Selective Activation of Aromatic C–H Bonds Catalyzed by Single Gold Atoms at Room Temperature

Selective activation and controlled functionalization of C–H bonds in organic molecules is one of the most desirable processes in synthetic chemistry. Despite progress in heterogeneous catalysis using metal surfaces, this goal remains challenging due to the stability of C–H bonds and their ubiquity in precursor molecules, hampering regioselectivity. Here, we examine the interaction between 9,10-dicyanoanthracene (DCA) molecules and Au adatoms on a Ag(111) surface at room temperature (RT). Characterization via low-temperature scanning tunneling microscopy, spectroscopy, and noncontact atomic force microscopy, supported by theoretical calculations, revealed the formation of organometallic DCA–Au–DCA dimers, where C atoms at the ends of the anthracene moieties are bonded covalently to single Au atoms. The formation of this organometallic compound is initiated by a regioselective cleaving of C–H bonds at RT. Hybrid quantum mechanics/molecular mechanics calculations show that this regioselective C–H bond cleaving is enabled by an intermediate metal–organic complex which significantly reduces the dissociation barrier of a specific C–H bond. Harnessing the catalytic activity of single metal atoms, this regioselective on-surface C–H activation reaction at RT offers promising routes for future synthesis of functional organic and organometallic materials

Correction to Photochemical Creation of Covalent Organic 2D Monolayer Objects in Defined Shapes <i>via</i> a Lithographic 2D Polymerization

Correction to Photochemical Creation of Covalent Organic 2D Monolayer Objects in Defined Shapes via a Lithographic 2D Polymerizatio

Photochemical Creation of Covalent Organic 2D Monolayer Objects in Defined Shapes <i>via</i> a Lithographic 2D Polymerization

In this work we prepare Langmuir–Blodgett monolayers with a trifunctional amphiphilic anthraphane monomer. Upon spreading at the air/water interface, the monomers self-assemble into 1 nm-thin monolayer islands, which are highly fluorescent and can be visualized by the naked eye upon excitation. In situ fluorescence spectroscopy indicates that in the monolayers, all the anthracene units of the monomers are stacked face-to-face forming excimer pairs, whereas at the edges of the monolayers, free anthracenes are present acting as edge groups. Irradiation of the monolayer triggers [4 + 4]-cycloadditions among the excimer pairs, effectively resulting in a two-dimensional (2D) polymerization. The polymerization reaction also completely quenches the fluorescence, allowing to draw patterns on the monomer monolayers. More interestingly, after transferring the monomer monolayer on a solid substrate, by employing masks or the laser of a confocal scanning microscope, it is possible to arbitrarily select the parts of the monolayer that one wants to polymerize. The unpolymerized regions can then be washed away from the substrate, leaving 2D macromolecular monolayer objects of the desired shape. This photolithographic process employs 2D polymerizations and affords 1 nm-thin coatings