Soliton wall and Au adatom-induced <i>trans</i>-to-<i>cis</i> isomerization promoting the formation of multiple pairs of chiral isomers of methylcyano-functionalized molecules

The modulation of molecular adsorption configurations on surfaces, particularly regarding chirality and<i>trans</i>-<i>cis</i>isomerization, holds significant importance for interfacial molecular science and the construction of functional nanostructures. However, limited studies have focused on the formation of multiple chiral isomer pairs from monomolecular species and the exploration of more strategies for stimulating<i>trans</i>-<i>cis</i>isomerization. Herein, we characterize chiral behavior of methylcyano-functionalized molecules upon adsorption on Au(111) and elucidate their<i>trans</i>to<i>cis</i>isomerization. The soliton wall of reconstructed Au(111) surface functions as a confinement, hindering molecules from crossing the fcc region and instead prompting those in close proximity to undergo<i>trans</i>to<i>cis</i>isomerization. Additionally, during the thermal annealing process, the released Au adatoms coordinate with cyano groups, inducing their flipping and leading to the formation of paired molecular chains exclusively composed of<i>cis</i>-configured molecules. Three chiral enantiomeric pairs are generated from monomolecular species. The morphological changes are characterized by scanning probing measurements. Our work establishes a solid platform for fundamental research on the adsorption of methylcyano-functionalized molecules on metal surfaces and advance the understanding of surface-induced isomerization mechanisms and their dependence on substrate topology.