A Strategy to Control Yield and Selectivity of Carbon-Based Reactions in Reaction Chemistry on Cu

Although the reaction mechanism of olefin cyclization has been extensively studied, the control of this process using basic experimental techniques remains an unresolved challenge in chemistry. School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Scienctist introduce carbon into the subsurface of Cu(111) (C-Cuδ+) and UV irradiation on OSS. The total olefin coupling rate increases to 10.1- and 5.3-fold higher than that on pristine Cu(111) at 298 and 323 K, respectively. The initial cyclization temperature reduces by 55 K on C-Cuδ+. UV irradiation further promotes the cyclization ratio from 22% to 40.3%.

The TVT compound changed into sublimated at 450 K from an evaporator and deposited onto a clean, pristine Cu(111) floor saved at 298 K. Without post-treatment, extended, ordered 2D domain names had been fashioned at the floor, as had been determined in scanning tunneling microscopy (STM) images (Figure 2A). Each three-blade motif withinside the area corresponds to an person TVT molecule. The molecules are carefully packed alongside the three equiv <1> guidelines of Cu(111) indicated through the blue arrows. The community periodicity is a = b = 15.2 ± 0.2 Å, and the perspective among the 2 vectors is 60° ± 0.5° (indicated through a blue rhombus). The molecules are remoted from each other and display a clean interspace among the neighbors, indicating no polymerization of TVT on this case.

The merchandising of olefin cyclization upon irradiation will be attributed to the subsequent  aspects:

1.  TVT compound is an ordinary triazine-kind UV absorber which could effectively harvest photons withinside the UV region, and the absorbed photons could excite the molecules and growth their inner strength at some point of next de-excitation thru the electron-vibration coupling relaxation,forty three or
2. The advent of C atoms to the subsurface can alter the band shape of Cu(111) and beautify the optical absorption in a extensive variety from the UV to the near-infrared region  the image absorption should set off nearby plasmon resonance to generate warm electrons and in addition gain the on-floor response of the molecules.

Reaction control, particularly the yield and selectivity, is a critical problem in on-surface synthesis. In this manuscript, after the introduction of surface carbonaceous layer, the cyclization reaction between olefins and allenes was optimized by controlling various parameters. The yields and selectivities of cyclizations could be greatly improved by the C-Cuδ+ catalyst, and new functionalized products were produced on its surface via UV irradiation. These results suggested that the strategy we have developed can be widely applied to other surface reaction systems.