TEMPERATURE-DEPENDENT FLUORESCENCE OF TUNABLE FLUOROPHORE-FISSILE BOND SYSTEMS BASED ON 1-PHENYL, 3-ARYL DELTA(2)-PYRAZOLINES AS A MEANS OFQUANTITATING PHOTOFISSION PROCESSES

The activation energy for the C(5)-N(1) bond homolysis in the lowest e xcited singlet state of the l-Phenyl, 3-Aryl, 5-(2'-Phenyl ethenyl) De lta(2)-pyrazolines as deduced from the temperature dependence of the f luorescence quantum yield (Phi(F)) can be combined with the correspond ing singlet energy to give a constant value of 75.5 kcal mol(-1) as th e total photofission energy. The corresponding value for 1,3-Diphenyl, 5-(2'-Iodo phenyl) Delta(2)-pyrazoline significantly exceeds the bond dissociation energy (BDE) of the aryl carbon-iodine linkage.