Figure 1.

Evidence of CE3F4R and ESI-09 aggregation. (A) Molecular structure of CE3F4R. Hydrogens are labeled C1–C6 for NMR peak assignments. (B) DLS intensity profile of CE3F4R at 500 μM (2.5% DMSO). (C) EM images of CE3F4R aggregates ([CE3F4R] = 200 μM; 1% DMSO). (D) Molecular structure of ESI-09. Hydrogens are labeled E1–E4 for NMR peak assignments. (E) DLS intensity profile of ESI-09 at 500 μM (2.5% DMSO). (F) EM images of ESI-09 aggregates ([ESI-09] = 200 μM). (G) Relative ¹H peak intensities of CE3F4R at different concentrations. The solid black line represents a linear extrapolation of the relative peak intensities based on the average of CE3F4R peaks at 50 μM. The vertical dashed line highlights the lowest CE3F4R concentration above which at least three peaks exhibit a significant deviation from the linearly projected relative peak intensity. The asterisks mark the appearance of solid precipitate. (H) Saturation transfer reference (STR) (black) and STD spectra of CE3F4R at 100 (blue), 150 (green), and 200 (purple) μM. The peaks are assigned relative to the labeling in panel A. CE3F4R was saturated at the C1t resonance (sat. arrow). Additional arrows mark peaks arising from STDs. The # symbol marks a buffer impurity. (I) Similarly to panel G, the relative ¹H peak intensities of ESI-09 at different concentrations. (J) STD spectra of ESI-09 at different concentrations. ESI-09 was saturated at the E3 resonance (sat. arrow).