Yeerin Choi

Synthetic chloride transporters containing two urea groups linked through a diazobenzene spacer have been prepared and the trans-to-cis isomerization by light stimulation results in dramatic changes in the chloride transport activities across lipid and cell membranes.

Adopting the concept of procarrier for the first time, we demonstrated the controlled transport of chloride ions across lipid and cellular membranes. Procarriers containing highly hydrophilic appendages were initially inactive due to the lack of their partitioning into lipophilic membranes but were activated to transport chloride ions in the presence of specific enzymes that were able to hydrolyze off the appendages to generate an active carrier under specific conditions. Namely, the procarrier

Synthetic molecules which selectively transport sodium or potassium chloride across a lipid membrane have been prepared. The salt carriers consist of two heteroditopic binding sites, an anion-binding cavity with three hydrogen bond donors and an azacrown ether for binding an alkali metal cation. The association constants between the carriers and chloride ion have been enhanced by 1 order of the magnitude in the presence of sodium or potassium ion in 10% (v/v) CD3OH/CD3CN, due to the formation of

Binding of α-amino carboxylates to a helically twisted imine macrocycle based on the indolocarbazole scaffold gives rise to characteristic circular dichroism spectra, and the patterns of the Cotton effects are consistent with the absolute configuration of α-amino carboxylates.

Indolocarbazole-pyridine hybrid foldamers are strongly fluorescent in an extended random conformation, but the fluorescence is completely quenched upon folding to a helical conformation due to the compact stacking between aryl planes in the backbone. Anion binding disturbs the helical conformation, thus regenerating the fluorescence of the foldamers. This unique property has been utilized to develop a fluorescence turn-on probe for anions such as sulfate and fluoride.

An indolocarbazole–naphthyridine hybrid oligomer capable of adopting a stable helical conformation was prepared, and its folding properties were thoroughly studied in the solid state and in solution. As a result of folding, a hydrophilic cavity was generated inside the helix wherein monosaccharides were able to be encapsulated in the order of glucose (9.6 × 10 4 M –1 ) > galactose (1.0 × 10 4 M –1 ) ≫ mannose (∼0) in 10% (v/v) DMSO/CH 2 Cl 2 .

A mild and efficient three-component thio(seleno)cyano-difluoroalkylation of simple alkenes is demonstrated using an iridium(ruthenium) photocatalyst. This protocol provides a direct and regioselective installation of both C–S(Se)CN [thio(seleno)cyanation] and C–C F (difluoroalkylation) bonds.

A series of synthetic molecules bearing the same hydrogen bonding mode observed in StClC were prepared and their transport ability of chloride ion across a lipid membrane was systematically optimized.

A series of indolocarbazole-pyridine (IP) hybrid foldamers containing chiral residues at multiple different positions were prepared to reveal the matched and mismatched phenomena of local stereocenters on the induction of helical bias. These foldamers adopted stable helical conformations, thus affording well-resolved separate sets of ¹H NMR signals for right- ( P) and left-handed ( M) helices in water saturated organic solvents such as toluene and dichloromethane. The ratios of P- and

High Resolution Image Download MS PowerPoint Slide A mild and general method for photoredox-catalyzed trifluoromethylative and pentafluoroethylative heterofunctionalization of alkenes is proposed. In this reaction, the Togni reagent serves as a CF 3 - or CF 2 CF 3 -radical source for the regioselective formation of the C–CF 3 and C–CF 2 CF 3 bonds from alkenes, and additional nucleophiles (O, S, N) provide C–O, C–S, and C–N bonds, respectively. These reactions provide a common gateway to access

Abstract The use of hypervalent iodine with Lewis acid provided alkyne trifluoromethylation and pentafluoroethylation to access trifluoro‐and pentafluoro‐substituted thiazoles. This simple and efficient method is compatible with a broad range of aryl‐ and alkyl‐substituted thiourea starting materials. Additionally, a gram‐scale reaction proves the practicality of this transformation.

본 논문은 1920~30년대 식민지 조선의 축산 정책을 ‘부업 축산’과 ‘개량종’ 장려라는 두 축을 중심으로 고찰했으며, 이에 대한 피식민자의 반응을 당대의 기록/문학을 통해 분석하고자 했다. 다양한 축산 형태 가운데서도 특히 양돈과 양계를 주요 사례로 삼았다. 그로써 이러한 과정이정업/부업, 개량/재래, 식민본국/식민지, 식민자/피식민자 사이의 위계를 어떻게 구성하고 강화했는지를 밝히고자 했다. 먼저 ‘부업 축산’은 부업 장려 정책의 일환으로 권장된 가정 내 소규모 동물 사육을 가리킨다. 본 논문은 조선을 식민본국 산업의 부차적 생산지로 위치시키고, 저렴한 가내 노동력을 활용해 자본 축적을 도모하고자 했던 식민지 부업 장려책의 맥락 속에서 부업 축산의 성격을 검토했다. 다음으로 ‘개량종’ 장려는 재래종 돼지와 닭이 외래 품종 또는 교잡종으로 대체되어 간 일련의 과정이다. ‘개량’이라는 용어에 내포된, 재래의 것을 열등한 것으로 전제하고 개량된 것을 우위에 두는 위계적 관점이 피식민

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.