Yaghi and co-workers used aniline as a modulator for reversible binding with the building block. This reversibility enhances the error-correction process for the growth of defect-free single crystals having a covalent-organic framework. Fischer et al have used benzoic acid derivatives to control the dimensions of MOFs. A larger access to a derivative of benzoic acid competes with the organic linker for coordination to the metal cluster, [Zn4O] 6+ , resulting in decreased crystal size.