Reversible light-dependent molecular switches on Ag/AgCl nanostructures

• Published in: Nanoscale Vol. 9; no. 24; pp. 8380 - 8387
• Main Authors: Song, W, Querebillo, C J, Götz, R, Katz, S, Kuhlmann, U, Gernert, U, Weidinger, I M, Hildebrandt, P
• Format: Journal Article
• Language: English
• Published: England 28.06.2017
• Subjects: Chemical bonds; Cleavage; Dimerization; Monitoring; Nanostructure; Silver; Substrates; Switches
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c7nr02760e

Nanostructured Ag/AgCl substrates were used to generate reversible and highly efficient light-dependent chemical switches based on adsorbed 4,4'-dimercaptoazobenzene (DMAB). DMAB was formed in situ via laser-induced dimerization either from 4-nitrothiophenol (4-NTP) or 4-aminothiophenol (4-ATP). The subsequent reaction pathways of DMAB, however, were quite different as monitored by surface enhanced Raman spectroscopy. In the 4-NTP/DMAB system, AgCl catalyses the reversal of the dimerization. Conversely, irradiation of adsorbed 4-ATP first generated cis-DMAB attached to the surface via two Ag-S bonds, followed by AgCl-catalysed cleavage of one Ag-S bond and cis → trans photoisomerisation of DMAB. In the dark, the trans-isomer thermally reverts to cis-DMAB. The here presented light-dark chemical switches, which work without changing other parameters (e.g., pH, anaerobic vs. aerobic), are based on the (photo)catalytic properties of the Ag/AgCl substrate and do not function on pure metal surfaces.