131
6.3.7 Aggregation-Induced CPL (AICPL)
Effects of chiral alkyl side chains in poly(9,9-dialkylfluorene-2,7-vinylene)s [PFVs,
(S)-3-methylpentyl (3mpe), (S)-4- methylhexyl (4mhex), (S)-5-methylheptyl
(5mhep), (S)-6-methyloctyl (6moct) and (S)-3,7-dimethyloctyl (dmo)] towards
aggregation-induced circular dichroism (AICD) and AICPL and CD/CPL was studied Yamada et al. (2018) from the spectra in solution and in thin film. The (all-trans)
PFV samples with similar conjugation repeating units containing well-defined
(vinyl) end groups were prepared by acyclic diene metathesis polymerization using
a Ru catalyst. The PFV aggregates, prepared in situ in a mixed CHCl 3 /MeOH solution, showed clear CD signals attributed to AICD, while these samples showed
CD-silent in the CHCl 3 solution. According to Yamada et al. (2018) the absolute
magnitude (g CD value) was affected by the chiral side chains (without obey the evenodd rule) and increased in the order 3mpe, 5mhep < 4mhex < dmo < 6mcot. Both the
6-moct and dmo aggregates showed clear CPL signals attributed to AICPL, while
signals of the others were not obvious. Figure 6.7 shows the CPL and photoluminescence (PL, fluorescence) spectra (at 1.0 × 10
–6
M in CHCl 3 or CHCl 3 /MeOH at
25 °C, excitation at 380–390 nm) for PFVs containing chiral alkyl side chains in
CHCl 3 solution and aggregates prepared by pouring MeOH slowly into the CHCl 3
solution values prepared under an optimized ratio of CHCl 3 /MeOH = 15/85 (v/v)
except 1/19 (3mpe) and 25/75 (dmo). It should be noted that some PFV aggregates,
especially containing 6moct and S-dmo side chains, prepared in situ in a mixed
CHCl 3 /MeOH solution, showed clear CPL signals attributed to aggregation-induced
Fig. 6.7 CPL and fluorescence (PL) spectra (1.0 × 10
–6 M at 25 °C) for PFVs containing chiral
side chains [(S)-4-methylhexyl (4mhex), (S)-5-methylheptyl (5mhep), (S)-6-methyloctyl (6moct),
(S)-3,7-dimethyloctyl (S-dmo)] in (left) CHCl 3 /MeOH and (right) THF/MeOH. Reproduced with
permission from Yamada et al. (2018)
6 Circularly Polarized Luminescent Polymers: Emerging Materials for Photophysical…
6.3.7 Aggregation-Induced CPL (AICPL)
Effects of chiral alkyl side chains in poly(9,9-dialkylfluorene-2,7-vinylene)s [PFVs,
(S)-3-methylpentyl (3mpe), (S)-4- methylhexyl (4mhex), (S)-5-methylheptyl
(5mhep), (S)-6-methyloctyl (6moct) and (S)-3,7-dimethyloctyl (dmo)] towards
aggregation-induced circular dichroism (AICD) and AICPL and CD/CPL was studied Yamada et al. (2018) from the spectra in solution and in thin film. The (all-trans)
PFV samples with similar conjugation repeating units containing well-defined
(vinyl) end groups were prepared by acyclic diene metathesis polymerization using
a Ru catalyst. The PFV aggregates, prepared in situ in a mixed CHCl 3 /MeOH solution, showed clear CD signals attributed to AICD, while these samples showed
CD-silent in the CHCl 3 solution. According to Yamada et al. (2018) the absolute
magnitude (g CD value) was affected by the chiral side chains (without obey the evenodd rule) and increased in the order 3mpe, 5mhep < 4mhex < dmo < 6mcot. Both the
6-moct and dmo aggregates showed clear CPL signals attributed to AICPL, while
signals of the others were not obvious. Figure 6.7 shows the CPL and photoluminescence (PL, fluorescence) spectra (at 1.0 × 10
–6
M in CHCl 3 or CHCl 3 /MeOH at
25 °C, excitation at 380–390 nm) for PFVs containing chiral alkyl side chains in
CHCl 3 solution and aggregates prepared by pouring MeOH slowly into the CHCl 3
solution values prepared under an optimized ratio of CHCl 3 /MeOH = 15/85 (v/v)
except 1/19 (3mpe) and 25/75 (dmo). It should be noted that some PFV aggregates,
especially containing 6moct and S-dmo side chains, prepared in situ in a mixed
CHCl 3 /MeOH solution, showed clear CPL signals attributed to aggregation-induced
Fig. 6.7 CPL and fluorescence (PL) spectra (1.0 × 10
–6 M at 25 °C) for PFVs containing chiral
side chains [(S)-4-methylhexyl (4mhex), (S)-5-methylheptyl (5mhep), (S)-6-methyloctyl (6moct),
(S)-3,7-dimethyloctyl (S-dmo)] in (left) CHCl 3 /MeOH and (right) THF/MeOH. Reproduced with
permission from Yamada et al. (2018)
6 Circularly Polarized Luminescent Polymers: Emerging Materials for Photophysical…