Abstract:

Abstract Fabrication of diverse and complex 2D molecular architectures using surface-confined supramolecular coordination chemistry has been continuously attracting considerable attention for years. Here, the on-surface synthesis of 2D coordination networks exhibiting both crystalline and vitreous phases employing the same constituents is reported. Robust and flexible bimolecular 2D coordination networks, structurally analogous to 2D bilayer silica films on Ru(0001) and graphene, are achieved by iron-directed self-assembly of indigo and 1,3,5-tris[4-(pyridin-4-yl)phenyl]benzene (ext-TPyB) or 1,3,5-tris(pyridyl)benzene (TPyB) linkers on Au(111). The crystalline phase features honeycombed nanopores, displaying long-range order with local defects that can be attributed to variations in coordination nodes and shape flexibility of the ext-TPyB (/ TPyB) ligand. The vitreous phase evolves upon annealing the honeycomb network to higher temperatures and exhibits reticulated polygons similar to Zachariasen's 2D random network theory. The size of the polygons follows a lognormal distribution, with the probability density function showing an almost linear behavior as characteristic of the structure of glass. The results enrich avenues toward the fabrication and understanding of novel nanostructured condensed matter systems, such as 2D crystalline and vitreous structures, as well as provide the unique possibility to understand structurally bulk glasses.

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