Raman Mapping and In Situ SERS Spectroelectrochemical Studies of 6-Mercaptopurine SAMs on the Gold Electrode

Abstract

The self-assembled monolayers (SAMs) of 6-mercaptopurine (6MP) were formed at the roughened polycrystalline gold surfaces in acid and alkaline media. The time-dependent Raman mapping spectral analysis in conjunction with the quantum calculations for the vibrational modes using ab initio BLYP/6-31G method suggested that both of the resulted 6MP SAMs adopted the same adsorption mode through the S atom of pyrimidine moiety and the N7 atom of the imidazole moiety anchoring the gold surface in a vertical way. The in situ surface-enhanced Raman scattering spectroelectrochemical experiment was conducted to examine the stability of the SAMs at various bias potentials. It was found that the detaching process of the 6MP SAMs from the surface involved one electron reduction as the voltage was applied at ca. 0.7 V vs a standard calomel electrode.

Voltammetric determination of 6-mercaptopurine using [Co(phen)3]3+/MWNT modified graphite electrode

“…In comparison, electrochemical methods are considered as a convenient tool to realize the determination of specimen. The electrochemical reaction or adsorption of 6-MP and its derivates on some electrodes such as Hg [20][21], Au [22][23][24], Ag [2,[25][26], pyrolytic graphite [27], and so on, has extensively been reported. However, electrochemical determination of 6-MP have so far received little attention due to its poor reversibility, especially, dependent on its interaction with metal complexes such as polypyridyl cobalt(III) compounds.…”

Spectroelectrochemical studies of self assembled monolayers of biphenyl ethynyl thiols on gold electrodes

“…However, the appearance of the strong band between 1082 and 1087 cm À1 caused by the in-plane 628 cm À1 ) different from that observed in the normal Raman spectrum (633 cm À1 ). Such a red shift after adsorption was observed for 6-mercaptopurine [35], 4-isopropylsulfanylmethyl-1,2,3-triazole [32], 1-propanethiol [36] and 2-methylpropane-lthiol [37], it may be induced by electron donation from the sulfur atom to the gold surface. This already implies adsorption via a gold-sulfur interaction.…”

Amperometric L‐cysteine Sensor Using a Gold Electrode Modified with Thiolated Catechol

“…The band of 1124 cm −1 belongs to the S−H vibration. After the electro‐assisted thiol addition, the intensity of S−H vibration partially decreases, while the intensity of C−S band (1221 cm −1 ) increases. And at 1610 cm −1 , there is an obvious band, which is assigned to the C=O vibration , indicating that the o ‐quinone is successfully bounded onto the HDT.…”