These computational studies confirm that macrocycle 1 is well preorganized for H2P2O7 2-binding, with all NH groups pointing into the cavity even in absence of a guest. However, its rigidity hinders it from forming four Hbonds to the small Cl -anion. Macrocycle 2 is less preorganized than 1, with only two NH groups pointing into the cavity in its lowest energy conformer, but it can adapt its conformation to bind H2P2O7 2-or Cl -with all NH groups. Macrocycle 3 is least preorganized for anion binding with intramolecular H-bonds closing the cavity in absence of a guest, but it has a good adaptability to anionic guests of different sizes. Note that only NH protons are shown in Figure but that CH protons pointing into the cavity could also contribute to anion binding. Synthesis. Macrocycle 1 was synthesized by the condensation of diacylchloride 8 36 with 3,6-diamino-9,10-dihexoxyphenanthrene 7 (Scheme 1). Diamino-phenanthrenes with this substitution pattern have not been reported to date but could be useful building blocks in organic synthesis for various applications. While 3,6-diamino-9,10-dihexoxyphenanthrene 7 could not be obtained in pure form as the free base due to its propensity to decompose, a synthesis route to obtain the HCl salt of 7 in three steps from commercially available 3,6-dibromophenanthrene-9,10-dione 4 was developed. This route starts by reductive etherification of 4 to get 3,6-dibromo-9,10-dihexoxyphenanthrene 5, followed by a Buchwald-Hartwig cross coupling with benzophenone imine 6 and subsequent acid hydrolysis of the formed bisimine. The reaction between the HCl salt of phenanthrenediamine 7•2(HCl) and diacylchloride 8 in the presence of DIPEA as base affords the desired macrocycle in around 10% yield. However, addition of 45 equivalents of tetrabutylammonium chloride (TBACl) improved the yield significantly and facilitated purification by column chromatography due to the better solubility of 1 in the presence of TBACl. Additional optimization steps such as slow addition of reagents and performing the reaction in the dark and under an argon atmosphere to try and prevent decomposition of the free base of 7•2(HCl) ultimately improved the yield to 27%.