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The singlet-singlet intramolecular energy transfer between naphthalene moiety and dansylgroup held apart by a rigid steroid bridge was investigated for two molecules:3β-(1-naphthyl)acetoxy-17α-dansyl-△~5androstene(3a)and 3β-(1-naphthyl)acetoxy-17β-dansyl-△~5androstene(3b).Therates of energy transfer for 3a and 3b in cyclohexane are 6.9×10~6 and 1.1×10~8s~(-1) respectively.Thedifference in energy transfer rate between 3a and 3b is attributed to the different donor-acceptorseparation and orientation.The ratio of the two epimers in the synthesized product mixture wasobtained from the fluorescence decay measurements.