Simple and efficient size-controllable engineering of zeolitic imidazolate framework (ZIF-8) and M-ZIF-8 by changing addition order

As one of most studied MOFs, extensive efforts have been devoted on the novel strategy for tailoring the size of zeolitic imidazolate framework (ZIF-8). We report here a facile and general method that enables the size-controllable engineering of zeolitic imidazolate framework (ZIF-8) by changing the addition order of Zn(NO3)2·6H2O (A) and 2-methylimidazole (B), which is very different from the all reported methods. Significant size difference for ZIF-8 s was observed between adding A-methanol solution to B-methanol solution and adding B-methanol solution to A-methanol solution under room temperature magnetic stirring. The influence of addition order on the crystal size was also applicable for preparing ZIF-8 encapsulating metal precursor (M-ZIF-8). We believe that this work not only pave a new way for efficient and general size-controllable design of ZIF-8 and M-ZIF-8, but can be also bridged with other size engineering methods (such as solvothermal method).