En-Type Ligands as Dimensional Reduction Agents in Coordination Polymers containing Dicarboxylic Acids.

Dimensional reduction, as published by Tulsky and Long in 2001, is “a practical Formalism for Manipulating Solid Structures”.^[1] The introduction of a dimensional reduction agent can reduce the dimensionality of a metal anion framework by several degrees, from a 3D parent compound all the way to a discrete child compound. In our research^[2] we extended the scope of this formalism to metal organic coordination polymers and found similar results.

The use of different types of en-type blocking ligands such as tetramethylethylenediamine (TMEDA), 2,2’-bipyridine (BIPY), 2-(aminomethyl)pyridine (AMPY) and ethylenediamine (EDA) can lead to reduction of the dimensionality of coordination polymers by a degree of one. This effect was observed both for one-dimensional chain polymers, that were reduced to discreet molecular compounds, and for two-dimensional layer structures, that were reduced to one dimensional strands. A reduction by more than one degree of dimensionality could not be observed yet. So far, this dimensional reduction was successfully conducted with Cu(II)aspartate, all stereoisomers of copper(II)tartrate and the copper(II) complex of the tartaric acid derivative dibenzoyl-tartaric acid. The addition of the blocking ligands usually leads to an increase in solubility of the polymer compound, allowing all reactions and crystallisations presented here to be performed in aqueous solutions at room temperature.

[1] E. G. Tulsky and J. R. Long, Chem. Mater. 2001, 13, 1149-1166

[2] M. Kremer, J. v. Leusen and U. Englert, Crystals 2020, 10, 485