• Bulletin of the Korean Chemical Society
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• v.21 no.9
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• pp.923-928
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• 2000

[FeIII(BBA)DBC]ClO4 as a new functional model for catechol dioxygenases has been synthesized, where BBA is a bis(benzimidazolyl-2-methyl)amine and DBC is a 3,5-di-tert-butylcatecholate dianion.The BBA complex has a structuralfeature that iron cent er has a five-coordinate geometry similar to that of catechol dioxygenase-substrate complex.The BBA complex exhibits strong absorptionbands at 560 and 820 nm in CH3CN which are assigned to catecholate to Fe(III) charge transfer transitions. It also exhibits EPR signals at g = 9.3 and 4.3 which are typical values for the high-spin FeIII (S = 5/2) complex with rhombicsymmetry. Interestingly, the BBA complex reacts with O2 within an hour to afford intradiol cleavage (35%) and extradiol cleavage (60%) products. Surprisingly, a green color intermediate is observed during the oxygenation process of the BBA com-plex in CH3CN. This green intermediate shows a broad isotropic EPR signal at g = 2.0. Based on the variable temperature EPR study, this isotropic signalmight be originated from the [Fe(III)-peroxo-catecholate] species havinglow-spin FeIII center, not from the simple organic radical. Consequently,it allows O2 to bind to iron cen-ter forming the Fe(III)-superoxide species that converts to the Fe(III)-peroxide intermediate. These present data can lead us tosuggest that the oxygen activation mechanism take place for the oxidative cleavingcatechols of the five-coordinate model systems for catechol dioxygenases.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1428-1432
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• 1999

[Fe$^{II}$(BLPA)DBCH]BPh₄ (1), a new functional model for the extradiol-cleaving catechol dioxygenases, has been synthesized, where BLPA is bis(6-methyl-2-pyridylmethyl)(2-pyridylmethyl)amine and DBCH is 3,5-di-tert-butylcatecholate monoanion. ¹H NMR and EPR studies confirm that 1 has a high-spin Fe(II) (S = 2) center. The electronic spectrum of 1 exhibits one absorption band at 386 nm, showing the yellow color of the typical [Fe$^{II}$(BLPA)] complex. Upon exposure to O₂, 1 is converted to an intense blue species within a minute. This blue species exhibits two intense bands at 586 and 960 nm and EPR signals at g = 5.5 and 8.0 corresponding to the high-spin Fe(III) complex (S = 5/2, E/D = 0.11). This blue complex further reacts with O₂ to be converted to (μ-oxo)Fe$^{III}_2$ complex within a few hours. Interestingly, 1 affords intradiol cleavage (65%) and extradiol cleavage (20%) products after the oxygenation. It can be suggested that 1 undergoes two different oxygenation pathways. The one takes the substrate activation mechanism proposed for the intradiol cleavage products after the oxidation of the $Fe^II\;to\;Fe^{III}$. The other involves the direct attack of O₂ to $Fe^{II}$ center, forming the $Fe^{III}$-superoxo intermediate which can give rise to the extradiol cleavage products. 1 is the first functional Fe(II) complex for extradiol-cleaving dioxygenases giving extradiol cleavage products.

• Bulletin of the Korean Chemical Society
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• v.28 no.9
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• pp.1609-1612
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• 2007

• The Journal of the Korean dental association
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• v.51 no.1
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• pp.12-17
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• 2013

Curing methods for denial resin-based materials are limited because of the need to polymerize quickly in the oral cavity at an ambient temperature. At present, most dental restorative composites use a camphorquinone-amine complex initiation, visible light-cure, one-component systems. Clinically, it is important to try to optimize the degree of conversion of res in composites using proper manipulation and adequate light-curing techniques to ensure the best outcome.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5221-5231
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• 2010

The complex formation from Ni(II) ion and 2-(2-Hydroxyethylamino)-2-(hydroxymethyl)-1,3-propanediol(Monotris) in aqueous solution at $25^{\circ}C$ and at ionic strength of 0.10M has been studied potentiometrically. In the Monotris(L) comlex $NiL^{2+}$, hydroxyl oxygen atom as well as the amine nitrogen of the ligand are coordinated to the Ni(II) ion.. The complex $NiL^{2+}$ undergoes further dissociation as the pH is increased forming triply deprotonated dinuclear complex $Ni_2L_2H_{-3}^+$.

