Kedia Niraja, Roy Saswati Ghosh, De Priyadarsi, Bagchi Sanjib
Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata , Mohanpur Campus, BCKV Main P.O., Nadia 741252, West Bengal, India.
J Phys Chem B. 2014 May 1;118(17):4683-92. doi: 10.1021/jp4127557. Epub 2014 Apr 18.
A copolymer bearing several pendent dyes (coumarin derivatives) along the side chain has been synthesized, and its fluorescence parameters have been monitored in pure solvents and also as a function of composition of binary solvent mixtures. Fluorescence parameters (the maximum energy of fluorescence, quantum yield, and rate constant for the decay of the excited state) of the free fluorophore show significant dependence on the nature of the immediate environment around it. The value of a parameter measured in neat solvent for the fluorophore covalently bound to the polymer is different from that of the free fluorophore, indicating that the polymer chain influences the spectroscopic properties of the dye. Whereas the energy of maximum fluorescence of the free fluorophore shows a nonlinear correlation with the solvent composition of solvent mixtures, an almost linear correlation has been observed for the polymer. A significant variation of photophysical parameters of the dye dissolved in binary solvent mixtures, which is different from that of the free fluorophore, has been observed. Thus, the free fluorophore and the fluorophore bound to the polymer sense different environments in binary solvent mixtures. A dramatic variation of fluorescence intensity of the fluorophore bound to the polymer has been observed when sodium dodecyl sulfate (SDS) is added to an aqueous solution of the polymer. The results have been explained in terms of the existence of different species (polymer, polymer-SDS aggregates, micelles) in equilibrium in solution.
一种沿着侧链带有几种侧挂染料（香豆素衍生物）的共聚物已被合成，并且其荧光参数在纯溶剂中以及作为二元溶剂混合物组成的函数进行了监测。游离荧光团的荧光参数（荧光的最大能量、量子产率和激发态衰减的速率常数）显示出对其周围直接环境性质的显著依赖性。在纯溶剂中测量的与聚合物共价结合的荧光团的参数值与游离荧光团的不同，这表明聚合物链影响染料的光谱性质。虽然游离荧光团的最大荧光能量与溶剂混合物的溶剂组成呈非线性相关，但对于聚合物观察到几乎呈线性相关。已观察到溶解在二元溶剂混合物中的染料的光物理参数有显著变化，这与游离荧光团的不同。因此，游离荧光团和与聚合物结合的荧光团在二元溶剂混合物中感知到不同的环境。当将十二烷基硫酸钠（SDS）添加到聚合物的水溶液中时，已观察到与聚合物结合的荧光团的荧光强度有显著变化。这些结果已根据溶液中处于平衡的不同物种（聚合物、聚合物 - SDS 聚集体、胶束）的存在进行了解释。
