• Korean Journal of Environmental Agriculture
• /
• v.12 no.2
• /
• pp.162-168
• /
• 1993

This research was conducted to assess the influence of humic or fulvic acid on Bentazone phytotoxicity using a bioassay with hydroponically grown cabbage (Brassica campestris subsp. napus var. pekinensis Makino). Concentrations of Bentazone in the water culture media were ranged from 0 to 32 ${\mu}M $ and those of the organic ligands were 1.0mM as a soluble carbon. Media were prepared in a complete factorial combination with pHs of 4.5, 6.5 and 8.5. The phytotoxicity indices on growth rate and dry weight decrement were employed to evaluate the effects of organic ligands on the Bentazone phytotoxicity. Humic or fulvic acid without Bentazone treatment enhanced the growth of cabbage and this effect was evident at low pH of 4.5. Bentazone led to chlorosis and necrosis on cabbage leaves resulting in the decreases of dry and fresh weights and growth rate. This phytotoxic effect was increased with Bentazone concentration and evident at low pH. At pH 4.5, dry weight was decreased about 63% with 8${\mu}$M of Bentazone treatment. Effective concentration of Bentazone causing 50% decreases in fresh weight as compared to the control was estimated to be 21${\mu}$M. Presence of organic ligand reduced the phytotoxicity of Bentazone to cabbage significantly by increasing yields and growth rates as compared to the treatment of Bentazone alone. At pH 4.5, fulvic acid reduced phytotoxicity of Bentazone upto 46%, and this efficiency of fulvic acid was better than that of humic acid under the same condition.

• Journal of the Korean Chemical Society
• /
• v.35 no.5
• /
• pp.512-519
• /
• 1991

The axial ligations of nitrogenous bases (pyridine, imidazole, 1-methylimidazole and 2,6-lutidine) to Zn(II)-, Cu(II)-, and Ni(II)-tetrakis(o-chlorophenyl)porphyrin(o-ClTPP), and -tetraphenylporphyrin (TPP) were investigated in organic solvents $(CH_2Cl_2,\;C_6H_6,\;CH_3NO_2,\;(CH_3)_2CO,\;CHCl_3,\;DMF\;and\;DMSO)$ and at 0.01M of ionic strength. The equilibrium constants for the ligation reactions of methalloporphyrins were determined using spectrophotometric method at 15∼35${\circ}C$. In case of M(II)-TPP the equilibrium constants K were considerably larger than those of M(II)-(o-Cl)TPP, depending on steric effect of the porphyrin. The linear relationships between logK of the axial ligation and $pK_a$ of nitrogenous base were shown in M(II)-TPP, but not in M(II)-(o-Cl)TPP. The stabilities of MTPP(L) were controlled by the reation enthalpy and entropy, while those of M(o-Cl)TPP almost by the reaction entropy. The coordinating power of solvent to the methalloporphyrin were also studied in $CHCl_3,\;(CH_3)_2CO$, DMF and DMSO. From those results the solvent effects on the equilibrium constants were discussed.

• Applied Chemistry for Engineering
• /
• v.10 no.5
• /
• pp.804-807
• /
• 1999

New copper complexes with a ligand, L(L=N,N'-cyclohexane bis(ferrocenylmethylene)amine) which was obtained from ferrocene carboxaldehyde and 1,2-diaminocyclohexane with a mole ratio of 2:1, were prepared and characterized. Those were adapted to asymmetric catalysis. The copper(II) complexes do not work in cyclopropanation of styrene and ethyl diazoacetate but copper(I) complex catalyzes. The Cu(I)LOTf (OTf=trifluorometanesulfonate) shows a good regioselectivity giving high trans to cis ratio of up to 80:20.

• Journal of the Korean Chemical Society
• /
• v.32 no.6
• /
• pp.549-556
• /
• 1988

In order to study the changes for the structure of N-benzylisonitrosoacetylacetone imine synthesized already in organic solution, nmr and carbon-13nmr DEPT spectra of the this reagent have been studied. Based on the present studies, it is suggested that this reagent is monoxime having syn- and anti-form isomers and has tautomers in solution respectively.

• Journal of the Korean Chemical Society
• /
• v.38 no.2
• /
• pp.122-128
• /
• 1994

Macrocyclic ligand has been known to selectively bind with metal ions so that ability applied for the transport of metal ions across the emulsion liquid membrane in this study. The metal ions are transproted from the source phase to the receiving phase by the carrier of the organic phase. Several factors involved in the transport of metal ions acrose the emulsion membrane we reported here and these factors provided the informations for the selective seperation of some metal ion. Stability constants for cation-macrocyclic ligand and metal ion-anion receiving phase interaction are examined as parameters for the prediction of metal ion transport selectivities. $Pb^{2+}$ was transported higher rates than the other metal ions in the mixture solution. The interaction of metal ion to anion in receiving phase is important. $S_2O_3^{2-}$- in replacement of $NO_3^-$ in the receiving phase enhances the transport of $Pb^{2-}$since $Pb^{2-}-S_2O_3^{2-}$interaction is greater than $Pb^{2+}-NO_3^-$ interaction.

