The effect of the metal-to-ligand ratio on the morphology and crystallographic structure was also investigated for other metal cations (Mn 2+ , Co 2+ , and Ni 2+ ). The crystallization of the Mn-based crystals at Mn(NO3)2-to-AdDB ratios of 0.25:1 and 0.5:1 affords hexagonal prisms, whereas in the ratio range of 1:1 to 4:1, hexagonal bipyramids are obtained. The Co-based MOF crystals show prisms at a Co(NO3)2-to-AdDB ratio of 0.25:1 to 1:1 and spherical morphology at 2:1 and 4:1, without any clear facets (Figure ) and resemble the "brain-like" crystals previously reported for Ni(NO3)2. As seen with the Cu system, with an increase in the metal, the nucleation events are increased and the overall size of the crystals is reduced, while still maintaining the proportions. PXRD measurements show that the Mn, Co, and Ni structures are isostructural to P622 Cu-AdDB (Figure ).