• Rapid Communication in Photoscience
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• 제1권1호
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• pp.1-9
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• 2012

Luminescent lanthanide complexes have been overviewed for advanced photonics applications. Lanthanide(III) ions ($Ln^{3+}$) were encapsulated by the luminescent ligands such as metalloporphyrins, naphthalenes, anthracene, push-pull diketone derivatives and boron dipyrromethene(bodipy). The energy levels of the luminescent ligands were tailored to maintain the effective energy transfer process from luminescent ligands to $Ln^{3+}$ ions for getting a higher optical amplification gain. Also, key parameters for emission enhancement and efficient energy transfer pathways for the sensitization of $Ln^{3+}$ ions by luminescent ligands were investigated. Furthermore, to enhance the optophysical properties of novel luminescent $Ln^{3+}$ complexes, aryl ether-functionalized dendrons as photon antennas have been incorporated into luminescent $Ln^{3+}$ complexes, yielding novel $Ln^{3+}$-cored dendrimer complex such as metalloporphyrins, naphthalenes, and anthracenes bearing the Fr$\acute{e}$chet aryl-ether dendrons, namely, ($Er^{3+}-[Gn-Pt-Por]_3$ (terpy), $Er^{3+}-[Gn-Naph]_3$(terpy) and $Er^{3+}-[Gn-An]_3$(terpy)). These complexs showed much stronger near-IR emission bands at 1530 nm, originated from the 4f-4f electronic transition of the first excited state ($^4I_{13/2}$) to the ground state ($^4I_{15/2}$) of the partially filled 4f shell. A significant decrease in the fluorescence of metalloporphyrins, naphthalenes and anthracene ligand were accompanied by a strong increase in the near IR emission of the $Ln^{3+}$ ions. The near IR emission intensities of $Ln^{3+}$ ions in the lanthanide(III)-encapsulated dendrimer complexes were dramatically enhanced with increasing the generation number (n) of dendrons, due to the site-isolation and the light-harvesting(LH) effects. Furthermore, it was first attempted to distinguish between the site-isolation and the light-harvesting effects in the present complexes. In this review, synthesis and photophysical studies of inert and stable luminescent $Ln^{3+}$ complexes will be dealt for the advanced photonics applications. Also, the review will include the exploratory investigation of the key parameters for emission enhancement and the effective energy transfer pathways from luminescent ligands to $Ln^{3+}$ ions with $Ln^{3+}$-chelated prototype complexes.

• Bulletin of the Korean Chemical Society
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• 제30권9호
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• pp.1925-1926
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• 2009

• 폴리머
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• 제38권3호
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• pp.386-390
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• 2014

덴드리머의 중심에 삼발이 핵을 갖는 덴드리머의 합성을 위한 효율적인 연결 방법이 개발되었다. 합성전략은 알데히드 덴드론과 아자이드기를 갖는 삼발이 핵 사이의 반응을 톨루엔 용매와 triphenylphosphine 존재하에서 진행하는 새로운 클릭화학(Staudinger/aza-Wittig 반응)을 이용하였다. 덴드리머의 삼발이 핵으로 작용할 수 있는 단위체인 1,3,5-tris-(3-azido-propoxy)-benzene을 합성하였고, 이 화합물의 아자이드기는 덴드리머의 형성에 이용되었다. 1,3,5-Tris-(3-azido-propoxy)-benzene을 이용하여 알데히드 덴드론과 Staudinger/aza-Wittig 반응을 통해 덴드리머를 합성하였으며, 모든 덴드리머는 높은 수득률로 얻어졌다.

• Macromolecular Research
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• 제11권3호
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• pp.133-145
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• 2003

We have developed novel lanthanide-cored supramolecular systems with highly efficient light-harvesting dendritic arrays for integrated planar waveguide-typed amplifiers. Er$^{3+}$ ions were encapsulated by the supramolecular ligands, such as porphyrins and macrobicyclics. The supramolecular ligands have been designed and synthesized to provide enough coordination sites for the formation of stable Er(III)-chelated complexes. For getting a higher optical amplification gain, also, the energy levels of the supramolecular ligands were tailored to maintain the effective energy transfer process from supramolecular ligands to erbium(III) ions. Furthermore, to maximize the light-harvesting effect, new aryl ether-functionalized dendrons as photon antennas have been incorporated into lanthanide-cored supramolecular systems. In this paper, molecular design, synthesis and luminescent properties of novel lanthanide-cored integrated supramolecular systems with highly efficient light-harvesting dendritic arrays will be discussed.d.

