• Journal of the Korean Chemical Society
• /
• v.44 no.6
• /
• pp.518-525
• /
• 2000

The open-chain hexadentate N$_4$, O$_2$ ligands 1,13-bis(2-hydroxybenzyl)-2,5,9,12-tetraazatridecane-tetrahydrochloride (BSATD${\cdot}$4HCl) and 1,14-bis (2-hydroxybenzyl)-2,6,9,12-tetraazatetradecane-tetrahydrochloride (BSATED${\cdot}$ 4HCl) have been synthesized as their tetrahydrochloride salt and characterized by EA, IR, NMR and Mass. Their proton dissociation constants(log$K^{n}_{H}$) and stability constants(log$K_{ML}$) for Cu(II), Ni(II), Co(II), and Zn(II) ions were determined in aqueous solution by potentiometry and compared with those of analogous N$_4$, O$_2$ ligands contain ethylenic spacers or propylenic spacers, which make six-membered chelate rings between the aliphatic nitrogen atoms. Synthesis and characterization of [Cu(BSATD)]ClO$_4$ and [Cu(BSATED)](ClO$_4$)$_2$ complexes are described.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.7
• /
• pp.2193-2199
• /
• 2012

A series of novel polytriazoleimides were prepared from various aromatic dianhydrides and a new kind of 1,2,3-triazole-containing aromatic diamine synthesized by the Cu (I)-catalyzed 1,3-dipolar cycloaddition reaction in DMAc, and characterized by FT-IR, $^1H$-NMR, XRD, DSC and TGA techniques. The results show the polytriazoleimides are soluble in most of strong polar solvents and have inherent viscosity values of 0.51-0.62 dL/g(DMAc). The polytriazoleimide films exhibit a tensile strength of 62.3-104.5 MPa and an elongation at breakage of 4.0-8.1%, a glass transition temperature ($T_g$) of $257-275^{\circ}C$, a decomposition temperature (at 5% weight loss) of $350-401^{\circ}C$ in $N_2$ atmosphere, and a dielectric constant of 2.47-3.01 at 10 MHz, which depend on the structure of the polymers. The polytriazoleimides perform good resistance to acid and alkali solution.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.2
• /
• pp.558-564
• /
• 2013

A simple and effective method is introduced to synthesize a series of polystyrene-b-poly(oligo(ethylene oxide) monomethyl ether methacrylate)-b-polystyrene (PSt-b-POEOMA-b-PSt) triblock copolymers. The structures of PSt-b-POEOMA-b-PSt copolymers were characterized by Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance ($^1H$ NMR) spectroscopy. The molecular weight and molecular weight distribution of the copolymer were measured by gel permeation chromatography (GPC). Furthermore, the self-assembling and drug-loaded behaviours of three different ratios of PSt-b-POEOMA-b-PSt were studied. These copolymers could readily self-assemble into micelles in aqueous solution. The vitamin E-loaded copolymer micelles were produced by the dialysis method. The micelle size and core-shell structure of the block copolymer micelles and the drug-loaded micelles were confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The thermal properties of the copolymer micelles before and after drug-loaded were investigated by different scanning calorimetry (DSC). The results show that the micelle size is slightly increased with increasing the content of hydrophobic segments and the micelles are still core-shell spherical structures after drug-loaded. Moreover, the glass transition temperature (Tg) of polystyrene is reduced after the drug loaded. The drug loading content (DLC) of the copolymer micelles is 70%-80% by ultraviolet (UV) photolithography analysis. These properties indicate the micelles self-assembled from PSt-b-POEOMA-b-PSt copolymers would have potential as carriers for the encapsulation of hydrophobic drugs.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.5
• /
• pp.605-609
• /
• 2003

