ENLIGHTENING STRUCTURE AND PROPERTIES OF DENDRIMERS BY FLUORESCENCE DEPOLARIZATION - Designing Dendrimers - page 344

11.2.1.1 Steady-State Properties The steady-state anisotropy r ss of T and den-

drimers G0 T ,G1 T , G1.5 T , and G2 T in dichloromethane is constant throughout the

emission band, is practically zero for and increases with increasing dimension of the

dendrimer (Figure 11.1a). The terphenyl-cored dendrimers show a noticeably high
steady-state anisotropy taking into account the experimental conditions used (a low
viscosity solvent at room temperature). Indeed, the maximum anisotropy value (r 0 ),
determined by the relative orientation of the absorption and emission dipoles, is 0.33

T

FIGURE 11.1 Steady-state fluorescence anisotropy r ss in dichloromethane solutions at 298 K
(light gray bars) of compounds (a) G0 T -G2 T , and T [13], and (b) G0 P ,G2 P , and G4 P [16].
The dashed line corresponds to the corresponding r 0 values in rigid matrix. For the
pentaphenyl cored dendrimers the r ss values observed for powder on a glass slide at
298 K are also reported (dark gray bars).