Plasmon assisted reactions on a metal surface occur through a different mechanism compared to traditional reaction conditions. Based on a SERS study of the model plasmon assisted reaction of PNTP to DMAB, we present the first regulation strategy for these reactions, enabled here, through the controlled adjustment of acidic properties.

4-Aminothiophenol (PATP) and 4-aminophenyl disulfide (APDS) in contact with silver will form HN-CH-S-Ag (PATP-Ag), and under the conditions of surface-enhanced Raman spectroscopy (SERS), a coupling reaction will generate 4,4-dimercaptoazobenzene (DMAB). DMAB is strongly Raman-active, showing strong peaks at ν ≈ 1140, 1390, and 1432 cm, and is widely used in surface-plasmon-assisted catalysis. Using APDS, PATP, p-nitrothiophenol (PNTP), and p-nitrodiphenyl disulfide (NPDS) as probe molecules, Raman spectroscopy and imaging techniques have been used to study the effect of intermolecular distance on surface-plasmon-assisted catalysis. Theoretically, PATP-Ag formed from APDS will be bound at proximal Ag atoms on the Ag surface due to S-S bond cleavage. The results show that APDS is more prone to surface-plasmon-assisted catalytic coupling due to the smaller distance between surface PATP-Ag moieties than those derived from PATP. Therefore, APDS has a higher reaction efficiency, better Raman activity, and better Raman imaging than does PATP. Analogous experiments with PNTP and NPDS gave similar results. Thus, this technique has great application prospects in the fields of surface chemistry and materials chemistry.

4-Aminophenyl disulfide (APDS) forms on the surface of silver nanoparticles due to chemical adsorption and disulfide bond breakage. This leads to the formation of new silver chemical bonds to result in the new compound NH2-C6H6-S-Ag. This novel material produces enhanced Raman spectra under weak laser light irradiation. When irradiated a plasma-assisted catalytic coupling reaction of NH2-C6H6-S-Ag occurs leading to the formation of 4,4-dimercaptoazobenzene (DMAB). Raman spectroscopy was used to monitor this reaction process, showing clear spectral changes associated with each step after addition of Ag nanoparticles onto the APDS powder. This method clearly shows the mechanism of the plasma-assisted catalytic reaction and may also be useful for spectral imaging purposes.

The coupling reaction of 4‐nitrothiophenol to 4,4′‐dimercaptoazobenzene was investigated by surface enhancement Raman scattering method. The reaction was found to be controlled by the compatibility of organic alkalis and silver nanoparticles. The effect of hot electron–hole pairs on the reaction was evaluated. Furthermore, the mechanism of organic alkalis affecting hot electron–hole pairs to achieve regulation of the coupling reaction of 4‐nitrothiophenol to 4,4′‐dimercaptoazobenzene was studied. A comprehensive analysis of the different surface enhancement Raman scattering signals collected was conducted. The forward‐looking view of capturing holes through the hydrolysis of organic alkalis to ensure the integrity of the substrate was also presented.

The vibrational spectra have been investigated for revealing the comprehensive structure of diferrocenyl-oligothienylene-vinylene complex, stimulated by the excellent experimental reports [group of Casado J. Am. Chem. Soc. 2012, 134, 12, 5675]. The IR and Raman spectra were simulated. It is found that the change of charge distribution and bond length are associated with the variation in the frequencies of specific vibration in infrared spectra for the neutral and radical oxidation states. The theoretical simulation of charge difference density indicate that charge transfer mechanism for neutral and dication states are significant different. The results can offer hints for the rational design of novel and interesting oligomer semiconductor.