Soumya Sivalingam, Seth Sudipta, Paul Sneha, Samanta Anunay
School of Chemistry, University of Hyderabad, Hyderabad 500046 (India).
Chemphyschem. 2015 Aug 3;16(11):2440-6. doi: 10.1002/cphc.201500316. Epub 2015 Jun 12.
The microenvironments of a leucine-based organogel are probed by monitoring the fluorescence behavior of coumarin 153 (C153) and 4-aminophthalimide (AP). The steady-state data reveals distinctly different locations of the two molecules in the gel. Whereas AP resides close to the hydroxyl moieties of the gelator and engages in hydrogen-bonding interactions, C153 is found in bulk-toluene-like regions. In contrast to C153, AP exhibits excitation-wavelength-dependent emission, indicating that the environments of the hydrogen-bonded AP molecules are not all identical. A two-component fluorescence decay of AP in gel, unlike C153, supports this model. A time-resolved fluorescence anisotropy study of the rotational motion of the molecules also reveals the strong association of only AP with the gelator. That AP influences the critical gelation concentration implies its direct involvement in the gel-formation process. The results highlight the importance of guest-gelator interactions in gels containing guest molecules.
通过监测香豆素153（C153）和4-氨基邻苯二甲酰亚胺（AP）的荧光行为，对基于亮氨酸的有机凝胶的微环境进行了探测。稳态数据揭示了凝胶中这两种分子明显不同的位置。AP靠近凝胶剂的羟基部分，并参与氢键相互作用，而C153则存在于类似甲苯的主体区域。与C153不同，AP表现出激发波长依赖性发射，这表明氢键结合的AP分子的环境并非完全相同。与C153不同，凝胶中AP的双组分荧光衰减支持了这一模型。对分子旋转运动的时间分辨荧光各向异性研究也揭示了只有AP与凝胶剂有强烈的缔合。AP影响临界凝胶化浓度，这意味着它直接参与了凝胶形成过程。结果突出了客体-凝胶剂相互作用在含有客体分子的凝胶中的重要性。
