6-苄氨基腺嘌呤-Cu(Ⅱ)-三苯甲烷类染料体系的吸收和共振瑞利散射光谱及其分析应用

Absorption and Resonance Rayleigh Scattering Spectra of 6-Benzylaminopurine-Cu(Ⅱ)-Triphenylmethane Dyes Systems and Their Analytical Applications

在pH值为5.37～5.58的HAc-NaAc缓冲溶液中,6-苄氨基嘌呤(6-BA)能与Cu(Ⅱ)反应生成螯合物[6-BA.Cu]2+,可再与三苯甲烷类染料形成三元离子缔合物,其摩尔比分别为2∶1(里斯沙明绿)、3∶1(固绿)和2.5∶1(水溶性苯胺蓝)。反应体系的吸收光谱发生变化,其共振瑞利散射光谱(RRS)和倍频散射(FDS)显著增强,3个体系的最大RRS峰均位于372 nm附近,6-BA浓度在一定范围内的增加与相应的RRS强度(ΔIRRS)、FDS(ΔIFDS)强度和吸光度(ΔA)均呈线性关系。其RRS检出限分别为5.48μg/L(里斯沙明绿)、18.43μg/L(固绿)和9.34μg/L(水溶性苯胺蓝)。据此建立6-BA-Cu(Ⅱ)-里斯沙明绿染料体系测定痕量6-BA的RRS法,并用于豆芽中6-BA的快速测定,结果令人满意。此外,还应用计算化学软件Gaussview3.07和Gaussian03W,采用密度泛函法,在B3LYP/6-31G基组水平上计算6-BA的电荷分布,并对里斯沙明绿体系的反应机理及RRS增强的主要原因进行了初步探讨。

In HAc-NaAc buffer medium with pH=5.37~5.58,6-benzylaminopurine（6-BA） reacted with Cu（Ⅱ） to form a chelate [6-BA·Cu]2＋,which further reacted with triphenylmethane dyes to form 2∶1（Lissamine green system）,3∶1（fast green system） and 2.5∶1（water-soluble aniline blue system） ternary ion-associations,respectively.It resulted in the change of the absorption spectra,the great enhancement of resonance Rayleigh scattering（RRS） spectra and frequency doubling scattering（FDS） intensities.The maximum RRS wavelengths were all located at 372 nm.And the increased amount of absorption,the enhancement degree of RRS（ΔIRRS）,FDS（ΔIFDS） were all proportional to the concentration of 6-BA during a certain range.The detection limits of methods for Lissamine green system were 5.48 μg/L,119.70 μg/L and 64.20 μg/L,respectively.Therefore,a sensitive method for determination of trace 6-BA with RRS spectrum in 6-BA-Cu（Ⅱ）-LG system has been developed.The method could be applied to the determination of 6-BA in bean sprouts with satisfactory results.In this paper,we used Gaussview 3.07 and Gaussian 03W softwares at a B3LYP/6-31G（base group） level based on the density functional theory（DFT） to calculate the charge distribution of 6-BA.Furthermore,the reaction mechanism and the main reasons for the enhancement of RRS of the Lissamine green system were preliminarily discussed.