On-Surface Reaction between Tetracarbonitrile-Functionalized Molecules and Copper Atoms

Abstract

Self-assembly at surfaces has proven to be very efficient in creating ordered, atomically controlled organic nanostructures. On-surface synthesis has recently emerged as a promising strategy to create stable structures bound by strong and irreversible covalent bonds. Here we present on-surface reaction between pyrazino phenanthroquinoxaline-tetracarbonitrile (PPCN) molecules and copper atoms on a Au (111) substrate. The reaction is monitored in ultrahigh vacuum conditions by scanning tunneling microscopy and X-ray photoelectron spectroscopy (XPS). After a 475 K annealing, phthalocyanine cyclization occurs around a copper atom; the increase of annealing temperature to 540 and 675 K leads to the formation of 1D and 2D phthalocyanine polymers, respectively. This reaction is confirmed by the modification of the Cu 2p 3/2 and C 1s XPS spectra upon annealing.

Di‐ and Tetracyano‐Substituted Pyrene‐Fused Pyrazaacenes: Aggregation in the Solid State

“…After the reaction the crude products were isolated by filtration and washed with methanol. Subsequently, PQDC , H‐PPQTC , and t Bu‐PPQTC were heated to reflux in 30 % nitric acid and filtered while still hot …”

“…These compounds were studied for the formation of amino‐iminopyrazines as valuable precursors for phthalocyanines, which was realized by Nardi et al. for H‐PPQTC in 2014 on Cu surfaces . A tert ‐butyl‐substituted derivative of PPQTC was synthesized by Liu and co‐workers in 2011 .…”

Surface chemistry of porphyrins and phthalocyanines

“…The on-surface synthesis of FePc(CN) 8 was later achieved by annealing co-adsorbed Fe and TCNB on Au(1 1 1) to 550 K [287]. Extension of this approach to a larger tetracarbonitrile-functionalized aromatic molecule, pyrazino-phenanthroquinoxaline-tetracarbonitrile, which was coadsorbed with Cu on Au(1 1 1), resulted in the formation of the respective Cu phthalocyanine derivative and various coordination and covalent networks, depending on the reaction conditions [722].…”

Covalent‐Bond Formation via On‐Surface Chemistry

“…A few on‐surface cyclization reactions comprising carbon–heteroatom bond formation have been published to date. For example, Abel and co‐workers described a transition‐metal‐assisted cyclopolymerization of 1,2,4,5‐tetracyanobenzene (TCNB) to provide a well‐controlled network structure via C−N bond formation on various surface materials . By subliming single iron atoms onto a submonolayer of TCNB molecules, these authors were able to generate Fe‐coordinated phthalocyanine frameworks at room temperature on an Ag(111) or an Au(111) surface.…”