• Nuclear Medicine and Molecular Imaging
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• 제43권2호
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• pp.91-99
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• 2009

Noninvasive imaging of molecular and biological processes in living subjects with positron emission tomography(PET) provides exciting opportunities to monitor metabolism and detect diseases in humans. Measuring these processes with PET requires the preparation of specific molecular imaging probes labeled with $^{18}F$-fluorine. In this review we describe recent methods and novel trends for the introduction of $^{18}F$-fluorine into molecules which in turn are intended to serve as imaging agents for PET study. Nucleophilic $^{18}F$-fluorination of some halo- and mesyloxyalkanes to the corresponding $^{18}F$-fluoroalkanes with $^{18}F$-fluoride obtained from an $^{18}O(p,n)^{18}F$ reaction, using novel reaction media system such as an ionic liquidor tert-alcohol, has been studied as a new method for $^{18}F$-fluorine labeling. Ionic liquid method is rapid and particularly convenient because $^{18}F$-fluoride in $H_2O$ can be added directly to the reaction media, obviating the careful drying that is typically required for currently used radiofluorination methods. The nonpolar protic tert-alcohol enhances the nucleophilicity of the fluoride ion dramatically in the absence of any kind of catalyst, greatly increasing the rate of the nucleophilic fluorination and reducing formation of byproducts compared with conventional methods using dipolar aprotic solvents. The great efficacy of this method is a particular advantage in labeling radiopharmaceuticals with $^{18}F$-fluorine for PETimaging, and it is illustrated by the synthesis of $^{18}F$-fluoride radiolabeled molecular imaging probes, such as $^{18}F$-FDG, $^{18}F$-FLT, $^{18}F$-FP-CIT, and $^{18}F$-FMISO, in high yield and purity and in shorter times compared to conventional syntheses.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.363-363
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• 2014

Ruthenium (Ru) has attractive material properties due to its promising characteristics such as a low resistivity ($7.1{\mu}{\Omega}{\cdot}cm$ in the bulk), a high work function of 4.7 eV, and feasibility for the dry etch process. These properties make Ru films appropriate for various applications in the state-of-art semiconductor device technologies. Thus, it has been widely investigated as an electrode for capacitor in the dynamic random access memory (DRAM), a metal gate for metal-oxide semiconductor field effect transistor (MOSFET), and a seed layer for Cu metallization. Due to the continuous shrinkage of microelectronic devices, better deposition processes for Ru thin films are critically required with excellent step coverages in high aspect ratio (AR) structures. In these respects, atomic layer deposition (ALD) is a viable solution for preparing Ru thin films because it enables atomic-scale control of the film thickness with excellent conformality. A recent investigation reported that the nucleation of ALD-Ru film was enhanced considerably by using a zero-valent metallorganic precursor, compared to the utilization of precursors with higher metal valences. In this study, we will present our research results on the synthesis and characterization of novel ruthenium complexes. The ruthenium compounds were easy synthesized by the reaction of ruthenium halide with appropriate organic ligands in protic solvent, and characterized by NMR, elemental analysis and thermogravimetric analysis. The molecular structures of the complexes were studied by single crystal diffraction. ALD of Ru film was demonstrated using the new Ru metallorganic precursor and O2 as the Ru source and reactant, respectively, at the deposition temperatures of $300-350^{\circ}C$. Self-limited reaction behavior was observed as increasing Ru precursor and O2 pulse time, suggesting that newly developed Ru precursor is applicable for ALD process. Detailed discussions on the chemical and structural properties of Ru thin films as well as its growth behavior using new Ru precursor will be also presented.

• 대한화학회지
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• 제18권4호
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• pp.223-238
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• 1974

염화포름산 알킬의 할로겐화 이온 교환반응을 반응속도론적으로 연구하고, 이의 전자 구조적 특성을 CNDO/2 MO계산으로 연구하였으며 이로부터 구조와 반응성 간의 관계를 논의하였다. 염화포름산 알킬의 에너지면에서의 가장 안정한 입체배치가 알킬기와 염소원자 사이가 서로 트랜스인 입체배치임을 알았으며, 결합주위의 회전장애가 {\pi}-전자 비편재화에 기인됨을 밝혔다. 염화포름산 알킬은 하전분리가 심한 극성물질이며, 이것이 카르보닐 산소와 알콕시 산소의 효과 및 염소의 효과에 기인됨을 밝혔다. 반응속도에 미치는 용매효과는 $(CH_3)_2CO>CH_3CN{\gg}MeOH$순으로 반응성이 감소되는 작용을 나타냈으며, 친핵성도는 양성자성 용매중에서 $I^->Br^->Cl^-$, 비양자성 용매 중에서 $Cl^->Br^->I^-$이었으며 알킬기의 기여는 $CH_3->C_2H_5->i-C_3H_7-$순이었다. 초기상태와 천이상태의 안정화 기여를 기초로 용매효과를 해석하였으며 초기상태 탈용매화의 특성으로 친핵성도를 논의하였다. 이 반응에 대하여 가장 유리한 메카니즘을 첨가-제거 메카니즘으로 제안하였다. 염화포름산 알킬의 반응성을 결정하는 구조적 요인은 하전, C-Cl 결합에 대하여 ${\alpha}^{\ast}$인 LUMO의 에너지준위 및 이 MO에서 C-Cl결합의 반결합세기임을 밝혔다.