Determination of molecular dynamics from proton multiple quantum relaxation and carbon-13 differential line broadening: application to the deoxycholate micelles

Abstract

1517, 1446, 1308, 1167 cm-’. Anal. Calcd. for CI9Hl9NO5: C, 66.85; H, 5.61; N , 4.10. Found: C, 66.87; H, 5.76; N, 4.03. Fluorescence Efficiencies. Fluorescence efficiencies of methyl ester 3 and ethyl ester 4 were determined as follows. An airsaturated solution of coumarin 343 was prepared in chloroform having an absorbance CO.10 at 448 nm. The ‘Po was determined by direct comparison with an ethanol solution of coumarin 343 having a similar ab~orbance.~ A solution of ester 3 or 4 in a chosen solvent was prepared and diluted until the absorbance maximum for the ester solution was the same as that of the chloroform solution of coumarin 343. The fluorescence emission spectra for both solutions were recorded with the excitation wavelength set at the wavelength where their absorbance spectra were identical to eliminate the need to correct for the spectral output of the excitation lamp. Fluorescence lifetimes were measured by the phase delay and modulation method. Air-saturated solutions of the esters were prepared in the chosen solvent so that the absorbance at 442 nm was less than 0.10. The samples were irradiated with the 442-nm line from a heliumedmium laser modulated with a Pockel’s cell. An aqueous solution of Ficoll (Sigma) was used as the blank for zero lifetime. Scatter was eliminated from the sample by removing all light below 480 nm with a UV cutoff filter. Data were taken at 1, 5, 10, 20, 30, 50, 80, 100, and 150 MHz and were analyzed by using the ISS 178 software package.