Photoinduced Charge Separation and Photophysical Dynamics in Polynorbornene Chromophore Labeled and Quencher-Labeled Block Copolymers

Photophysical measurements have been used to characterize a series of well-defined block copolymers labeled with aromatic chromophores and quenchers. These include measurements of (1) energy migration kinetics in the homopolymers and diblock copolymers; (2) solvent effects (CH 2 Cl 2, THF, THF/CH 3 CN and CHCl 3 ) on exciplex emission in the diblock copolymers; (3) temperature effects on the fluorescence and phosphorescence of the diblock copolymers; (4) the dependence of the efficiency of steady-state and time-resolved emission in several triblock copolymers (dicyanobenzene) 5 −(phenanthrene) n −(dimethylaniline) 5 on relay length ( n ); and (5) transient absorbance and photoinduced charge separation in these triblock copolymers as a function of relay length. A photoinduced charge separation of 7.2 μs was achieved in a polynorbornyl triblock copolymer bearing a graded series of electron transfer relays: (dicyanobenzene) 5 −(phenanthrene) 10 −(dimethylaniline) 5 .