• Bulletin of the Korean Chemical Society
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• v.23 no.8
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• pp.1062-1066
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• 2002

The complexes [Ni(L)(INT)2]${\cdot}$5H2O (1) and [Cu(L)(H2O)](Cl)(INT)${\cdot}$3H2O (2) (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.18 ,07.12 ]docosane, INT = isonicotinate) have been prepared and characterized by X-ray crystallography, electronic absorption, and cyclic voltammetry. The crystal structure of 1 reveals an axially elongated octahedral geometry with two axial isonicotinate ligands. The electronic spectra, magnetic moment, and redox potentials of 1 also show a high-spin octahedral geometry. However, 2 shows that the coordination environment around the copper atom is a distorted square-pyramid with an axial water molecule. The spectra and electrochemical behaviors of 2 are also discussed.

• Journal of the Korean Applied Science and Technology
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• v.18 no.4
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• pp.254-260
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• 2001

The Mo(V) $di-{\mu}-oxo$ type [$Mo_{2}O_{4}(H_{2}O)_{2}L_{2}$] $SO_{4}$ complexes(L: 2,2'-dipyridyl,4,4'-ethylenedianlline) have been prepared by the reaction of $[Mo_{2}O_{4}(H_{2}O)_{6}]SO_{4}$ with a series of chelate ligands. These complexes are completed by two terminal oxygens arranged trans to one another and each ligand forms a chelate types. In $Mo_{2}O_{4}(H_{2}O)_{2}L_{2}$, two $H_{2}O$ coordinated at trans site of terminal oxygens. The prepared complexes have been characterized by elemental analysis, infrared spectra, $^{1}H$ nuclear magnetic resonance spectra, and thermal analysis(TG-DTA). In the potential range -0.00V to -1.00V at a scan rate of $50mVs^{-1}$, a cathodic peak at -0.81V ${\sim}$ -0.87V (vs SCE) and an anodic peak at -0.61V ${\sim}$ -0.63V (vs SCE) have been observed in aquous solution. We infer these redox are irreversible reaction.

• Analytical Science and Technology
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• v.8 no.1
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• pp.55-62
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• 1995

Tetradentate Schiff base cobalt(II) complexes such as $Co(II)_2-N$, N-bis(salicylidene)-m-phenylendiimine; [$Co(II)_2(SMPD)_2(H_2O)_4$] and $Co(II)_2-N$, N-bis(salicylidene)-p-phenylendiimine: [$Co(II)_2(SPPD)_2(H_2O)_4$], and oxygen adducted cobalt (III) complexes such as [$Co(III)_2O_2(SMPD)_2(Py)_2$] and [$Co(III)_2O_2(SPPD)_2(Py)_2$] in pyridine solutions were synthesized. It was identified that the oxygen adducted cobalt(III) complexes have hexacoordinated octahedral configuration with pyridine and oxygen from the measurement of elemental analysis, AA, IR spectra, and TGA. The redox processes were investigated for the oxygen adducted complexes in 0.1M TEAP-pyridine solution, using cyclic voltammetry on the glassy carbon electrode. The redox processes of oxygen adducted Co(III) complexes result in $$[Co(III)_2-O_2-CO(III)]\rightarrow^{e^-}[Co(III)-O_2-Co(II)]\rightarrow^{e^-}[Co(II)-O_2-Co(II)]\rightleftarrows^{e^-}[Co(II)+Co(II)+O_2{\cdot}^-]\rightleftarrows^{e^-}[Co(II)+Co(I)+O_2{\cdot}^-]\rightleftarrows^{e^-}[Co(I)+Co(I)+O_2{\cdot}^-]$$.

• Journal of Pharmaceutical Investigation
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• v.22 no.3
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• pp.65-76
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• 1992

The superoxide dismutase (SOD)-mimetic activities of copper complexes of a series of salicylic acid (SA) analogs were tested and compared to the activity of bovine erythrocyte SOD using ferricytochrome c reduction assay. Stability constants of copper complexes were measured potentiometrically using SCOGS2 program. In the presence of 10 g/l albumin, all the copper complexes lost their SOD mimetic activities. Multiple regression analysis was employed for the statistical comparisons between the SOD mimetic activity and their physicochemical properties. Correlation exists for the SOD mimetic activity and steric parameter $(E_s)$ and/or electronic parameter $({\Sigma}{\sigma})$ in xanthine/xanthine oxidase (XOD) system, demonstrating that E, plays a key role in SOD activity whereas ${\Sigma}{\sigma}$ influences it to a lesser extent. The protective effect of copper complexes against membrane damage was measured by counting D-glucose released frm $EG_s$. D-glucose and XOD were entrapped within $EG_s$ and acetaldehyde was used as a substrate for XOD. In this membrane model system using $EG_s$, hydrophobic parameter $({\Sigma}{\pi})$ is of most importance, producing parabolic equation while $E_s$, and ${\Sigma}{\sigma}$ appear to playa minor role in protection against D-glucose release. In summary, to design an efficient SOD mimetic, stability, steric factor, lipophilicity and redox potential should be considered.

