Dendrimers Functionalized with Palladium Complexes of N-, N,N-, and N,N,N-Ligands

Abstract

Pyridine, pyridine imine, and bipyridine imine ligands functionalized by a phenol have been synthesized and characterized, in many cases by X-ray diffraction. Several of these N-, N,N-, and N,N,N,-ligands have been grafted onto the surface of phosphorhydrazone dendrimers, from generation 1 to generation 3. The complexation ability of these monomers and dendrimers towards palladium(II) has been assayed. The corresponding complexes have been either isolated or prepared in situ. In both cases, the monomeric and dendritic complexes have been tested as catalysts in Heck couplings and in Sonogashira couplings. In some cases, a positive dendritic effect has been observed, that is, an increase of the catalytic efficiency proportional to the dendrimer generation.

“Click” Chemistry for the Functionalization of Graphene Oxide with Phosphorus Dendrons: Synthesis, Characterization and Preliminary Biological Properties

“…The last step of the synthesis of the dendrons was the decoration of their surface with diverse phenol‐pyridine derivatives. These compounds were synthesized as previously described by condensation reactions of tyramine with 2‐pyridine carboxaldehyde or di(2‐pyridyl) ketone, affording compounds 5 a and 5 b , respectively [37] . Compound 5 c was obtained by condensation reaction of 4‐hydroxybenzaldehyde with 2‐hydrazinopyridine [22a] .…”

“…These compounds were synthesized as previously described by condensation reactions of tyramine with 2-pyridine carboxaldehyde or di(2-pyridyl) ketone, affording compounds 5 a and 5 b, respectively. [37] Compound 5 c was obtained by condensation reaction of 4-hydroxybenzaldehyde with 2hydrazinopyridine. [22a] Compounds 5 a-c were then reacted in basic conditions with the first generation dendrons 2-G 1 and 3-G 1 , to afford dendrons 2 a-c-G 1 and 3 a-c-G 1 isolated with a yield range of 62-91 % (Scheme 3).…”