National Centre for Ultrafast Processes, University of Madras, Taramani Campus, Chennai, 600 113, India.
J Fluoresc. 2010 Sep;20(5):993-1002. doi: 10.1007/s10895-010-0646-9. Epub 2010 Apr 6.
Photophysical studies of photoinduced electron transfer (PET) and non-PET based acridinedione dyes with guanidine hydrochloride (GuHCl) were carried out in water and methanol. Addition of GuHCl to photoinduced electron transfer (PET) based acridinedione dye (ADR 1) results in a fluorescence enhancement, whereas a non-PET based dye (ADR 2) shows no significant change in the fluorescence intensity and lifetime. Addition of GuHCl to ADR 1 dye in methanol results in single exponential decay behaviour, on the contrary a biexponential decay pattern was observed on the addition of GuHCl in water. Absorption and emission spectral studies of ADR 1 dye interaction with GuHCl reveals that the dye molecule is not in the protonated form in aqueous GuHCl solution, and the dye is confined to two distinguishable microenvironment in the aqueous phase. A large variation in the microenvironment around the dye molecule is created on the addition of GuHCl and this was ascertained by time-resolved area normalized emission spectroscopy (TRANES) and time-resolved emission spectroscopy (TRES). The dye molecule prefers to reside in the hydrophobic microenvironment, rather in the hydrophilic aqueous phase is well emphasized by time-resolved fluorescence lifetime studies. The mechanism of fluorescence enhancement of ADR 1 dye by GuHCl is attributed to the suppression of the PET process occurring through space.
在水和甲醇中，对基于光诱导电子转移（PET）和非 PET 的吖啶二酮染料与盐酸胍（GuHCl）的光物理研究。向光诱导电子转移（PET）基吖啶二酮染料（ADR 1）中添加 GuHCl 会导致荧光增强，而基于非 PET 的染料（ADR 2）则不会导致荧光强度和寿命发生显著变化。在甲醇中向 ADR 1 染料添加 GuHCl 会导致单指数衰减行为，而在水中添加 GuHCl 则会观察到双指数衰减模式。ADR 1 染料与 GuHCl 相互作用的吸收和发射光谱研究表明，在水溶液中的 GuHCl 溶液中，染料分子不是质子化形式，并且染料在水相中被限制在两个可区分的微环境中。在添加 GuHCl 时，染料分子周围的微环境会发生很大变化，这可以通过时间分辨面积归一化发射光谱（TRANES）和时间分辨发射光谱（TRES）来确定。通过时间分辨荧光寿命研究，染料分子更倾向于存在于疏水性微环境中，而不是亲水性水相中。GuHCl 增强 ADR 1 染料荧光的机制归因于抑制通过空间发生的 PET 过程。
