On-surface synthesis of ferrocenylene polymers up to 50 nm length 

Ferrocene polymers are particularly attractive in this regard, but research of the iconic poly(1,1′‐ferrocenylene), a main‐chain ferrocene polymer with the most densely bound redox‐active iron centers, has practically stopped because it is an insoluble and rather inhomogeneous material. Herein, we demonstrate synthesis on the Ag(111) surface using the Ullmann coupling of 1′,1″′‐diiodo‐1,1″‐biferrocene. Conformationally flexible single‐chain nanowires up to 50 nm in length, thus overcoming the limits of conventional solution polymerization, are characterized by scanning probe microscopy techniques achieving atomic resolution. Moreover, we performed single‐chain electrical conductivity measurements in the longitudinal directions revealing apparent metal‐to‐semiconductor transition (depending on the number of ferrocene units lifted from the surface). We developed a simple transport model  to rationalize this observation.

V. M. Santhini, O. Stetsovych, M. Ondráček, J. I. Mendieta Moreno, P. Mutombo, B. de la Torre, M. Švec, J. Klívar, I. G. Stará, H. Vázquez, I. Starý, P. Jelínek
On-Surface Synthesis of Polyferrocenylene and its Single-Chain Conformational and Electrical Transport Properties
Adv. Funct. Mater. 2020 (2020) 2006391(1) - 2006391(11).