Capturing Even the Invisible: A Comprehensive Understanding of Methyl Viologen Adsorption Distribution on Clay Nanosheets

The H-aggregate population reached about 70% of all adsorbed species at a loading of 50% relative to the CEC. Second, a van’t Hoff analysis of the equilibrium between the isolated and closely spaced monomers separated Δ<i>H</i> (electrostatic attraction, which stabilizes the isolated arrangement) and Δ<i>S</i> (hydrophobic interaction, which stabilizes the closely spaced arrangement), showing that Δ<i>S</i> dominates at 293 K. Third, lengthening the alkyl chain from C1 to C8, which strengthens the hydrophobic interaction without changing the cationic charge, shifted the closely spaced (short-lifetime) fraction from 63% to 88%, thereby demonstrating control of the adsorption distribution.

Through quantification including the invisible component, thermodynamic understanding, and demonstrated control, this work provides a comprehensive understanding of a complex adsorption distribution and a guideline for designing two-dimensional dye arrays on inorganic surfaces.