Redox Properties of some Dipyridyl Quaternary Salts

Reactivity of paraquat with sodium salicylate: Formation of stable complexes

“…Based on our results, NaSAL may possess a similar behaviour to that of polyphenols leading to the formation of CT complexes between the electron-poor pyridinium rings of PQ and the more electron-rich aromatic rings of NaSAL. The herbicidal efficacy of PQ is related to the concentration of free PQ 2+ in solution inside the chloroplast and on the nature of the anion and any complexing agent with which it is applied (Homer and Tomlinson, 1959). Similarly to the plant kingdom, the same rational could be applied for the lungs in order to explain the full survival.…”

Resolution of the First Nonracemic Diquats

“…Keywords: chirality · configuration determination · diquats · racemization barriers · resolution served (de < 36 %, 1 H NMR, [D 6 ]acetone (8 %) in CDCl 3 , 298 K). [12] Nevertheless, as mentioned, nonracemic diquats had never been reported and it was thus debatable whether simple analogues with large enough enantiomerization barriers could be synthesized and subsequently resolved into single enantiomers; the resulting nonracemic dicationic moieties being possible precursors to novel chiral ionic liquids or phase-transfer catalysts.…”

“…Diquats are able to accept one electron and form relatively stable radical cations (with a reversible first reduction wave of low potential). [1,2] The resulting unpaired-electron species are known to interfere with photosynthesis and, as such, diquats may display herbicidal activity. [3] Diquats may also be used as structural templates for efficient supramolecular synthesis, [4] as electron acceptors in light-harvesting chromophore-quencher systems, [5] for the construction of ion-pair charge-transfer complexes, [6] and in nonlinear optics.…”

Diquats with Robust Chirality: Facile Resolution, Synthesis of Chiral Dyes, and Application as Selectors in Chiral Analysis

“…[7] Next, we addressed resolution of the chiral dication 3 via its diastereomeric dibenzoyltartrate salts [P-3] [R,R-DBT] 2 The presenceo ft wo active methyl groups in system 1 calls for derivatization by meanso fm ethods established for pyridinium type systems. At the outseto ft he experimental investigation, we established ap ractical route to non-racemic samples of diquat 3.…”

“…[1] Electrond eficient systemsb ased on diquat and paraquat [2] have been also instrumental as buildingb locks for supramolecular chemistry, [3] as well as in the design of electron-transfer systems. [1] Electrond eficient systemsb ased on diquat and paraquat [2] have been also instrumental as buildingb locks for supramolecular chemistry, [3] as well as in the design of electron-transfer systems.…”