Crown ethers in graphene.
Crown ethers are at their most basic level rings constructed of oxygen atoms linked by two- or three-carbon chains. They have attracted attention for their ability to selectively incorporate various atoms or molecules within the cavity formed by the ring. However, crown ethers are typically highly flexible, frustrating efforts to rigidify them for many uses that demand higher binding affinity and selectivity. Here we present atomic-resolution images of the same basic structures of the original crown ethers embedded in graphene. This arrangement constrains the crown ethers to be rigid and planar. First-principles calculations show that the close similarity of the structures should also extend to their selectivity towards specific metal cations. Crown ethers in graphene offer a simple environment that can be systematically tested and modelled. Thus, we expect that our finding will introduce a new wave of investigations and applications of chemically functionalized graphene.
1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
Junjie
J
Guo
1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
Jaekwang
J
Lee
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Cristian I
CI
Contescu
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Nidia C
NC
Gallego
1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
Sokrates T
ST
Pantelides
1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
Stephen J
SJ
Pennycook
Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Bruce A
BA
Moyer
1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
Matthew F
MF
Chisholm