• Bulletin of the Korean Chemical Society
• /
• v.21 no.10
• /
• pp.1052-1054
• /
• 2000

Binding geometries of $[Ru(II)(110-phenanthroline)_2L]^2+$, complexes (where L = dipyrido [3,2-a:2',3'-c]phena-zine (DPPZ) or benzodipyrido[3,2-a:2',3'-c] phenazine (BDPPZ)) to poly(dG)${\cdot}$poly(dC)${\cdot}$poly(dC) + triplex DNA (CGC + triplex) has been investigated by linear dichroism and normal absorption spectroscopy. Analysis of the linear dichroism for the CGC+ triplex and $[Ru(II)(phen)_2BDPPZ]^2+$ complex indicates that the extended ligand of the metal complex lie perpendicular to the polynucleotide helix axis. Together with strong hypochromism and red shift in the interligand absorption region, we concluded that the extended BDPPZ or DPPZ ligand in-tercalated between the bases of polynucleotide. The spectral properties of the metal complexes bound to CGC+ triplex are similar to those bound to $poly(dA)[poly(dT)]^2$ triplex (Choi et al., Biochemistry 1997, 36, 214), sug-gesting that the metal complex is located in the minor groove of the CGC+ triplex.

• BMB Reports
• /
• v.38 no.1
• /
• pp.104-110
• /
• 2005

We extended the measurable time scale of DNA dynamics to microsecond using $[Ru(phen)_2(dppz)]^{2+}$ (phen = 1,10-phenanthroline, dppz = dipyrido[3,2-a:2',3'-c]phenazine) (RuPD), which displays a mean lifetime near 500 ns. To evaluate the usefulness of this luminophore (RuPD) for probing nucleic acid dynamics, its intensity and anisotropy decays when intercalated into supercoiled and linear pBluescript (pBS) II SK(+) phagemids were examined using frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The mean lifetime for the supercoiled phagemids (< $\tau$ > = 489.7 ns) was somewhat shorter than that for the linear phagemids (< $\tau$ > = 506.4 ns), suggesting a more efficient shielding from water by the linear phagemids. The anisotropy decay data also showed somewhat shorter slow rotational correlation times for supercoiled phagemids (997.2 ns) than for the linear phagemids (1175.6 ns). The slow and fast rotational correlation times appear to be consistent with the bending and torsional motions of the phagemids, respectively. These results indicate that RuPD can have applications in studies of both bending and torsional dynamics of nucleic acids.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.9
• /
• pp.3255-3260
• /
• 2011

Two novel binuclear metal-organic coordination complexes $[Cd_2(L)_2(bpy)_2(H_2O)_2]{\cdot}6H_2O$ (1), $[Cd_2(L)_2(phen)_2-(H_2O)_2]{\cdot}2H_2O$ (2) (where L = 2-methylquinoline-3,4-dicarboxylate dianion, bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) have been synthesized under hydrothermal conditions and characterized by single crystal Xray diffraction, spectral method (IR), elemental analysis and thermal gravimetric analysis (TGA). Both 1 and 2 consist of two Cd(II) atoms bridged by two monoatomic bridging carboxylate groups from two L ligands, and the second carboxylate group of each L is monodentately coordinated to Cd(II), creating a sevenmembered chelating ring. The coordination at each metal nucleus is completed by a water molecule and a chelating bidentate molecule. The 3D structures of the complexes are stabilized by ${\pi}-{\pi}$ stacking interactions and hydrogen-bonds.

• Bulletin of the Korean Chemical Society
• /
• v.9 no.5
• /
• pp.317-322
• /
• 1988

Premicellar precipitation, resolubilization and luminescing behaviors of $RuL_3^{2+}$ (L = bpy, phen, $Me_2bpy$) in aqueous alkylsulfate and sulfonate solutions were studied. Addition of the anionic surfactants to $RuL_3\;^{2+}$ solutions caused initial precipitation which was redissolved by further addition of the surfactants. The apparent solubility products $K_{sp}$'s of the precipitates were evaluated assuming 1:2 salt formation. The values were smaller as the ligand is more hydrophobic and the length of hydrocarbon chain of the surfactant is longer. The $K_{sp}$ values for L = bpy were constant over wide surfactant concentration range. However, those for L = $Me_2bpy$ and also for phen, but to less extent, increased with the surfactant concentration. The resolubilization of 1:2 salts was followed by red-shift of emission band and extensive emission quenching above critical concentration of the surfactants. The critical concentration was lower for more hydrophobic surfactant. For L = $Me_2bpy$, the blue-shifted emission band with enhanced emission intensity was observed in intermediate surfactant concentration region. The high ionic strength of media prevented the precipitate formation, but facilitated the red-shift of the emission bands. The results support that the precipitate is dissolved by accretion of surfactant anions to the salts to form water-soluble surfactant-rich $RuL_3$-surfactant anionic species. These species appeared to aggregate cooperatively to produce large clusters which exhibited the red-shifted emission.

