文摘
Calix[4]resorcinarenes were prepared by the condensation of resorcinol and aldehydes (acetaldehyde, benzaldehyde, and 4-isopropylbenzaldehyde), and two isomers, C4v (ccc) and C2v (ctt), were separated by fractional crystallization. The products were characterized by NMR and FTIR, and their dissolution rate in aqueous base was measured. The eight hydroxyl groups of the calix[4]resorcinarenes were protected with acid labile t-butoxycarbonyl and t-butoxycarbonylmethyl. The protected calixarenes were thoroughly characterized by differential scanning calorimetry, FTIR, and variable-temperature 1H and 13C NMR. Their interaction with 4-isopropylphenol through hydrogen bonding was investigated by 13C NMR and correlated with their inhibition effect of dissolution of poly(4-hydroxystyrene-co-t-butyl acrylate) in an aqueous base, as studied by quartz crystal microbalance. Finally, the protected calixarenes were employed as a dissolution inhibitor of polyhydroxystyrene-based deep UV and electron beam chemical amplification resists to improve their contrast and performance.
