Three isostructural covalentorganicframeworks (COFs) with either methoxyl, or hydroxyl or bearing both groups on the channel wall, are synthesized and served as metal-free hetergeneous catalysts for chemical fixation of CO2 . Among them, the COF decorating with both hydroxyl and methoxyl groups named OMe-OH-TPBP-COF exhibits the highest catalytic activity and efficiency for CO2 cycloaddition under
Effect of aryl substituents on intramolecular cyclizations of 3,3',5,5'-tetraaryl-2,2'-biphenoquinones (Ar = phenyl (1a) and 4-methoxyphenyl (1b)) has been studied. In benzene, 1a gave 2,4,6,8-tetraphenyldibenzofuran-1-ol (10) gradually as a main product, indicating the phenyl substituents preferred to stabilize the intermediate by delocalization of the negative charge rather than that of the positive one. In contrast, the reaction of 1b occurred spontaneously in order to give a complex mixture, which should be due to 4-methoxyphenyl substituent at the 3 position.