Quinone electrochemistry altered by local hydrophobic environment and hydrogen bonding interactions

• Quinone SAMs with a hydrophobic alkyl chain layer above the quinone were created.
• New peaks arose from hydrogen bonding between quinone and the amine linker.
• Local hydrophobicity strengthened hydrogen bonding between quinone and amine.
• Self-hydrogen bonding in o-quinone hindered hydrogen bonding with amine.

Creating SAMs on gold from hydroquinone containing molecules capped with long alkyl chains, we studied the influence of a hydrophobic alkyl layer on the electrochemical reaction of quinones beneath it. A new pair of redox waves emerged and grew in size as the thickness of the alkyl spacer layer increased. The origin of the new peaks was attributed to hydrogen bonding interaction by the nearby amine group, and its strength was influenced by local hydrophobicity and the presence of other intramolecular hydrogen bonding.