• Bulletin of the Korean Chemical Society
• /
• 제33권11호
• /
• pp.3581-3588
• /
• 2012

A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in the cavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexes show irreversible one electron reduction process around -2.15 to -1.60 V The reduction potential of gadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. The catalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determined. All gadolinium(III) complexes were screened for antibacterial activity.

• 자연과학논문집
• /
• 제5권1호
• /
• pp.77-86
• /
• 1992

양이온 교환반응에 의해 몬트모릴로나이트내의 금속 양이온을 긴 chain을 갖는 유기 양이온 tenside로 치환시킴으로써 물성이 다른 몬트모닐롤나이트의 층간화합물을 형성하게 된다. 이러한 층간화합물은 공업적으로 아주 광범위하게 이용되는가 하면, model-systems로서 물질의 거동을 밝혀내는 학문적 연구에 또한 많이 이용되기도 한다. 따라서 본 연구에서는 이러한 몬트모릴로나이트의 층간화합물을 형성하여 여러 상이한 조건하에서의 이들의 거동에 대하여 연구했다.

• 한국식품과학회지
• /
• 제46권2호
• /
• pp.180-188
• /
• 2014

본 실험에서는 coenzyme $Q_{10}$을 cyclodextrin, starch를 이용하여 각각 복합체를 형성하고 형성된 복합체의 용해도 및 구조적 특성을 확인하였다. Starch 복합체는 용해 온도가 증가할수록 복합체 및 복합체내의 coenzyme $Q_{10}$의 용해도가 유의적으로 증가하는데 비해 cyclodextrin 복합체는 $37^{\circ}C$에서 coenzyme $Q_{10}$의 최대 용해도를 보였으며 이후 $50^{\circ}C$에서는 강하게 aggreagation이 일어났고, $80^{\circ}C$에서는 약해진 결합에 의해 복합체가 깨짐으로써 coenzyme $Q_{10}$이 물 위에 뜨는 형상을 나타내었다. 두 복합체의 구조적 차이를 FT-IR, XRD, DSC를 통하여 확인한 결과 cyclodextrin 복합체는 coenzyme $Q_{10}$의 isoprenoid chain에 주로 포접이 되어 있는데 반해 starch 복합체는 coenzyme $Q_{10}$의 isoprenoid chain 뿐만 아니라 benzoquinone ring에도 포접되어 있는 것을 확인하였고, 또한 starch 복합체가 cyclodextrin 복합체에 비해 coenzyme $Q_{10}$ 무정형영역이 더 크게 증가되어 있는 것을 확인하였다. In vitro simulated digestion model을 통하여 각 소화기관 별 복합체의 방출 패턴을 확인 한 결과 두 복합체 모두 구강, 위장의 효소 및 조건에 비해 소장의 효소와 조건에서 유의적으로 크게 coenzyme $Q_{10}$의 방출이 확인되었다. 따라서 coenzyme $Q_{10}$은 cyclodextrin, starch와 포접되어 복합체를 형성함으로서 생체이용율의 향상을 기대할 수 있다.

• Bulletin of the Korean Chemical Society
• /
• 제33권9호
• /
• pp.2917-2924
• /
• 2012

Four novel metal-organic complexes $[Cd_2(IP)_2(TBZ)_2(H_2O)_2]{\cdot}(H_2O)$ (1), $[Zn_4(IP)_4(TBZ)_4]{\cdot}2(H_2O)$ (2), $[Zn_2(BTC)(TBZ)_2(CO_2H)]$ (3), [Co(PDC)(TBZ)] (4) (where IP = isophthalate; TBZ = thiabendazole; BTC = 1,3,5-benzenetricarboxylate; PDC = pyridine-3,4-dicarboxylate) have been prepared and characterized by IR spectrum, elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. X-ray structure analysis reveals that 1, 2, and 3 are one-dimensional chain polymers, while 4 is a two-dimensional network polymer. The TBZ acts as a typical chelating ligand coordinated to the metal center in all complexes. The 1D chain architecture of 1 is constructed from isophthalates and cadmium atoms. A simultaneous presence of chelating, monodentate and bidentate coordination modes of IP ligands is observed in complex 2. In complex 3, the 16-membered rings are alternately arranged forming an infinite 1D double-chain structure. The 2D skeleton of 4 is formed by cobalt ions as nodes and PDC dianions as spacers, through coordination bonds. The hydrogen bonds and ${\pi}-{\pi}$ stacking play important roles in affecting the final structure where complexes 1 and 3 have 2D supramolecular networks, while complexes 2 and 4 have 3D supramolecular architectures.