• Bulletin of the Korean Chemical Society
• /
• v.9 no.6
• /
• pp.355-359
• /
• 1988

The Pfeiffer effect was examined on the systems of racemic [$Co^{II}(acac)_2$(diamine)] with d-cinchonine and l-cinchonidine as chiral environment substances in methanol, ethanol, chloroform and methanol-chloroform mixture solvents. It was found that the ${\Delta}$-enantiomer is enriched for the [$Co^{II}(acac)_2$(diamine)]-d-cinchonine system, but the Λ -enantiomer is enriched for the [$Co^{II}(acac)_2$(diamine)]-l-cinchonidine system. The complexes having no N-H protons such as [$Co^{II}(acac)_2$(bpy)] and [$Co^{II}(acac)_2$(phen)] were Pfeiffer-inactive in alcoholic solvents, where bpy = 2,2'-bipyridine and phen = 1,10-phenanthroline. This was interpreted to mean that the hydrogen bonding between N-H proton of diamine ligand and C-9 hydroxyl group of alkalid plays an important role in the chiral discrimination. And the rate of antiracemization ($k_{anti}$) by the Pfeiffer effect was also measured for the [$Co^{II}(acac)_2$(diamine)]-d-cinchonine system in alcoholic solvents. It was found that the rate of appearance of the Pfeiffer effect was enhanced as the concentration of added chloroform is increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.529-532
• /
• 1999

본 연구에서는 유기 전기 발광 소자에서 녹색 발광층으로 사용되는 terbium(Tb) complexes와 europium(Eu) complex, 정공 수송층으로 사용되는 TPD (N, N\`-diphenyl-N,\`(3-methylphenyl)-1, 1\`biphenyl-4, 4\`-diamine), 그리고 전자 수송층으로 사용되는 Alq$_{3}$ (trois(8-hydroxyquinolino)aluminum), Bebq$_2$들의 Uv/Vis. 홉광도와 PL 스펙 트럼과 같은 광학적 특성을 조사하였으며 또한 이러한 물질들을 이용하여 다양한 종류의 유기 전기 발광 소자를 제작하고 제작된 소자들의 전류밀도-전압-조도 등의 전기 . 광학적 특성을 조사하였으며, 그 결과 다 음과 같은 결곤을 얻을 수 있었다. 다양한 ligand를 갖는 Tb complex들의 경우에도 EL 스펙트럼의 파장대 (wavelength)는 546nm~548nm의 녹색 발광을 하는 것을 알 수 있었고, 제작된 소자 중에서 Tb(ACAC)$_3$(Phen) 을 발광충으로 하고, TPD, 그리고 Bebq$_2$를 각각 정공 수송층, 전자 수송 층으로 한 소자가 가장 낮은 구동 전압을 갖는다는 것을 확인하였으며 logJ-logV 특성에서도 모든 전계 구간에서 이러한 구조의 소자가 가장 높은 전류밀도를 나타냈으며 저 전계 구간에서 전류밀도 타이가 가장 컸다. 소자의 전류밀도와 휘도의 관계에 있어서는 제작된 네 종류의 소자 중 Tb(ACAC)3(Cl-Phen)를 발광층으로 하고 TPD, 그리고 Bebq2를 각각 정공 수송층, 전자 수송 층으로 한 소자가 가장 휘도가 우수한 것을 알 수 있었다. 또한 red (europium complex), green (terbium complex), 그리고 blue (TPD) 색깔을 나타내는 유기 재료를 사용하여 한 소자에서 백색 소자를 제작하여 cyclic voltametric방법을 이용하여 각 유기 물질들의 에너지 준위를 조사하여, 각각의 소자들을 에너지 밴드 다이어그램(energy band diagram)으로 자세히 설명하였다.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.9
• /
• pp.3223-3228
• /
• 2011

