SOLVENT AND TEMPERATURE INFLUENCE ON THE FLUORESCENCE-SPECTRUM OF 6-AMINO-5-METHYL-2,3-DIPHENYLBENZO[B]FURAN

6-amino-5-methyl-2,3-diphenylbenzo[b]furan (ABF) exhibits a strong flu orescence in the near UV and visible regions. The effects of temperatu re and solvent on the fluorescence spectrum have been the object of ca reful study. Both solvent polarity (18 solvents have been used) and te mperature variations (from 77 to 473 K) should have an effect on the c onformations of the excited state of ABF by deformation of the polycyc lic molecular frame. Eleven of these conformations have been highlight ed whose fluorescence maxima differ over a range of about 500 cm(-1) ( 1.4 kcal/mol), a value of the same order as the energy of deformation of a benzenic or a Furanic ring, as shown by IR spectra. Very importan t solvatochromic effects have been observed at room temperature, almos t 3500 cm(-1) in highly polar solvents compared to nonpolar ones. Simi larly, thermochromic effects are also large (1000 cm(-1) for solutions in nonpolar solvents as compared to 2500 cm(-1) for the ones in polar solvents) so, the data obtained so far must be only slightly affected by the current experimental errors.