Porous Salts as Platforms for Heterogeneous Catalysis

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2023-07, Vol.19 (30), p.e2207507-n/a
• Main Authors: Korman, Kyle J., Dworzak, Michael R., Yap, Glenn P. A., Bloch, Eric D.
• Format: Article
• Language: English
• Subjects: Adducts; catalysis; Chlorides; Chromium; heterogeneous; Hydrogen atoms; Inductively coupled plasma; Inductively coupled plasma mass spectrometry; Magnesium; Mass spectrometry; metal‐organic polyhedra (MOPs); metal–organic frameworks (MOFs); Metathesis; Nanotechnology; Photoelectrons; porous; Single crystals
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202207507

The preparation of a new class of reactive porous solids, prepared via straightforward salt metathesis reactions, is described here. Reaction of the dimethylammonium salt of a magnesium‐based porous coordination cage with the chloride salt of [CrIICl(Me4cyclam)]+ affords a porous solid with concomitant removal of dimethylammonium chloride. The salt consists of the ions combined in the expected ratio based on their charge as confirmed by UV–vis and X‐ray photoelectron spectroscopies, ion chromatography (IC), and inductively coupled plasma mass spectrometry (ICP‐MS). The porous salt boasts a Brunauer‐Emmett‐Teller (BET) surface area of 213 m2 g−1. Single crystal X‐ray diffraction reveals the chromium(II) cations in the structure reside in the interstitial space between porous cages. Importantly, the chromium(II) centers, previously shown to react with O2 to afford reactive chromium(III)‐superoxide adducts, are still accessible in the solid state as confirmed by UV–vis spectroscopy. The site‐isolated reactive centers have competence toward hydrogen atom ion chemistry and display significantly increased stability and reactivity as compared to dissolved ions. Straightforward salt metathesis reaction between the dimethyl ammonium salt of a porous cage and chloride salt of a reactive transition metal complex affords a new class of reactive material: reactive porous salts. The resultant solid not only displays increased stability as compared to the homogeneous system, it has increased reactivity as a result of the site‐isolated nature of the catalyst.