UV-Vis spectra were recorded at 25°C on an Evolution 300 spectrophotometer (Thermo Scientific) over the spectral range of 210-900 nm. Quartz cuvettes with an optical path of 1 cm were used (Starna Scientific). TDMQ20 concentration was determined by UV-Vis titration using CuCl2. Additionally, UV-Vis spectroscopy was used in order to characterise TDMQ20 deprotonation in phosphate buffer solutions. Samples containing TDMQ20 were titrated with NaOH in the pH range 3-8 by manual additions of the concentrated base solution.