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本文考察了VOSO_4与半胱氨酸在不同酸度(pH=1-1.4)的乙二醇/水(1:1)溶液中,在液氮温度下的ESR波谱。发现在pH<2,pH>11范围内,半胱氨酸不能与VO~(2+)生成络合物,当pH<2时,A=118G,归属于[VO(H_2O)_5]~(2+);当pH>11时,A=90G,归属于[VO(OCH_2CH_2O)_2)~(2-];pH=3-4时,A=116G,归属于VO~(2+)与半胱氨酸1:1单齿络合物,[VO(H_2O)_3(CysH)]~(2+);pH=5.0～5.5,A=102G,归属于1:1双齿螫合物[VO(H_2O)_2(Cys)]~+;pH=7.O～7.5,A=87G;pH=8-10,A=85G,分别归属于V0~(2+)与半胱氨酸1:2双齿顺式和反式螯合物[VO-(Cys)_2]~(2-)。利用测得的波谱参数,计算了键参数和电子能级。
In this paper, the ESR spectra of VOSO_4 and cysteine in ethylene glycol / water (1: 1) solution with different acidity (pH = 1-1.4) at liquid nitrogen temperature were investigated. It was found that cysteine could not form complexes with VO ~ (2+) at pH <2, pH> 11, and A = 118G at pH <2, which belonged to [VO (H_2O) _5] (2); when pH> = 11, A = 90G, belonging to [VO (OCH_2CH_2O) _2) ~ (2 - Cystine 1: 1 monodentate complex, [VO (H 2 O) 3 (CysH)] ~ (2 +); pH = 5.0-5.5, A = (H_2O) _2 (Cys)] ~ +; pH = 7.O ~ 7.5, A = 87G; pH = 8-10, A = 85G, belonging to the ratio of V0 ~ (2+) to cysteine 1: 2 Bidentate cis and trans chelates [VO- (Cys) _2] ~ (2-). Using the measured spectral parameters, the bond parameters and electronic energy levels were calculated.