光谱法研究2-(4-二甲氨基苯基)-5-氟-6-吗啉-1-氢-苯并咪唑与小牛胸腺DNA的相互作用

研究了2-(4-二甲氨基苯基)-5-氟-6-吗啉-1-氢-苯并咪唑(1)在不同pH条件下的紫外-可见吸收光谱，采用非线性最小二乘法得出分子1的三级加质子常数lgβ₁, lgβ₂, lgβ₃分别为4.96±0.03, 5.72±0.07和7.95±0.10。当pH 3.40时，分子1主要以一价离子状态存在，紫外-可见吸收光谱及荧光光谱表明该条件下分子与小牛胸腺DNA存在明显的相互作用，并得出分子1与DNA的结合常数K_b为(2.30±0.10)×104 mol-1·L。当分子浓度为10-8～1.2×10-6 mol·L-1时，荧光强度随DNA含量的增加而线性增强，分子1是一种潜在的测定DNA的定量试剂。

Spectroscopic Research on the Interaction of 2-(4-Dimethylaminophenyl)-5-Fluoro-6- (Morpholin-4-yl)-1H-Benzimidazole and Calf Thymus DNA

UV-Vis spectra of the aqueous solutions of 2-(4-dimethylaminophenyl)-5-fluoro-6-(morpholin-4-yl)-1H-benzimidazole (1) at different pH values revealed that compound 1 is a tertiary base, which can combine three protons. Through the non-linear least square method, the logarithm of the three accumulative protonation constants of compound 1, namely, lgbeta1, lgbeta2 and lgbeta3, were determined to be 4.96 +/- 0.03, 5.72 +/- 0.07 and 7.95 +/- 0.10, respectively. UV-Vis and the steady-state fluorescence spectra indicated that a special interaction occurs between compound 1 and calf thymus DNA at the pH value of 3.40, of which thebinding constant, Kb, is (2.30 +/- 0.10) x 10(4) mol(-1) x L. Compound 1 in the concentration range of 10(-8) to 1.2 x 10(-6) mol x L(-1) has a potential application to the quantitative determination of DNA.