Luminescence Quenching of Rhodamines by Cyclooctatetraene

Abstract

Cyclooctatetraene (COT) as a quencher o f fluorescence o f a series o f Rhodamine solutions was studied. The second order rate constants for the quenching process o f Rhodamine 110, Rhodamine 19 pchl., Rhodamine 6G pchl., R hodam ine 6G, Tetramethylrhodamine, Rhodamine B and Rhodamine 3B pchl. are given. It was found that COT enhances rather intersystem crossing than internal conversion.

On the impact of competing intra- and intermolecular triplet-state quenching on photobleaching and photoswitching kinetics of organic fluorophores

“…To optimize signal strength and quality, quencher molecules, herein denoted as photostabilizers, are used to deplete triplet-or radical-states. Common quenching mechanisms for high photostability are triplet-triplet annihilation via molecular oxygen, [6][7][8] dexter-type triplet energy transfer (cyclooctatetraene (COT), [9][10][11] diphenylhexatriene (DPHT) 12 ) or photo-induced electron transfer (nitrophenyl-compounds, 11 Trolox (TX), 1,13 methylviologen (MV), ascorbic acid (AA) 2,14 ). Whereas other damage pathways such as multi-photon absorption processes and bleaching from singlet states are known to occur, 15 the primary strategy for photostabilization relies on suppressing triplet-and radicalstate formation as well as removal of molecular oxygen 14 to avoid formation of reactive oxygen species (ROS [6][7][8]16,17 ).…”

“…1a) with buffer cocktails is the most flexible approach to stabilize various classes of organic fluorophores in different biochemical environments. [1][2][3][9][10][11][12][13][14][15][26][27][28][29][30] This approach is widely applied in fluorescence microscopy and the antioxidant TX, 13 COT [9][10][11] or combinations of redox-active compounds (''ROXS'' 2 ) have become the additives of choice.…”

On the impact of competing intra- and intermolecular triplet-state quenching on photobleaching and photoswitching kinetics of organic fluorophores

“…To optimize signal strength and quality, quencher molecules, herein denoted as photostabilizers, are used to deplete triplet-or radical-states. Common quenching mechanisms for high photostability are triplet-triplet annihilation via molecular oxygen [4][5][6] , dexter-type triplet energy transfer (cyclooctatetraene (COT), 7,8 diphenylhexatriene (DPHT) 9 ) or photo-induced electron transfer (Trolox (TX), 10 methylviologen (MV), ascorbic acid (AA) 2,11 ). Whereas other damage pathways such as multi-photon absorption processes and bleaching from singlet states are known to occur 12 , the primary strategy for photostabilization relies on suppressing triplet-and radical-state formation as well as removal of molecular oxygen 11 to avoid formation of reactive oxygen species (ROS).…”

A general method for near-infrared photoswitching in biology, demonstrated by the >700 nm photocontrol of GPCR activity in brain slices

“…linker-extended conformation), the chromophore should stay in a biocompatible singlet manifold photocycle. (We later found a 1987 report by Targowski and coworkers, potentially showing conditional TET from rhodamine to cyclooctatetraene 36 , that may support the plausibility of this idea.) This conditional TET might avoid the O2incompatibility of previous TET approaches.…”