Soon W. Lee

Nanomolar Hg(II) detection using nile blue chemodosimeter in biological media

A Nile blue-based chemodosimeter (1) was newly synthesized, and its application for detection of the Hg(2+) ion in 100% aqueous solution was demonstrated. Upon its addition into aqueous Hg(2+) ion solution, it exhibited a considerable blue-shift in its absorption and emission spectra, driven by a desulfurization reaction. Detection at an emission of 652 nm was extremely sensitive (less than 1.0 ppb), even in biological media such as blood plasma and albumin.

One-dimensional copper–pyridinedicarboxylate polymer containing square-planar Cu(II) centers exhibiting antiferromagnetic coupling

Abstract The hydrothermal reaction of Cu(NO 3 ) 2 ·2.5H 2 O with 2,5-pyridinedicarboxylic acid (2,5-PDCH 2 ) led to the formation of aone-dimensional coordination polymer with the empirical formula of Cu(2,5-PDC)(H 2 O) ( 1 ). On the other hand, the hydrothermalreaction of Cu(NO 3 ) 2 ·2.5H 2 O with 2,4-pyridinedicarboxylic acid (2,4-PDCH 2 ) gave a mononuclear Cu(II) compound Cu(2,4-PDC) 2 ( 2 ). The structures of both compounds have been determined by X-ray diffraction. In both compounds, the coordinationsphere of the Cu metal is square-planar. The polymer 1 exhibits strong antiferromagnetic coupling between the paramagneticCu(II) metals in the adjacent layers even in the absence of intervening groups.

Terbium-oxalate-pyridinedicarboxylate coordination polymers suggesting the reductive coupling of carbon dioxide (CO2) to oxalate (C2O42-):[Tb2 (3,5-PDC)2(H2O)4(C2O4)]2H2O and [Tb(2,4-PDC)(H2O)(C2O4)0.5] (PDC=pyridinedicarboxylate)

Abstract Under hydrothermal conditions, Tb(NO3)3·5H2O reacted with 3,5-pyridinedicarboxylic acid (3,5-PDCH2) to give a 3-D coordination polymer with the empirical formula of [Tb2 (3,5-PDC)2(H2O)4(C2O4)]·2H2O (1). Tb(NO3)3·5H2O also reacted with 2,4-pyridinedicarboxylic acid (2,4-PDCH2) to give another 3-D coordination polymer [Tb2 (2,4-PDC)2(H2O)2(C2O4)] (2). The structures of both polymers have been determined by X-ray diffraction. X-ray structure analyses show that both polymers contain bridging oxalate (C2O42−) ligands, which might have been formed by the reductive coupling of CO2 molecules released from the PDC2− ligands through the C–C bond cleavage.

Triply interpenetrating coordination polymers based on paddle-wheel type secondary-building units of M2(CO2R)4: [Ni3(2,6-NDC)3(bipy)1.5], [Co3(2,6-NDC)3(bipy)1.5], and [Co(1,3-BDC)(bipyen)] (2,6-NDC = 2,6-naphthalenedicarboxylate; 1,3-BDC = 1,3-benzenedicarboxylate; bipy = 4,4'-bipyridine; bipyen = trans-1,2-bis(4-pyridyl)ethylene)

Abstract Triply interpenetrating 3-dimensional nickel and cobalt coordination polymers, [M3(2,6-NDC)3(bipy)1.5], were prepared from metal nitrate {M(NO3)2·6H2O}, 2,6-naphthalenedicarboxylic acid (2,6-NDCH2), and 4,4′-bipyridine (bipy) under hydrothermal (M=Ni) or water–benzene hydro(solvo)thermal (M=Co) conditions. Both polymers have the same secondary building units (SBUs) of paddle-wheels of the type [M2(CO2R)4], which are composed of two metals and four di(monodentate) bridging carboxylates. On the other hand, the hydrothermal reaction of Co(NO3)2·6H2O with 1,3-benzenedicarboxylic acid (1,3-BDCH2) and trans-1,2-bis(4-pyridyl)ethylene (bipyen) gave a 2-dimensional polymer [Co(1,3-BDC)(bipyen)]. The structures of all products were determined by X-ray diffraction.

A three-dimensional cobalt(II)-coordination polymer based on 3,5-pyridinedicarboxylate

Abstract Hydrothermal reaction between cobalt(II) nitrate and 3,5-pyridinedicarboxylic acid in the presence of NaOAc and NaCl gave a 3-D cobalt(II)-coordination polymer, Co(3,5-pyridinedicarboxylato)(H 2 O) ( 1 ). X-ray structure determination showed that compound 1 has a 3-D infinite network based on cobalt–carboxylate building blocks.

