• 대한화학회지
• /
• 제62권1호
• /
• pp.14-18
• /
• 2018

The complexes $[Zn(L)(H_2O)_2]{\cdot}2NO_2$ (1) and $[Zn(L)(NO_3)_2]$ (2) (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo $[14,4,0^{1.18},0^{7.12}]$docosane) have been synthesized and structurally characterized. The compound 1 crystallizes in the monoclinic system $P2_1/c$ with a = 8.74650(10), b = 18.6880(3), c = $7.96680(10){\AA}$, ${\beta}=109.1920(10)^{\circ}$, $V=1229.84(3){\AA}^3$, Z = 2. The compound 2 crystallizes in the monoclinic system P1 with a = 8.1292(5), b = 8.9244(5), c = $9.1398(5){\AA}$, ${\alpha}=68.035(2)$, ${\beta}=70.109(2)$, ${\gamma}=75.649(3)^{\circ}$, $V=572.70(6){\AA}^3$, Z = 1. The crystal structures of the compounds 1 and 2 show a distorted octahedral coordination geometry around the zinc(II) ion, with four secondary amines and two oxygen atoms of the two water and two nitrate ligands at the axial position. The TGA behaviors of the complexes are significantly affected by the nature of the tetraaza macrocycle and the axial ligands.

• Bulletin of the Korean Chemical Society
• /
• 제17권9호
• /
• pp.854-857
• /
• 1996

Absorption and luminescence spectra of Eu3+ (aquo) and the two different 1: 3 Eu3+: ligand systems in aqueous solutions are measured under mild acidic pH condition. The oxydiacetate (ODA) and dipicolinate (DPA) ligands, forming the similar geometric complexes, are used in this work. The three intensity parameters, Ωλ (λ=2, 4, and 6) are empirically determined by applying the Judd-Ofelt theorem to the oscillator strengths of the six absorption bands arising from the ground 7F0 state. Among the three intensity parameters, the Ω2 is found to response markedly to a miner change in the ligand environment via the 7F0→5D0 transition. In addition, the relative oscillator strengths of the four luminescence bands in the visible region, assigned to the 5D0→7FJ (J=1, 2, 3 and 4) transitions are obtained to investigate their sensitivity to the ligand environment. Among the four bands, the 610 nm band, attributed to the 5D0→7F2 transition, shows hypersensitivity in the luminescence.

• BMB Reports
• /
• 제44권3호
• /
• pp.170-175
• /
• 2011

We identified a bovine $B_{12}$ trafficking chaperone bCblC in Bos taurus that showed 88% amino acid sequence identity with a human homologue. The protein bCblC was purified from E. coli by over-expression of the encoding gene. bCblC bound cyanocobalamin (CNCbl), methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl) in the base-off states and eliminated the upper axial ligands forming aquo/hydroxocobalamin ($OH_2$/OHCbl) under aerobic conditions. A transition of $OH_2$/OHCbl was induced upon binding to bCblC. Interestingly, bCblC-bound $OH_2$/OHCbl did not react with reduced glutathione (GSH), while the reaction of free$OH_2$/OHCbl with GSH resulted in the formation of glutathionylcobalamin (GSCbl) and glutathione disulfide (GSSG). Furthermore we found that bCblC eliminates the GSH ligand of GSCbl forming $OH_2$/OHCbl. The results demonstrated that bCblC is a $B_{12}$ trafficking chaperone that binds cobalamins and protects $OH_2$/OHCbl from GSH, which could be oxidized to GSSG by free $OH_2$/OHCbl.

• Bulletin of the Korean Chemical Society
• /
• 제13권1호
• /
• pp.54-59
• /
• 1992

Spectroscopic measurements and theoretical calculations are performed for the four 1 : 3 Sm(III) : ligand solutions. The ligands included in this study are oxidiacetate, iminodiacetate, methyliminodiacetate and dipicolinate. The oscillator strengths for the $4f{\to}4f$ multiplet-to-multiplet transitions are empirically determined from the absorption spectra. The intensity parameters ${\Omega}_{\lambda}\;({\lambda}=2,\;4,\;6)$ of $Sm^{3+}$(aquo) and ${SmL_3}^{3-}$ complexes are also evaluated by applying the Judd-Ofelt theorem to the observed oscillator strengths. The values of the intensity parameters are compared and discussed in term of structural properties of the complexes. In addition, the fluorescence spectra are reported for the Sm(III) complex systems under mild alkaline condition. The excitation from the $^6H_{5/2}$ ground state to any excited states lying above the emitting energy level $(^4G_{5/2})$ produces four fluorescence bands, following nonradiative transitions from a certain excited state to the $^4G_{5/2}$ state. The ratios of oscillator strengths of ${SmL_3}^{3-}$ complexes to that of $Sm^{3+}$(aquo) are also evaluated from the fluorescence spectra and compared to the results obtained from the absorption bands.

• 대한화학회지
• /
• 제54권6호
• /
• pp.687-695
• /
• 2010

L이 urea, acetamide, semicrabazide, formamide 인 thiocyanato (L) Cobaloxime 착물을 합성하고 특성을 규명하였다. Thiocyanato(L)cobaloximes (SCNCo$(DH)_2$(L))과 benzyl (aquo) cobaloxime $PhCH_2Co(DH)_2(OH_2)$를 반응시켜 일반 분자식 $PhCH_2Co(DH)_2SCNCo(DH_2)(L)$를 갖는 일련의 thiocyanato로 연결된 dicobaloximes 생성물을 얻었다. Thiocyanato 리간드의 다리결합을 포함하고 있는 dicobaloximes의 조성에 대한 증거로 말단의 thiocyanocobaloxime (SCNCo$(DH)_2$(L))으로부터 dicobaloxime이 형성되면서 vCN이 $20-45cm^{-1}$ 증가하게 되는 적외선 데이터를 들 수 있다. 이러한 두 일련의 물질에 대한 더많은 특성을 ($^1H$, $^{13}C$) NMR, LCMS 및 원소분석을 통하여 확인하였다. Thiocyanato (L) cobaloximes 및 thiocyanato로 연결된 dicobaloxime의 항균 활성은 E. Coli에 의해 조사하였다. 두 단량체와 이합체 모두의 DNA-결합 행동은 분광학적 방법 및 점성도 측정을 통하여 조사하였다. 그 결과 이합체 착물은 calf-thymus DNA와 DNA의 염기쌍에 말단의 벤질 고리를 통해 사이에 끼인 형태로 결합되어 있음을 나타내었다. 단량체 착물은 DNA와 상호작용하지 않는 것으로 관찰되었다.