烷基苄基铵对芘的荧光猝灭行为研究

广义的荧光猝灭系指所有能使荧光强度降低的物理和化学过程,但通常涉及的主要有动态猝灭和静态猝灭,二者均遵从Stern-Volmer方程,但由于猝灭作用本质不同,它们在荧光寿命变化、温度效应及吸收光谱等方面表现出差异可资区别.本文通过稳态荧光强度变化和荧光衰减速率的比较研究了具有不同烷基链长的十四烷基苄基二甲基氯化铵(Zeph)和苄基三甲基溴化铵(TMBA)对芘的荧光猝灭,并基于电导实验结果以及猝灭剂全反式构象从理论上计算了Zeph和TMBA的猝灭速率常数,讨论了荧光猝灭的性质和长链分子的构型。

BEHAVIOR OF QUENCHING OF PYRENE FLUORESCENCE BY ALKYLBENZYLAMMONIUM IN AQUEOUS SOLUTION

The quenchings of pyrene fluorescence were studied with tetradecylbenzyldime- thylammonium chloride (Zeph) and benzyltrimethylammonium bromide (TMBA) throughtheir Stern-Volmer plots. Transient and steady state fluorescence experiments indicatedthat the quenching was dynamic and the quenching rate constant (k_q) of Zeph wasmuch larger than that of TMBA with a ratio of 23.2. Theoretical calculations basedon conductance measurement and the full-anti configuration of quencher moleculeshowed that the k_q of TMBA was larger than that of Zeph with a ratio of 2.29 and1.85, respectively, which were opposite to the experimental results. Coiling of thelong alkyl chain in Zeph molecule and the hydrophobic interaction between pyreneand the coiled microenvironment were considered as the causes for the contradictionbetween experimental results and theoretical calculations.