. [reaction: see text].

Cesium lead halide perovskite nanocrystals have been the first time utilized as photocatalysts for organic bond formations.

Metal halide perovskites have demonstrated rich photophysics and remarkable potential in photovoltaic and electroluminescent devices. However, the photoactivity of perovskite semiconductors in chemical processes remains relatively unexplored. Here, a general approach toward the synthesis of luminescent perovskite-polymer nanocomposites is reported, whereby perovskite nanocrystals are used as photoinitiators in the polymerization of vinyl monomers. The white-light illumination of a perovskite-monomer mixture triggers a free-radical chain-growth polymerization process, giving rise to high molecular weight polymers of ≈200 kDa. The in situ growth of polymer chains from the perovskite crystal surface allows the formation of individually dispersed nanocrystal cores within an encapsulating polymer matrix, and leads to a significant threefold enhancement in photoluminescence quantum yield. This photoluminescence enhancement is attributed to the spatial separation of the perovskite nanocrystals and hence the deactivation of energy transfer to dark crystals. The resulting perovskite-polymer nanocomposites exhibit excellent stability against moisture and are shown to be useful as functional downconversion phosphor films for luminescent displays and lighting.

facile bandgap tuning. Earlier works on photovoltaics rely on lead iodide and lead bromide based perovskites to achieve devices with different light-absorption profile and open-circuit voltages. [1,17] However, the true benefit of bandgap tuning is realized in lightemitting devices, where strong and narrow line-width emission can be conveniently produced across an extensive ultraviolet to visible to near-infrared spectral region. [6,18] The tailoring of perovskite bandgap and light-emission profile is typically achieved through the variation of halides (i.e., chloride, bromide, or iodide) in the chemical precursors, or via postsynthetic halide exchange. Various strategies for halide exchange have been reported in the literature, [19][20][21][22] and are typically attributed to a direct exchange of anionic halide species. Here, we report a photo-activated halide exchange process between cesium lead halide perovskite nanocrystals and a variety of molecular haloalkanes to achieve full spectral tuning in the visible region. We show, through detailed mechanistic studies, that this process is surface-mediated and involves the photo-activated breakage of covalently linked carbon-halogen bonds. This is consistent with our earlier reports, where we show that perovskite nanocrystals are capable of performing surface-mediated photocatalytic reactions. [23,24] Crucially, we demonstrate that our halide exchange approach could be employed in the micrometer-sized patterning of perovskite films to achieve trichromatic light emission, which has important utility in the manufacturing of functional color displays.We prepared luminescent cesium lead bromide (CsPbBr 3 ) nanocrystals following literature-reported methods, [25] and dispersed the nanocrystals into dichloromethane (DCM) solvent. We added 0.007 m of thiophenol into the solution, which we show in our previous work [23] is capable of enhancing the photo luminescence (PL) of the perovskite nanocrystals. The solution was then illuminated with a coiled white LED strip (1 m, 9 W). The reaction progress was tracked by extracting aliquots of the reaction mixture at timed intervals, followed by the measurement of their PL spectra.As shown in Figure 1a, the PL of the nanocrystal solutions blueshifted monotonically from 523 nm (green) at 0 h to 447 nm (blue) at 8 h. This observation suggests that the bromide ions in CsPbBr 3 were progressively replaced by chloride Lead halide perovskite possesses a semiconductor bandgap that is readily tunable by a variation in its halide composition. Here, a photo-activated halide exchange process between perovskite nanocrystals and molecular haloalkanes is reported, which enables the perovskite luminescence to be controllably shifted across the entire visible spectrum. Mechanistic investigations reveal a mutual exchange of halogens between the perovskite crystal surface and a chemisorbed haloalkane, yielding nanocrystals and haloalkanes with mixed halide contents. Exchange kinetics studies involving primary, secondary, and tertiary haloalkanes sho...

We have discovered a novel series of quinazoline-based CXCR4 antagonists. Of these, compound 19 mobilized CXCR4(+) cell types, including hematopoietic stem cells and endothelial progenitor cells, more efficiently than the marketed 1 (AMD3100) with subcutaneous administration at the same dose (6 mg/kg) in mice. This series of compounds thus provides a set of valuable tools to study diseases mediated by the CXCR4/SDF-1 axis, including myocardial infarction, ischemic stroke, and cancer metastasis. More importantly, treatment with compound 19 significantly lowered levels of blood urea nitrogen and serum creatinine in rats with renal ischemia-reperfusion injury, providing evidence for its therapeutic potential in preventing ischemic acute kidney injury. CXCR4 antagonists such as 19 might also be useful to increase circulating levels of adult stem cells, thereby exerting beneficial effects on damaged and/or inflamed tissues in diseases that currently are not treated by standard approaches.