Adsorption of 4-(N,N-Dimethylamino)-4′-nitrostilbene on an Amorphous Silica Glass Surface

Stilbenes are a compelling class of organic photoswitches with a high degree of tunability that sensitively depend on their environment. In this study, we investigate the adsorption properties of 4-(N,N-dimethylamino)-4 '-nitrostilbene (DANS), a push-pull stilbene, on amorphous silica glass. Plane-wave density functional theory (DFT) calculations are used to understand how the trans and cis isomers of DANS interact with the amorphous surface and which are the most preferred modes of adsorption. Our calculations revealed that the O-H<middle dot><middle dot><middle dot>O hydrogen bonds between the nitro group and hydroxyl groups of the silica surface dominate the intramolecular interaction. In addition to hydrogen bonding, O-H<middle dot><middle dot><middle dot>pi interactions with the aromatic ring and double bond play a critical role in adsorption, whereas C-H<middle dot><middle dot><middle dot>O interactions are present, but contribute little. Therefore, both isomers of DANS favor parallel orientations such that not only the functional groups but also the aromatic parts can strongly interact with the glass surface.