Unraveling a self-assembling mechanism of isomeric aminothiophenol on Ag dendrite by correlated SERS and matrix-free LDI-MS

Abstract

Correlated spectroscopic analysis can provide complementary chemical insights that are often unattainable by either approach used in isolation. We distinguished the different self-assembling behavior of isomeric aminothiophenols (ATPs) on Ag dendrite by the correlation of surface-enhanced Raman spectroscopy and laser-induced desorption ionization mass spectrometry, demonstrating that steric effect impinged significantly upon surface molecular density and plasmon-driven catalytic reaction yield, which led to drastic variations in the resulting SERS spectra. The correlative measurement shows that ortho-substitute barely formed a self-assemble monolayer, relative to the para-isomer, which can form a close-packed self-assembled monolayer and perform a decent azo-coupling reaction. Comparison between normal and SERS spectra of ATP isomers supports the fact that additional disulfide- or hydrogen-bonding interactions are established in para-ATP solid crystal, but neither of ortho- nor meta-isomers. This work is expected to create a significant impact on the development of an orthogonally correlated spectroscopic tool in deciphering chemical insights and underlying reaction mechanism. Graphical abstract.