Fluorophilicity and lipophilicity of fluorinated rhodamines determined by their partition coefficients in biphasic solvent systems

• Published in: Journal of fluorine chemistry Vol. 193; pp. 67 - 72
• Main Authors: Jbeily, Mark, Kressler, Jörg
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2017
• Subjects: Fluorinated rhodamines; Fluorophilicity; Giant unilamellar vesicles; Partition coefficients; Fluorinated rhodamines; Giant unilamellar vesicles; Partition coefficients; Fluorophilicity
• ISSN: 0022-1139; 1873-3328
• DOI: 10.1016/j.jfluchem.2016.11.018

Four previously reported synthesized fluorinated rhodamines with a good quantum yield were used to stain mixed GUVs of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1H,1H,2H,2H-perfluoro-1-octanol (F6H2OH). [Display omitted] The 1-octanol/water (ln PO/W) and perfluoro(methylcyclohexane)/toluene (ln PPFMC/Tol) partition coefficients were measured for four fluorinated rhodamine-based fluorescence dyes (F-rhodamines) functionalized with F-ponytails of various lengths CnH2n-CmF2m+1 (n=1,2 and m=3,7,8,10) at both amine groups. Here, the ln PO/W accounts usually for the lipophilic-hydrophilic ratio in aqeous (biological) media whereas the ln PPFMC/Tol is a standard value for the description of the fluorophilic-lipophilic ratio. Both partition coefficients correlated with the CmF2m+1/CnH2n ratio, but not directly with the length of the F-ponytails. The ability of the F-rhodamines to incorporate into the hydrophobic part of the bilayer of giant unilamellar vesicles (GUVs) of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) mixed with 1H,1H,2H,2H-perfluoro-1-octanol (F6H2OH) using confocal laser scanning microscopy was tested and the partitioning of the F-rhodamines into the mixed GUVs could not be explained exclusively using the two ln P values mentioned above. Two other partition coefficients between F6H2OH/W (ln PF6H2OH/W) and perfluoro-n-octane/n-octane (ln PF-oct/oct) were measured. The ln PF-oct/oct correlated in a comparable way with the ln PPFMC/Tol, whereas ln PF6H2OH/W accounting for the fluorophilic-hydrophilic ratio correlated with the length of the F-ponytails and additionally clarified the different staining abilities of the synthesized F-rhodamines in the mixed GUVs.