• 대한화학회지
• /
• 제8권4호
• /
• pp.147-152
• /
• 1964

有機溶媒(benzene)에 의한 抽出法을 利用하고, 分光光度法에 의한 몰比法과 連續變化法을 써서, V(IV)-cupferrate와 V(V)-cupferrate의 化學沮成이 水溶液相에서 有機溶媒相으로 分配된 다음에도 雙하지 않을 것이라는 假定밑에서, 水溶液의 酸性度에 따르는 cupferrate 錯化合物의 化學組成을 決定하였다. V(IV)-cupferrate의 benzene 溶液에서의 最大吸光波長은 pH에 따라 445$m{\mu}$ 또는 450$m{\mu}$이고, V(V)-cupferrate의 그것은 pH 1.8以下에서는 pH에 無關하게 445$m{\mu}$이었다. V(V)-cupferrate의 化學組成은 沈澱이 形成되는 水溶液의 pH에 따라 다르며, pH 1.0 以下에서는 $VCupf_4$, pH 1.3∼1.7에서는 $HVOCupf_3$ 또는 $VCupf_4$와 $VOCupf_2$의 거의 같은 몰씩으로된 混合物이고, pH 1.8∼4.3에서는 $VOCupf_2$이었다. V(V)-cupferrate의 化學組成은 水溶液의 pH에 따라 變化가 없고, pH 1.8 以下에서는 $HVO_2Cupf_2$이었다.

• Bulletin of the Korean Chemical Society
• /
• 제8권5호
• /
• pp.384-388
• /
• 1987

Modified Bloch equations were used to simulate the solution EPR spectra of mixed-valence heteropolyanions containing vanadium(IV) and vanadium(V). Simulated are the 15-, 22-, 36- and 43-line spectra of $\alpha$-1,2-$[PV(IV)VW_{10})O_{40}]^{6-},\;[P_2V(IV)V_2W_{15}O_{62}]^{10-},\;[HP_2V(IV)V_2W_{15}O_{62}]^{9-}$ and $\alpha$-1,2,3-$[HSiV(IV)V_2W_9O_{40}]^{7-}$, respectively. The transition probabilities for the intramolecular electron transfer were determined from the simulations.

• Bulletin of the Korean Chemical Society
• /
• 제19권9호
• /
• pp.927-933
• /
• 1998

Polycrystalline powder of vanadium-doped forsterite (Vδ $Mg_2SiO_4$) was synthesized by the $H_2O_2$-assisted sol-gel method. The vanadium dopant, which was added as VO$(OMe)_3$ in methanol, went through several redox reactions as the sol-gel reaction proceeded. Upon adding VO$(OMe)_3$ to a mixture of $Mg(OMe)_2$ and Si$(OEt)_4$ in methanol, V(V) reduced to V(IV). As hydrolysis reaction proceeded, the V(IV) oxidized all back to V(V). Apparently, some of the V(V) reduced to V(IV) during subsequent gelation by condensation reaction. The V(IV) remained even after heat treatment of the gel in highly oxidizing atmosphere. The crystallization of the xerogel around 880 ℃ readily produced single phase forsterite without any minor phase. Using the polycrystalline powder as feeding stock, single crystals of vanadium-doped forsterite were grown by the floating zone method in oxidizing or reducing atmosphere. The doping was limited in low level because of the high partitioning of the vanadium in liquid phase during melting. The greenish single crystal absorbed visible light of 700∼1100 nm. But, no emission was obtained in near infrared range.

• 분석과학
• /
• 제13권1호
• /
• pp.22-26
• /
• 2000

2-Hydroxybenzaldehyde-5-nitro-pyridylhydrazone (2HB-5NPH)를 합성하여 계면활성제 하에서 바나듐 이온(IV)의 분광학적 정량에 응용하였다. pH, 용매효과, 리간드 농도와 계면활성제의 최적조건을 구하였다. 이 과정을 혼합 시료와 실제 시료 중의 바나듐(IV) 정량에 적용하여 만족한 결과를 얻었다(회수율 ${\geq}$ 97% ; $0{\sim}1.5{\mu}g/mL$ 농도 범위에서 상대 표준 편차 ${\leq}$ 3.0% ; 용액중에서 검출 한계 $0.02{\mu}g/mL$).

