Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213-3890, USA.
Langmuir. 2011 Feb 15;27(4):1472-9. doi: 10.1021/la104329c. Epub 2010 Dec 21.
Double-helical DNA was used as a template for the assembly of helical cyanine dye aggregates. The aggregates consist of cofacial dimers aligned end-to-end in the minor groove of the DNA. The effect of methoxy or fluoro substituents placed on the periphery of the cyanine dye heterocycles on aggregation both in water and on the DNA template was studied by UV-vis and circular dichroism spectroscopy. Methoxy groups were found to be stronger promoters of aggregation than fluoro, and a dimethoxy dye exhibited a higher propensity to aggregate compared with an unsymmetrical methoxy/fluoro dye. Semiempirical calculations supported the experimental observation of methoxy substitution favoring aggregation. These results indicate that dispersion and hydrophobic effects contribute more to dimerization/aggregation than do electron donor-acceptor effects.
双链 DNA 被用作组装螺旋状菁染料聚集体的模板。这些聚集体由面对面的二聚体在 DNA 的小沟中头尾相连排列而成。通过紫外可见光谱和圆二色光谱研究了菁染料杂环外围的甲氧基或氟取代基对水相和 DNA 模板中聚集的影响。结果发现，甲氧基比氟更能促进聚集，而二甲氧基染料比不对称的甲氧基/氟染料更倾向于聚集。半经验计算支持了甲氧基取代有利于聚集的实验观察。这些结果表明，分散和疏水效应对二聚体/聚集的贡献大于供体-受体效应。