To quantify the presence of mercuric ions in aqueous solution, double-stranded DNA (dsDNA) of poly(dT) was employed using a light switch compound, $Ru(phen)_2(dppz)^{2+}$ (1) which is reported to intercalate into dsDNA of a right-handed B-form. Addition of mercuric ions induced the dehybridization of poly(dT)${\cdot}$poly(dA) duplexes to form a hairpin structure of poly(dT) at room temperature and the metal-to-ligand charge transfer emission derived from the intercalation of 1 was reduced due to the dehybridization of dsDNA. As the concentration of $Hg^{2+}$ was increased, the emission of 1 progressively decreased. This label-free emission method had a detection limit of 0.2 nM. Other metal ions, such as $K^+$, $Ag^+$, $Ca^{2+}$, $Mg^{2+}$, $Zn^{2+}$, $Mn^{2+}$, $Co^{2+}$, $Ni^{2+}$, $Cu^{2+}$, $Cd^{2+}$, $Cr^{3+}$, $Fe^{3+}$, had no significant effect on reducing emission. This emission method can differentiate matched and mismatched poly(dT) sequences based on the emission intensity of dsDNA.

• Journal of Plant Biotechnology
• /
• v.48 no.4
• /
• pp.289-303
• /
• 2021

Covid-19 is an ongoing pandemic as we speak in 2022. This infectious disease is caused by the SARS-CoV-2 virus, which infects cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor on the cell surface. Thus, strategies that inhibit the binding of SARS-CoV-2 to the ACE2 receptor can stop this contagion. Hanjeli (Coix lacryma-jobi) essential oil contains many bioactive compounds, including dodecanoic acid; tetradecanoic acid; 7-Amino-8-imino-2-(2-imino-2H-chromen-3-yl); and 1,5,7,10-tetraaza-phen-9-one. These compounds suppress viral replication and may prevent Covid-19. Accordingly, this study assessed whether, these four limonoid compounds can block the ACE2 receptor. To this end, their physicochemical properties were predicted using Lipinski's "rule of five" on the SwissADME website, and their toxicity was assessed using the online tools ProTox and pkCSM. Additionally, their interactions with the ACE2 receptor were predicted via molecular docking using Autodock Vina. All the four compounds satisfied the "rule of five" and tetradecanoic acid was predicted to have a higher affinity than the comparison compound remdesivir and the original ligand of ACE2. Molecular docking results suggested that the compounds from hanjeli essential oil interact with the active site of the ACE2 receptor similarly as the original ligand and remdesivir. In conclusion, hanjeli essential oil contains compounds predicted hinder the interaction of SARS-CoV-2 with the ACE2 receptor. Accordingly, our data may facilitate the development of a phytomedical strategy against SARS-CoV-2 infection.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.12
• /
• pp.1775-1780
• /
• 2003

A continuous flow system has been developed to determine trace Cu(II), Mn(II), Ni(II) and Zn(II) in a large volume of water samples by a solvent sublation technique. The mixed solution of 1,10-phenanthroline(phen) and thiocyanate ion was used as ligands for the formation of their ternary complexes. The continuous system was constructed in this laboratory with a peristaltic pump, a mini shaker, three mixing bottles and a flotation cell by connecting each part with a polyethylene tube. The flotation conditions such as the flow rate of sample solution and the injection rates of ligand, buffer and surfactant solutions have been investigated to obtain the best sublation efficiencies. Each solution flowed into the flotation cell through each polyethylene tube by the peristaltic pumps. The ternary complexes were floated and extracted into MIBK in a flotation cell of 2 L by bubbling a nitrogen gas. The absorbances of extracted analytes in MIBK were directly measured by graphite furnace-AAS. The concentrations of 1,10-phenanthroline and thiocyanate ion were $2.6\;{\times}\;10^{-3}$ M and $2.3\;{\times}\;10^{-2}$ M in the mixed solution, respectively. The pH of sample solution was adjusted to 5.0 with a buffer solution and 1%(m/v) sodium lauryl sulphate solution was added as a surfactant to support the effective flotation of the complexes. The $N_2$ gas was bubbled at 30 mL/min for 90 minutes for 20 L of sample. Reproducible results of less than 10% RSD and recoveries of 80-120% could be obtained in real samples.