On-surface synthesis of covalent coordination polymers on micrometer scale

On-surface synthesis under ultrahigh vacuum provides a promising strategy to control matter at the atomic level, with important implications for the design of new two-dimensional materials having remarkable electronic, magnetic, or catalytic properties. This strategy must address the problem of limited extension of the domains due to the irreversible nature of covalent bonds, which prevents the ripening of defects. We show here that extended materials can be produced by a controlled co-deposition process. In particular, co-deposition of quinoid zwitterion molecules with iron atoms on a Ag(111) surface held at 570 K allows the formation of micrometer-sized domains based on covalent coordination bonds. This work opens up the construction of micrometer-scale single-layer covalent coordination materials under vacuum conditions.