• Journal of the Korean Chemical Society
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• v.51 no.4
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• pp.339-345
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• 2007

Urea reacts with PtCl2, H2[PtCl6]·6H2O, H2[IrCl6] and Ni(CH3CO2)2 in aqueous solution at high temperature (60-80 °C) yielding [PtCl2(Urea)]·2H2O (1), (NH4)2[PtCl6] (2), (NH4)2[IrCl6]·H2O (3) and [Ni2(OH)2(NCO)2(H2O)2] (4) complexes, respectively. In complex 1, urea coordinates to Pt(II) as a neutral bidentate ligand via amido nitrogen atoms. In complexes 2, 3 and 4 it seems that the coordinated urea molecules decompose during the reaction at high temperature and a variety of reaction products are obtained. All complexes were isolated in moderate yields as dark green (1), yellow (2), pale brown (3) and faint green (4) precipitates, respectively. The reaction products were characterized by their microanalysis, IR, 1H and 13C NMR spectra as well as thermal analysis. General mechanisms describing the formation of these complexes were suggested.

• Mycobiology
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• v.36 no.2
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• pp.93-98
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• 2008

Two Schiff base ligands $L_1\;and\;L_2$ were obtained by the condensation of glycylglycine respectively with imidazole-2-carboxaldehyde and indole-3-carboxaldehyde and their complexes with Zn(II) were prepared and characterized by microanalytical, conductivity measurement, IR, UV-Vis., XRD and SEM. The molar conductance measurement indicates that the Zn(II) complexes are 1:1 electrolytes. The IR data demonstrate the tetradentate binding of $L_1$ and tridentate binding of $L_2$. The XRD data show that Zn(II) complexes with $L_1\;and\;L_2$ have the crystallite sizes of 53 and 61 nm respectively. The surface morphology of the complexes was studied using SEM. The in vitro biological screening effects of the investigated compounds were tested against the bacterial species Staphylococcus aureus, Escherichia coli, Klebsiella pneumaniae, Proteus vulgaris and Pseudomonas aeruginosa and fungal species Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by the disc diffusion method. A comparative study of inhibition values of the Schiff base ligands and their complexes indicates that the complexes exhibit higher antimicrobial activity than the free ligands. Zinc ions are proven to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.12
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• pp.837-840
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• 2014

Novel materials of $Zn(HPB)_2$ and Ir-complexes were respectively synthesized as blue or red emitting material. White Organic Light Emitting Diodes (OLED) were fabricated by using $Zn(HPB)_2$ for a blue emitting layer, Ir-complexes for a red emitting layer and $Alq_3$ for a green emitting layer. White OLED was fabricated by using double emitting layers of $Zn(HPB)_2$ and $Alq_3:Ir$-complexes, and hole blocking layer of BCP. We also varied the thickness of BCP. When the thickness of BCP layer was 5 nm, white emission was achieved. We obtained a maximum luminance of $3,500cd/m^2$. The CIE coordinates was (0.375, 0.331). From this study, we could propose that the hybrid structure is efficient in lighting application of white OLED by improvement of color purity.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3711-3717
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• 2010

Four orange-red phosphorescent Ir(III) complexes were designed and synthesized based on the benzoylphenylpyridine ligand with a fluorine substituent. Multilayered OLEDs with the device structure, ITO/2-TNATA/NPB/CBP : 8% Ir(III) complexes/BCP/Liq/Al, were fabricated using these complexes as dopant materials. All the devices exhibited orange-red electroluminescence and their electroluminescent properties were quite sensitive to the structural features of the dopants in the emitting layers. Among these, the maximum luminance ($14700\;cd/m^2$ at 14.0 V) was observed in the device containing Ir(III) complex 1 as the dopant. In addition, its luminous, power and quantum efficiency were 11.7 cd/A, 3.88 lm/W and 9.58% at $20\;mA/cm^2$, respectively. The peak wavelength of electroluminescence was 606 nm with CIE coordinates of (0.61, 0.38) at 12.0 V. The device also showed stable color chromaticity with various voltages.

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.167-173
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• 2013

A series of highly efficient red phosphorescent heteroleptic iridium(III) complexes 1-6 containing two cyclometalating 2-(2,4-substitued phenyl)quinoxaline ligands and one chromophoric ancillary ligand were synthesized: (pqx)$_2Ir$(mprz) (1), (dmpqx)$_2Ir$(mprz) (2), (dfpqx)$_2Ir$(mprz) (3), (pqx)$_2Ir$(prz) (4), (dmpqx)$_2Ir$(prz) (5), (dfpqx)$_2Ir$(prz) (6), where pqx = 2-phenylquinoxaline, dfpqx = 2-(2,4-diflourophenyl)quinoxaline, dmpqx = 2-(2,4-dimethoxyphenyl)quinoxaline, prz = 2-pyrazinecarboxylate and mprz = 5-methyl-2-pyrazinecarboxylate. The absorption, emission, electrochemical and thermal properties of the complexes were evaluated for potential applications to organic light-emitting diodes (OLEDs). The structure of complex 2 was also determined by single-crystal X-ray diffraction analysis. Complex 2 exhibited distorted octahedral geometry around the iridium metal ion, for which 2-(2,4-dimethoxyphenyl)quinoxaline N atoms and C atoms of orthometalated phenyl groups are located at the mutual trans and cis-positions, respectively. The emission spectra of the complexes are governed largely by the nature of the cyclometalating ligand, and the phosphorescent peak wavelengths can be tuned from 588 to 630 nm with high quantum efficiencies of 0.64 to 0.86. Cyclic voltammetry revealed irreversible metal-centered oxidation with potentials in the range of 1.16 to 1.89 V as well as two quasi-reversible reduction waves with potentials ranging from -0.94 to -1.54 V due to the sequential addition of two electrons to the more electron-accepting heterocyclic portion of two distinctive cyclometalated C^N ligands.

