Fig. 3. Nanoscale MOF sizes depend on the equivalents and pKa values of added modulator reagents. (A) MIL-101(Cr) nanocrystal sizes decrease with increasing modulator pKa values. Sizes were determined by TEM.98 (B) As modulator equivalents increases, sizes of UiO-66 particles increase. (TFA: trifluoroacetic acid, DCA: dichloroacetic acid, FA: formic acid, and AA: acetic acid). Shaded boxes are provided to emphasize sizes below 200 nm. Sizes were determined with STEM and DLS (DLS not shown).72 (C) MIL-101-Cr nanocrystal sizes decrease with increased modulator equivalents, while MIL-88B-NH2-Fe exhibits the opposite trend. Interestingly, MIL-88B microcrystals are formed as an impurity at and above 5 benzoic acid equivalents (orange). Sizes were determined with SEM (orange and pink) and TEM (blue).48,49,94 .