• Korean Journal of Soil Science and Fertilizer
• /
• v.26 no.1
• /
• pp.37-42
• /
• 1993

Influences of metal concentration, pH and temperature on metal-ligand precipitate formation were investigated, as a part of projects for removing heavy metals from aqueous solution employing the principles in metal-ligand complexation. Aqueous solutions of HA or FA were reacted with those of heavy metals with 1:1 ratio. Efficiency of humic (HA) or fulvic acid (FA) on removing metals was evaluated by separating the precipitates from soltuions with the filtering method. When HA was a counter ligand, there existed three ranges of metal concentrations affecting precipitation : precipitate fromation was not available, was reached to the maximum, and afterwards was decreased again. The concentration ratios of metal to HA for initiating complexation were dependent upon kinds of metal and concentrations of ligand. Amount of Pb to form maximum precipitates per unit mg of HA was 1.3 times higher than that of Cu. When FA was a counter ligand, concentrations of metal-FA precipitates were increased proportionally with the treated metal concentrations. Efficiency of FA fro removing Pb was nearly 100%, but it was ranged from 12 to 19% for Cu, depending on FA concentration. pH exerted a considerable effect on complexation between Pb and FA, showing precipitates were increased six times at most per unit increase of pH. Ranges of pH increasing significantly the mounts of precipitates were coincied with pH jump ranges of the titration curve of organic ligands. As increasing temperature from 15 to $55^{\circ}C$, increases of FA-Cu precipitates were doubled, but those of FA-Pb were accounted for only 6%, However, HA-metal complexation was not affected by temperature.

• Journal of Adhesion and Interface
• /
• v.25 no.1
• /
• pp.157-161
• /
• 2024

Amphiphilic gold nanoparticles, synthesized by the simultaneous binding of hydrophilic and hydrophobic ligands on their surfaces, find diverse applications in energy, bio, optical, electronic technologies, and various other fields. Particularly, these amphiphilic gold nanoparticles possess both hydrophilic and hydrophobic characteristics, enabling them to activate interface at the interface of immiscible fluids and form organized structures. The surface properties of gold nanoparticles play a crucial role in influencing the behaviors of amphiphilic gold nanoparticles at the interface of two fluids. Therefore, this study investigated the adsorption behaviors of gold nanoparticles at the organic solvent-water interface based on the surface characteristics of amphiphilic gold nanoparticles and the type of organic solvents. It was observed that the amount of adsorbed gold nanoparticles at the interface increased with the length of hydrocarbon chains in hydrophobic ligands and increased with shorter hydrocarbon chains in the organic solvent. Furthermore, using the Langmuir isotherm model, the study confirmed the formation of a monolayer by amphiphilic gold nanoparticles and obtained significant thermodynamic parameters simultaneously.

• Journal of the Korean Chemical Society
• /
• v.34 no.5
• /
• pp.430-437
• /
• 1990

Various tris (${\eta}^4$-diene) molybdenums were easily synthesized by the reaction of various 1,3-dienes and molybdenum metal vapors by using metal atom reactor. The methyl substituent effect of the tris (${\eta}^4$-diene) molybdenum produced were discussed. And some alkadiene-molybdenum complexes which were easily decomposed in the air at room temperature were also formed.(C$_6$H$_{10}$)$_2$(CO)$_3$Mo were synthesized and its molybdenum-diene bond type were discussed.

• Polymer Science and Technology
• /
• v.5 no.3
• /
• pp.236-253
• /
• 1994

양이온형 $d^0\;Cp_2M(R)(L)^+$ 착물과 무염기 $Cp_2M(R)^+$ 착물은 $Cp_2M(R)_2$화합물로부터 쉽게 합성할 수 있다. 이들 친전자성 착물에서는 여러가지 리간드 교환반응, 삽입반응, ${\beta}$-H 제거반응 및 ${\sigma}$-결합 복분해반응이 일어날 수 있다. 일반적으로 $Cp2M(R)(L)^+$ 착물은 불포화도와 전하가 크기때문에 중성의 $Cp_2M(R)(X)$나 $Cp_2M(R)_2$보다 반응성이 크며 $d^0\;{Cp_2}^*M(R)^+$ (M=제 3족과 란탄계) 착물과 여러가지 반응에서 유사한 거동을 보인다. $Cp_2MX_2$를 기초로하여 합성된 Ziegler-Natta 촉매에 의한 올레핀 중합에서 활성점이 $Cp_2M(R)^+$ 양이온이라는 여러가지 직접적인 증거가 발표되었다. 분리가능한 $Cp_2M(R)(L)^+$ 착물은 올레핀중합에서 높은 활성을 보이며, 유기합성의 관점에서 흥미있는 C-C 재조합반응과 같은 다른 여러가지 반응이 일어날 수 있는 기회를 제공한다.

• Membrane Journal
• /
• v.27 no.1
• /
• pp.1-42
• /
• 2017

Metal-organic frameworks (MOFs) are nanoporous materials that consist of organic and inorganic moieties, with well-defined crystalline lattices and pore structures. With a judicious choice of organic linkers present in the MOFs with different sizes and chemical groups, MOFs exhibit a wide variety of pore sizes and chemical/physical properties. This makes MOFs extremely attractive as novel membrane materials for gas separation applications. However, the synthesis of high-quality MOF thin films and membranes is quite challenging due to difficulties in controlling the heterogeneous nucleation/growth and achieving strong attachment of films on porous supports. Microwave-based synthesis technology has made tremendous progress in the last two decades and has been utilized to overcome some of these challenges associated with MOF membrane fabrication. The advantages of microwaves as opposed to conventional synthesis techniques for MOFs include shorter synthesis times, ability to achieve unique and complex structures and crystal size reductions. Here, we review the recent progress on the synthesis of MOF thin films and membranes with an emphasis on how microwaves have been utilized in the synthesis, improved properties achieved and gas separation performance of these films and membranes.