Rational Design of Organically Functionalized Polyoxopalladates and Their Supramolecular Properties

Abstract

The Sr -centered 12-palladate(II) open-cube {SrPd (OAc) } has been systematically evolved by substitution of the three acetate ligands by a library of saturated carboxylic acids with increasing chain lengths leading to four novel polyoxopalladates(II) with the formula [SrPd O (OH) (PhAsO ) (L) ] (SrPd L , L=C H COO, n=2 to 5). These first examples of surfactant-type polyoxopalladates with a hydrophilic metal-oxo unit and three hydrophobic alkyl chains were characterized in the solid state (single-crystal XRD, FTIR, TGA), in solution ( H, C NMR spectroscopy), and in the gas phase (ESI-MS). The two polyanions SrPd L with chain lengths of 5 and 6 are the first examples of polyoxopalladates that are soluble and stable in organic media. The Na salts of the amphiphilic polyoxopalladates SrPd L were shown to self-assemble into "blackberry"-type spherical supramolecular structures in dilute solutions, of which an unusual "volcano"-shaped trend of assembly size versus solvent polarity is chiefly influenced by directional hydrogen bonding interactions.

Beyond Charge Balance: Counter‐Cations in Polyoxometalate Chemistry

“…Since their initial discovery, Blackberry formation is now accepted as a common phenomenon for inorganic POMs and for amphiphilic POMs that are functionalized by hydrophobic organic “tails” . Also noteworthy, the uranyl peroxide polyoxometalates of several distinct geometries and compositions, as well as the noble metal POMs, also assemble into blackberry structures, indicating the universality of the underlying structure formation processes. Beyond the scope of this Review, blackberry structures have also assembled from cationic coordination compound nanocages …”

Polyoxometalates: Tailoring metal oxides in molecular dimension toward energy applications

“…The formation of polyoxopalladates with various sizes including Pd 15 , Pd 22 , Pd 72 , and Pd 84 has been achieved . In addition, the supramolecular properties and self‐assembly of novel polyoxopalladates based on Pd 12 functionalized by organic ligands and Pd 13 have been investigated, and the host‐guest chemistry of Pd 13 ‐based polyoxopalladate is identified to exhibit non‐covalent interactions between the polyoxopalladate and cyclodextrins …”

Jenseits von Ladungsausgleich: Gegenkationen in der Polyoxometallat‐Chemie

“…Aufsätze gen [52,[96][97][98] sowie durch Edelmetall-POMs. [99,100] Dies lässt auf eine generelle Zugänglichkeit von POM-basierten Blackberrys schließen. Jenseits des Schwerpunktes dieses Aufsatzes ist festzuhalaten, dass Blackberrys auch ausgehend von kationischen Koordinationskäfigen aufgebaut wurden.…”