• Journal of the Korean Applied Science and Technology
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• v.16 no.3
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• pp.205-210
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• 1999

The Mo(V) $di-{\mu}-oxo$ type $[Mo_2O_4(H_2O)_2L]Cl_2$ complexes(L: 4,4'-Diphenyl-2,2'-dipyridyl, 4,4'-Dimethyl-2,2'-dipyridyl, 4,7-Diphenyl-1,10-phenanthroline) have been prepared by the reaction of $[Mo_2O_4(H_2O)_6]^{2+}$ with a series of chelate ligands. These complexes are completed by two terminal oxygens arranged trans to one another and each ligand forms a chelate types. In $Mo_2O_4(H_2O)_2L$ two $H_2O$ coordinated at trans site of terminal oxgens. The prepared complexes have been characterized by elemental analysis, infrared spectra, electronic spectra, $^1H$ nuclear magnetic resonance spectra, and thermal analysis(TG-DTA). In the potential range -0.00V to -1.00V at scan rate of $50mVs^{-1}$, a cathodic peak at -0.83V ${\sim}$ -0.88V (vs SCE) and an anodic peak at -0.54V ${\sim}$ -0.88V (vs SCE) have been observed in aquous solution. The ratio of the cathodic to anodic current(Ipc/Ipa) is almost 2, we infer that redox is irreversible as dimer forms broken.

• Bulletin of the Korean Chemical Society
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• v.27 no.1
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• pp.99-105
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• 2006

Polyamine dendrimers functionalized with electrochemiluminescent (ECL) polypyridyl Ru(II) complexes, dend-$[CO-(CH_2)_3-mbpy{\cdot}Ru(L)_2]_3(PF_6)_6$ (dend: N$(CH_2CH_2NH)_3$-, L: bpy, o-phen, phen-Cl, DTDP), were synthesized through the complexation of dendritic polypyridyl ligands to Ru(II) complexes. Their electrochemical redox potentials, photoluminescence (PL), and relative ECL intensities were studied. The ECL emissions produced by the reaction between the electro-oxidized $Ru^{3+}$ species of polyamine dendrimers and tripropylamine as a coreactant were measured in a static system with potential cycles between 0.8 and 1.3 V or through flow injection analysis with a potential of +1.3 V, and were compared to that of $[Ru(o-phen)_3](PF_6)_2{\cdot}Dend-[CO-(CH_2)_3-mbpy{\cdot}Ru(bpy)_2]_3(PF_6)_6$ showed an ECL intensity that was two-fold greater than that of the reference complex $[Ru(o-phen)_3](PF_6)_2$.

• Journal of the Korean Applied Science and Technology
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• v.21 no.1
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• pp.76-88
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• 2004

The catalytic oxidation reaction of several cycloolefins in $CH_2Cl_2$ have been investigated using non-redox metalloporphyrin(M = Ga(III), In(III) and TI(III) complexes as a catalyst and sodium hypochlorite as a terminal oxidant. Porphyrins were $(p-CH_3O)$TPP, $(p-CH_3)$TPP, TPP, (p-F)TPP, (p-Cl)TPP and $(F_{20})$TPP (TPP=5,10,15,20-tetraphenyl-21H,23H-porphyrin) and olefins were cyclopentene, cyclohexene, cycloheptene and cyclooctene, The substrate conversion yield(%) was investigated according to the radius effect of non-redox metal ion, substituent effect and hindrance effect of metalloporphyrin. The conversion yield of cycloolefin was in the following order : $C_5$ < $C_6$ < $C_7$ = $C_8$.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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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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• v.11 no.2
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• pp.89-94
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• 1990

The redox properties of 2-amino-1-cyclopentene-1-dithiocarboxylate anion (acdc) and its oxovanadium complex, $VO(acdc)_2$ have been investigated in dimethylformamide (DMF) with polarography and cyclic voltammetry. Bis(2-amino-1-cyclopentene-1-dithiocarboxylate) oxovanadium(IV) exhibits two polarographic oxidation waves and two reduction waves in the potential range from +0.50V to - 2.4V vs. the Ag/AgCl (DMF) reference electrode. The second oxidation wave appeared at - 0.08V is found to be reversible and is attributed to the formation of $VO(acdc)_2\;^+$. The first reduction process (at - 0.60V) is also reversible and this reduction process is caused by the electrode process of formation of $VO(acdc)_2$-species. The half wave potential for the reduction, V(IV)$\to$V(III) is more positive for oxovanadium complexes containing sulfur donor atoms than other VO(IV) complexes having oxygen or nitrogen donor atoms.

• Bulletin of the Korean Chemical Society
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• v.18 no.9
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• pp.1022-1028
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• 1997

The reaction between Ni(Ⅱ) and sodium salt of 5,6-dihydro-1,4-dithiin-2,3-dithiolate (DDDT2-) in the presence of oxygen results in the formation of Ni(Ⅲ) species, Ni(DDDT)2-, which is isolated as tetraalkylammonium salt. The same reaction performed in the absence of oxygen yields dianionic Ni(Ⅱ) species, Ni(DDDT)22-, which is also isolated as the tetraethylammonium salt. The bis(5,6-dihydro-1,4-dithiin-2,3-dithiolato) nickelate (Ⅱ) dianion, Ni(DDDT)22-, reacts with methyl iodide to yield unusually stable bis(methylthio)dithiolene complex, Ni(CH3)2C8H8S8. All the isolated dithiolato-nickel(Ⅱ) and nickel(Ⅲ) complexes are characterized by 1H NMR, UV/Vis, IR and mass spectroscopic methods. The internal redox reaction of the nickel(Ⅱ)-dithiolate has been studied by spectro-electrochemical method and the results were compared with those of other metal-dithiolenes. The alkylated nickel(dithiolene) complex presumably undergoes cis-trans isomerization reaction in solution, judging from the experimental results of variable-temperature 1H NMR measurements.