• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.594-602
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• 2011

The effect of ${\alpha}$-, ${\beta}$- and ${\gamma}$-picolines on the stereochemistry of the coordination compounds of lanthanide(III) nitrates derived from 4[N-(furfural)amino]antipyrine semicarbazone (FFAAPS) has been studied. The general composition of the present coordination compounds is [Ln(FFAAPS)$(NO_3)_3$Pic] (Ln=La, Pr, Nd, Sm, Gd, Tb, Dy or Ho and Pic=${\alpha}$-, ${\beta}$- or ${\gamma}$-picolines). All these coordination compounds have been characterized by elemental analyses, molecular weight, molar conductance, magnetic susceptibility, infrared and electronic spectra. The infrared studies suggest that the FFAAPS behaves as a neutral tridentate ligand with N, N, O donor while ${\alpha}$-, ${\beta}$- or ${\gamma}$-picoline is coordinated to the lanthanide(III) ions via heterocyclic N-atom. Nitrates are bicovalently bonded in these compounds. From the electronic spectral data, nephelauxetic effect (${\beta}$), covalence factor ($b^{1/2}$), Sinha parameter (${\delta}%$) and the covalence angular overlap parameter (${\eta}$) have been calculated. Thermal stabilities of these complexes have been studied by thermogravimetric analysis. The coordination number of lanthanide(III) ions in the present compound is found to be ten. The antibacterial studies screening of the primary ligand FFAAPS and the complexes showed that the present complexes have moderate antibacterial activities.

• Progress in Medical Physics
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• v.17 no.2
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• pp.61-66
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• 2006

To evaluate the T1, T2 magnetic relaxation properties of water molecule according to molecular weight of paramagnetic complex. 4-aminomethyicyclohexane carboxylic acid (0.63 g, 4 mmol) was mixed with the suspension solution of DMF (15 ml) and DTPA-bis-anhydride (0.71 g, 2 mmol) to synthesize the ligand. The ligand was then mixed with $Gd_2O_3$ (0.18 g, 0.5 mmol) to synthesize Gd-chelate. For the measurement of magnetic relaxivity of paramagnetic compounds, the compounds were diluted to 1 mM and then the relaxation times were measured at 1.57 (64 MHz). Inversion-recovery pulse sequence was employed for T1 relaxation measurement and CPMG (Carr-Purcell-Meiboon-Gill) pulse sequence was employed for T2 relaxation measurement. In case of inversion recovery sequence, total 35 images with different inversion time(T1)s ranging from 50 msec to 1,750 msec. To estimate the relaxation times, the signal intensity of each sample was measured using region of Interest (ROI) and then fitted by non-linear least square method to yield T1, T2 relaxation times and also R1 and R2. Compared to T1=($205.1{\pm}2.57$) msec and T2=($209.4{\pm}4.28$) msec of Omniscan (Gadodiamide), which is commercially available paramagnetic MR agent, T1 and T2 values of new paramagnetic complexes were reduced along with their molecular weight. That is, T1 value was ranged from $(96.35{\pm}2.04)\;to\;(79.38{\pm}1.55)$ msec and T2 value was ranged from $(91.02{\pm}2.08)\;to\;(76.66{\pm}1.84)$ msec. Among new paramagnetic complexes, there is a tendency that the R1 and R2 increase as the molecular weight is increases. As molecular weight of paramagnetic complex increases, T1 and T2 relaxation times reduce and thus the increase of relaxivity (R1 and R2) Is proportional to molecular weight.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.212-217
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• 1992

The thermodynamic parameters for the formation of gadolinium benzoate have been determined in the ionic medium of 0.1 M $NaClO_4$ at $25^{\circ}C$ in aqueous solution. The thermodynamic results indicate that the complex is stabilized by the excess entropy effect caused by the dehydration of reacting ions. The especially high stability of Gd(III)-benzoate compared to the monodentate ligand complexes might be ascribed to the conjugation effect of the benzene ring in the benzoate ligand. IR spectra show that benzoate anion acts as a bidentate ligand toward $Gd^{3+}$ to form a chelate ring in solid state. Magnetic susceptibility data of the compound were also obtained and well described by Curie-Weiss law in the temperature range 80${\sim}$300K.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.628-635
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• 1999

