Regensburg 2019 – wissenschaftliches Programm
CPP 17.20: Poster
Montag, 1. April 2019, 17:30–19:30, Poster B1
Stabilization of tubular J-aggregates by silica coating for use in dry environment — •Katherine Herman, Holm Kirmse, Jürgen P. Rabe, and Stefan Kirstein — Humboldt Universität zu Berlin, Institut für Physik
The amphiphilic cyanine dye C8S3 is known to self-assemble in aqueous solution into tubular J-aggregates with a diameter of 13 nm and lengths exceeding microns. Their optical spectra are dominated by exciton bands which are very sensitive to structural changes. A major disadvantage of these aggregates is their low stability during drying. Here we use a coating of a thin layer of silica to stabilize these aggregates. In earlier work  shells of silica with controlled and homogeneous thickness of a few nanometer were synthesized around these aggregates without disrupting their optical spectra and hence their J-aggregate character. It is demonstrated here that these silica coatings mechanically and chemically stabilize the C8S3 J-aggregates and allow them to survive not only drying under ambient, but also under vacuum conditions of an electron microscope. Transmission electron microscope images confirm that the thickness of the silica coatings is 5 nm or less and energy dispersive X-ray spectroscopy confirms the presence of true silica. Emission spectra of dried silica coated samples indicate that the molecular structure of the aggregates is preserved and photobleaching under ambient conditions is significantly reduced.
 Y. Qiao, F. Polzer, H. Kirmse, S . Kirstein, and J.P. Rabe, Chem. Commun. 51, 11980 (2015)