Water-soluble carbon nanocrystals (CNCs) with electrochemiluminescence (ECL) activity were released into aqueous solution from a graphite rod by applying a scanning potential. ECL emission of CNCs observed during their preparation probably provides a useful method for monitoring and screening nanocrystal preparation. The ECL behavior and its mechanism in CNCs have been studied in detail for the first time. The results suggest promising applications of CNCs in the development of new types of biosensors and display devices in the future on the basis of their strong and stable ECL emission, good stability, low cytotoxicity, excellent water solubility, easy labeling, and environmental friendliness.

A series of diamagnetic divalent nickel complexes supported by a tridentate amido diphosphine ligand [N(o-C6H4PR2)2]- ([R-PNP]-; R = Ph, i Pr, Cy) have been prepared and characterized. Deprotonation of H[Ph-PNP], H[ i Pr-PNP], and H[Cy-PNP] with n-BuLi in ethereal solutions at −35 °C produced the lithium complexes [Ph-PNP]Li(THF)2, [ i Pr-PNP]Li(solv) (solv = THF, Et2O), and [Cy-PNP]Li(solv) (solv = THF, Et2O), respectively. The reactions of [R-PNP]Li(solv) n with NiCl2(DME) in THF at −35 °C generated [R-PNP]NiCl, which was then reacted with a variety of Grignard reagents to afford the corresponding hydrocarbyl complexes [R-PNP]NiR‘ (R = Ph, R‘ = Me, Et, n-Bu, i-Bu, n-hexyl, CH2SiMe3, Ph; R = i Pr, R‘ = Me, Et, n-Bu; R = Cy, R‘ = Me, Et, n-Bu). Of particular interest among the compounds isolated are alkyl complexes that contain β-hydrogen atoms. Treatment of the hydrocarbyl complexes with halogenated hydrocarbons such as dichloromethane, benzyl bromide, and phenyl iodide produced the corresponding nickel halide derivatives. The chloride complexes [Ph-PNP]NiCl, [ i Pr-PNP]NiCl, and [Cy-PNP]NiCl are all active catalyst precursors for Kumada coupling reactions, including those of alkyls containing β-hydrogen atoms. In addition to spectroscopic data for all new compounds, X-ray structures of [Cy-PNP]Li(OEt2), [Ph-PNP]NiCl, [Ph-PNP]NiBr, [Ph-PNP]NiMe, [Ph-PNP]Ni(n-Bu), [Ph-PNP]NiCH2SiMe3, [ i Pr-PNP]NiCl, [ i Pr-PNP]NiMe, [ i Pr-PNP]Ni(n-Bu), and [Cy-PNP]NiMe are presented.

Six coal samples of different ranks have been used to prepare single-layer graphene quantum dots (S-GQDs). After chemical oxidation and a series of centrifugation separation, every coal could be treated into two fractions, namely, CoalA and CoalB. According to the characterization results of TEM, AFM, XRD, Raman and FTIR, CoalA was revealed to be mainly composed of S-GQDs, which have an average height of about 0.5 nm and an average plane dimension of about 10 nm. The obtained S-GQDs showed excitation-dependent fluorescence and excellent electrochemiluminescence. CoalB was found to be some other carbon-based nanomaterials (CNMs), including agglomerated GQDs, graphene oxide, carbon quantum dots and agglomerated carbon nanocrystals. Generally, low-ranked coals might be more suitable for the preparation of S-GQDs. The production yield of S-GQDs from the six investigated coals decreased from 56.30% to 14.66% when the coal rank increased gradually. In contrast, high-ranked coals had high production yield of CoalB and might be more suitable for preparing other CNMs that were contained in CoalB, although those CNMs were difficult to separate from each other in our experiment.

A series of nickel(II) alkyl and aryl complexes supported by the bis(2-diphenylphosphinophenyl)amide ligand, [PNP]-, have been prepared, including those in which the alkyl contains β-hydrogen atoms. The stability of these compounds toward β-elimination is attributed to the rigidity and robustness of the new tridentate amido diphosphine ligand.