Jin Seong Tae

A new rhodamine-hydroxamic acid-based fluorescent chemosensor for the rapid detection of HOCl in aqueous media was developed. The system, which utilizes an irreversible HOCl-promoted oxidation reaction, responds instantaneously at room temperature with linear proportionality to the amount of HOCl. This system is highly selective for HOCl over other reactive oxygen species (ROS) and highly sensitive in aqueous solutions. Biological imaging studies using living cells and organisms (A549 cells and

A highly selective and sensitive fluorescent chemosensor for Au(3+) has been reported. The system utilizes an irreversible Au(3+)-promoted cyclization reaction of a rhodamine amide tethered with an alkyne. The probe can sense Au(3+) ions selectively over other biologically relevant metal ions, and approximately 50 nM of Au(3+) could be readily detected in aqueous media. Fluorescent imaging of Au(3+) in living cells is also successfully demonstrated.

A new turn-on fluorescent probe utilizing the "chemosensing ensemble" method is developed to detect thiol-containing amino acids. A complex of Au(+) and a rhodamine hydroxylamine having 2-deoxyribose can selectively detect cysteine and homocysteine in water.

Exposure to methylmercury causes severe damage to various tissues and organs in humans. Although a variety of fluorescent chemosensors have been exploited, only few biological monitoring systems for organomercury species have been described to date. In this report, we describe an irreversible rhodamine chemosensor for the detection of methylmercury and real-time monitoring of methylmercury in living cells and organisms.

A new rhodamine fluorescent probe for monitoring ˙OH has been developed based on the oxidative C-H abstraction reaction of rhodamine cyclic hydrazide. The probe exhibits excellent selectivity for ˙OH with virtually no interference by other ROS/RNS species. Fluorescent imaging of A549 and RAW264.7 cells is also successfully demonstrated to detect intracellular ˙OH in live cells.

A rhodamine triazole-based fluorescent chemosensor has been developed for the selective detection of platinum ions in aqueous solutions. The rhodamine 6G hydroxamate linked with a propargyl group is converted to the corresponding triazole by a "click" reaction. The dual binding unit composed of a hydroxamate and a triazole shows high selectivity and sensitivity toward Pt(2+) over a range of other metal ions in water. The fluorescent probe is applied to monitor cisplatin in aqueous solutions.

You′re my hydroxamate: A chemosensor based on rhodamine hydroxamate with cyclen-tri (tert-butyl ester) and pyridine moiety binding units binds selectively with Pd2+ to induce a strong fluorescence enhancement and color change in aqueous solution. This probe system discriminates Pd2+ over Pt2+ fluorescently and colorimetrically.

Ring-closing metathesis reactions of para-disubstituted aromatic substrates produced macrocyclic [n.n]-, and [n.n.n]paracyclophanes efficiently through dimerization and trimerization reactions. Sufficiently long alkyl chains allowed direct monocyclizations to yield [n]paracyclophanes. A small library of paracyclophanes were generated by the combinatorial cross-metathesis approach.

Asymmetric total synthesis of (–)-galanthamine was accomplished starting from an epoxide. Intramolecular Heck reaction of a conjugated diene system was employed to construct the key quaternary carbon center. The cyclohexene-1,3-diol unit of (–)-galanthamine is derived from an optically active epoxy alkenol.