• Rapid Communication in Photoscience
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• v.4 no.1
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• pp.22-24
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• 2015

A new trinuclear complex $[Ru(TPrPc)(CO)]_2[Ru(pytpy)_2](PF_6)_2$ (TPrPc = 2,7,12,17-tetra-n-propylporphycenato dianion and pytpy = 4'-(4-pyridyl)-2,2':6',2"-terpyridine) has been synthesized and characterized as the first example of a discrete molecular wire containing metalloporohycenes as a building block. The trinuclear complex shows multiple-step redox behavior in 0.1 M n-$Bu_4NPF_6$-dichloromethane. The mononuclear $[Ru(pytpy)_2]^{2+}$ precursor shows emission at 640 nm (deaerated acetone, 298 K) upon illumination at the metal-to-ligand charge transfer (MLCT) band at 495 nm, but the trinuclear molecular wire is found to be non-emissive upon photoexcitation at the central $[Ru(pytpy)_2]^{2+}$ entity, indicating an efficient quenching ability of the axially-linked, ruthenium(II)-porphycene chromophores in an intramolecular fashion.

• Journal of the Korean Chemical Society
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• v.29 no.3
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• pp.257-264
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• 1985

Dioxobis(3-methoxysalicyaldehydato)molybdeum(VI) complex has been synthesized by reactions of 3-methoxysalicylaldehyde and ammonium paramolybdate in methanol solution. With appropriate primary amine, the resulting complex gave schiff-base complexes, MoO$_2$(CH$_3$O-sal-N-R)$_2$ in which C=O oxide ligands had been replaced by nitrogen. The properties and possible molecular structure of these complexes were discussed by elemental analysis, spectroscopic studies and electric conductivities measurements. It was found that the Mo(VI) complexes contain a cis-MoO$_2$ group since their infrared spectra two Mo=O band at about 900cm$^{-1}$ and the combining ratios for MoO$_2$-ligand are 1 : 2. Also, electronic spectra of molybdenyl complexes assigned to ligand-to-metal charge transfer transition. All of these complexes are yellow or orange, depolar compound and slightly soluble in alcohol, dichloromethane, chloroform and N,N-dimethylformamide.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.199-199
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• 2016

본 연구에서는 고상반응법을 사용하여 제조한 MgWO4:Dy,Na 형광체의 광학특성과 결정구조를 조사하였다. Fig.1 XRD 주 피크는 $23.9^{\circ}$에서 관측 되었으며 (110) 면에서 발생한 회절신호이다. 결정구조는 단사정계임을 알 수 있었다. Dy,Na의 함량비를 0 mol, 0.02 mol, 0.04 mol, 0.06 mol, 0.08 mol, 0.10 mol로 변화시켜 합성했으나, 함량비와는 관계없이 동일한 XRD 회절 피크 패턴이 관측되었다. Fig.2. 그림의 220-340 nm에서 관찰되는 넓은 밴드는 $O2-{\rightarrow}W6+$에 의해 발생한 LMCT(ligand to metal charge transfer)이고, Dy에서 WO42- 그룹으로 에너지 전달에 의해서 생긴 CTB 이다. 합성한 형광체를 295 nm로 여기 시킨 모든 형광체 분말의 발광 스펙트럼은 Dy 이온의 $4F9/2{\rightarrow}6H15/2$ 전이에 의한 487 nm, $4F9/2{\rightarrow}6H13/2$ 전이에 의한 577 nm, $4F9/2{\rightarrow}6H11/2$ 전이에 의한 668 nm의 발광 스펙트럼이 관측되었다. Dy 이온이 0.02 mol일 때, 발광 세기가 가장 강하였으며, 몰 비가 증가함에 따라 발광의 세기는 감소하는 농도 소광현상이 관측되었다.

• Journal of the Korean Society of Radiology
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• v.9 no.1
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• pp.39-45
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• 2015

$La_2W_3O_{12}:Eu^{3+}$ phosphors were prepared by solid state reaction method. The crystal structure was characterized by XRD pattern and ICSD card (78180). Luminescence properties of $La_2W_3O_{12}:Eu^{3+}$ are investigated by optical and laser-excitation spectroscopy in which emission and excitation spectra and time-resolved spectra are measured. The 1 mol % $Eu^{3+}$-doped $La_2W_3O_{12}$ phosphor exhibits broad excitation band peaking at 286 nm due to the ligand-to-metal charge transfer transition. The excitation lines due to the $^7F_0{\rightarrow}{^5D_4},{^5D_4},{^5L_6},{^5G_4},{^5D_3},{^5D_2}$ transitions of $Eu^{3+}$ are observed in the wavelength region 350-500 nm. The strong line emission is observed at 618 nm corresponding to the due to the $^5D_0{\rightarrow}^7F_2$ transition. The lifetime of 618 nm emission decreases with increasing temperature as 7 K ($114{\mu}s$), 100 K ($94{\mu}s$), 200 K ($10{\mu}s$) and 300 K ($0.5{\mu}s$).

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4084-4092
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• 2012

Theoretical calculations based on density functional theory (DFT) were performed to study the substituent effect on the geometric and electronic structures as well as the biological behavior of technetium-99m-labeled diphosphonate complexes. Optimized structures of these complexes are surrounded by six ligands in an octahedral environment with three unpaired 4d electrons ($d^3$ state) and the optimized geometry of $^{99m}Tc$-MDP agrees with experimental data. With the increase of electron-donating substituent or tether between phosphate groups, the energy gap between frontier orbitals increases and the probability of non-radiative deactivation via d-d electron transfer decreases. The charge distribution reflects a significant ligand-to-metal electron donation. Based on the calculated geometric and electronic structures and biologic properties of $^{99m}Tc$-diphosphonate complexes, several structure-activity relationships (SARs) were established. These results may be instructive for the design and synthesis of novel $^{99m}Tc$-diphosphonate bone imaging agent and other $^{99m}Tc$-based radiopharmaceuticals.

• Journal of the Korean Chemical Society
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• v.19 no.2
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• pp.92-97
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• 1975

The molecular and electronic structures of $TiCl(OC_6H_5)_3{\cdot}C_6H_5OH\;and\;Ti(OC_6H_5)_4{\cdot}C_6H_5OH$ have been studied by employing cryoscopic and electronic spectroscopic methods. The cryoscopic data have shown that the dimeric tetraphenoxytitanium(Ⅳ) phenolate in solid undergoes complete dissociation into monomer in solution and also the chlorocomplex starts dissociation around the concentration of 8 m mole/l. Therefore, these two Ti-complexes are pentacoordinated in dilute solution and the local symmetry of the titanium ion in these complexes seems to be trigonalbipyramid. The electronic spectra of $TiCl(OC_6H_5)_3{\cdot}C_6H_5OH$ and $Ti(OC_6H_5)_4{\cdot}C_6H_5OH$ each show two band, systems, one vibration-structural band characteristic of the aromatic ring in the near UV and another visible band at 26.8 kK, 29.6 kK, respectively, which are assigned as a ligand to metal charge transfer band corresponding to $^1A_1''{\to}^1E'\;or\;^1E''$ transition.