• Macromolecular Research
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• 제17권7호
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• pp.499-505
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• 2009

General, fast, and efficient stitching methods are presented for the synthesis of Fr$\acute{e}$chet-type dendrimers with linear units at a core, as a preliminary investigation for the synthesis of dendritic-linear-dendritic materials. The synthetic strategy involved an inexpensive, 1,3-dipolar, cycloaddition reaction between an alkyne and an azide in the presence of the Cu(I) species, which is known as the best example of click chemistry. The linear core building blocks, 1,7-octadiyne and 1,6-diazidohexane, were chosen to serve as the alkyne and azide functionalities for dendrimer growth via click reactions with the azide and alkyne-dendrons, respectively. These two building blocks were employed together with the azide- and alkyne-functionalized Fr$\acute{e}$chet-type dendrons in a convergent strategy to synthesize two kinds of Fr$\acute{e}$chet-type dendrimers with different linear core units. This comparative efficiency of the click methodology supports the fast and efficient synthesis of dendritic-linear-dendritic materials with the tailor made core unit.

• Bulletin of the Korean Chemical Society
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• 제29권8호
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• pp.1545-1553
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• 2008

Using a one-pot reaction technique, monodisperse $\gamma-Fe_2O_3$ nanoparticles were prepared by thermal decomposition of Fe$(CO)_5$ in the presence of a long alkyl chain terminated dendron surfactant. The size of the particles is controlled by adjusting the concentration of the dendron ligands in the reaction solution. Spherical, 2 nm sized nanoparticles were obtained with a 3:1 ratio of dendrons to Fe$(CO)_5$, while 4.6 nm sized particles were formed with a 1:3 ratio. Superparamagetic properties of 2 nm, 4 nm, and 4.6 nm sized particles were measured using a SQUID magnetometer.

• Bulletin of the Korean Chemical Society
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• 제29권8호
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• pp.1485-1490
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• 2008

Dumbbell-shaped aromatic amphiphilic molecules consisting of a dodeca-p-phenylene as a rigid segment and oligoether dendrons as a flexible chains were synthesized, characterized, and their aggregation behavior was investigated in the bulk and at the air-water interface. In contrast to the molecule 2 which shows a nematic liquid crystalline state, molecule 1 based on shorter dendritic chains was observed to self-assemble into a 3-D primitive orthorhombic supercrystal. And molecule 1 at the air-water interface was observed to reorganize from circular plates to ring structures by lateral compressions.

• Bulletin of the Korean Chemical Society
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• 제28권10호
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• pp.1777-1780
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• 2007

The synthesis of well-defined dendrons based on aliphatic polyether dendritic cores and glassy polystyrene peripheries is described. The synthetic route involves a combination of living anionic polymerization and a stepwise convergent method consisting of iterative Williamson etherification and hydroboration/oxidation reactions. On the basis of molecular weight, as characterized by gel permeation chromatography (GPC), the first generation dendron (Generation-1) shows a random coil conformation like a linear polystyrene, while higher generations (Generation-2 and 3) reveal globular forms in solution.

• Rapid Communication in Photoscience
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• 제3권4호
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• pp.85-87
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• 2014

We studied the characteristics of emissive state of the first (p-G1) and second (p-G2) generation of phenylacetylene dendrimers bearing stilbene as a core by using time-resolved fluorescence spectroscopy in cyclohexane (c-Hex) and N, N-dimethylformide (DMF), which are nonpolar and polar solvents, respectively. Time-dependent red-shift of emission spectra p-G2 both in c-Hex and DMF was observed in comparison with p-G1. Besides, the time constant of red-shift of spectra was found to be larger in DMF than in c-Hex. This indicates that the emissive state of p-G2 has a polar character in DMF as a result of charge delocalization from core to peripheral dendrons followed by stabilization of emissive state.

• Bulletin of the Korean Chemical Society
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• 제33권1호
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• pp.137-142
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• 2012

The convergent synthetic strategy for the emissive dendrimers having the chromophore at core via the coppercatalyzed 1,3-dipolar cycloaddition reaction between alkyne and azide was described. 2,7-Diazido-9,9-dioctyl-9H-fluorene, designed to serve as the core in dendrimer, was stitched with the alkyne-functionalized Frechettype and PAMAM dendrons by the click chemistry leading to the formation of the corresponding fluorescent dendrimers in high yields. The preliminary photoluminescence studies indicated that 2,7-diazido-9,9-dioctyl-9H-fluorene showed no fluorescence due to the quenching effect from the electron-rich ${\alpha}$-nitrogen of the azido group but the dendrimers fluoresced due to the elimination of the quenching through the formation of the triazole ring.