Dipartimento di Scienze Chimiche, Università di Napoli 'Federico II', Complesso Universitario di M.S.Angelo, via Cintia, I-80126 Napoli, Italy.
J Phys Chem A. 2012 Jul 19;116(28):7491-7. doi: 10.1021/jp3021485. Epub 2012 Jul 9.
Although lifetimes and quantum yields of widely used fluorophores are often largely characterized, a systematic approach providing a rationale of their photophysical behavior on a quantitative basis is still a challenging goal. Here we combine methods rooted in the time-dependent density functional theory and fluorescence lifetime imaging microscopy to accurately determine and analyze fluorescence signatures (lifetime, quantum yield, and band peaks) of several commonly used rhodamine and pyronin dyes. We show that the radiative lifetime of rhodamines can be correlated to the charge transfer from the phenyl toward the xanthene moiety occurring upon the S(0) ← S(1) de-excitation, and to the xanthene/phenyl relative orientation assumed in the S(1) minimum structure, which in turn is variable upon the amino and the phenyl substituents. These findings encourage the synergy of experiment and theory as unique tool to design finely tuned fluorescent probes, such those conceived for modern optical sensors.
尽管广泛使用的荧光染料的寿命和量子产率通常在很大程度上得到了充分表征，但基于定量基础提供其光物理行为基本原理的系统方法仍然是一个具有挑战性的目标。在这里，我们结合基于时间相关密度泛函理论和荧光寿命成像显微镜的方法，准确地确定和分析几种常用的罗丹明和吡咯啉染料的荧光特征（寿命、量子产率和带峰）。我们表明，罗丹明的辐射寿命可以与从苯基到吖啶部分的电荷转移相关联，该电荷转移发生在 S(0) ← S(1) 退激发时，并且与 S(1) 最低结构中假定的吖啶/苯基相对取向相关联，而该取向又取决于氨基和苯基取代基。这些发现鼓励实验和理论协同作用，将其作为设计精细调整的荧光探针的独特工具，例如为现代光学传感器设计的那些探针。
