On the photophysical and photochemical behavior of fenbufen: a study in homogeneous media and micellar environments

The photochemistry of fenbufen, gamma -oxo-[1,1'-biphenyl]-4-butanoic acid (FB), has been investigated in homogeneous solutions and in micellar enviro nments. The photochemical and photophysical properties of the drug are medi ated by its lowest excited triplet states. The presence of a low-lying pi,p i* triplet is responsible for the inefficient Norrish Type I photocleavage, whereas an upper n,pi* triplet promotes a large intersystem crossing yield . FB interacts with both anionic and cationic micelles. The different bindi ng mode of the drug with the microheterogeneous environments can significan tly change its photoreactivity. These changes are rationalized on the basis of "micellar cage effects''.