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Circularly Polarized Luminescence from a Pyrene-Cyclodextrin Supra-Dendron

Zhang, Yuening, Yang, Dong, Han, Jianlei, Zhou, Jin, Jin, Qingxian, Liu, Minghua, Duan, Pengfei
Langmuir 2018 v.34 no.20 pp. 5821-5830
beta-cyclodextrin, gamma-cyclodextrin, hydrogels, luminescence, moieties, nanofibers, nanosheets, optical isomerism, pH
Soft nanomaterials with circularly polarized luminescence (CPL) have been currently attracting great interest. Here, we report a pyrene-containing π-peptide dendron hydrogel, which shows 1D and 2D nanostructures with varied CPL activities. It was found that the individual dendrons formed hydrogels in a wide pH range (3–12) and self-assembled into helices with pH-tuned pitches. Through chirality transfer, the pyrene unit could show CPL originated from both the monomer and excimer bands. When cyclodextrin was introduced, different supra-dendrons were obtained with β-cyclodextrin (PGAc@β-CD) and γ-cyclodextrin (PGAc@γ-CD) through host–guest interactions, respectively. Interestingly, the PGAc@β-CD and PGAc@γ-CD supra-dendrons self-assembled into 2D nanosheet and entangled nanofibers, respectively, showing cyclodextrin induced circularly polarized emission from both the monomer and excimer bands of the pyrene moiety. Thus, through a simple host–guest interaction, both the nanostructures and the chiroptical activities could be modulated.