• Textile Coloration and Finishing
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• v.8 no.6
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• pp.40-46
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• 1996

In order to investigate a practical application of fibrous absorbents to transition metals such as copper, nickel, cobalt, chrome, and iron, amidoximated fiber as a particular class of solid chelate agents were prepared from acrylic fibers treatment with hydroxylamine. The adsorption mechanisms of metal ions onto amidoximated acrylic fibers and their complexes were studied. Amidoximation of acrylic fiber with hydroxylamine is found to be first-order reaction, followed by the disappearance of infrared adsorption peaks due to nitrile groups of acrylic fibers. The uptake of metal ions onto amidoximated acrylic fiber is increased with temperature raising and the adsorption is also depended on pH of the soiutions. About 70% of metal ions can be recovered from aqueous solutions of Ni(II), Co(II), Cr(III), and Fe(II) on the concentration below 5x 10$^$^{-4}$ in the range of pH 2.1~10.0. Transition metals are adsorbed to form complex with amidoxime group by the ligand sites such as C=N, NH, NO, NHOH.OH.

• Bulletin of the Korean Chemical Society
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• v.27 no.5
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• pp.759-761
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• 2006

The compound B(C6F5)3 and its variations have been widely employed as alkyl carbanion abstracting reagents to produce metallocene cations for olefin polymerization.1-3 Weakly coordinating anions containing boron can greatly improve the activity of metallocene catalysts used in industrial olefin polymerization4 and thus group IV and V metallocene complexes of the organohydroborate anions have been intensively investigated.5 Recently, many organohydroborate metallocene complexes have been reported by Shore and co-workers.6-8 A common structural feature of those complexes is the three-center two electron M-H-B bond, like that observed in transition metal tetrahydroborate complexes but the reactivity and fluxional behavior of organohydroborate complexes are unlike those of the tetrahydroborate analogues.6 Although many of those metallocenes have been synthesized, few complexes could be used in the olefin polymerization and then this laboratory has been involved in the chemistry of the cyclic organohydroborate anions, and their group IV metallocene derivatives for the catalyst.9 Described here is recent work that led to the preparation of a novel cyclic organohydroborate hafnocene complex (h5-C5H5)2Hf ？(μ-H)2BC8H14 ,Cl. The hafnocene complex contains the three-center two electron bond Hf-H-B10 in which the hydride abstraction for olefin polymerization may occur.

• Bulletin of the Korean Chemical Society
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• v.15 no.5
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• pp.364-368
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• 1994

Growth inhibition potency of the anthraquinones, anthraquinone-1,5-disulfonic acid and carminic acid, for Sarcoma 180 and L1210 leukemia cells in vivo and in vitro, was induced by the divalent transition metal ion, $Cu^{2+}$. On the other hand spectroscopic titration data show that the anthraquinone drugs form $Cu2^+$ chelate complexes (carminic acid : $Cu^{2+}$ = 1 : 6; anthraquinone-1,5-disulfonic acid : $Cu^{2+}$ = 1 : 3). Furthermore the $Cu^{2+}$-drug complexes associate with DNA to form the $Cu^{2+}$-anthraquinone-DNA ternary complexes. The formation of the complexes was further supported by the $H_2O_2-dependent$ DNA degradation, which can be inhibited by ethidium bromide, caused by the $Cu^{2+}$-drug complexes. It is likely that the $Cu^{2+}$-mediated cytotoxicity of the anthraquinone drugs is related with the $Cu^{2+}-mediated$ binding of the anthraquinone drugs to DNA and DNA degradation.

• Bulletin of the Korean Chemical Society
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• v.17 no.9
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• pp.840-845
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• 1996

Rate constants have been measured spectrophotometrically for the reactions of p-and m-nitrophenyl 2-thiophenecarboxylate (5a and 5b, respectively) with alkali metal ethoxides (EtO-M+) in absolute ethanol at 25.0±0.1 ℃. The reactivity of EtO-M+ exhibits dependence on the size of alkali metal ions, i.e. the reactivity of EtO-M+ toward 5a decreases in the order EtO-K+ ≥ EtO-Na+ > EtO-Li+ > EtO-, while the one toward 5b does in the order EtO-Na+ ≥ EtO-K+ > EtO-Li+ > EtO-. This result indicates that ion paired EtO-M+ is more reactive than dissociated EtO-, and alkali metal ions form complexes with the substrate more strongly at the transition state than at the ground state. The catalytic effect shown by alkali metal ions appears to be less significant in the reaction of 5 than in the corresponding reaction of 4, indicating that complexation of alkali metal ions with 5 is not as strong as the one with 4.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2711-2718
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• 2012

The alkylation of the ambident enolates of a methyl glycinate Schiff base with ethyl chloride was studied at B3LYP and MP2 levels with $6-31+G^*$ basis set. The free (E)-enolates and (Z)-enolate are similar in energy and geometry. The transition states for the alkylation of the free (E)/(Z)-enolate with ethyl chloride have similar energy barriers of ~13 kcal/mol. However, with a lithium ion, the (E)-enolate behaves as an ambident enolate and makes a cyclic lithium-complex in bidentate pattern which is more stable by 11-23 kcal/mol than the (Z)-enolate-lithium complexes. And the TS for the alkylation of (E)-enolate-lithium complex coordinated with one methyl ether is lower in energy than those from (Z)-enolate-lithium complexes by 4.3-7.3 kcal/mol. Further solvation model (SCRF-CPCM) and reaction coordinate (IRC) were studied. This theoretical study suggests that the alkylation of ambident enolates proceeds with stable cyclic bidentate complexes in the presence of metal ion and solvent.

