• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.355-361
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• 1999

To improve the volatility and stability of lead complexes, the principle of stabilization by saturating the metal coordination sphere by intramolecular coordination through a β-diketonates with an ethereal group has was tested. Several new lead complexes with alkoxyalkyl-substituted β-diketonates, Pb(R1C(O)CHC(O)(CH2)3OR2)2(Rl=t-Bu, Me, OMe, i-Pr, R2=Me, Et), or carboxylate, Pb(OC(O)(CH2)3OEt)2, were prepared by the reaction between Pb(OAc)2 and corresponding alkoxyalkyl-substituted β-diketonates, and they were found to have a viscous liquid phase. The nature of the head (β-diketonate or carboxylate) or tails and substituents of β-diketonates appeared not to be important for the formation of the liquid phase. It is worth mentioning that Pb(OAc)2, which has limited use due to its low solubility, was successfully adopted as a starting material for the preparation of new lead complexes. Easy hydrolysis, reaction with HCl, and 13C NMR spectra indicated that tail portions were not coordinated to the metal as a copper derivative, Cu(t-BuC(O)CHC(O)(CH2)3OMe)2. All these complexes were not volatile enough for the MOCVD experiments, but a methyl derivative, Pb(MeC(O)CHC(O)(CH2)3OEt)2, showed some sublimation. The methoxy derivative, Pb(MeOC(O)CHC(O)(CH2)3OEt)2, was thermally unstable due to possible equilibrium between species coordinating with a keto oxygen atom and an ethereal atom of a methoxy group, which was confirmed by IR and 13C NMR spectra.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.725-730
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• 2013

An investigation of the coordination behavior of sulfur-containing mixed-donor tribenzo-macrocycles $L^1-L^3$ ($L^1$: 20-membered $O_3S_2$, $L^2$: 20-membered $O_2S_3$, and $L^3$: 23-membered $O_4S_2$) with $d^{10}$-metal ($Ag^+$, $Hg^{2+}$, and $Pb^{2+}$) salts is reported. The X-ray structures of five complexes (1-5) with different structural types and stoichiometries, including mono- to dinuclear species have been determined. Reactions of $L^2$ and $L^3$ with the silver(I) salts ($PF_6{^-}$ and $SCN^-$) afforded two dinuclear 2:2 (metal-to-ligand) complexes with different arrangements: a sandwich-type cyclic dinuclear complex $[Ag_2(L^2)_2](PF_6)_2{\cdot}3CH_2Cl_2$ (1) and a linear dinuclear complex $[Ag_2(L^3)_2(SCN)_2]$ (2), in which two monosilver(I) complex units are linked by an Ag-Ag contact. Reactions of $L^1$ and $L^2$ with mercury(II) salts ($SCN^-$ and $Cl^-$) gave a mononuclear 1:1 complexes $[Hg(L^1)(SCN)_2]$ (3) and $[Hg(L^2)Cl_2]$ (4) with anion coordination in both cases. $L^2$ reacts with lead(II) perchlorate to yield a mononuclear sandwich-type complex $[Pb(L^2)_2(ClO_4)_2]$ (5), giving an overall metal coordination geometry of eight with a square antiprism arrangement. From these results, the effects of the donor variation and the anioncoordination ability on the resulting topologies of the soft metal complexes are discussed.

• Bulletin of the Korean Chemical Society
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• v.23 no.10
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• pp.1439-1444
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• 2002

6-Nitroquipazine has higher binding affinity for SERT than other selective serotonin reuptake inhibitors. We have prepared 6-nitroquipazine based rhenium complexes which would lead to the development of potential SPECT imaging agents with $^{99m}Tc$ for 5-HT transporter.

