NaDC was dissolved in water to achieve solutions with concentrations between 25 and 200 mM. A pyrene stock solution of 3 mM was prepared in methanol. Required volumes of this stock solution were injected into solutions of OTPh/NaDC or NaDC to prepare solution samples or hydrogels. NaI stock solutions (1M) were prepared by dissolving the solid in water, while nitromethane stock solutions (1 M) were prepared by diluting liquid nitromethane in water. A fresh stock solution of NaI was prepared for each experiment and was kept in the dark.