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 InIII-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.