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1036-1042
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• 1998

The preconcentration and determination of trace elements in water samples were studied by a solvent sublation utilizing dithizonate complexation. After metal dithizonates were formed, trace amounts of cadmium, cobalt, copper and lead were floated and extracted into small volume of a water-immiscible organic solvent on the surface of sample solution and determined in the solvent directly by GF-AAS. Several experimental conditions as formation condition of metal-dithizonate complexes, pH of solution, amount of dithizone, stirring time, the type and amount of surfactants, N2 bubbling rate and so on were optimized for the complete formation and effective flotation of the complexes. And also four kinds of light solvents were compared each other to extract the floated complexes, effectively. After the pH was adjusted to 4.0 with 5 M HNO3, 8.0 mL of 0.05% acetone solution of dithizone was added to 1.00 L water sample. The dithizonate complexes were flotated and extracted into the upper methyl isobutylketone (MIBK) layer by the addition of 2.0 mL 0.2% ethanolic sodium lauryl sulfate solution and with the aid of small nitrogen gas bubbles. And this solvent sublation method was applied to the analysis of real water samples and good results of more than 85% recoveries were obtained in spiked samples.

• Journal of Applied Biological Chemistry
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• v.64 no.2
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• pp.159-164
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• 2021

Heavy metals exist in soils in various chemical forms including free metal ions and organo-metal complexes. The ratio of free metal ions has been known to be highly associated with the plant absorption of heavy metals. This study aims to understand the effect of free ions and organo-metal complexes on the absorption of lead (Pb) and cadmium (Cd) by plants. For this, lettuce grown in a hydroponic system for 28 days was consequently grown another 48 hours using Pb and Cd solutions. The ratios of free ion to organo-metal complexes in the solutions were adjusted at 100:0, 90:10, 70:30, 60:40 by four different organic acids (citric, oxalic, acetic, and humic acid). After that, the concentration of Pb and Cd in lettuce were analyzed. The Pb and Cd absorption by lettuce was more relied on the types of organic acids treated and the type of metals rather than the ratio of free metal ions. For example, citric acid increased the Pb absorption while it decreased the Cd absorption by lettuce. There was no significant relationship between free metal ion ratios and both Pb and Cd uptake by lettuce. It could be explained that citric acid, a relatively higher molecular weight organic acid, has higher ion binding capacity, so it forms organo-Pb complex easily due to the higher affinity of Pb on the binding site in comparison with Cd. Consequently, this complexation would assist Pb uptake by lettuce.

• Bulletin of the Korean Chemical Society
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• v.14 no.5
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• pp.625-631
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• 1993

The types of the products of the reactions between RuH(NO)(Cyttp) and alkynes are sensitive to the nature of alkynes. Terminal, nonactivated alkynes (HC${\equiv}$CR, R=Ph, hexyl and $CH_2OH)$ produce acetylide complexes and terminal (HC${\equiv}$CR, R=C(O)Me, COOEt) or internal activated ones (RC${\equiv}$ CR, R=COOMe) lead to form alkenyl complexes. On the other hand, internal nonactivated alkynes (RC${\equiv}$CR, R=Ph) do not show reactivity toward RuH(NO)(Cyttp). These products can be rationalized by the cis-concerted mechanism but the radical pathway appears to work in the reaction of propargyl chloride. From the spectroscopic data, the trigonal bipyramidal structure with a linear NO group is proposed for these products.

• Journal of Environmental Science International
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• v.12 no.8
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• pp.871-879
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• 2003

The complexation of co-contaminant mixtures between Ag(I) and polycyclic aromatic hydrocarbon (PAH) molecules (naphthalene, pyrene, and perylene) were investigated to quantify the equilibrium constants of their complexes and elucidate the interactions between Ag(I) and PAH molecules. The apparent solubilities of PAHs in aqueous solutions increased with increasing Ag(I) ion concentration. The values, K$_1$ and K$_2$ of equilibrium constants of complexes of Ag(I)-PAHs, were 2.990 and 0.378, 3.615 and 1.261, and 4.034 and 1.255, for naphthalene, pyrene, and perylene, respectively, The K$_1$and K$_2$ values of PAHs for Ag(I) increased in the order of naphthalene ＜ pyrene ＜ perylene and naphthalene ＜ pyrene ≒ perylene, respectively, indicating that a larger size of PAH molecule is likely to have more a richer concentration of electrons on the plane surfaces which can lead to stronger complexes with the Ag(I) ion. For the species of Ag(I)-PAH complexes, a 1:1 Ag(I) : the aromatic complex, AgAr$\^$＋/, was found to be a predominant species over a 2:1 Ag(I) : aromatic complex, Ag$_2$Ar$\^$＋＋/. The PAH molecules with four or more aromatic rings and/or bay regions were observed to have slightly less affinity with the Ag(I) ion than expected, which might result from inhibiting forces such as the spread of aromatic $\pi$ electrons over o wide molecular surface area and the intermolecular electronic repulsion in bay regions.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.717-722
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• 1993

