Study of Singlet Oxygen Equilibrium in Dioctadecyldimethylammonium Chloride Vesicles Employing 2-(n-(N,N,N-trimethylamine)-n-alkyl)- 5-alkylfuryl Halides


  • This paper is part of a symposium-in-print dedicated to Professor Eduardo A. Lissi on the occasion of his 70th birthday.

*email: (Antonio L. Zanocco)


Steady state photolysis and time resolved near infrared luminescence detection were employed to study the reaction kinetics of singlet oxygen with three different lipid-soluble probes incorporated in large unilamellar dioctadecyldimethylammonium chloride (DODAC) vesicles. The probes: 2-(4-(N,N,N-trimethylamine)-butyl)-5-dodecylfuryl bromide (DFTA), 2-(12-(N,N,N-trimethylamine)-dodecyl)-5-hexylfuryl bromide (HFDA) and 2-(1-(N,N,N-trimethylamine)-methyl)-5-methylfuryl iodide (MFMA) are useful in studying both singlet oxygen dynamics and its equilibrium in microcompartmentalized systems because they are actinometers in lipidic microphases. These probes contain a reactive furan ring, which will be located at different depths in the bilayer of DODAC vesicles. In the limit of the approximations, the result indicates an inhomogeneous equilibrium distribution of singlet oxygen across the bilayer. The calculated mean partitioning constant of singlet oxygen equals 2.8 and 8.3 at 20°C and 40°C, respectively, in the order of the previously reported constants for other micro-organized systems such as sodium dodecylsulfate and cetyltrimethylammonium halide micelles and water/oil microemulsions.