A colorimetric and far-red fluorescent probe for rapid detection of bisulfite/sulfite in full water-soluble based on biquinolinium and its applications

Bisulfite (HSO₃^-) and sulfite (SO₃^2-) are involved in numerous physiological processes of living systems. However, high levels of these substances are often correlated to many diseases. Herein, we designed and synthesized a simple full water-soluble colorimetric and far-red fluorescent probe (E)-1-methyl-4-(2-(1-methylquinolin-1-ium-3-yl)vinyl)quinolin-1-ium iodide trifluoromethanesulfonate (DQ) for HSO₃^-/SO₃^2- detection by coupling 1,4-dimethylquinolinium with 3-quinolinium carboxaldehyde for the first time. The probe DQ showed high selectivity for HSO₃^- detection via a 1,4-nucleophilic addition reaction with distinct color changes from colorless to purple-red and remarkable far-red fluorescence enhancement in pure aqueous solutions. Specifically, the probe displayed a fast response (<15 s) for bisulfite, which renders it suitable for real time detection of HSO₃^-. Under the optimized conditions, the far-red fluorescence intensity was linear to the concentrations of HSO₃^- in the range from 0 to 25 μM and the detection limit was as low as 0.11 μM. Additionally, the probe could be applied to sense HSO₃^- on paper strips, real sample including vermicelli and sugar and image HSO₃^- in living cells, which indicated that probe DQ has potential application in food samples and living systems.

A convergent formal [4 + 2] cycloaddition of 1,6-diynes and benzyl azides: construction of spiro-polyheterocycles

A convergent formal [4 + 2] cycloaddition reaction for the construction of structurally appealing spiro-tetrahydroquinolines has been developed, in which, a one-pot reaction is established for the in situ generation of two reagents, a cyclic alkyne and an N-aryliminium ion, from the corresponding precursors in the presence of an Au-catalyst and Brønsted acid, respectively.

3d Transition Metals for C-H Activation

C-H activation has surfaced as an increasingly powerful tool for molecular sciences, with notable applications to material sciences, crop protection, drug discovery, and pharmaceutical industries, among others. Despite major advances, the vast majority of these C-H functionalizations required precious 4d or 5d transition metal catalysts. Given the cost-effective and sustainable nature of earth-abundant first row transition metals, the development of less toxic, inexpensive 3d metal catalysts for C-H activation has gained considerable recent momentum as a significantly more environmentally-benign and economically-attractive alternative. Herein, we provide a comprehensive overview on first row transition metal catalysts for C-H activation until summer 2018.

Facile one-pot synthesis of 2,3-dihydro-1H-indolizinium derivatives by rhodium(iii)-catalyzed intramolecular oxidative annulation via C–H activation: application to ficuseptine synthesis

Various substituted indolizidinium, quinolizinium and pyrido[1,2-a]azepinium salts were synthesized from benzaldehydes (α,β-unsaturated aldehydes) and alkyne–amines via Rh-catalyzed C–H activation.