The lower-order lithium organocyanocuprate compound, (THF)₃Li(NC)Cu($C_6$H₃-2,6-Mes₂) (1), and the bulky terphenyl Grignard reagent, Br(THF)₂Mg($C_6$H₃-2,6-Trip₂) (2), have been synthesized and structurally characterized both in the solid state by single crystal x-ray crystallography and in solution by multi-nuclear NMR and IR spectroscopy. The compound (1) was isolated as a monomeric contact ion-pair in which the C (organic ipso)-Cu-CN-Li atoms are coordinated linearly. The lithium has a tetrahedral geometry as a result of solvation by three THF molecules. The compound (1) is the first example of fully characterized monomeric lower order lithium organocyanocuprate. The bulky Grignard reagent (2) was also isolated as a monomer in which the magnesium, solvated by two THF molecules, has a distorted tetrahedral geometry. The crystals of (1) possess triclinic symmetry with the space group $P{\={1}}$, Z = 2, with a = 12.456(3) Å, b = 12.508(3) Å, c = 13.904(3) Å, α = 99.81°, β = 103.72(3)°, and γ = 119.44(3)°. The crystals (2) have a monoclinic symmetry of space group $P2_{1/C}$, Z = 4, with a = 13.071(3) Å, b = 14.967(3) Å, c = 22.070(4) Å, and β = 98.95(3)°.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.9
• /
• pp.1331-1335
• /
• 2004

Angiogenesis is essential for the growth and persistence of solid tumors. Their metastases, anti-angiogenesis could lead to the suppression of tumor growth. One of the main strategies of cancer treatment is developing molecules of anti-angiogenic activity. In this study, two angiogenic inhibitors, Ang3 (KLFDF) and Ang4 (XLFDF) derived from KLYDY, which is the sequence of angiostatin active sites kringle 5, were designed and synthesized. Previously we reported the activities and structures of two inhibitors, Ang1 (KLYDY) and Ang2 (KLWDF). In order to investigate the effect of Phe substitution, Ang3 was designed with a sequence of KLFDF. In order to reduce conformational flexibility of side chain in Lys, Ang4 was designed with a sequence of XLFDF, where X has amino substituted phenyl ring. Solution structures of those inhibitors were investigated using NMR spectroscopy and their activities as angiogenesis inhibitors were studied. Ang1 and Ang2 show angiogenic activities, while Ang3 and Ang4 have no activities and have extended structures compared to Ang1 and Ang2. Therefore, Phe rings do not have effective hydrophobic interactions with other aromatic residues in Ang3 and Ang4. The representative structure of Ang2 has a stable intramolecular hydrogen bond. Therefore, intramolecular hydrogen bonding might be more important in stabilizing the structure than the hydrophobic interactions in these inhibitors. More rigid structure, which can be expected to have higher activities and better match with the receptor bound conformations, can be obtained with a constrained cyclic structure. Further peptidomimetic approaches should be tried to develop angiogenesis inhibitors.

• Polymer(Korea)
• /
• v.26 no.5
• /
• pp.589-598
• /
• 2002

thiathlophene (EDiTT) was synthesized. The yield of the synthesis was about 29%. The monomer was identified by using NMR, IR and UV/Vis spectroscopic methods. Poly (3,4-ethylenedithiathiophene) (PEDiTT) was prepared using this monomer and FeCl$_3$. The deep blue green color of the product was changed into brown color by the reduction with $N_2$H$_4$. This was soluble to common organic solvents. Spectroelectrochemistry was used to characterize the PEDiTT. NMP was the best solvent for PEDiTT. PEDiTT/NMP solution was used for making SAM type thin film of the polymer on gold electrode. Electrochemical and IR spectroscopic methods were used to identify the thin film.

• Macromolecular Research
• /
• v.15 no.5
• /
• pp.437-442
• /
• 2007

Poly(ethylene glycol) methyl ether (PEG)-poly(${\beta}$-amino ester) (PAE) block copolymers were synthesized using a Michael-type step polymerization, and the construction of pH-sensitive polymeric micelles (PM) investigated. The ${\beta}$-amino ester block of the block copolymers functioned as a pH-sensitive moiety as well as a hydrophobic block in relation to the ionization of PAE, while PEG acted as a hydrophilic block, regardless of ionization. The synthesized polymers were characterized using $^1H-NMR$, with their molecular weights measured using gel permeation chromatography. The $pK_b$ values of the pH-sensitive polymers were measured using a titration method. The pH-sensitivity and critical micelle concentration (CMC) of the block copolymers in PBS solution were estimated using fluorescence spectroscopy. The pH dependent micellization behaviors with various bisacrylate esters varied within a narrow pH range. The critical micelle concentration at pH 7.4 decreased from 0.032 to 0.004 mg/mL on increasing the number of methyl group in the bisacrylate from 4 to 10. Also, the particle size of the block copolymer micelles was determined using dynamic light scattering (DLS). The DLS results revealed the micelles had an average size below 100 nm. These pH-sensitive polymeric micelles may be good carriers for the delivery of an anticancer drug.

