One of the keys to analyzing self-assembled media such as mixed chain-length lipid aggregates is charactering the emission of multi-state probes in simpler solvents. For example, the dyes PRODAN and LAURDAN have been used by biophysicists investigating lipid properties for many years under the assumption that the emission consisted of species interacting with gel (solid) and liquid crystalline (melted) phase lipids. The results of our recent work with these probes demonstrates that these probes emit from multiple states in many isotropic solvents and more than three states in microheterogeneous media. Based on differences observed in emission spectra and decay times and predicted by time-dependent density functional theory, we postulated that PRODAN (and LAURDAN) molecules that are hydrogen bonded to the solvent via the amine group emit a different spectrum than those that are hydrogen bonded via the carbonyl group.  Similar analyses of the environment sensitive polynuclear aromatic hydrocarbon pyrene distinguish molecules by their degree of self-association rather than hydrogen bonding. Future studies will expand preliminary multivariate investigations of the photokinetics of flavone derivatives, which are important anti-oxidants and undergo simultaneous excited state proton and electron transfer reactions.

Related Publications

  •  B. A. Rowe, C. A. Roach, J. Lin, V. Asiago, O. Dmitrenko and S. L. Neal, “Spectral Heterogeneity of PRODAN Fluorescence in Isotropic Solvents Revealed by Multivariate Photokinetic Analysis,” Journal of Physical Chemistry A, 2008 112 (51),  13402–13412. 

1. •• B.A. Rowe and S.L. Neal, “Photokinetic Analysis of PRODAN and LAURDAN in Large Unilamellar Vesicles Using Multivariate Frequency-Domain Fluorescence,” Journal of Physical Chemistry B, 2006 110(30); 15021-15028. 
   

•  • M.M. Villegas and S.L. Neal, “Model-Independent Analysis of Pyrene Photokinetics in SDS Micelles,” Journal of Physical Chemistry A, 1997 101(37) 6890-6896.