Deuterium substitution study on solvation dynamics of liquid poly(ethylene glycol)s

We have compared the picosecond to nanosecond solvation dynamics of coumarin 153 in liquid poly(ethylene glycol)s to that in the deuterated analogues. The observed solvation dynamics in the poly(ethylene glycol)s shows a biexponential feature. Deuterium substitutions of the end hydroxyl groups on the poly(ethylene glycol)s do not affect on the faster solvation time constant of about 130 ps, but the slower solvation process in the deuterated poly(ethylene glycol)s is about 1.2 times slower than that in the undeuterated poly(ethylene glycol)s. In contrast to the solvation dynamics, the fluorescence anisotropy decay of coumarin 153 in poly(ethylene glycol)s shows no deuterium isotope effect. The retardation of the slower solvation component in deuterated poly(ethylene glycol)s in comparison with the undeuterated poly(ethylene glycol)s may be due to an indirect motion of the end groups of poly(ethylene glycol)s