• Journal of the Korean Applied Science and Technology
• /
• v.18 no.2
• /
• pp.111-117
• /
• 2001

Density, viscosity, conductance, dye solubility and carbon-13 nmr studies were performed in aqueous solution of three disodium 4-n-alkyl-3-sulfonatosuccinate anionic surfactant at $20^{\circ}C$. The cmc values were 0.14 mol/l for the disodium-4-n-octyl-3-sulfonatosuccinate($R_{8)S$), 0.041mol/l for the disodium-4-n-decyl-3-sulfonatosuccinate($R_{10}S$), and 0.018mol/l for the disodium-n-dodecyl-3-sulfonatosuccinate <$R_{12}S$). The aggregation numbers determined viscometrically and conductimetrically were 28 for $R_{8}S$, 48 for $R_{10}S$, and 67 for $R_{12}S$. The volume changes upon micellization were $8.9cm^{3}/mol$ for $R_{8}S$, $9.5cm^{3}/mol$ for $R_{10}S$, and $10.1cm^{3}/mol$ for $R_{12}S$. Binding constants for the dye pada to the micelles and the fractions of unbound counter-ion were also obtained. The two polar heads with their carbon linkage were likely in an aqueous environment in the $R_{8}S$ micelles with the micelles themselves being spherical.

• Journal of the Korean Electrochemical Society
• /
• v.22 no.2
• /
• pp.53-59
• /
• 2019

To examine the solution structure of electrolytes, it is very important to understand ion-ion and ion-solvent interactions. In this review, we introduce the basic principle of dielectric relaxation spectroscopy (DRS) and studies of electrolyte structure. DRS is a type of impedance method, which measures the dielectric properties of electrolytes over a high frequency domain at levels of tens of GHz. Therefore, DRS provides information on the different polar chemical species present in the electrolyte, including the type and concentration of free solvents and ion pairs with dipole moments. The information of DRS is complementary to the information of conventional analytical techniques (Infrared/Raman spectroscopy, nuclear magnetic resonance (NMR), etc.) and thus enables a broad understanding of electrolyte structure.

• Biomaterials Research
• /
• v.22 no.4
• /
• pp.249-258
• /
• 2018

Background: Mucoadhesive polymers, which may increase the contact time between the polymer and the tissue, have been widely investigated for pharmaceutical formulations. In this study, we developed a new polysaccharide-based mucoadhesive polymer with thermogelling properties. Methods: Hexanoyl glycol chitosan (HGC), a new thermogelling polymer, was synthesized by the chemical modification of glycol chitosan using hexanoic anhydride. The HGC was further modified to include thiol groups to improve the mucoadhesive property of thermogelling HGC. The degree of thiolation of the thiolated HGCs (SH-HGCs) was controlled in the range of 5-10% by adjusting the feed molar ratio. The structure of the chemically modified polymers was characterized by $^1H$ NMR and ATR-FTIR. The sol-gel transition, mucoadhesiveness, and biocompatibility of the polymers were determined by a tube inverting method, rheological measurements, and in vitro cytotoxicity tests, respectively. Results: The aqueous solution (4 wt%) of HGC with approximately 33% substitution showed a sol-gel transition temperature of approximately $41^{\circ}C$. SH-HGCs demonstrated lower sol-gel transition temperatures ($34{\pm}1$ and $31{\pm}1^{\circ}C$) compared to that of HGC due to the introduction of thiol groups. Rheological studies of aqueous mixture solutions of SH-HGCs and mucin showed that SH-HGCs had stronger mucoadhesiveness than HGC due to the interaction between the thiol groups of SH-HGCs and mucin. Additionally, we confirmed that the thermogelling properties might improve the mucoadhesive force of polymers. Several in vitro cytotoxicity tests showed that SH-HGCs showed little toxicity at concentrations of 0.1-1.0 wt%, indicating good biocompatibility of the polymers. Conclusions: The resultant thiolated hexanoyl glycol chitosans may play a crucial role in mucoadhesive applications in biomedical areas.