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We report an eco-friendly strategy for fabrication of nitrogen-doped carbon nanodots (N-CDs) and demonstrate their applications for multicolor cell imaging, patterning, and biosensing. N-CDs have been synthesized using wool as raw material via pyrolysis and microwave treatment, providing a green way for the production of N-CDs without the use of toxic/expensive solvents and starting materials. The prepared N-CDs exhibit exceptional advantages including high fluorescent quantum yield (22.5%), excellent biocompatibility, low toxicity, and satisfactory chemical stability. Depending on these superior properties, the N-CDs have been applied in multicolor bioimaging, patterning, and biosensing. Imaging of living cells has been observed with high resolution using N-CDs as a probe, which validates their use in imaging applications and their multicolor property in the living cell system. Additionally, the obtained N-CDs have been used as fluorescent inks for drawing luminescent patterns, showing favorable application in anti-counterfeit and optoelectronic dimensions. Most strikingly, the as-prepared N-CDs could visualize Fe 3+ fluctuations in living cells with negligible autofluorescence based on their high sensitivity and selectivity detection for Fe 3+ ions with a linear range of 0.1–10 μM and a detection limit of 10 nM. [ABSTRACT FROM AUTHOR]

In the presence of ( R )-SEGPHOS-PdCl 2 catalyst, 5- endo -hydroaminocyclization of various 2-( tert -butyl)- N -(2-ethynylphenyl)anilines proceeds enantioselectively to afford optically active N–C axially chiral N -(2- tert -butylphenyl)indole derivatives in good yields. The enantioselectivity depends strongly on the bulkiness of ortho -substituents and the electron density on the arylethynyl group, and it is explained by the dynamic axial chirality generated by the twisting of the aryl substituent. [ABSTRACT FROM AUTHOR]

Axially chiral N -arylindoles and realated compounds were stereoselectively synthesized using the following three protocols; 1) diastereoselective nucleophilic aromatic substitution, 2) desymmetrization via a stereoselective Cr(CO) 3 migration reaction, and, 3) catalytic enantioselective synthesis via asymmetric ring-closing metathesis. Arene chromium tricarbonyls were utilized as key building blocks, and all of these methods induced extremely high stereoselectivities. Moreover, Cr(CO) 3 fragments were easily removed via air oxidation condition to afford Cr-free N -arylindoles with axially chiral N–C bonds. [ABSTRACT FROM AUTHOR]