Yuanqi Ding

Dehydrogenative Homocoupling of Terminal Alkenes on Copper Surfaces: A Route to Dienes

Homocouplings of hydrocarbon groups including alkynyl (sp(1) ), alkyl (sp(3) ), and aryl (sp(2) ) have recently been investigated on surfaces with the interest of fabricating novel carbon nanostructures/nanomaterials and getting fundamental understanding. Investigated herein is the on-surface homocoupling of an alkenyl group which is the last elementary unit of hydrocarbons. Through real-space direct visualization (scanning tunneling microscopy imaging) and density functional theory calculations, the two terminal alkenyl groups were found to couple into a diene moiety on copper surfaces, and is contrary to the common dimerization products of alkenes in solution. Furthermore, detailed DFT-based transition-state searches were performed to unravel this new reaction pathway.

On-Surface Dual-Response Structural Transformations of Guanine Molecules and Fe Atoms

Structural transformation of metal-organic nanostructures holds great promise for structural diversity and flexibility and opens the way towards an adaptive and evolutive chemistry owing to the dynamic characteristic of coordination bonds. It is thus generally interesting and also challenging to develop systems showing reversible structural transformations which involve multiple metal-organic motifs on surfaces. Here, we have successfully constructed a system that presents structural transformations on a solid surface, in which controllable formation of multiple metal-organic nanostructures (with different coordination binding modes by use of distinct binding sites) in response to both metal atoms and molecules is achieved at room temperature (RT) under ultrahigh vacuum (UHV) conditions. The key to making these interconversions successful is the intrinsic dynamic characteristic of coordination bonds together with the coordination priority and diversity.

Dehydrogenative Homocoupling of Alkyl Chains on Cu(110).

Through the interplay of high-resolution scanning tunneling microscopy imaging and density functional theory calculations, the stepwise dehydrogenative homocoupling of alkyl chains on Cu(110) is demonstrated, proceeding from the intact chain, via the dehydrogenative intermediates, to the formation of the divers final coupling products.

Structural Transformation and Stabilization of Metal-Organic Motifs Induced by Halogen Doping

The structural transformation of supramolecular nanostructures with constitutional diversity and adaptability by dynamic coordination chemistry would be of fundamental importance for potential applications in molecular switching devices. The role of halogen doping in the formation of elementary metal-organic motifs on surfaces has not been reported. Now, the 9-ethylguanine molecule (G) and Ni atom, as a model system, are used for the structural transformation and stabilization of metal-organic motifs induced by iodine doping on Au(111). The iodine atoms are homogeneously located at particular hydrogen-rich locations enclosed by G molecules by electrostatic interactions, which would be the key for such an unexpected stabilizing effect. The generality and robustness of this approach are demonstrated in different metal-organic systems (G/Fe) and also by chlorine and bromine.

On-Surface Synthesis of Adenine Oligomers via Ullmann Reaction

Despite the fact that DNA bases have been well-studied on surface, the on-surface synthesis of one-dimensional DNA analogs through in situ reactions is still an interesting topic to be investigated. Herein, from the interplay of high-resolution scanning tunneling microscopy (STM) imaging and density functional theory (DFT) calculations, we have delicately designed a halogenated derivative of adenine as precursor to realize the combination of DNA bases and Ullmann reaction, and then successfully synthesized adenine oligomers on Au(111) via Ullmann coupling. This model system provides a possible bottom-up strategy of fabricating adenine oligomers on surface, which may further give access to man-made DNA strands with multiple bases.