Bioorthogonal Phosphorogenic Rhenium(I) Polypyridine Sydnone Complexes for Specific Lysosome Labeling.

Invited for this month's cover is the group of Prof. Kenneth Kam-Wing Lo at City University of Hong Kong, Hong Kong, P. R. China. The cover picture shows the selective landing of a bioorthogonal spacecraft on a lysosomal planet modified with a strained cyclooctyne moiety in an intracellular environment with other organelles and a plethora of biomolecules. A sydnone moiety is appended to a luminescent rhenium(I) diimine unit as both an emission quencher and a bioorthogonal handle. Selective strain-promoted sydnone-alkyne cycloaddition (SPSAC) of the complex with a strained alkyne leads to impressive emission turn-on, which can be exploited in bioimaging and phototherapeutic applications. Read the full text of the article at 10.1002/cplu.202000029.

Bioorthogonal Phosphorogenic Rhenium(I) Polypyridine Sydnone Complexes for Specific Lysosome Labeling.

Many novel bioorthogonal reactions have been developed for labeling, such as the strain-promoted sydnone-alkyne cycloaddition (SPSAC), but sydnone-based probes with phosphorogenicity (i. e., phosphorescence turn-on upon reaction) have not been investigated to date. Herein, we report the synthesis, characterization, and photophysical properties of rhenium(I) polypyridine complexes containing a sydnone moiety as bioorthogonal phosphorogenic probes. Their reactions with strained alkyne derivatives and the associated photophysical changes were examined. Upon SPSAC with bicyclo[6.1.0]non-4-yn-9-ylmethanol (BCN-OH), the complexes exhibited emission enhancement in the range of 8.8 to 17.3. Importantly, conjugation of the complexes with BCN-modified bovine serum albumin (BCN-BSA) led to the increase in emission enhancement to as high as 38.9 and extended lifetimes in the range of 1.80 to 4.71 µs. Additionally, the bioorthogonal ligation of one of the complexes with a morpholine derivative was shown to induce specific lysosomal labeling in live cells; colocalization studies with LysoTracker Deep Red indicated a Pearson's coefficient of 0.83.

Phosphinoyl Radical-Initiated 1,2-Bifunctional Thiocyanodiphenylphosphinoylation of Alkenes.

1,2-Bifuctional thiocyanodiphenylphosphinoylation of alkenes is established through the phosphinoyl radical addition followed by Cu-catalyzed thiocyanation. This one-pot reaction is applicable to a range of aromatic, aliphatic, and cyclic alkenes to afford thiocyanodiphenylphosphinoylated compounds in satisfactory yields.

Phosphinoyl Radical Initiated Vicinal Cyanophosphinoylation of Alkenes.

A double-functionalization reaction of alkenes through Mn(OAc)3-mediated phosphinoyl radical addition followed by CuCN-catalyzed cyanation is introduced. This one-pot reaction is performed under mild conditions to afford vicinal cyanophosphinoylation products.

Phosphinoyl Radical-Initiated α,ß-Aminophosphinoylation of Alkenes.

A new double functionalization reaction of alkenes through AgNO3-mediated phosphinoyl radical addition followed by Cu(II)-catalyzed amination is introduced. This one-pot, three-component reaction is performed under mild conditions to afford α,ß-aminophosphinoylation products.

Ultralow-power near-infrared excited neodymium-doped nanoparticles for long-term in vivo bioimaging.

Lanthanide-doped luminescent nanoparticles with both emission and excitation in the near-infrared (NIR-to-NIR) region hold great promise for bioimaging. Herein, core@shell structured LiLuF4:Nd@LiLuF4 (named as Nd@Lu) nanoparticles (NPs) with highly efficient NIR emission were developed for high-performance in vivo bioimaging. Strikingly, the absolute quantum yield of Nd@Lu NPs reached as high as 32%. After coating with polyethylene glycol (PEG), the water-dispersible Nd@Lu NPs showed good bio-compatibility and low toxicity. With efficient NIR emission, the Nd@Lu NPs were clearly detectable in tissues at depths of up to 20 mm. In addition, long-term in vivo biodistribution with a high signal-to-noise ratio of 25.1 was distinctly tracked upon an ultralow-power-density excitation (10 mW cm-2) of 732 nm for the first time.

Air Oxidative Radical Oxysulfurization of Alkynes Leading to α-Thioaldehydes.

Air oxidative radical oxysulfurization of alkynes initiated by 0.5 mol % tert-butyl hydroperoxide with arylthiols is described. The reaction proceeded at room temperature in the presence of 5% mol water to afford selective α-thioaldehydes.

Upconversion of rare Earth nanomaterials.

Rare earth nanomaterials, which feature long-lived intermediate energy levels and intraconfigurational 4f-4f transitions, are promising supporters for photon upconversion. Owing to their unique optical properties, rare earth upconversion nanomaterials have found applications in bioimaging, theranostics, photovoltaic devices, and photochemical reactions. Here, we review recent advances in the photon upconversion processes of these nanomaterials. We start by considering energy transfer models involved in the study of upconversion emissions, as well as well-established synthesis strategies to control the size and shape of rare earth upconversion nanomaterials. Progress in engineering energy transfer pathways, which play a dominant role in determining upconversion emission outputs, is then discussed. Lastly, representative optical applications of these materials are considered. The aim of this review is to provide inspiration for researchers to explore novel upconversion nanomaterials and extended optical applications.

(E)-4-Chloro-2-{[4-(3,5-dichloro-pyridin-2-yl-oxy)phenyl-imino]-meth-yl}phenol.

In the title mol-ecule, C(18)H(11)Cl(3)N(2)O(2), the central benzene ring is oriented at 8.44 (12) and 70.57 (11)° with respect to the terminal chloro-phenol and dichloro-pyridine rings, respectively. The mol-ecular structure is stabilized by an intra-molecular O-H⋯N hydrogen bond, which generates an S(6) ring motif. In the crystal, π-π stacking between parallel pyridine rings is observed [centroid-centroid distance = 3.6561 (14) Å].

A facile synthesis of 2-aryloxypyrimidine derivatives via a tandem reductive amination/intermolecular S(N)Ar sequence.

A novel tandem reductive amination/intermolecular nucleophilic aromatic substitution (S(N)Ar) sequence has been established for the synthesis of amine containing pyrimidine in formation of one carbon-oxygen and one carbon-nitrogen bonds in a one-pot fashion. Treatment of aldehyde with arylamine, 2-methanesulfonyl-4,6-dimethoxypyrimidine and sodium borohydride provides good overall yield. The p-toluenesulfonic acid (PTSA) can be used as activator and is generally needed in the reaction. Dioxane is the preferred reaction solvent, but reactions can also be carried out in tetrahydrofuran (THF), MeCN, toluene and dichloromethane. The procedure is carried out effectively in the presence of K(2)CO(3). The reaction proceeds smoothly with aromatic aldehydes and arylamines possessing electron-donating or -withdrawing groups. This method can be applied to the synthesis of the oilseed rape herbicide and is superior to the classical one in several aspects: cutting out several purification steps, minimizing solvent use and chemical waste, and saving time. Its advantages such as operational convenience, high-efficient synthesis, and starting material availability make it a desirable method for preparing amines with molecular diversity and biological activity.