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Updated: Apr 14, 2026

Self-assembly of Complex Two-dimensional Shapes from Single-stranded DNA Tiles
Published on: May 8, 2015
Assembling molecular Sierpiński triangle fractals
Jian Shang1, Yongfeng Wang2, Min Chen3
1SKLSCUSS, BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Abstract:
Fractals, being "exactly the same at every scale or nearly the same at different scales" as defined by Benoit B. Mandelbrot, are complicated yet fascinating patterns that are important in aesthetics, mathematics, science and engineering. Extended molecular fractals formed by the self-assembly of small-molecule components have long been pursued but, to the best of our knowledge, not achieved. To tackle this challenge we designed and made two aromatic bromo compounds (4,4″-dibromo-1,1':3',1″-terphenyl and 4,4‴-dibromo-1,1':3',1″:4″,1‴-quaterphenyl) to serve as building blocks. The formation of synergistic halogen and hydrogen bonds between these molecules is the driving force to assemble successfully a whole series of defect-free molecular fractals, specifically Sierpiński triangles, on a Ag(111) surface below 80 K. Several critical points that govern the preparation of the molecular Sierpiński triangles were scrutinized experimentally and revealed explicitly. This new strategy may be applied to prepare and explore various planar molecular fractals at surfaces.
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