Three new europium(III) methanetriacetate metal-organic frameworks: the influence of synthesis on the product topology

Abstract

Three new metal-organic framework structures containing EuIIIand the little explored methanetriacetate (C7H7O63−, mta3−) ligand have been synthesized. Gel synthesis yields a two-dimensional framework with the formula [Eu(mta)(H2O)3]n·2nH2O, (I), while two polymorphs of the three-dimensional framework material [Eu(mta)(H2O)]n·nH2O, (II) and (III), are obtained through hydrothermal synthesis at either 423 or 443 K. Compounds (I) and (II) are isomorphous with previously reported GdIIIcompounds, but compound (III) constitutes a new phase. Compound (I) can be described in terms of dinuclear [Eu2(H2O)4]6+units bonded through mta3−ligands to form a two-dimensional framework with topology corresponding to a (6,3)-connected binodal (43)(466683)-kgdnet, where the dinuclear [Eu2(H2O)4]6+units are considered as a single node. Compounds (II) and (III) have distinct three-dimensional topologies, namely a (41263)(4966)-nianet for (II) and a (41065)(41164)-K2O2; 36641net for (III). The crystal density of (III) is greater than that of (II), consistent with the increase of temperature, and thereby autogeneous pressure, in the hydrothermal synthesis.