• Bulletin of the Korean Chemical Society
• /
• 제25권10호
• /
• pp.1477-1483
• /
• 2004

We present the tandem mass spectrometry applications carried out to elucidate the coordination structure of Zn(II) bound lysine ternary complexes, $(Zn+Lys+Lys-H)^+$, which is a good model system to represent a simple (metallo)enzyme-substrate complex (ES). In particular, experimental efforts were focused on revealing the involvement of a lysine side chain ${\varepsilon}$-amino group in the coordination of $Zn^{2+}$ divalent ions. MS/MS fragmentation pattern showed that all the oxygen species within a complex fell off in the form of $H_2O$ in contrast to those of other ternary complexes containing amino acids with simple side chains (4-coordinate geometries, Figure 1a), suggesting that the lysine complexes have different coordination structures from the others. The participation of a lysine basic side chain in the coordination of Zn(II) was experimentally evidenced in MS/MS for $N{\varepsilon}$-Acetyl-L-Lys Zn(II) complexes with acetyl protection groups as well as in MS/MS for the ternary complexes with one $NH_3$ loss, $(Zn+Lys+Lys-NH_3-H)^+$. Detailed structures were predicted using ab initio calculations on $(Zn+Lys+Lys-H)^+$ isomers with 4-, 5-, and 6-coordinate structures. A zwitterionic 4-coordinate complex (Figure 7d) and a 5-coordinate structure with distorted bipyramidal geometry (Figure 7b) are found to be most plausible in terms of energy stability and compatibility with the experimental observations, respectively.

• 대한화학회지
• /
• 제36권5호
• /
• pp.770-779
• /
• 1992

$Fe(CO)_5와 알킨일리튬의 반응에서 생성된 아실 음이온 착물을 CH_3CH_2OSO_2F로 처리하는 방법으로 5종의 철 알킨일카르벤 착물 유도체(1)들을 합성하였다. [R-C≡C-C(OCH_2CH_3)]Fe(CO)_4(R = n-프로필, 시클로헥실, t-부틸, 트리메틸실릴, 페닐). 트리메틸시릴기가 치환된 유도체(1d)와 8종의 열린 고리 1,3-디엔과의 반응에서 {\eta}^3-비닐카르벤 착물 유도체(2)를 주생성물로 얻었다.$

• Journal of Electrochemical Science and Technology
• /
• 제14권2호
• /
• pp.152-161
• /
• 2023

Vanadium redox flow batteries (VRFBs) have been considered one of promising power sources for large scale energy storage systems (ESS) because of their excellent cycle performance and good safety. However, VRFBs still have a few challenging issues, such as poor Coulombic efficiency due to vanadium crossover between catholyte and anolyte, although recent efforts have shown promise in electrochemical performance. Herein, the vanadium complexes with various glyme ligands have been examined as active materials to suppress vanadium crossover between catholyte and anolyte, thus improving the Coulombic efficiency of VRFBs. The conventional Nafion membrane has a channel size of ca. 10 Å, whereas vanadium cation species are small compared to the Nafion membrane channel. For this reason, vanadium cations can permeate through the Nafion membrane, resulting in significant vanadium crossover during cycling, although the Nafion membrane is a kind of ion-selective membrane. In this regard, various glyme additives, such as 1,2-dimethoxyethane (monoglyme), diethylene glycol dimethyl ether (diglyme), and tetraethylene glycol dimethyl ether (tetraglyme) have been examined as complexing agents for vanadium cations to increase the size of vanadium-ligand complexes in electrolytes. Since the size of vanadium-glyme complexes is proportional to the chain length of glymes, the vanadium permeability of the Nafion membrane decreases with increasing the chain length of glymes. As a result, the vanadium complexes with tetraglyme shows the excellent electrochemical performance of VRFBs, such as stable capacity retention (90.4% after 100 cycles) and high Coulombic efficiency (98.2% over 100 cycles).