• Bulletin of the Korean Chemical Society
• /
• 제7권2호
• /
• pp.108-110
• /
• 1986

The solution epr spectra of ${\alpha}-1,2,3-[H_nPV(IV)V_2W_9O_{40}]^{(7-n)-}$were measured at various pH and three protonated species have been identified. The spectrum of $H_3PV(IV)Ⅴ_2$ consisting of 8 lines indicates that the V-OH-V bridge prevents effectively the electron transfer between the vanadium atoms. The spectrum of $H_2PV(IV)V_2$ consisting of 15 lines can be interpreted by assuming that the electron is hopping fast between the two vanadium atoms in the V-O-V sequence. The multi-line spectrum of $HPV(IV)V_2$ is interpreted as a poorly resolved 43-line spectrum which originates from the electron hopping among the three vanadium atoms with the forward and backward transition probabilities of 4:1 in the OH-V-O-V sequence.

• 대한화학회지
• /
• 제32권6호
• /
• pp.567-574
• /
• 1988

바나듐(IV)촉매가 존재하는 물 및 알코올 수용매에서 과산화수소에 의한 디메틸술폭시드의 산화반응은 디메틸술폭시드와 산농도에 각각 일차의존성임을 보여주었다. 이 산화반응의 속도 결정단게는 황이 바나듐(V)-과산화물의 O-O결합에 대하여 친핵적 공격을 함으로서 디메틸술폭시드가 산화되는 과정임을 제시한다.

• Biomolecules & Therapeutics
• /
• 제9권4호
• /
• pp.270-276
• /
• 2001

Vanadium yeast was prepared by uptaking vanadate in yeast cells. The growth rate of yeast cells was enhanced by 1-5% glucose. While the growth rate of yeast cells was not significantly affected by YEPD containing less than 1mM vanadate, it was completely inhibited by 2.5 mM vanadate. Vanadium uptake in yeast cells was increased with increasing vanadate concentration in growth medium. Vanadate (V) was reduced to vanadyl (IV) in yeast cells associating with macromolecular compounds in cells. Oral administration of vanadium yeast significantly reduced blood glucose levels of streptozotocin treated rats same as vanadate. Vanadate and vanadium yeast similarly increased glucose oxidation in isolated adipocytes. Therefore, it was suggested that vanadium yeast could have an antidiabetic activity potency similar to that of vanadate.

• Bulletin of the Korean Chemical Society
• /
• 제9권6호
• /
• pp.362-364
• /
• 1988

Reaction of Keggin- or Dawson-type heteropolyanions containing two adjacent vanadium atoms with acetic anhydride in the presence of acid produced acylated anions. Heteropolyanions with one or no vanadium atom do not react under the same conditions, indicating that the acyl group is attached to the bridging oxygen atom between the two vanadium atoms. A characteristic infrared band at 1760 $cm^{-1}$ was observed for the acylated anions. The 8-line EPR spectrum shows that one of the vanadium atoms is reduced to V(IV ). The acylated heteropolyanions are easily hydrolyzed, and its acyl group can also be transferred to aniline.

• 한국자기공명학회논문지
• /
• 제11권2호
• /
• pp.95-109
• /
• 2007

Vanadium-incorporated aluminophosphate microporous molecular sieve VH-SAPO-42 has been studied by electron spin resonance(ESR) and electron spin-echo modulation (ESEM) spectroscopies to determine the vanadium location and interaction with various adsorbate molecules. The results are interpreted in terms of V(IV) ion location and coordination geometry. Assynthesized VH-SAPO-42 contains only vanadyl species with distorted octahedral or trigonal bipyramidal coordination. Vanadium incorporated into H-SAPO-42 occupied extra-framework site. After calcinations in $O_2$ and exposure to moisture, only species A is observed with reduced intensities. Species A is identified as a $VO(H_2O)_2^{2+}$ complex coordinated to three framework oxygen atoms bonded to aluminum. When hydrated VH-SAPO-42 is dehydrated at elevated temperature by calcination, species A loses its water ligand and transforms to $VO^{2+}$ ions coordinated to three framework oxygens (species B). Species B reduces its intensities significantly after treatment with $O_2$ at high temperature, thus suggesting oxidation of $V^{4+}$ to $V^{5+}$. When dehydrated VH-SAPO-42 makes contact with $D_2O$ at room temperature, the ESR signal of species A is regained. The species is assumed as a $VO(O_f)_3(D_2O)_2$ by considering three framework oxygens. Adsorption of deuterated methanol on dehydrated VH-SAPO-42 results in another new vanadium species D, which is identified as a $VO(CD_3OH)_2$ complex. When deuterated ethylene is adsorbed on dehydrated VH-SAPO-42, another new vanadium species E identified as a $VO(C_2D_4)^{2+}$, is observed. Possible coordination geometries of these various complexes are discussed.

• Bulletin of the Korean Chemical Society
• /
• 제7권6호
• /
• pp.483-484
• /
• 1986