(CMC¼9 mM) was used. The nonluminescent cationic surfactant
seemed to play a noninnocent role. Indeed for concentration of
CTAB above the CMC, both 1 and 2 displayed an increase of
their emission intensity as well as an elongation of their
excited-state lifetimes, suggesting an incorporation of the
metallosurfactant in the CTAB-based micelles. In Fig. 8 are
depicted the emission spectra of equimolar mixtures of the
metallosurfactants 1 and 2 , upon variation of the concentration
of CTAB. These experiments clearly showed the dependence of
the intramicellar energy transfer process occurring between the
two amphiphilies due to the micellization equilibrium of CTAB.
Thus, such findings demonstrated the possibility to obtain
luminescent soft structure made by self-assembling donor/accep-
tor metallosurfactants based on ruthenium and iridium
complexes, in which the energy transfer process can be easily
tuned by addition of a nonluminescent surfactant. As a result,
two emission colors can be obtained and one could even imagine
to have more than two emitters or to combine other properties
within the same aggregate. These aggregates could therefore
be employed as novel electroluminescent materials, as the size
of the spherical aggregates is compatible with ink-jet printing
and the emitters can be tuned in color and efficiency in a
desired way.
aabcdeb1010010001.00.50.0Log(relative intensity)0 500 1000 1500 2000 2500 3000 3500 4000 400 500 600 700 800
Channels λ (nm)I (a.u.)FIG. 8. Left: Time-resolved intensity decays and fits for 1 at (a)
0.01 mM and (b) 0.10 mM in aqueous solutions at room temperature
(lexc¼431 nm); right: emission spectra of a 1:1 mixture of the
complexes 1 and 2 , at different amounts of CTAB. [CTAB] (mM): (a)
0.0, (b) 1.0, (c) 1.5, (d) 2.0, and (e) 3.0 (lexc¼350 nm). Reproduced with
the permission of the American Chemical Society ( 122 ).
66 CRISTIAN A. STRASSERTet al.