Modulating the redox property of a flavin analog through adjustment of its microenvironment in a self-assembled monolayer.

Self-assembled monolayers (SAMs) have been used to examine the effects of electrostatic interactions and changing microenvironment on the pH-dependent redox properties of a flavin analog. The pKa value of the N1 proton for the reduced flavin analog was determined to be approximately 9.7 in the SAM of disulfide 5, 8.5 in the SAM of disulfide 7, and 6.7 when free in solution. The pyridinium ion of 7 stabilizes the anionic form of reduced flavin analog and provides a dielectric medium more closely resemblingthat experienced by the flavin analog free in solution.