Metal–organic coordination with thermally controlled protection

The field of On-Surface Synthesis, which involves creating two-dimensional structures by covalently coupling simple molecules directly on surfaces, has seen remarkable advancements in the past decade, with new synthetic methods constantly emerging. The inherent constraints of working in two dimensions and the inability to use solutions for precursor exchange and byproduct removal are slowing down progress. Recent breakthroughs, such as using atomic hydrogen to remove byproducts and synthesize radicals on surfaces, have shown promise.

Drawing inspiration from traditional chemistry, we introduce the concept of protective groups to gain greater control over on-surface reactions. Specifically, we demonstrate the chemical protection of an imide group by attaching an alkyl functional group to a [5]phenacenediimide molecule. This protection strategy effectively delays the metal coordination of the imide group until the significantly higher temperature at which the alkyl group detaches. Furthermore, the volatile nature of the alkyl byproducts allows for their inherent removal, facilitates clean surfaces. Our findings successfully illustrate the potential of using protective groups as a powerful tool to further direct and refine On-Surface Synthesis.