Reactions of [PtCl$_4$]$^{2-}$ with excess of dithiocarbamates in water lead to facile replacement of the chloro ligand by dithiocarbamato ligand to give [Pt(A)], [Pt(B)$_2$]Cl$_2$, [Pt(C)$_2$], and [Pt(D)(CH$_2$=CH$_2$)Cl]Cl. The complexes of platinum have been characterized by elemental analyses, infrared and UV-visible spectra, and conductivity measurements. Platinum(II)-dithiocarbamate complexes were soluble in polar solvents such as water, alcohol, acetone, dimethylformamide, and dimethylsulfoxide etc. The possible structure was proposed on the basis of elemental analyses and physical properties.

• YAKHAK HOEJI
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• v.40 no.2
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• pp.218-224
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• 1996

This laboratory has recently reported the synthesis and in vitro antitumor activity of PT(II) complexes containing ethylenediamine and diphosphine. In view of the reports of others, cisplatin is toxic to the kidney since the kidney's vulnerability to PT(II) complexes may originate in its ability to accumulate and retain platinum to a greater degree than other organs. The in vitro cytotoxicity of these synthetic PT(II) complexes on the primary cultured proximal tubular cells of rabbit kidney and renal cortical cells of human kidney was investigated. Three endpoints for cytotoxicity tests were evaluated:3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), $^3H$-thymidine uptake and the glucose consumption tests. The rank order of sensitivity exhibited $^3H$-thymidine uptake>MTT>glucose consumption test. The agents with diphosphine leaving group were significantly less cytotoxic than cisplatin. Moreover, 1,2-bis(diphenylphosphino)ethane (DPPE) exhibited less cytotoxicity than 1.3-bis (diphenylphosphino)propane (DPPP) against on rabbit and human cultured kidney cells. Based on these results, the decreased nephrotoxicity of these new complexes over cisplatin appeared to be partially attributable to a leaving group of DPPP and DPPE. This novel class of platinum compound represents a valuable lead in the development of a "third-generation" agent.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.671-676
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• 1998

The formation and dissociation rates of $Ce^{3+}$ Complexes of the 1,4,7,10-tetraaza-13,16-dioxacyclooctadecane-NN', N",N"'-tetraacetic acid (1), 1,4,7,10-tetraaza-13,16-dioxacyclooctadecane-N,N',N",N"'-tetramethylacetic acid (2), and 1,4,7,10-tetraaza-13,16-dioxacyclooctadecane-N,N',N",N"'-tetrapropionic acid (3) have been measured by the use of stopped-flow spectrophotometry. Observations were made at 25.0±0.1 ℃ and at an ionic strength of 0.10 M $NaClO_4$. The complexation of $Ce^{3+}$ ion with 1 and 2 proceeds through the formation of an intermediate complex $(CeH_3L^{2+})^*$ in which the $Ce^{3+}$ ion is incompletely coordinated. This may then lead to be a final product in the rate-determining step. Between pH 4.76 and 5.76, the diprotonated $(H_2L^{2-})$ from is revealed to be a kinetically active species despite of its low concentration. The stability constants $(logK(CeH_3L^{2+}))$ and specific water-assisted rate constants $(k_{OH})$ of intermediate complexes have been determined from the kinetic data. The dissociation reactions of $Ce^{3+}$ complexes of 1, 2, and 3 were investigated with $Cu^{2+}$, ions as a scavenger in acetate buffer. All complexes exhibit acid-independent and acid-catalyzed contributions. The effect of buffer and $Cu^{2+}$ concentration on the dissociation rate has also been investigated. The ligand effect on the dissociation rate of $Ce^{3+}$ complexes is discussed in terms of the side-pendant arms and the chelate ring sizes of the ligands.