On the correlation between electronic intramolecular delocalization and Au-S bonding strength of ruthenium tetraammine SAMs

Abstract

Complexos do tipo trans-[Ru(L)(NH, and L' = CNpy, 1,4-dithiane (1,4-dt), 4-mercaptopyridine (pyS) and thionicotinamide (tna), were synthesized and characterized. SAMs on gold of the complexes containing sulfur were studied by reductive desorption and SERS spectroscopy. Depending on the nature of L', the withdrawing capability of the CNpy ligand is strong enough to partially oxidize the ruthenium atom and, as a consequence, delocalize the s electronic density from the trans located ligand. The reductive desorption results showed that the stability of the SAMs is directly related to this effect.

Hydroxyl Radical Generation and DNA Nuclease Activity: A Mechanistic Study Based on a Surface‐Immobilized Copper Thioether Clip‐Phen Derivative

“…The SERS spectrum of the modified gold electrode obtained in air (Figure S2 of the Supporting Information) shows a relative enhancement, in comparison to the normal Raman spectrum, of the vibrational modes associated to CS bonding at 717 and 736 cm −1 . This result indicates that the adsorption of the [Cu(2CP‐Bz‐SMe)] 2+ complex occurs through the sulfur atom of the thioether fragment, as expected for sulfur‐containing molecules . In addition, the relative enhancement of the band at 427 cm −1 , which is assigned to CC stretching modes of the benzene ring, mainly composed of the α zz tensor, suggests a perpendicular configuration; although, based on previous works on the adsorption of thiols on metallic surfaces, a tilted‐perpendicular geometry may be more appropriate for describing the adsorption of the [Cu(2CP‐Bz‐SMe)] 2+ complex on gold.…”

“…In this work, we have deliberately attached a SCH 3 fragment to a clip‐phen derivative to make possible the modification of gold substrates, due to the known affinity of sulfur towards gold . In this way, we could combine data obtained in solution with those obtained by using surface techniques such as surface plasmon resonance (SPR) and scanning electrochemical microscopy (SECM) in an attempt to identify the ROS species generated during the redox processes and, in the end, to better understand the degradation mechanism of DNA by copper complexes.…”