Tecnai g2 spirit twin 120 kv

The TEM micrographs were taken on a Tecnai G2 Spirit Twin 120 kV (FEI, Czech Republic). The studied compounds (2 L droplets; methanol solution, concentration 5 mg•mL -1 ), were dropped onto a copper TEM grid (300 mesh), which was coated with thin, electron-transparent carbon film. After 2 min the rest of the solution was removed by touching the bottom of the grid with filtering paper. Then the sample was left to dry completely at the ambient temperature. The transmission electron micrographs were obtained using bright field imaging at electron accelerating voltage of 120 kV (Fig. 1).

The morphology of self-assembled nanoparticles was also probed by transmission electron microscopy (TEM) using a Tecnai G2 Spirit Twin 120kV (FEI, Czech Republic) microscope. Two-μL, 0.1 L of the aqueous solutions were dropped onto a copper TEM microscopic grid (400 mesh) coated with thin, electron-transparent carbon film. The excess of solution was removed by touching the bottom of the grid with filtering paper. This fast removal of the solution was performed after 5 min of sedimentation in order to minimize oversaturation during the drying process. The assemblies were negatively stained with uranyl acetate (2 µL of 2 wt.% solution dropped onto not completely dried nanoparticles and removed after 30 s in the same way as described above). The samples were left to dry completely at environment temperature and then observed by TEM. Under these conditions, the micrographs displayed negatively stained background with bright nanoparticles.