• Journal of the Korean Chemical Society
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• v.63 no.1
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• pp.29-36
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• 2019

A potentially tetradentate Schiff base ligand, 2-((2-((pyridin-2-ylmethylene)amino)ethyl)amino)ethan-1-ol (PMAE), and its cadmium(II) complex, [$Cd(PMAE)I_2$] (1), were prepared and characterized by elemental analysis, FT-IR, Raman, $^1H$ and $^{13}C$ NMR spectroscopies and single-crystal X-ray diffraction. In the crystal structure of 1, the cadmium atom has a slightly distorted square-pyramidal geometry and a $CdN_3I_2$ environment in which the PMAE acts as an $N_3$-donor. In the crystal packing of the complex, the alcohol and amine groups of the coordinated ligands participate in hydrogen bonding with iodide ions and form $R^2{_2}(14)$ and $R^2{_2}(8)$ hydrogen bond motifs, respectively. In addition to the hydrogen bonds, the crystal network is stabilized by ${\pi}-{\pi}$ stacking interactions between pyridine rings. The thermodynamic stability of the isolated ligand and its cadmium complex along with their charge distribution patterns were studied by DFT and NBO analysis.

• Analytical Science and Technology
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• v.15 no.2
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• pp.135-141
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• 2002

The new tridentate poly-amine ligands, N,N-Bis(2-amino-ethyl)-methyl amine${\cdot}$2HBr (BAMA${\cdot}$2HBr), N,N-Bis(2-amino-ethyl)-ethylamine${\cdot}$2HBr (BAEA${\cdot}$2HBr), N,N-Bis(2-amino-ethyl)-propylamine${\cdot}$2HBr (BAPA${\cdot}$2HBr) and N,N-Bis(2-amino-ethyl)-butylamine${\cdot}$2HBr (BABA${\cdot}$2HBr) were synthesized as their dihydrobromic-salt and characterized by EA, IR, NMR and Mass spectroscopy. The protonation constants of the ligands and stability constants of transition metal(II) complexes were determined in aqueous solutions by potentiometry and compared with diethylenetriamine. Stability constants for transition metal complexes of ligands are in the order of BAMA < BAEA < BAPA > BABA. The larger value of stability constants of BAPA compared to these BABA, may be attributed to the more distorted structure of the complex due to the increased steric crowding caused by the presence of the bulky N-butyl group.

• Journal of the Korean Chemical Society
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• v.31 no.3
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• pp.271-279
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• 1987

A nitrate ion-selective PVC membrane electrode based on ammonia modified bakelite A-Ni$(NO_3)_2$ complex as ion exchanger was prepared. The electrode gave a linear response with a Nernstian slope of 60mV per decade within the concentration range $1{\sim}10^{-4}$ M $KNO_3$ but nonresponse to hydrogen ion and multivalent anions. The selectivity, response time and life time of the electrode were investigated and it was found that the electrode exhibited good selectivity for four univalent anions ($Cl^-,\;Br^-,\;I^-,\;{ClO_4}^-$). Analytical application to the determination of nitrate were also studied.

• Bulletin of the Korean Chemical Society
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• v.26 no.9
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• pp.1381-1384
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• 2005

Surface modification of tridimensional cubic mesoporous silica, SBA-16, was investigated with pendant arm functionalized cobalt diaminosarcophagine (diAMsar) cage complex which covalently grafted onto the silica surface through the silication with sylanol group. The spectroscopic results showed that the mesoporous structure was preserved under the $[Co(diAMsar)]^{3+}$ grafting reaction condition. Successful grafting prevented the cobalt diAMsar cage from leaching out from the SBA-16 support.

• Journal of Environmental Science International
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• v.16 no.1
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• pp.27-32
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• 2007

In this study, the concentrations of offensive odorous compounds seasonally emitted from the chemical plant at Chongju industrial complex in Korea were determined by the analytical methods of gas chromatography, high performance liquid chromatography and uv/vis spectroscopy. The kinds of offensive odorous compounds examined are formaldehyde, acetaldehyde, butyl aldehyde, propion aldehyde, n-valeric aldehyde, iso-valeric aldehyde, hydrogen sulfide, methyl mercaptan, dimethyl sulfide, dimethyl disulfide, trimethyl amine and ammonia. The seasonally emission levels of all odorous compounds except dimethyl sulfide at 13 sampling points of plant were lower than those of the regulation standard levels of the industrial complex in Korea. The levels were the highest in June, and lowest in December. The propion aldehyde and iso-valeric aldehyde in June and December, butyl aldehyde in December, and n-valeric aldehyde were not detected in all the three seasons at any sampling points of the plant examined. But in June, dimethyl sulfide was emitted up to 16 times than that of the regulation level.