High-yield postsynthetic modification of MOF with organic–metal precursors

The specific yield of postsynthetic modification for modified IRMOF-16 (HCC-1), synthesized using 1,4-di(4-carboxy-2-hydroxyphenyl)benzene as organic ligand and Zn(NO3)2·6H2O as metal source, respectively, has been investigated with the variation of its BET surface area, reaction time and organic–metal precursor. Two kinds of HCC-1 having different values of BET surface area (HCC-1H: 3000 m2/g and HCC-1L: 2000 m2/g) were prepared via solvothermal method for the study of effect of BET surface area, whereas isopropoxytitanatrane and tetrabenzyl titanium were adopted as organic–metal precursors It was observed that even if the specific yields of postsynthetic modification for both organic–metal precursors increased with the value of BET surface area of HCC-1, isopropoxytitanatrane showed relatively higher values than those of tetrabenzyl titanium during the entire range of reaction. These observations led us to conclude that HCC-1H has higher specific number of –OH groups, active sites for postsynthetic modification, and tetrabenzyl titanium experiences more difficulty in diffusing deep into HCC-1 due to its relatively larger molecular size. For the effect of reaction time, while it increased slowly with the reaction time until 48 h and then leveled off for HCC-1H, it increased during the entire range of reaction time for HCC-1L.