Chemistry Reference
In-Depth Information
TP
G1
TP
SCHEME 11.7
First-generation phosphorus dendrimer functionalized with two-photon
absorbing peripheral chromophores (
TP
).
11.3.3.1 Steady-State Properties
The r
ss
values of dendrimers in toluene solution
at room temperature decrease with dendrimer generation (r
ss
¼
0.032 for G1
TP
and
0.012 for G4
TP
), but they are, in all cases, much lower than the model
TP
chromophore (r
ss
¼
0.178). This result has been interpreted on the basis of a rapid
energy migration between
TP
chromophores in the dendritic structures.
11.3.3.2 Time-Dependent Properties
The fluorescence anisotropy decays of
dendrimers are fitted by a two-exponential model. In the case of G3
TP
, the resulting
values of
are of the order of hundreds of femtoseconds and one hundred of
picoseconds with slight variations upon changing the solvent. The first component
is shorter upon increasing dendrimer generation and is attributed to incoherent
hopping exciton transport, due to the increase in chromophore density upon increas-
ing dendrimer generation. The slower decay is weakly dependent on dendrimer
y
