• Bulletin of the Korean Chemical Society
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• 제21권10호
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• pp.1052-1054
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• 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.

• 대한화학회지
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• 제51권6호
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• pp.526-535
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• 2007

아다만탄 또는 β-cyclodextrin이 결합된 루테늄(II)-터피리딘 착화합물(8, 9, 11)을 합성하고 1H NMR, 13C NMR 및 질량분석스펙트럼으로 구조를 확인하였다. 아다만탄이 결합된 루테늄(II)-터피리딘 착화합물(8, 11) 은 물에 전혀 녹지 않으나, β-cyclodextrin 수용액에 혼합할 경우 β-cyclodextrin과의 초분자를 형성하여 물에 잘 녹아들어갔다. 비슷한 방법으로 수용액 중에서 루테늄(II)-터피리딘 착화합물(8, 11)을 각각 착화합물 9와 혼합 하였을 때, 착화합물(8, 11)의 아다만탄 부분이 루테늄 착화합물 9의 β-cyclodextrin 내부에 포접 됨으로써 안정 한 초분자를 형성하였다.

• Bulletin of the Korean Chemical Society
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• 제11권6호
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• pp.552-557
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• 1990

Luminescence quenching reactions of photoexcited tris(2,2'-bipyridine)ruthenium (Ⅱ) complex cation, $Ru(bpy)_3\;^{2+}$, by dialkylviologens (dimethyl, dioctyl, dibenzyl, methyloctyl, methyldodecyl, and methylbenzyl) were studied in sodium dodecylsulfate (SDS), poly(styrenesulfonate) (PSS), and poly(vinylsulfonate) (PVS) solutions. The relative quenching rate varies widely with the microheterogeneous media employed: the highest quenching rate is observed for methyldodecylviologen in homogeneous aqueous medium, dibenzylviologen in SDS and PVS solutions, and dimethylviologen in PSS solution; the lowest rate is found for dimethylviologen in homogeneous medium and SDS solution, methyldodecylviologen in PSS and PVS solutions. These results were interpreted in terms of reduction potential of viologens, affinity of $Ru(bpy)_3\;^{2+}$ and viologens to the microparticles, and the structures of the viologen-colloid complexes.

• Bulletin of the Korean Chemical Society
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• 제27권12호
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• pp.2084-2086
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• 2006

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.27-27
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• 2011

For the design of real applicable molecular devices, current-voltage properties through molecular nanostructures such as metal-molecule-metal junctions (molecular junctions) have been studied extensively. In thiolate monolayers on the gold electrode, the chemical bonding of sulfur to gold and the van der Waals interactions between the alkyl chains of neighboring molecules are important factors in the formation of well-defined monolayers and in the control of the electron transport rate. Charge transport through the molecular junctions depends significantly on the energy levels of molecules relative to the Fermi levels of the contacts and the electronic structure of the molecule. It is important to understand the interfacial electron transport in accordance with the increased film thickness of alkyl chains that are known as an insulating layer, but are required for molecular device fabrication. Thiol-tethered RuII terpyridine complexes were synthesized for a voltage-driven molecular switch and used to understand the switch-on mechanism of the molecular switches of single metal complexes in the solid-state molecular junction in a vacuum. Electrochemical voltammetry and current-voltage (I-V) characteristics are measured to elucidate electron transport processes in the bistable conducting states of single molecular junctions of a molecular switch, Ru(II) terpyridine complexes. (1) On the basis of the Ru-centered electrochemical reaction data, the electron transport rate increases in the mixed self-assembled monolayer (SAM) of Ru(II) terpyridine complexes, indicating strong electronic coupling between the redox center and the substrate, along the molecules. (2) In a low-conducting state before switch-on, I-V characteristics are fitted to a direct tunneling model, and the estimated tunneling decay constant across the Ru(II) terpyridine complex is found to be smaller than that of alkanethiol. (3) The threshold voltages for the switch-on from low- to high-conducting states are identical, corresponding to the electron affinity of the molecules. (4) A high-conducting state after switch-on remains in the reverse voltage sweep, and a linear relationship of the current to the voltage is obtained. These results reveal electron transport paths via the redox centers of the Ru(II) terpyridine complexes, a molecular switch.

• Bulletin of the Korean Chemical Society
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• 제12권6호
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• pp.686-691
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• 1991

Emission quenching of photoexcited tris(${\alpha},{\alpha} '$-diimine)-ruthenium(II) complex cations, $RuL_3^{2+}$ (L: 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine; 4,4'-diphenyl-2,2'-bipyridine; 1,10-phenanthroline; 5-methyl-1,10-phenanthroline; 5,6-dimethyl-1,10-phenanthroline or 4,7-diphenyl-1,10-phenanthroline) by $Cu^{2+}$, dimethylviologen $(MV^{2+})$, nitrobenzene (NB), and oxygen was studied in aqueous homogeneous and sodium dodecyl sulfate (SDS) micellar solutions. The apparent bimolecular quenching rate constants $k_q$ were determined from the quenching data and life-times of $^{\ast}RuL_3^{2+}$. In homogeneous media, the quenching rate was considerably slower than that for the diffusion-controlled reaction. The decreasing order of quenching activity of quenchers was $NB>O_2>MV^{2+}>Cu^{2+}$. The rate with $Cu^{2+}$ was faster as the reducing power of $^{\ast}RuL_3^{2+}$ is greater. On the other hand, the rates with NB and $O_2$ were faster as the ligand is more hydrophobic. This was attributed to the stabilization of encounter pair by van der Waals force. The presence of SDS enhanced the rate of quenching reactions with $Cu^{2+}$ and $MV^{2+}$, whereas it attenuated the quenching activity of NB and $O_2$ toward $RuL_3^{2+}$. The binding affinity of quenchers to SDS micelle and binding sites of the quenchers and $RuL_3^{2+}$ in micelle appear to be important factors controlling the micellar effect on the quenching reactions.

• Bulletin of the Korean Chemical Society
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• 제9권5호
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• pp.317-322
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• 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.