Encapsulation of various guests by an anionic in-metal-organic framework containing tritopic BTB ligand: Crystal structure of reichardt's dye captured in an in-metal-organic framework

The reaction between 1,3,5-benzenetribenzoic acid (H₃BTB) and In(NO₃)₃ hydrate in diethylformamide yielded a new In^III-metal-organic framework, [(CH₃CH₂)₂NH₂]₃[In₃(BTB)₄]·10DEF·14H₂O (I). The countercation and solvent-free doubly interpenetrated I potentially contains 71.0% of solvent accessible void. Although the framework of I was not stable enough to maintain its original structure when the solvent molecules were removed, the as-prepared I was found to be a very good sorbent for acridine orange hydrochloride, a large Reichardt's dye, and hydrophobic iodine molecule in solution. The as-prepared I exhibited increased uptake amount in the order of Reichardt's dye > acridine orange hydrochloride > iodine. The largest uptake of the bulky Reichardt's dye by I could be attributed to the optimized structural fitting of Reichardt's dye into the large three-dimensional void space of I. The structure of Reichardt's dye-encapsulated I-RD was unambiguously revealed by X-ray crystallography for the first time.