Non‐Covalent Supramolecular 1D Alternating Copolymer in Crystal toward 2D Anisotropic Photon Transport

Abstract

AbstractTo realize organic integrated optoelectronic circuits, there is a need for anisotropic optical waveguides at the micro/nanoscale. Anisotropic alignment of one‐dimensional‐ordered supramolecular structures composed of light‐emissive π‐conjugated molecules in a crystal may meet the requirements of such waveguides. Here, a bipyridyl‐appended acrylonitrile‐based π‐conjugated molecule was designed, which produced a one‐dimensional supramolecular polymer constructed through non‐covalent bonding between a lone pair in bipyridyl and a σ‐hole in 1,4‐diiodo‐2,3,5,6‐tetrafluorobenzene. The one‐dimensional copolymer of bipyridyl and 1,4‐diiodo‐2,3,5,6‐tetrafluorobenzene is aligned horizontally with the two‐dimensional crystal surface because of the angle‐controlled supramolecular synthons. As a result of control over the non‐covalent bonding direction, anisotropic photoluminescence and photon transport (optical waveguiding) characteristics are realized by orienting the transition dipole moment horizontally with respect to the two‐dimensional surface. Compared with the loss coefficient αL=52 dB cm−1 for the long‐axis direction of the two‐dimensional platelet cocrystal, a very large difference of αS=2111 dB cm−1 is present in the crystal short‐axis direction. The anisotropic waveguiding ability, αL/αS, is estimated to be 41, which is more than an order of magnitude greater than previously reported two‐dimensional platelet crystal waveguides. This supramolecular synthon provides an approach to designing anisotropic photon transporters and highly regulated optical logic circuits.