Influence of the substitution pattern of four naphthalenedicarboxylic acids on the structures and properties of group 13 metal-organic frameworks and coordination polymers

Metal-organic frameworks containing Ga 3+ ions and four differently substituted naphthalenedicarboxylates ( ndc 2− ) have been synthesized and characterized. The Ga 3+ ions are six-fold coordinated by oxygen atoms in all title compounds, but two different inorganic building units, i.e. trans corner-sharing and cis,trans edge-sharing octahedra are observed. Crystal structures were validated by Rietveld refinements against powder X-ray diffraction data. [Ga(OH)( 1,4-ndc )]·2H 2 O crystallizes in a non-breathing MIL-53 type structure with two different pore sizes (5.5 × 5.5 Å and 9 × 9 Å). It is non-porous with respect to nitrogen but has a water adsorption capacity of about 155 mg g −1 and a thermal stability of up to 240 °C. The dense compound [Ga(OH)( 1,8-ndc )] crystallizes in a new layered structure motif, which is related to the crystal structure of MIL-122 ([Al(OH)((O 2 C) 4 C 6 H 2 )]). The third and fourth compounds [Ga 2 (OH) 4 ( 2,3-ndc )]·H 2 O and [Ga(OH)( 2,6-ndc )]·H 2 O are isoreticular to CAU-15 ([Al 2 (OH) 4 ( 2,3-bdc )]·H 2 O) and MIL-69 ([Al(OH)( 2,6-ndc )]·H 2 O), respectively. The last two compounds are non-porous toward nitrogen but reversible dehydration was demonstrated. For comparison, the two new compounds [Al(OH)( 1,8-ndc )] and [Al 2 (OH) 4 ( 2,3-ndc )]·H 2 O, which are isostructural to the newly described gallium compounds, were also synthesized and fully characterized. The Al-containing coordination polymers exhibit higher temperature stabilities compared to their isostructural Ga compounds. Systematic investigation on Al- and Ga-MOFs and CPs containing differently substituted naphthalenedicarboxylate ions.