• Journal of the Korean Chemical Society
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• v.57 no.3
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• pp.341-351
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• 2013

Zn(II), Cd(II) and Hg(II) complexes with a general composition[$M(L)_2(X)_2$], where L=4-aminopyridine (4AP) and $X=NO_2{^-}$ were prepared under microwave irradiation. The metal complexes were characterized by elemental analyses, molar conductance, IR, Far-IR, electronic, NMR ($^1H$, $^{13}C$), XPS spectral and thermal studies. The spectroscopic studies reveal the composition, different modes of bonding, electronic transition, different chemical environment of C and H atoms and the electronic state of the metal atoms. On the basis of the characterization data, tetrahedral geometry is suggested for all the complexes. The free ligand (4-aminopyridine) and their metal complexes were screened against phytopathogenic fungi and bacteria in vitro and the activities were compared.

• Bulletin of the Korean Chemical Society
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• v.13 no.2
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• pp.158-162
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• 1992

Hydrocarbon solution of $(PPh_3)_2(CO)MOSO_2CF_3(M=Rh$, Ir)reacts rapidly with Pyrazine or 4,4'-bipyridyl to yield dinuclear metal complexes $[(PPh_3)_3(CO)M({\mu}-pyrazine)M(CO)(PPh_3)_2](SO_3CF_3)_2$ (I: M= RhH; III: M=Ir) or [$(PPh_3)_2$(CO)M(${\mu}$-44'-bipyridyl)M(CO)$(PPh_3)_2](SO_3CF_3)_2$, (II: M=Rh; IV: M=Ir), respectively. Compounds, I, II, III, and IV were characterized by $^1H-NMR$, $^{13}C-NMR$, $^{31}P-NMR$, and infrared spectrum. Ethanol solution of $(PPh_3)_2(CO)MOSO_2CF_3$ (M=Rh, Ir) also reacts with $(TBA)_2$M'$(CN)_4$ (M'=Pd, Pt) to yield trinuclear metal complexes [$(PPh_3)_2$(CO)dM-NCM'$(CN)_2$CN-M(CO)$(PPh_3)_2]$ (V : M=Rh, M'=Pd; VI : M=Rh, M'=Pt; VII: M=Ir, M'=Pd; VIII: M=Ir, M'=Pt). The trinuclear metal complexes V, VI, VII, and VIII are bridged by the cyanide groups. The infrared spectrum of V, VI, VII, and VIII supports the presence of the bridged cyanide and terminal cyanide group.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.510-511
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• 2005

Several iridium based complexes were investigated as blue phosphorescent dopants. They are achieved about 100 % quantum efficiencies due to utilization of both singlet and triplet excitons in the radiative processes. We have fabricated phosphorescent OLED with 8 % Ir$(ppz)_3$ as a triplet emissive dopnat in diverse host materials. In this study, the CBP obtained the luminance efficiency of 0.20 cd/A adapts to the host material. Furthermore, we synthesize metalorganic phosphor complexs based on Ir heavy metal with different ligands as to $Ir(ppz)_2acac$, $(Im)_2Ir(acac)$, $(Im-R)_2Ir(acac)$.

• Journal of the Korean Chemical Society
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• v.57 no.6
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• pp.712-720
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• 2013

Microwave assisted syntheses of Zn(II), Cd(II) and Hg(II) complexes with 3-aminopyridine (3AP) and nitrite ($NO_2{^-}$) ions have been reported. The metal complexes were characterized by elemental analyses, molar conductance, IR, Far-IR, electronic, NMR ($^1H$, $^{13}C$), thermal and electron impact mass spectral studies. The spectroscopic studies reveal the composition, the nature of nitrite ligand in the complexes, electronic transitions, chemical environments of C and H atoms thermal degradation of the complexes. On the basis of characterization data, distorted tetrahedral geometry is suggested for Zn(II), Cd(II) and Hg(II) complexes. The organic ligand (3AP) and their metal complexes were screened against gram negative pathogenic bacteria and fungi in vitro. The results are compared with our previous report J. Korean Chem. Soc. 2013, 57, 341 on 4-aminopyridine and nitrite ion complexes of the same metal ions.

• Journal of the Korean Chemical Society
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• v.57 no.5
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• pp.574-590
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• 2013

A new solid complexes of Ti(IV), Y(III) and Ce(IV) have been synthesized with ofloxacin. The formulae and structure of the complexes have been proposed in the light of analytical, spectral ($^1H$ NMR, IR and UV-Visible), magnetic, molar conductivities and thermal studies. The complexes are soluble in DMSO-$d_6$ and DMF. The measured molar conductance values indicate that, the three complexes are electrolyte in nature. The results support the formation of the complexes and indicated that ofloxacin reacts as a bidentate ligand chelate to the metal ion through the pyridone oxygen and one carboxylato oxygen. The kinetic parameters of thermogravimetric and its differential have been evaluated by using Coats Redfern (CR) and Horowitz-Metzeger (HM) methods. The thermodynamic data reflect the thermal stability for all complexes. The metal- ligand binding of the Ti(IV), Y(III) and Ce(IV) complexes is predicted using density funcational theory at the B3LYP-CEP-31G level of theory and total energy, dipole moment estimation of different Ti(IV), Y(III) and Ce(IV) ofloxacin structures. The biological activities of the ofloxacin, inorganic salts and their metal complexes were assayed against different bacterial species.