Sensing of Carbon Dioxide by a Decrease in Photoinduced Electron Transfer Quenching

Abstract

We described a new approach to sensing of carbon dioxide based on photoinduced electron transfer (PET) quenching. Fluorophores like naphthalene and anthracene are known to be quenched by unprotonated amines by the PET mechanism. We examined the fluorescence spectral properties of two amine-containing fluorophores, 1-naphthylmetylamine (NMA) and 9-ethanolaminomethylanthracene (EAA). When dissolved in an organic solvent, both fluorophores displayed increased intensity when equilibrated with gaseous carbon dioxide. In the case of NMA, we found that the mean lifetime increased with increasing partial pressures of CO(2). The intensity and lifetime changes of NMA are completely reversible when CO(2) is removed by purging with argon. Our results are consistent with decreased quenching by the covalently linked amino groups when CO(2) is dissolved in the solution. At present, we are not certain whether the increased intensity is due to protonation of the amino groups or to carbamate formation. In either event, these results suggest that CO(2) can be detected directly using amine-containing fluorophores without the use of bicarbonate and a pH-sensitive fluorophore.

Tuning the Photophysical Behavior of Luminescent Cyclam Derivatives by Cation Binding and Excited State Redox Potential

“…In this case, the quenching mechanism may be due to a combination of both electron and energy transfer processes. 10 By contrast, the naphthyl appended macrocycle, L 3 , when complexed with Ni(II), shows only a moderate reduction in fluorescence intensity that has been ascribed to a Dexter type energy transfer mechanism. 7 The temperature-dependent lowspin high-spin interconversion of this Ni(II) complex has been found to affect the efficiency of this mechanism due to changes in the metal's electronic structure, and this system has been proposed as a novel fluorescent thermometer.…”

Fluorescent Carbon Dioxide Indicators

“…Interestingly, others have recently promoted 42 the possibility of generating optical-sensors for carbon dioxide based on the quenching of an excited state by a pH-sensitive quencher. In this case, the quenching process is photoinduced electron transfer in non-aqueous solution between a fluorophore, such as naphthalene and anthracene, and an unprotonated quencher, such as an amine, which is unable, or less efficient, in its quenching ability when protonated.…”

Fluorescence lifetime imaging in biosciences: technologies and applications

“…The applications of FLIM in the biosciences are manifold and reach from monitoring cellular parameters (Ca 2+ 55-57 and Na + concentrations 58 , pH [59][60][61][62][63][64] , pO 2 and ROS concentrations [65][66][67] , pCO 2 68 ) and the distances between proteins on the nm-scale by means of FRET 5,35,42,[46][47][48][68][69][70][71][72][73][74][75][76][77][78][79][80][81] to observing central cellular processes in real time, e.g. interactions between proteins in living cells 48,[82][83][84][85][86] , photophysics of complexes involved in plant photosynthesis 87 or the redox metabolism 38,50,[88][89][90] .…”