1,32-DIHYDROXY-DOTRIACONTANE-BIS(RHODAMINE) 101 ESTER - A LIPID-MEMBRANE SPANNING BICHROMOPHORIC MOLECULE AS REVEALED BY INTRAMOLECULAR DONOR-DONOR ENERGY MIGRATION (DDEM)
St. Bogen et al., 1,32-DIHYDROXY-DOTRIACONTANE-BIS(RHODAMINE) 101 ESTER - A LIPID-MEMBRANE SPANNING BICHROMOPHORIC MOLECULE AS REVEALED BY INTRAMOLECULAR DONOR-DONOR ENERGY MIGRATION (DDEM), Journal of the Chemical Society. Faraday transactions (Print), 94(16), 1998, pp. 2435-2440
Citations number
26
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
The bichromophoric and monochromophoric probes, 1,32-dihydroxy-dotriac
ontane-bis(Rhodamine) 101 ester (Rh101C(32)Rh101) and Rhodamine 101 oc
tadecyl ester (Rh101C(18)), respectively, were solubilised in unilamel
lar lipid vesicles of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC),
1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1-palmitoyl-2-
oleoyl-sn-glycero-3phosphocholine (POPC). At molar ratios of less than
1/5000 for Rh101C(18)/lipid and Rh101C(32)Rh101/lipid, intermolecular
electronic energy migration is negligible, contrary to the intramolec
ular donor-donor energy migration (DDEM) within the Rh101C(32)Rh101 mo
lecules. The time-resolved fluorescence anisotropy determined for Rh10
1C(18) and Rh101C(32)Rh101 were globally analysed by using a recently
developed model that accounts for reorientational motions, as well as
the rate of DDEM (L. B-Angstrom. Johansson, F. Bergstrom, P. Edman, I.
V. Grechishnikova and J. G. Molotkovsky, J. Chem. Soc., Faraday Trans
., 1996, 92, 1563). It was found that the rate of intramolecular DDEM
within Rh101C(32)Rh101 is typically about 3 x 10(9) s(-1). In vesicles
formed by DOPC and POPC, the distance between the Rhodamine groups of
Rh101C(32)Rh101 is found to be about 35 Angstrom while it is about 32
Angstrom in DPPC vesicles. These values are in excellent agreement wi
th reported thicknesses of the lipid bilayers. Thus, the present work
strongly suggests that the Rh101C(32)Rh101 molecules are spanning acro
ss the lipid bilayer, that is, the Rhodamine residues are located on o
pposite sides of the lipid bilayer.