Circularly polarized luminescence (CPL) characteristics of hydrophobic pyrene derivatives/γ-cyclodextrin (γ-CD) complexes in aqueous solution dissolved by grinding

Circularly polarized luminescence (CPL) organic dyes are currently receiving a great interest, but there are still not many reported observations of CPL spectra of hydrophobic dyes from aqueous solution. We have prepared hydrophobic pyrene derivatives and dissolved them into aqueous solutions with gamma-cyclodextrin (gamma-CD) by using grinding technique. Among these derivatives, (pyrene-1-carbonyl)serine (PySer) forms a spatially restricted dimer in the hydrophobic chiral cavity of gamma-CD and exhibits excimer emission with a high quantum yield of Phi(f) = 0.68. In addition, circular dichroism and CPL signals were induced for the complex. The strong g(CPL) value of g(CPL) = + 2.2 x 10(-3) was obtained, which may be attributed to the interaction between the hydroxyl groups in the side chain of PySer with those of gamma-CD and it strengthens the chiral dimeric structure.

Automated summary

Hydrophobic pyrene derivatives combined with gamma-cyclodextrin formed spatially restricted dimer structures with high quantum yields of excimer emission in aqueous solution. The interaction between hydroxyl groups in the side chain of PySer with those of gamma-CD led to a strong circular dichroism and CPL signal, indicating a strengthened chiral dimeric structure.