Exploring different metal ions shows that Mn-MAHF-9 A8S and Fe-MAHF-9 A8S are dictated by the ion size, while Cu-MAHF-9 A8S and Zn-MAHF-9 A8S show how ligand field energies dictate framework topology. Ligand binding induces conformational change. The framework Co-MAHF-9 A8Q was found to exhibit reversible color changes between aqueous and nonaqueous or dry environments, suggesting a change of metal geometry in response to water adsorption in the framework. Firstly, single crystals of the Co-MAHF-9 A8Q were transferred from the mother liquor (Table ) to 100% water, and although the crystals remained a light pink color, typical of an octahedral geometry, analysis of SC-XRD data reveals a novel structure (Co-MAHF-9 A8Q-hydrated) where Co(II) has taken on a third water molecule along with other changes to the ligand set (Figure ). From the mother liquor, the Co-MAHF-9 A8Q framework has Co(II) centers with a 2His-2Glu-2H2O primary sphere that diverges into two unique Co(II) sites in Co-MAHF-9 A8Q-hy- drated. The unique sites consist of one with a 2His-3H2O ligand set and another with a 2His-1Glu-3H2O. Note, in the first site, a Glu4 ligand has dissociated. The coordination changes are coupled with significant helix shifting.