Ammonium hydroxide solution

All solvents and reagents used in this study are chemically pure. 1,4-Diethoxy benzene was purchased from Tokyo Chemical Industry Co. Ltd., polyformaldehyde and ammonium hydroxide solution were purchased from Shanghai Titan Scientific Co. Ltd (China), ethyl bromoacetate, triphenylphosphine, carbon tetrabromide and s-trioxane were purchased from the Saen Chemical Technology (Shanghai) Co. Ltd, boron tribromide and boron trifluoride diethyl etherate were purchased from Shanghai Macklin Biochemical Co. Ltd. Guests G1 and G2 were purchased from Aladdin Chemical Reagent Co. Ltd (Shanghai, China) and Bide Pharmatech Ltd (Shanghai). All solvents were purchased from Shanghai Titan Scientific Co. Ltd (China) and used directly without further purification. Hosts H1 and H2 were synthesized according to the reported procedures.^{33,34 (link)}