Disruption of “Coordination Polymer” Architecture in Cu²⁺ Bis-Phosphonates and Carboxyphosphonates by Use of 2,2′-Bipyridine as Auxiliary Ligand: Structural Variability and Topological Analysis

Abstract

The outcome of a synthesis involving a metal ion and a (poly)phosphonic acid depends on a plethora of variables such as solution pH, reactant molar ratios, nature of the metal ion, number of phosphonate groups, and other “functional” moieties present on the ligand backbone. Products are usually coordination polymers of diverse dimensionality. Here we report that the use of a chelating auxiliary ligand (2,2′-bpy) can “disrupt” the polymeric architecture of the copper phosphonate, causing the isolation of a series of molecular complexes (mononuclear or binuclear) that incorporate both the phosphonate and the 2,2′-bpy ligands. Synthetic details, crystal structures, and intermolecular interactions (π–π stacking and hydrogen bonding) are discussed. The structures of the obtained Cu complexes are extended into 2D or 3D networks via multiple hydrogen bonds involving the molecular units and crystallization water molecules. These H-bonded networks have been classified from the topological viewpoint, revealing diverse topologies that also include their undocumented types.

Three-component 1D and 2D metal phosphonates: structural variability, topological analysis and catalytic hydrocarboxylation of alkanes

“…As a short comment, we would like to report that the structure of 1 is rather different from the previously reported [Cu(bpy)(EDPA)(H 2 O)] 2 $3H 2 O derivative. 46 While the EDPA ligand is doubly deprotonated in both cases, only one of its two PO 3 H À groups is coordinated to the copper center in the case of [Cu(bpy)(EDPA)(H 2 O)] 2 $3H 2 O. In fact, this phosphonate group bridges two Cu atoms, leading to a dimeric structure, with two dangling phosphonate groups being hydrogen-bonded to the neighboring molecules.…”

“…[43][44][45] Incorporation of a secondary ligand into the reaction mixture can dramatically inuence the synthesis outcome and the structure of the nal product. Such ligands can either disrupt the "coordination polymer" architecture, by generating mononuclear complexes, 46 or "decorate" or structurally alter the initial "metal phosphonate" structural motif. Such ligands have been called secondary auxiliary ligands (SALs) and they are usually neutral or anionic.…”

“…$3H 2 O 46. In the present case, the discrete dicopper(II) units are assembled into 2D layers, which are then extended into a 3D framework by H-bonding interactions involving water clusters from crystallization H 2 O molecules 46. In contrast, the 3D H-bonded net of[Cu(phen)(EDPA)(H 2 O) 2 ] N (1) is directly assembled via H-bonds between adjacent 1D metal-organic chains.…”

Layered Tb‐Doped Yttrium Carboxyphosphonate Nanocrystals as Efficient Filler for PEDOT:PSS Composite Films

“…Several divalent or trivalent metal phosphonocarboxylate with different structures and dimensionalities, also containing auxiliary ligands, have been recently reported in literature …”

“…[11] Several divalent or trivalent metal phosphonocarboxylate with different structures and dimensionalities, also containinga uxiliary ligands, have been recently reported in literature. [12][13][14][15] Among them, N-(phosphonomethyl)glycine (glyphosate) and its related diphosphonica nalogous (glyphosine) are simple and cheap buildingb locks already used for the synthesis of layered bivalent( Mg, Ca and Ba) [15,16] trivalent (Gd and Eu) [17,18] and tetravalent( Zr) phosphonates used as fillers for polymeric composites, [19] in proton conductivity, [20] as MRI contrast agents [17] and in heterogeneous catalysis. Ac ommon feature of all these compounds is the presence of free carboxylic groups exposed on the layer surfacet hat make them strongly hydrophilic and able to interactw ith polar exfoliating agentsl ike alkylamines.…”