Photostabilizing effects of lidocaine and tris(8-hydroxy-quinoline) aluminum on organic fluorescent dyes

摘要

The photostabilization efficacy of lidocaine and tris(8-hydroxy-quinoline) aluminum (Alq_3) was determined for methanol solutions of the fluorescent laser dyes l,3,5,7,8-pentamethyl-2,6-diethylpyrromethene-difluoroborate complex (PM-567) and rhodamine 590 (R590) by evaluation with the. rose bengal (RB). The photostability was measured by noting the decrease in fluorescence with accumulated 532 nm Nd:YAG laser pulses. Rose bengal demonstrated dramatic photostability enhancement upon lidocaine or Alq_3 addition; whereas nominal photostability enhancement was observed for PM-567 and R590 upon lidocaine or Alq_3 addition. A geminate dye-singlet oxygen complex is proposed to explain the disparity in dye photostability enhancement between rose bengal and the laser dyes.