이은성 교수

The unnatural isotope fluorine-18 ((18)F) is used as a positron emitter in molecular imaging. Currently, many potentially useful (18)F-labeled probe molecules are inaccessible for imaging because no fluorination chemistry is available to make them. The 110-minute half-life of (18)F requires rapid syntheses for which [(18)F]fluoride is the preferred source of fluorine because of its practical access and suitable isotope enrichment. However, conventional [(18)F]fluoride chemistry has been limited

A one-step oxidative fluorination for carbon-fluorine bond formation from well-defined nickel complexes with oxidant and aqueous fluoride is presented, which enables a straightforward and practical (18)F late-stage fluorination of complex small molecules with potential for PET imaging.

Cucurbituril is used as the molecular “bead” for the synthesis of the first three-dimensional polyrotaxane network, which shows an inclined α-polonium topology. The novel solid-state interlocked structure is made up of binulcear Tb3+ centers and pseudorotaxane units containing cucurbituril “beads” threaded on a “string” with 3-phenylcarboxylate terminals (shown schematically). Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2000/z149

A seven-membered molecular necklace composed of six copper ions and six pseudorotaxane units behaves as a secondary building block in the formation of a two-dimensional polyrotaxane network with large voids. This novel metal-organic framework allows size-selective anion exchange as well as the exchange of coordinated ligands. Thus a new synthetic strategy has been identified for modular porous solids which utilizes large, rigid, interlocked supermolecules as primary or secondary building blocks.

Cucurbituril als molekulare "Perle"︁ wurde bei der Synthese eines dreidimensionalen Polyrotaxan-Netzwerks mit verzerrter α-Polonium-Struktur verwendet. Die neuartige Struktur ist aufgebaut aus zweikernigen Tb3+-Zentren und Pseudorotaxan-Einheiten, bei denen das Cucurbituril wie eine Perle auf einer Schnur aufgereiht ist. Die Schnüre tragen 3-Phenylcarboxylate in entständiger Position (siehe Bild).

Persistent radicals are potential building blocks of novel materials in many fields. Recently, highly stable persistent radicals are considered to be within reach, thanks to several radical stabilization strategies such as spin delocalization and steric protection. N-Heterocyclic carbene (NHC)-derived substituents can be attached to a radical center for these purposes, as illustrated by numerous NHC-stabilized radicals reported in the last two decades.This Account describes our recent work on de

Ein größenselektiver Anionenaustausch ist möglich mit dem hier dargestellten Polyrotaxan-Verbundnetz, dessen Sekundär-Baueinheiten sich aus je sechs Kupferionen und Pseudorotaxaneinheiten zusammensetzen. Zur Synthese wurde eine neue Strategie für die Herstellung modular aufgebauter poröser Feststoffe eingeführt, bei der große, starre, ineinander greifende Übermoleküle als Primär- und Sekundär-Baueinheiten dienen.

A new type of click reaction, sulfur(VI) fluoride exchange (SuFEx), has been utilized to prepare five postsynthetically modified UiO-67 series metal-organic frameworks (MOFs). The postsynthetic modification (PSM) via SuFEx can be achieved selectively for the sulfonyl fluoride (R-SO₂F) without degrading the MOF structure as confirmed by X-ray crystallographic analysis. The present SuFEx method provides a straightforward tool for introducing new functionality inside MOFs. Introduction o

The transition-metal-like behavior of N-heterocyclic carbenes (NHCs) in the activation of small molecules such as CO, NO, N₂O, H₂, and NH₃ is reviewed. The resemblance to transition metals is mainly attributed to the adjustable electronic properties of the carbene centers through modification of their structure. Furthermore, applications of NHCs in the activation of various C–H bonds for functionalization are explored.

IPr (1a) reacts with octafluorotoluene by an unexpected sequential substitution of fluorides in two separate rings. The resulting tetrasubstituted imidazolium salt was isolated and elaborated into Ag(i) and Au(i) complexes with a novel abnormal NHC ligand. Both IPr (1a) and IMes (1b) were also found to be moderately reactive by nucleophilic substitution of the aromatic C-F bond in a weakly-activated fluoroarene, 1-fluoro-4-trifluoromethylbenzene (5).

Abstract The isolation of cyclic(alkyl)(amino)carbenes (CAACs) and N , N ′‐diamidocarbenes (DACs) has opened up new avenues in the field of carbene chemistry due to their unique properties. CAACs are strong σ‐donors and π‐acceptors, whereas DACs are extremely strong π‐acceptors. The ambiphilicity of carbenes can facilitate new applications such as small molecule activation and catalysis. Since the isolation of CAACs and DACs, several new ambiphilic carbenes have been synthesized, thereby advanci

N-heterocyclic carbene (NHC) nitric oxide (NHCNO) radicals, which can be regarded as iminoxyl radicals stabilized by NHCs, were found to react with a series of silyl and alkyl triflates to generate the corresponding oxime ether radical cations. The structures of the resulting oxime ether radical cations were determined by X-ray crystallography, along with EPR and computational analysis. In contrast, lutidinium triflate produced a 1:1 mixture of [NHCNO⁺ ][OTf^- ] and [NHCNHOH

Herein, a coumaraz-2-on-4-ylidene (1) as a new example of an ambiphilic N-heterocyclic carbene, having electronic properties that can be fine-tuned, is reported. The N-carbamic and aryl groups on the carbene carbon center provide exceptionally high electrophilicity and nucleophilicity simultaneously to the carbene center, as evidenced by the ⁷⁷ Se NMR chemical shifts of their selenoketone derivatives and the CO stretching strengths of their rhodium carbonyl complexes. Since the precur

Non-aqueous all organic redox flow batteries (NORFBs) are one of the promising options for large-scale renewable energy storage systems owing to their scalability with energy and power along with the affordability. The discovery of new redox-active organic molecules (ROMs) for the anolyte/catholyte would bring them one step closer to the practical application, thus it is highly demanded. Here, we report a new class of ROMs based on cationic triazenyl systems supported by <i>N</i>-heterocyclic ca