Seok-Jong Lee

Blue Phosphorescent Ir(III) Complex with High Color Purity: fac-Tris(2′,6′-difluoro-2,3′-bipyridinato-N,C4′)iridium(III)

A blue phosphorescent iridium(III) complex (1) bearing fluorine-substituted bipyridine (dfpypy) has been synthesized and characterized to investigate the effect of the substitution and replacement of the phenyl ring in ppy (phenylpyridine) with pyridine on the solid state structure and its photoluminescence. The optical properties and electrochemical behaviors of 1 have also been systematically evaluated. The structure of 1 has also been determined by a single-crystal X-ray diffraction analysis. There are varied intermolecular interactions caused by the pyridine and fluorine substituents, such as C-H...N, C-H...F, and pi...pi interactions of either face-to-face type or edge-to-face C-H...pi and halogen...pi in crystal packing. In electrochemistry, the remarkably higher oxidation potential than that of FIrpic was observed. The emission lambda(max) of 1 at room temperature is at 438 nm with a higher PL quantum efficiency. Complex 1 exhibits intense blue emission with high color purity (CIE x = 0.14, y = 0.12), which has been attributed to metal-to-ligand charge-transfer triplet emission based on DFT calculations.

N-Substituted-3-arylpyrrolidines: Potent and Selective Ligands at Serotonin 1A Receptor

3-Arylpyrrolidines are synthesized through the coupling of N-benzyl-3-(methanesulfonyloxy)pyrrolidine with diarylcuprates. Pharmacological evaluation of a series of N-substituted-3-arylpyrrolidines toward several neurotransmitter receptors indicated that some of them are good ligands for serotonin 1A receptor. Particularly, N-[(N-saccharino)butyl]pyrrolidines were found to be potent and selective ligands. A preliminary biological evaluation for several selected compounds indicated that they are potentially effective antianxiety and antidepressant agents.

Conjugate addition of amides to α,β-unsaturated esters by CsF-Si(OEt)4 system

Abstract The conjugate addition of amides to α,β-unsaturated esters proceeds efficiently with an equimolar amount of Si(OEt) 4 and a catalytic amount of CsF to afford the corresponding N-substituted amides.

Syntheses of 1-oxaquinolizidines via reductive cyclization of hydroxy-lactams

Abstract The synthesis of the 1-oxaquinolizidine moiety of xestospongin A via reductive iminium ion formation from a lactam is described.

Improved Efficiency and Lifetime of Organic Light-Emitting Diode with Lithium-Quinolate-Doped Electron Transport Layer

In this letter, we analyze the device performance of organic light-emitting diodes (OLEDs) with a lithium-quinolate (Liq)-doped electron transport layer (ETL). When the ETL:Liq doping ratio is 1:3, the luminous efficiency of the OLED is 7.1 cd/A; that of an OLED with a nondoped ETL is 5.3 cd/A. The corresponding OLED lifetime is improved by threefold that with a nondoped ETL, owing to the improved hole-electron charge balance and electrical stability of the Liq-doped ETL film. Additionally, when the Liq-doped device was combined with a Mg/Al cathode, the OLED produced had a longer lifetime than the other tested devices.

Pharmacological characterization of LB50016, N-(4-amino)butyl 3-phenylpyrrolidine derivative, as a new 5-HT1A receptor agonist

LB50016 was characterized as a selective and potent 5-HT1A receptor agonist and evaluate its anxiolytic and antidepressant activities. It shows high affinity for 5-HT1A receptor, moderate affinity for α2 adrenergic and 5-HT2A receptors and no significant affinity for other receptors tested. Hypothermia and increased serum corticosterone level were observed in LB50016-treated rats, which are mediated mostly by post synaptic 5-HT1A receptor activation. In the mouse forced swim model for depression, LB50016-elicited dose-dependent reductions in immobility time, showing ED50 of approximately 3 mg/kg i.p., which was blocked by pretreatment of NAN-190, 5-HT1A antagonist. In face-to-face test for anxiolytic activity in mice, estimated ED50 was 2 mg/kg, i.p.. In isolation-induced aggression test with mice, fifty-fold increases in latency to attack were observed at 30 min and last up to 4 h after LB50016 treatment (3 mg/kg i.p.). Taken together, LB50016-induced pharmacological activities are mediated by activation of 5-HT1A receptors, offering an effective therapeutic candidate in the management of anxiety and depression in humans.

Synthesis of (R)- and (S)-Oxymethylmorpholine Derivatives

Abstract (S)-N-benzyl-3-tert-butyldiphenylsilyloxymethylmorpholine and (R)-N-benzyl-3-benzyloxymethylmorpholine are synthesized starting from (R)-1-benzylglycerol.