Direct preparative method of 2,6-diformyl-p-cresol and 2-hydroxy-3-hydroxy-5-methylbenzaldehyde from 2,6-bis(hydroxymethyl)-4-methylphenol using activated $Mn(IV)O_2$ was described. Hexadentate compartmental Iigands, $H_4L[A]\;and\; H_4L[B]$ were prepared by condensation reactions of 2-hydroxy-3-hydroxy methyl-5-methylbenzaldehyde with ethylenediamine and 1,3-diaminopropane respectively. By the reaction of macrocycle($H_4[20]DOTA$) with Ln(III) nitrate {Ln(III)=Pr, Sm, Cd, Dy }, discrete mononuclear Ln(III) complexes of the type $[Ln(H_2[20]DOTA)(ClO_4)(H_2O)]\;{\cdot}\;3H_2O$ were synthesized in the solid state. $[Ln([20]DOTA)(NO_3)(H_2O)](NO_3)_2\;{\cdot}\;xH_2O$ was placed in methanol for 2 days, and $[Ln([20]DOTA)(NO_3)(CH_3OH)]^{2+}$ was formed. The equilibrium constants(K) for the substitution of coordinated $CH_3OH$ in the Ln-[20]DOTA complexes by various auxiliary ligand, $L_a$(=salicylic acid, p-chlorobenzoic acid, benzoic acid, acetic acid, 4-bromophenol) were determined spectroscopically at 25$^{\circ}C$ and 0.1M $NaClO_4$. The K values calculated were in the order of salicylic acid > p-chlorobenzoic acid > benzoic acid > acetic acid > 4-bromophenol, while pKa of auxiliary ligands was in the opposite trend.

• Journal of the Korean Chemical Society
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• v.48 no.6
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• pp.577-582
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• 2004

The azacrown compounds, 1,4-dioxa-7,10,13-triazacyclopentadecane-N,N',N''-triacetic acid, $N-ac_3[15]aneN_3O_2(II_a)$ and 1,4-dioxa-7,10,13-triazacyclopentadecane-N,N',N''-tripropioc acid, $N-pr_3[15]aneN_3O_2(II_b)$ were synthesized by modified methods. Potentiometry was used to determine the protonation constant of the $N-ac_3[15]aneN_3O_2\;and\;N-pr_3[15]aneN_3O_2$. The stability constants of complexes of the trivalent metal ions of $Ce^{3+},\;Eu^{3+},Gd^{3+},and\;Yb^{3+}$ and divalent metal ions of $Co^{2+},\;Ni^{2+},\;Cu^{2+},\;and\;Zn^{2+}$ with the ligands $N-ac_3[15]aneN_3O_2\;and\;N-pr_3[15]aneN_3O_2$ have been determined at $25{\pm}0.1^{\circ}C$ in 0.1 M $NaClO_4$ solution by potentiometric methods. The metal ion affinities of the two triazamacrocyclic ligands with three pendant acetate or propionate groups are compared to those obtained for the similar ligands, 1,7-dioxa-4,10,13-triazacyclopentadecane-N,N',N''-triacetic acid, and 1,7-dioxa-4,10,13- triazacyclopentadecane-N,N',N''-tripropioc acid. The trends in stability of complexes for different metal ions due to changes in the nitrogen position of the donor atoms of the ligand are discussed.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.87-92
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• 2014

The work is directed toward the synthesis of a series of DO3A conjugates of tranexamates (1c-e) and their Gd complexes (2c-e) for use as a liver-specific MRI CA. All these complexes show thermodynamic and kinetic stabilities comparable to those of structurally related clinical agents such as Dotarem$^{(R)}$. Their $R_1$ relaxivities also compare well with those of commercial agent, ranging 3.68-4.84 $mM^{-1}s^{-1}$. In vivo MR images of mice with 2a-e reveal that only 2a exhibits liver-specificity. Although 2b and 2c show strong enhancement in liver, yet no bile-excretion is observed to be termed as a liver-specific agent. The rest behaves much like ordinary ECF CAs like Dotarem$^{(R)}$. The new series possess no toxicity to be employed in vivo.

