• Bulletin of the Korean Chemical Society
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• 제18권10호
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• pp.1090-1093
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• 1997

The solvent effects on the isotropic NMR shifts in conformationally rigid ligands such as quinuclidine, pyridine, and 4-aminopyridine coordinated to the paramagnetic polyoxometalate, [SiW11CoⅡO39]6- (SiW11Co), are reported. For these complexes the ligand exchange is slow on the NMR time scale and pure 1H NMR signals have been observed at room temperature. The signals for the SiW11Co complexes are shifted upfield whe dimethyl sulfoxide-d6 (DMSO) is added to a D2O solution. The isotropic shifts are separated into contact and pseudocontact contributions by assuming that the contact shifts are proportional to the isotropic shifts of the same ligands coordinated to [SiW11NiⅡO39]6-. It is shown that both the contact and pseudocontact shifts decrease (the absolute values of the pseudocontact shifts increase), when D2O is replaced by DMSO. It is suggested that D2O, a strong hydrogen bond donor, withdraws electron density from [SiW11CoⅡO39]6-, increasing the acidity of the cobalt ion toward the axial ligand. When D2O is replaced by DMSO, the acidity of the cobalt ion in SiW11Co decreases, weakening the Co-N bond. Then both the contact and pseudocontact shifts are expected to decrease in agreement with the observed solvent effects.

• Biomolecules & Therapeutics
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• 제31권4호
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• pp.359-369
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• 2023

Dependence receptors are a group of receptor proteins with shared characteristics of transducing two different signals within cells. They can transduce a positive signal of survival and differentiation in the presence of ligands. On the other hand, dependence receptors can transduce an apoptosis signal in the absence of ligands. The function of these receptors depends on the availability of their ligands. Several receptor tyrosine kinases (RTKs) have been reported as dependence receptors. When cells undergo apoptosis by dependence receptors, the intracellular domain of some RTKs is cleaved by the caspases. Among the RTKs that belong to dependence receptors, we focused on eight RTKs (RET, HER2, MET, ALK, TrkC, EphA4, EphB3, and c-KIT) that are cleaved by caspases. In this review, we describe the features of the receptors, their cleavage sites, and the fate of the cleaved products, as well as recent implications on them being used as potential therapeutics for cancer treatment.

• 센서학회지
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• 제33권2호
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• pp.93-97
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• 2024

With the development of promising future mobility and urban air mobility (UAM) technologies, the demand for LIDAR sensors has increased. The SWIR photodetector is a sensor that detects lasers for the 3D mapping of lidar sensor and is the most important technology of LIDAR sensor. An SWIR photodetector based on QDs in an eye-safe wavelength band of over 1400 nm has been reported. QDs-based SWIR photodetectors can be synthesized and processed through a solution process and have the advantages of low cost and simple processing. However, the organic ligands of QDs have insulating properties that limit their ability to improve the sensitivity and stability of photodetectors. Therefore, the technology to replace organic ligands with inorganic ligands must be developed. In this study, the organic ligand of the synthesized PbS QDs was replaced with a MAPI inorganic ligand, and an SWIR photodetector was fabricated. The analysis of the characteristics of the manufactured photodetector confirmed that the photodetector based on MAPI-capped PbS QDs exhibited up to 26.5% higher responsivity than that based on organic ligand PbS QDs.

• 대한화학회지
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• 제55권3호
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• pp.444-453
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• 2011

N'-(2-hydroxybenzyl)-2-(phenylamino)acetohydrazide ($H_2L^1$, 1) 및 N'-((3-hydroxy-naphthalen-2-yl)methylene)-2-(phenylamino)acetohydrazide ($H_2L^2$, 13)에 대한 VO(II), ZrO(II), Hf(IV), $UO_2$(II), Sn(II), V(V)$O_3$, Ru(III), Cd(II), Ho(III) 및 Yb(III) 착물을 합성하여 원소분석, $^1H$ NMR, IR, UV-Vis, 전기전도도 및 열분석 (DTA 및 TG)을 통해 특성을 조사하였다. 이들 리간드는 분광학적 결과에 의하면 중성 이배위, 일염기성 이배위, 일열기성 삼배위 또는 이염기성 삼배위 리간드로 행동한다. 그 결과 azomethine 질소원자, 양성자화 되어있거나 또는 탈양성자화 된 형태의 페놀 하이드록시 그룹 그리고 에놀 또는 케톤형 카드보닐 그룹을 통해 금속이온에 결합한다. 이들 리간드와 그 금속 착물들은 모체 리간드 및 금속이온 용액에 비해 높은 항균 및 항박테리아 저해효과를 보인다. 대부분의 금속 착물은 표준 항균성 시약 (amphotricene B) 보다 더 높은 항균 활동성을 보인다. 또한 이들 리간드와 착물은 항박테리아 활성도보다는 항균활성도에서 더 높은 수치를 보인다.

