Supramolecular architectures of molecularly thin yet robust free-standing layers
Mina Moradi1,2, Nadia L. Opara2,3, Ludovico G. Tulli1, Christian Wäckerlin4, Scott J. Dalgarno5, Simon J. Teat6, Milos Baljozovic2, Olha Popova7, Eric van Genderen2,*, Armin Kleibert8, Henning Stahlberg3, Jan Pieter Abrahams9,10, Celestino Padeste2, Philippe F.-X. Corvini1, Thomas A. Jung2,† and Patrick Shahgaldian1,†
1Institute of Chemistry and Bioanalytics, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland, Hofackerstrasse 35, CH-4132 Muttenz, Switzerland.
2Laboratory for Micro- and Nano-technology, Paul Scherrer Institute, Villigen CH-5232, Switzerland.
3Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland.
4Empa–Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland.
5Institute of Chemical Sciences, Heriot-Watt University, Riccarton, Edinburgh, Scotland EH14 4AS, UK.
6Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS6R2100, Berkeley, CA 94720, USA.
7Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.
8Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland.
9Biozentrum, University of Basel, Switzerland and Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland.
10Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, Netherlands.
↵†Corresponding author. Email: patrick.shahgaldian@fhnw.ch (P.S.); thomas.jung@psi.ch (T.A.J.)
↵* Present address: Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland.
Science Advances 22 Feb 2019: Vol. 5, no. 2, eaav4489
Fig. 3
Molecular resolution AFM imaging of the monolayer of 1.
(A) AFM images of the monolayer of 1 transferred onto HOPG via the LS method. (B) The high-resolution image of the crystalline network of the monolayer shows a highly ordered network formed from the single molecules of 1. [C (top view) and D (side view)] Molecular model of the building blocks of 1 interacting via the proposed dipole-dipole interaction in the well-ordered monolayer.
Abstract
Stable, single-nanometer thin, and free-standing two-dimensional layers with controlled molecular architectures are desired for several applications ranging from (opto-)electronic devices to nanoparticle and single-biomolecule characterization. It is, however, challenging to construct these stable single molecular layers via self-assembly, as the cohesion of those systems is ensured only by in-plane bonds. We herein demonstrate that relatively weak noncovalent bonds of limited directionality such as dipole-dipole (–CN⋅⋅⋅NC–) interactions act in a synergistic fashion to stabilize crystalline monomolecular layers of tetrafunctional calixarenes. The monolayers produced, demonstrated to be free-standing, display a well-defined atomic structure on the single-nanometer scale and are robust under a wide range of conditions including photon and electron radiation. This work opens up new avenues for the fabrication of robust, single-component, and free-standing layers via bottom-up self-assembly.
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