• Bulletin of the Korean Chemical Society
• /
• 제12권2호
• /
• pp.219-224
• /
• 1991

New binuclear Ni(Ⅱ) and Cu(Ⅱ) complexes with various alkyl derivatives of 1,2-bis(1,3,6,8,10,13-hexaaza-1-cyclotetradecyl) ethane, in which two fully saturated 14-membered hexaaza macrocyclic subunits are linked together by an ethylene chain, have been synthesized by the one step template condensations of formaldehyde with ethylenediamine and appropriate primary alkyl amines in the presence of the metal ions. Each macrocyclic subunit of the double-ring macrocyclic complexes contains one alkyl pendant arm and has a square planar geometry with a 5-6-5-6 chelate ring sequence. The visible spectra and oxidation properties indicate that the metal-metal interaction of the binuclear complexes are not significant. Synthesis, characterization, and the properties of the complexes are presented.

• Bulletin of the Korean Chemical Society
• /
• 제33권5호
• /
• pp.1581-1585
• /
• 2012

Two pyridinecarboxamide dicyanidecobalt(III) building blocks and two mononuclear seven-coordinated macrocycle manganese(II) compounds have been rationally selected to assemble cyanide-bridged heterobimetallic complexes, resulting in three cyanide-bridged $Co^{III}-Mn^{II}$ complexes. Single X-ray diffraction analysis show that these complexes $\{[Mn(L^1)][Co(bpb)]\}ClO_4{\cdot}CH_3OH{\cdot}0.5H_2O$ ($\mathbf{1}$), $\{[Mn(L^2)][Co(bpb)]\}ClO_4{\cdot}0.5CH_3OH$ ($\mathbf{2}$) and ${[Mn(L^1)][Co(bpb)]\}ClO_4{\cdot}H_2O$ ($\mathbf{3}$) ($L^1$ = 3,6-diazaoctane-1,8-diamine, $L^2$ = 3,6-dioxaoctano-1,8-diamine; $bpb2^{2-}$ = 1,2-bis(pyridine-2-carboxamido)benzenate, $bpmb2^{2-}$ = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate) all present predictable one-dimensional single chain structures. The molecular structures of these one-dimensional complexes consists of alternating units of $[Mn(L)]^{2+}$ ($L=L^1$ or $L^2$) and $[Co(L^{\prime})(CN)2]^-$ ($L^{\prime}=bpb2^{2-}$, or $bpmb2^{2-}$), forming a cyanide-bridged cationic polymeric chain with free $ClO_4{^-}$ as the balance anion. The coordination geometry of manganese(II) ion in the three one-dimensional complexes is a slightly distorted pentagonal-bipyrimidal with two cyanide nitrogen atoms at the trans positions and $N_5$ or $N_3O_2$ coordinating mode at the equatorial plane from ligand $L^1$ or $L^2$. Investigation over magnetic properties of these complexes reveals that the very weak magnetic coupling between neighboring Mn(II) ions connected by the diamagnetic dicyanidecobalt(III) building block. A best-fit to the magnetic susceptibility of complex ${\mathbf}{1}$ leads to the magnetic coupling constants $J=-0.084(3)cm^{-1}$.

• Bulletin of the Korean Chemical Society
• /
• 제28권8호
• /
• pp.1299-1304
• /
• 2007

New sulfur functionalized cyclopentadiene ligands, 1-[2-(thioanisole)]-2,5-dimethylcyclopentadiene (3), 1-[2- (thioanisole)]-2,3,5-trimethylcyclopentadiene (4), and 1-[2-(thioanisole)]-2,3,4,5-tetramethylcyclopentadiene (5), were prepared. In these ligands, the S-donor atom is connected to a cyclopentadiene ring by a rigid phenylene spacer. CpCo(III)-diiodo half-sandwich complexes (6-8) were obtained from reaction the ligands (3- 5) with Co2(CO)8, followed by treatment of I2. Substitution reaction of CpCo(III)-diiodo complexes with MeLi yielded the corresponding CpCo(III)-dimethyl complexes (9-11). Further transformation to the corresponding cationic cobalt complexes (12-14) were achieved by reaction of the CpCo(III)-dimethyl complexes with HB(ArF)4·2Et2O and trapping with CD3CN. The new sulfur functionalized cyclopentadiene ligands having a rigid phenylene spacer and the corresponding cobalt complexes were characterized by 1H, 13C and 19F NMR spectroscopy. The diiodo Complex 6 was also characterized by a single crystal X-ray diffraction method.