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Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Conformational Dynamics of Monomer- versus Dimer-like Features in a Naphthalenediimide-Based Conjugated Cyclophane
Sudhir Kumar Keshri1, Atsuro Takai1, Tomoya Ishizuka2
1Molecular Design and Function Group, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, 305-0047, Japan.
Abstract:
The design and synthesis of an enantiomeric pair of 1,8-diethynylanthracene-bridged naphthalenediimide (NDI)-based cyclophanes (Cyclo-NDIs) are reported. Each enantiomer of Cyclo-NDI exhibits a circularly polarized luminescence signal with a relatively large luminescence dissymmetry factor (glum =±8×10-3 ). We have further investigated the modulation of through-space electronic communication between co-facially oriented NDIs in a discrete Cyclo-NDI with changes in the temperature. Tuning of the electronic communication results from the conformational transformation of monomer- versus dimer-like features of Cyclo-NDI, as confirmed by UV/Vis, fluorescence, circular dichroic, and NMR spectroscopic analysis. The temperature-dependent optical response in the Cyclo-NDI through the conformational transformation could be utilized as a highly sensitive and reversible optical thermometer in a wide temperature range (100 to -80 °C).
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