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

Abstract

Three new metal-organic framework structures containing Eu(III) and the little explored methanetriacetate (C7H7O6(3-), mta(3-)) 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 Gd(III) compounds, but compound (III) constitutes a new phase. Compound (I) can be described in terms of dinuclear [Eu2(H2O)4](6+) units bonded through mta(3-) ligands to form a two-dimensional framework with topology corresponding to a (6,3)-connected binodal (4(3))(4(6)6(6)8(3))-kgd net, 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 (4(12)6(3))(4(9)6(6))-nia net for (II) and a (4(10)6(5))(4(11)6(4))-K2O2; 36641 net 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.

MOF the beaten track: unusual structures and uncommon applications of metal–organic frameworks

“…One of the main advantages of this type of synthesis is the pore size of these aerogel products exceeds that of MOFs, allowing them to interact with larger molecules leading to many new applications. These synthesis methods also inspired work by Ruiz-Pérez and co-workers to investigate the polymorphic control of Eu(III) frameworks through gel and hydrothermal methods [ 21 ]. Microwave-assisted synthesis of frameworks is also of increasing prevalence.…”

“…Interest in framework materials which lie outside the boundaries of traditional crystalline materials obtained from solvothermal methods has surged, and, similarly to the synthesis of MOFs in the gel-state described earlier in this review [ 19 – 21 ], examples of framework melting into a glass state are increasingly being reported. Bennett et al explored the effect of melting a framework on the extended framework structure of a series of zeolitic imidazolate frameworks [ 46 ].…”

Temperature-Dependent Supramolecular Isomerism of Lutetium-Aminoterephthalate Metal–Organic Frameworks: Synthesis, Crystallography, and Physical Properties

“…In particular, the use of temperature enables researchers to take advantage of entropic differences between alternative products . As illustrated by several studies, − different polymorphic phases of MOFs can be obtained from a single reaction mixture held at different temperatures. Among them, the experimental and theoretical studies carried out on a series of polymorphic La-based MOFs reveal that the kinetic metastable and thermodynamic phases could be isolated as pure products over certain temperature ranges .…”