Nat Commun 9, 4871 (2018)

Two-dimensional tessellation by molecular tiles constructed from halogen–halogen and halogen–metal networks

Fang Cheng^1,#, Xue-Jun Wu^2,#, Zhixin Hu^3,#, Xuefeng Lu¹, Zijing Ding⁴, Yan Shao⁵, Hai Xu^1,4, Wei Ji⁶, Jishan Wu¹ & Kian Ping Loh^1,4,*

1. Department of Chemistry, National University of Singapore, Singapore 117543, Singapore.

2. State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, 210023 Nanjing, China.

3. Center for Joint Quantum Studies and Department of Physics, Institute of Science, Tianjin University, 300350 Tianjin, China.

4. Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore.

5. Institute of Physics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, 100190 Beijing, China.

6. Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices, Renmin University of China, 100872 Beijing, China

# Equal contribution

* Corresponding Authors:  Kian Ping Loh ( chmlohkp@nus.edu.sg )

Abstract

Molecular tessellations are often discovered serendipitously, and the mechanisms by which specific molecules can be tiled seamlessly to form periodic tessellation remain unclear. Fabrication of molecular tessellation with higher symmetry compared with traditional Bravais lattices promises potential applications as photonic crystals. Here, we demonstrate that highly complex tessellation can be constructed on Au(111) from a single molecular building block, hexakis(4-iodophenyl)benzene (HPBI). HPBI gives rise to two self-assembly phases on Au(111) that possess the same geometric symmetry but different packing densities, on account of the presence of halogen-bonded and halogen–metal coordinated networks. Subdomains of these phases with self-similarity serve as tiles in the periodic tessellations to express polygons consisting of parallelograms and two types of triangles. Our work highlights the important principle of constructing multiple phases with self-similarity from a single building block, which may constitute a new route to construct complex tessellations.