• 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.

• 대한화학회지
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• 제47권6호
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• pp.569-577
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• 2003

피리딘과 페놀을 포함하는 N2O계 세 자리 리간드 2-[(2-pyridine-2- ethylamino)-methyl]-phenol(H-PEMP)를 합성하였다. 또한 H-PEMP 페놀의 5-위치에 치환기로 브롬, 염소 및 메톡시를 가지는 Br-PEMP, Cl-PEMP 및 $CH_3O-PEMP$를, 그리고 2-hydroxy-1-naphthalene기를 가진 Naph-PEMP을 합성하였다. 합성된 각 리간드들을 수용액에서 전위차 적정 결과 양성자 해리는 3 단계로 일어났으며, 계산된 각 리간드의 총괄 양성자 해리상수(log${\beta}$) 값은 $CH_3O-PEMP$〉Naph-PEMP〉H-PEMP〉Br-PEMP〉Cl-PEMP의 순서로 Hammett식의 치환기 상수(${\sigma}_p$) 값 크기 순서와 일치하였다. 전이금속 이온들의 착물 안정도상수(logML 및 log$ML_2$) 값의 크기는 금속이온에 따라 Co(II)< Ni(II)< Cu(II)>Zn(II)의 순서이었고, 치환기에 따른 각 리간드의 착물 안정도상수 값은 리간드의 총괄 양성자 해리상수 값의 크기순서와 일치하였다.

• 대한화학회지
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• 제42권4호
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• pp.422-431
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• 1998

Salicyladehyde와 2-hydroxy-1-naphthaldehyde를 2-aminophenol과 2-amino-p-cresol에 반응시켜 세자리 Schiff base 리간드$(SIPH_2,\;SIPCH_2,\;HNIPH_2,\; HNIPCH_2)$들을 합성하였으며 이들 리간드를 Co(II) 이온과 반응시켜 세자리 Schiff base Co(II) 착물들을 합성하였다. 리간드와 착물들의 구조와 특성을 원소분석, $^1H$-NMR, IR, UV-vis 분광법과 열 무게 분석법으로 예측하였다. Co(II) 착물들은 Schiff base 리간드와 금속(II)의 몰비가 1:1로 결합하였으며, 3분자의 수화물이 배위된 6배위 착물 구조임을 알았다.지지 전해질로서 0.1M TBAP를 포함한 DMSO 용액에서 순환 전압전류법으로 세자리 Schiff base 리간드와 이들의 Co(II) 착물들의 전기 화학적인 산화·환원 과정을 알아보았다. 리간드들의 전기 화학적 환원은 확산 지배적이고 비가역적으로 진행되었으며 Co(II) 착물의 전기 화학적 환원과정은 2단계의 1전자 반응으로 확산 지배적이고 비가역적으로 진행되었다. Co(II) 착물들의 환원전위는 [Co(II)$(HNIPC)(H_2O)_3$]>[Co(II)$(HNIP)(H_2O)_3$]>[Co(II)$(SIPC)(H_2O)_3$]>[Co(II)$(SIP)(H_2O)_3] 순으로 약간 양전위 방향으로 이동하였으나 리간드의 영향은 크게 받지 않았다.