• Journal of the Korean Chemical Society
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• v.39 no.8
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• pp.611-616
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• 1995

Oxovanadium(IV) complexes with salicylaldoxime, o-vanilline oxime, 2-hydroxy-4-methoxybenzaldoxime, 2-hydroxy-5-methoxybenzaldoxime and 2-hydroxy-5-nitrobenzaldoxime were synthesized. The complexes have been characterized by elemental analysis, electric conductivity measurement, infrared spectrometry, electronic spectrometry, mass spectrometry, and thermal analysis. The results of elemental analysis were well coincided with the theoretical values. The values of molar conductance of the complexes in DMF implicated that the complexes were non-electrolyte. The characteristic stretching frequency of V=O appeared strong band in the range of $980{\pm}20\;cm^{-1}.$ All the complexes showed two d-d transition in visible spectra and two charge transfer transitions in ultraviolet spectra. Results of mass spectrometry of $VO(sal)_2\;and\;VO(van)_2$ indicated two peaks corresponding to vanadium containing ion(I) of 1 : 2(metal to ligand) chelate and a fragment ion(II) of 1 : 1 chelate due to loss of ligand radical from ion(I). The thermal analysis showed the endothermic peak due to the thermal decomposition.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.702-710
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• 1993

Electrochemical reduction of thionyl chloride has been carried out at glassy carbon and molybdenum electrodes, the surface of which is modified by binuclear tetradentate schiff base Co(II), Ni(II),Cu(II) and Fe(II) complexes. The catalyst molecules of transition metal(II) complexes were adsorbed on the electrode surface and reduced thionyl chloride resulting in a generation of oxidized catalyst molecules. There was an optimum concentration for each catalyst compound. The catalytic effects of SOCl$_2$ reduction were larger on glassy carbon electrodes compared to molybdenum electrodes and enhancements in reduction current of up to 120${\%}$ at the glassy carbon electrodes. The reduction currents of thionyl chloride were increased and the reduction potentials were shifted to the negative potential when scan rates became faster. The reduction of thionyl chloride was proceed to diffusion controlled reaction.

• Journal of the Korean Chemical Society
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• v.23 no.4
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• pp.198-205
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• 1979

A valence bond method of calculation of the dipole moments for octahedral $(M(III)0_3S_3)$ type complexes are developed, using $d^2sp^3 $hybrid orbitals of the central metal ions and the single basis set orbital of ligands. (M (III) =V (III), Cr (III), Mn (III), Fe (III), Co (III), Ru (III), Rh (III) and OS (III)). In this method the mixing coefficient of the valence basis sets for the central metal ion with the appropriate ligand orbitals is not required to be the same, differently from the molecular orbital method. The valence bond method is much more easier to calculate the dipole moments for octahedral complexes than the approximate molecular orbital method and the calculated results are also in the range of the experimental vaues.

• Journal of Environmental Science International
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• v.22 no.10
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• pp.1273-1278
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• 2013

Novel rhodamine 6G fluorescent chemosensors 1 and 2 for the detection of transition metal cations were synthesized through the condensation of rhodamine 6G ethylenediamine with each of 2-hydroxy-1-naphthaldehyde and 2,6-pyridinedicarbaldehyde, respectively. 1 and 2 were characterized using $^{13}C$ NMR, $^1H$ NMR and mass spectroscopy. Fluorometric and colorimetric measurements involving various metal ions revealed the ring opening of the rhodamine 6G spirocycle framework. In the absence of metal cations, 2 was colorless and non-fluorescent, whereas the addition of metal cations ($Hg^{2+}$ and others) changed the color to pink, accompanied by the appearance of an orange fluorescence. The chemosensors exhibited high selectivity for $Hg^{2+}$ over other divalent first-row transition metals. The complexes of $Hg^{2+}$ with 1 and 2 were successfully isolated. A huge enhancement in the fluorescence for both one- and two-photon excitations makes these compounds suitable candidates to be used for fluorescent labeling of biological systems.

• Bulletin of the Korean Chemical Society
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• v.18 no.12
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• pp.1264-1268
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• 1997

The poly(methylsilene) (1) was modified with the group 4 metallocene Cp2MCl2/Red-Al (M = Ti, Zr, Hf) combination catalyst and with the group 6 metal carbonyl M(CO)6 (M = Cr, Mo, W) catalyst, producing the highly cross-linked isoluble polymer and the lowly cross-linked soluble polymer, respectively. An interrelationship between molecular weight and percent ceramic residue yield with metal within the respective group was not found. The polymers modified with the group 4 metallocene combination catalysts have higher molecular weight and lower percent ceramic residue yield than the polymers modified with the group 6 metal carbonyl catalysts do. The catalytic activity of group 4 metallocene combinations appears to be higher at ∼100 ℃, but to be lower at very high temperature than those of group 6 metal carbonyls. The pyrolysis of the modified 1 yielded SiC ceramic.