Molecular Motion and Ligand Stacking Influence Thermal Expansion Behavior and Argentophilic Forces in Silver Coordination Complexes

Abstract

We designed a series of metal–organic solids using ligands with similar molecular structures that were expected to afford coordination complexes with similar solid-state structures. The metal component is silver­(I) p-toluenesulfonate, and the ligands differ in their ability to undergo dynamic molecular motion. Although the ligands are similar in their molecular structure, the metal complexes exhibit different solid-state structures because of differences in π-stacking arrangements and the presence or lack of Ag···Ag interactions. The coordination units (ligand-Ag-ligand) in each complex respond differently to temperature changes, which results in thermal expansion behaviors ranging from negative to zero to positive within the series. Two unique complexes were obtained with the azo-containing ligand, and preparation of each complex in bulk was controlled by synthetic conditions. Two polymorphs were obtained with the olefin-containing ligand, and both complexes undergo dynamic molecular motion, although the supramolecular structures differed dramatically. Overall, we show that simple modifications to the ligand structure can significantly affect solid-state structure, crystal form, and subsequent thermal expansion behavior.

Combining Molecular Motion with a 2,6-Diiodo BODIPY to Engineer Highly Anisotropic Thermomechanical Properties in Organic Binary and Ternary Molecular Materials

“…Previous studies have reported molecules containing groups that undergo molecular pedal motion , can disrupt the interactions along the π stack and lead to changes in the thermomechanical properties. − In an effort to exploit this, the current study was extended to include the ditopic HaB acceptors with topologies similar to those of BPA: BPE, Azo, and Cl-Azo (Figure ). The cocrystals of these three bipyridines with 1 yield structures that are analogous to 1 ·BPA.…”

Polymorphism and π Stacking Affect Thermal Expansion Behavior in Halogen-Bonded Cocrystals Based on 1,4-Diiodoperchlorobenzene

“…21 Recently, we reported the roles of molecular pedal motion and ligand stacking on the TE parameters for a series of related silver(I) coordination complexes. 22 In these discrete-based assemblies, ligands πstacked in an edge-to-face or face-to-face geometry and polymorphic behavior was also observed. We determined that the combination of pedal motion and edge-to-face stacking of the aromatic rings resulted in the largest TE within these silver-based solids.…”

“…Specifically, we have reported that motion-capable functional groups such as the azo (NN) or ethylene (CC) will yield larger TE tensors along the direction in the solid where this motion happens if the group undergoes solid-state pedal motion. , Moreover, the tensors are larger in solids that undergo motion when compared to those containing a rigid group, such as acetylene (CC), which is not capable of pedal motion . Recently, we reported the roles of molecular pedal motion and ligand stacking on the TE parameters for a series of related silver­(I) coordination complexes . In these discrete-based assemblies, ligands π-stacked in an edge-to-face or face-to-face geometry and polymorphic behavior was also observed.…”

Synthesis, X-ray structures, and magnetic properties of seven polynuclear Cu(ii) complexes containing pyrazole-3,5-dicarboxylate with various ancillary ligands

“…The structural self-assembly is governed by many factors such as metal ions, ligands, reaction temperature, counterions, solvents, and pH of the reaction. [7][8][9][10][11][12] The parameters that are most important for the magnetic property are the bridging ligand and the paramagnetic metal center. Changes in the type of metal center and bridging ligand result in the creation of materials with varying magnetic properties.…”