To rationalize predicted trends regarding Zn concentration increase (Figure ), it is necessary to consider several aspects. In both cases, an increase in Zn concentration equals a relative decrease in HmIm concentration, thus a decrease in the main ratio. Considering the previous discussions, these trends could be explained in terms of CNT: an increase in Zn concentration would lead to a larger number of nuclei being formed. In water-based synthesis, it has been reported that the relative decrease of HmIm concentration leads to a ZIF-8 phase with a higher -OH surface termination, which increases surface energy and presents a high surface barrier toward crystallization. One of the reasons behind it is the energy associated with water coordination on Zn sites (-153 kJ • mol -1 ) being comparable with the energy of Hmim coordination on free Zn sites (-191 kJ • mol -1 ). In the case of methanol-based synthesis, while the CNT explanation holds (i.e., a large number of nuclei being formed), the solvent properties are significantly different from water. Methanol energy interaction with ZIF-8 is almost 60% lower than Zn -N bond energy, which together with a low viscosity of methanol (about 40% lower than water), allows a higher reactants diffusivity and particle movement, with a lower surface energy barrier for crystallization, thus favoring growth and increasing the particle size. Panel c in Figure shows the predicted trend upon variation of Zn : HmIm molar ratio.