• Analytical Science and Technology
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• v.9 no.3
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• pp.244-252
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• 1996

Spectrophotometric properties of lanthanide complexes with methylthymol blue(MTB) and cetyltrimethylammonium bromide(CTAB) were studied and also lanthanide(III) ions were determined by flow injection analysis on the base of the above results. The absorption maxima of lanthanide(III)-MTB complexes in the presence of CTAB are 635nm with molar absorptivity of $4.51{\sim}6.11{\times}10^4Lmol^{-1}cm^{-l}$ at pH 5.8. The mole ratio of lanthanide(III) complexes with MTB is 1:2 in the presence of CTAB. The calibration curves of lanthanide(III) ions obey the Beer's law in the range of 0.1 to 0.4ppm under the optimum condition. The samples throughput was ca. $60hr^{-1}$. The interfering effect of some cations and anions was investigated. The ligand anions such as tartrate and citrate, many transition and rare earth elements interfered severely and must be removed before the determination of lanthanide(III) ions.

• Proceedings of the Korea Contents Association Conference
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• 2018.05a
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• pp.551-552
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• 2018

K/BxN serum can induce arthritis in normal mice because of abundant autoantibodies that trigger an innate inflammatory response in joints. To determine whether IL-17 is involved in the pathogenesis of serum-induced arthritis, we injected wild-type and $IL-17^{-/-}$ mice with K/BxN serum and evaluated them for signs of arthritis. Unlike wild-type mice, $IL-17^{-/-}$ mice did not show any signs of arthritis. IL-17 was produced predominantly by $CD3^-CD4^-gdTCR^-NK1.1^-Sca1^{int}Thy1^{hi}$ cells residing in the inflamed synovial tissue. When synovial cells extracted from normal joints were stimulated with IL-23 or autoantibody-containing immune complexes, a substantial fraction of $Sca1^{int}Thy1^{hi}$ cells produced IL-17. Thus, we have identified a novel population of IL-17-producing innate synovial cells that play a crucial role in the development of K/BxN serum-induced arthritis.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3777-3787
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• 2012

Three kinds of 3D isomorphous and isostructural coordination polymers, namely, $\{[Ln_2(PDA)_3(H_2O)_3]{\cdot}0.25H_2O\}_{\infty}$ (Ln = La(1), Sm(2), and Gd(3)) ($PDA^{2-}$ = pyridine-2,6-dicarboxylate anion) have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermal analyses and single crystal X-ray diffraction. In these MOFs, Ln(III) centers adopt eight-coordinated and nine-coordinated with the $N_1O_7$ and $N_2O_7$ donor sets to construct distorted trianglar dodecahedron geometry and tricapped trigonal prism configurations, respectively. Based on the building block of tetranuclear homometallic $Ln_4C_4O_8$ unit (16-membered ring), 1-3 are connected into highly ordered 2D sheets via O-C-O linkers and further constructed into 3D architectures through hydrogen bonds. Crystallographic parameters suggest that the lanthanide contraction effect exist in these coordination polymers. Luminescent properties of the lanthanide-based MOFs (metal-organic frameworks) have been measured at room temperature, which reveal that they presenting ionselective characters toward certain metals, such as $Mg^{2+}$, $Cd^{2+}$ and $Pb^{2+}$ ions.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.840-848
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• 1992

An ionizable macrocyclic ligand, diaza-18-crown-6-diisopropionic acid(K22DAP) has been synthesized. Protonation constants of this compound and stability constants with some lanthanides were determined by potentiometric titration method. The protonation constants are log$K_1$ = 9.05, log$K_2$ = 8.37, log$K_3$ = 1.88 and log$K_4$ = 0.99. The logarithmic values of stability constants with La(III), Nd(III), Gd(III) and Lu(III) are 11.14, 11.43, 11.74 and 10.88 respectively. Extraction behavior of Ln(III) ion was investigated using TTA(thenoyltrifluoroacetone) as extractant in the presence of K22DAP as macrocyclic ionophore. It was observed that Ln(K22DAP)TTA is the dominating species in aqueous complexes of La(III) and Nd(III).