C-H activation guided by aromatic N-H ketimines: synthesis of functionalized isoquinolines using benzyl azides and alkynes.

Aromatic N-H ketimines were in situ generated from various benzylic azides by ruthenium catalysis for the subsequent Rh-catalyzed annulation reaction with alkynes to give the corresponding isoquinolines. In contrast to conventional synthetic methods for aromatic N-H ketimines, our protocol works under mild and neutral conditions, which enabled the synthesis of isoquinolines having various functionalities such as carbonyl, ester, alkenyl, and ether groups. In addition, the imidates generated from α-azido ethers were successfully used for the synthesis of 1-alkoxyisoquinolines.

Isoflavones Found in Korean Soybean Paste as 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase Inhibitors

3-Hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase is the rate-limiting enzyme in the biosynthesis of cholesterol in mammals. Some microbial metabolites have been found to be HMG-CoA reductase inhibitors. Korean soybean paste is a unique food fermented by many microorganisms. The enzymatic method using the catalytic domain of Syrian hamster HMG-CoA reductase was employed for the screening of HMG-CoA reductase inhibitors. Soybean paste extract was fractionated by vacuum liquid chromatography. Fractions showing relatively high HMG-CoA reductase inhibition were further purified through Sephadex LH-20 column chromatography and C18 preparative HPLC, and the inhibitory compounds were identified as genistein, daidzein, and glycitein.

A porous, two-dimensional copper coordination-polymer containing guest molecules: hydrothermal synthesis, structure, and thermal property of [Cu(BDC)(bipy)](BDCH 2 ) (BDC=1,4-benzenedicarboxylate; bipy=4,4 ′ -bipyridine)

The hydrothermal reaction of Cu(NO 3 ) 2 ·2.5H 2 O with 1,4-benzenedicarboxylic acid (BDCH 2 ) and 4,4 ′ -bipyridine (bipy) gave a two-dimensional copper(II) coordination polymer with an empirical of formula of [Cu(BDC)(bipy)](BDCH 2 ) ( 1 ). Polymer 1 contains free BDCH 2 molecules as guests in channels constructed by Cu, BDC 2− , and bipy. The BDCH 2 guest molecules are involved in intermolecular hydrogen bonds of the type O–H⋯O, which seem to be main forces to hold the guests in the channels. X-ray powder diffraction (XRPD) studies suggest that polymer 1 and its guest-free form have the same framework. Polymer 1 was structurally characterized by X-ray diffraction.

Two-dimensional cobalt-bipyridinedicarboxylate coordination polymer: [Co(2,2 ′ -bipyridine-5, 5 ′ -dicarboxylato) (H 2 O)]·(H 2 O)

Abstract Hydrothermal reaction between cobalt(II) nitrate and 2,2′-bipyridine-5,5′-dicarboxylic acid in the presence of NaOAc gave a two-dimensional coordination-polymer of cobalt(II), [Co(2,2′-bipyridine-5,5′-dicarboxylato)(H2O)]·(H2O) (1). X-ray structure determination showed that compound 1 has a two-dimensional infinite network based on cobalt-bipyridinedicarboxylate building blocks and has a relatively small channel of 5.0×6.6 A.

Cyclotrimerization of phenylethynes to fulvene: reactivity of cis-dichloro(1,1′-bis(diphenylphosphino)ferrocene)palladium(II)

Abstract In the presence of triethylamine (NEt 3 ) and ethanol (EtOH), phenylethyne (or phenylacetylene, PhCCH) underwent cyclotrimerization: cis -dichloro(1,1′-bis(diphenylphosphino)ferrocene)palladium(II), [PdCl 2 (dppf)] ( 1 ), reacted with phenylethyne to give [Pd(dppf)(2,3,5-triphenylfulvene)] ( 2 ). Reaction of 2 with dimethyl acetylenedicarboxylate in dichloromethane gave [Pd(dppf)(CH 3 O 2 CCCCO 2 CH 3 )] ( 3 ) and a free 2,3,5-triphenylfulvene. Crystallographic data for 2 ·H 2 O: triclinic space group P 1 , a =10.658(2), b =10.896(2), c =21.080(3) A, α =85.303(9)°, β =76.556(9)°, γ =80.447(10)°, Z =2, R ( wR 2 )=0.0487(0.1083).