Ki-Hong Choi

A macrocycle containing an aminocoumarin fluorophore showed two different fluorescence emission bands on binding with certain anions. Proton transfer from the fluorophore excited state occurred depending on the basicity of the bound anion (see scheme, A−: anion) and this new pathway makes more-sensitive anion sensing possible.

The core functions of stem cells (SCs) are critically regulated by their cellular redox status. Glutathione is the most abundant non-protein thiol functioning as an antioxidant and a redox regulator. However, an investigation into the relationship between glutathione-mediated redox capacity and SC activities is hindered by lack of probe. Here, we demonstrate that cyanoacrylamide-based coumarin derivatives are ratiometric probes suitable for the real-time monitoring of glutathione levels in livin

The cyclic triamide of 3'-amino-3-biphenylcarboxlic acid is readily synthesized in a stepwise manner and represents a novel class of anion receptors with a large central cavity. This macrocycle binds more strongly to tetrahedral anions than spherical or planar anions in organic solvents. The binding stoichiometries for anions with symmetrical charge distribution depend on the solvent polarity, while tetrahedral p-tosylate binds to the macrocycle with 1:1 stoichiometry in all solvents studied. Th

As part of a programme to investigate the path of the nascent peptide through the large ribosomal subunit, peptides of different lengths (up to 30 amino acids), corresponding to the signal peptide sequence and N-terminal region of the Escherichia coli ompA protein, were synthesized in situ on E.coli ribosomes. The peptides each carried a diazirine moiety attached to their N-terminus which, after peptide synthesis, was photoactivated so as to induce cross-links to the 23S rRNA. The results showed

2,2-Diphenyl-[1,3]dioxolane-4,5-dicarboxylic acid (DPD) and 2,2-dinaphthalen-2-yl-[1,3]dioxolane-4,5-dicarboxylic acid (DND) have been synthesized starting from dimethyl tartrate. DPD and DND amides of alpha-chiral primary amines showed significantly different (1)H chemical shift values depending on the stereochemistry of the derivatizing agent. On the basis of this chemical shift difference, the absolute configuration of amine substrates could be assigned. DND amides showed significantly larger

On the basis of our modeling of pillared covalent organic frameworks (PCOFs) with pyridine molecules inserted between the COF-1 layers, we propose that the surface area and free volume of storage materials should be balanced to increase the gravimetric and volumetric hydrogen uptake capacities. Density functional theory and grand canonical Monte Carlo simulations show that these PCOFs have significantly improved gravimetric and volumetric hydrogen storage capacities of 8.8–10.0 wt % and 58.7–61.

Ein Makrocyclus mit einem Aminocumarin-Fluorophor zeigt nach Bindung bestimmter Anionen zwei Fluoreszenzemissionsbanden. Ein Protonentransfer vom angeregten Zustand des Fluorophors erfolgt in Abhängigkeit von der Basizität des gebundenen Anions (siehe Schema, A− = Anion), was einen empfindlicheren Anionennachweis ermöglicht. Supporting information for this article is available on the WWW under http://www.angewandte.com or from the author. Please note: The publisher is not responsible for the con