• Molecules and Cells
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• 제39권7호
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• pp.557-565
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• 2016

The paired immunoglobulin-like type 2 receptor (PILR) family consists of two functionally opposite members, inhibitory $PILR{\alpha}$ and activating $PILR{\beta}$ receptors. PILRs are widely expressed in various immune cells and interact with their ligands, especially CD99 expressed on activated T cells, to participate in immune responses. Here we investigated whether PILR-derived agonists inhibit ${\beta}1$ integrin activity as ligands for CD99. PILR-derived peptides as well as PILR-Fc fusion proteins prevented cell adhesion to fibronectin through the regulation of ${\beta}1$ integrin activity. Especially, PILRpep3, a representative 3-mer peptide covering the conserved motifs of the PILR extracellular domain, prevented the clustering and activation of ${\beta}1$ integrin by dephosphorylating FAK and vinculin, which are major components of focal adhesion. In addition, PILRpep3 inhibited transendothelial migration of monocytes as well as endothelial cell tube formation. Furthermore, upon intraperitoneal injection of PILRpep3 into mice with collagen-induced arthritis, the inflammatory response of rheumatoid arthritis was strongly suppressed. Taken together, these results suggest that PILR-derived agonist ligands may prevent the inflammatory reactions of rheumatoid arthritis by activating CD99.

• 공업화학
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• 제9권5호
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• pp.719-725
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• 1998

Salicylaldehyde와 2-hydroxy-1-naphthaldehyde를 2-aminophenol과 2-amino-p-cresol에 반응시켜 세자리 Schiff base 리간드들을 합성하였다. 이들 리간드를 Cu(II)이온과 반응시켜 세자리 Schiff base Cu(II) 착물들을 합성하였다. 리간드와 그 착물들의 구조와 특성을 원소분석, $^1H$-NMR, IR, UV-vis 분광법과 열 무게 분석법으로 알아보았다. Schiff base 리간드와 Cu(II)의 몰비는 1:1로 결합하며 Cu(II)착물들은 1 분자의 수화물이 배위된 4배위의 평면 사각형 구조임을 알았다. 지지전해질로서 0.1M TBAP를 포함한 DMSO 용액에서 순환 전압전류법과 미분 펄스 전압전류법으로 세자리 Schiff base 리간드와 이들의 Cu(II) 착물들의 전기 화학적인 산화 환원 과정을 알아보았다. 세자리 Schiff base 리간드들의 전기 화학적 환원은 확산 지배적이고 비가역적으로 진행되었다. Cu(II) 착물들의 전기화학적 환원과정은 1단계 1전자 반응으로 모두 확산 지배적이고 준가역적으로 진행되었다. Cu(II)착물들의 환원전위는 [Cu(II)(HNIPC)($H_2O$)]>[Cu(II)(HNIP)($H_2O$)]>[Cu(II)(SIP)($H_2O$)]>[Cu(II)(SIPC)($H_2O$)] 순으로 양전위 방향으로 이동하였다.

• 대한화학회지
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• 제54권5호
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• pp.541-550
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• 2010

새로운 일곱 자리 질소-산소($N_4O_3$)계 리간드 N,N'-Bis(2-hydroxybenzyl)-1,3-bis[(2-aminoethyl)amino]-2-propanol(H-BAP 4HCl)를 합성하였다. H-BAP 4HCl의 페놀 수산기의 para위치에 브롬, 염소, 메톡 시기 및 메틸기를 가진 Br-BAP 4HCl, Cl-BAP 4HCl, $CH_3O$-BAP 4HCl 및 $CH_3$-BAP 4HCl 염산염을 합성 하였다. 각 리간드의 화학구조는 C, H, N 원소분석법, $^1H$-NMR 및 $^{13}C$-NMR 분광법, 적외선 분광법 및 질량분석법을 통하여 확인하였다. 합성된 $N_4O_3$계 리간드의 전위차 적정 법을 이용하여 계산된 양성자 단계 해리상수는 여섯 단계의 해리상수(${\logK_n}^H$)값을 나타내었고, 각 리간드의 양성자 총괄 해리상수($log{\beta}_p$) 값은 Br-BAP < Cl-BAP < H-BAP < $CH_3O$-BAP < $CH_3$-BAP의 순서로 para Hammett 치환기상수($\sigma_p$) 값의 순서와 역순으로 잘 일치하였다. 각 리간드들과 전이금속(II) 이온들의 착물 안정도상수($logK_{ML}$) 값의 크기순서는 Co(II) < Ni(II) < Cu(II) > Zn(II) > Cd(II) > Pb(II)로 나타났다. 이때 각 리간드들과 전이금속(II) 이온들의 착물 안정도상수 값은 리간드의 총괄 해리상수 값의 크기순서와 같은 경향을 나타내었다.