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

Quentin Vanbellingen,Anaïs Coinaud,Paul Servin,Anne-Marie Caminade,Régis Laurent,Sonia Mallet-Ladeira

doi:10.3390/molecules26082333

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.

Highlights

Dendrimers are hyperbranched nanomolecules, called molecular trees, which pertain to the “nanoworld” by virtue of their size, but which differ fundamentally from “hard” nanoparticles constituted of metals
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

Summary

Introduction

Dendrimers are hyperbranched nanomolecules, called molecular trees, which pertain to the “nanoworld” by virtue of their size, but which differ fundamentally from “hard” nanoparticles constituted of metals. Phosphorhydrazone dendrimers have outstanding properties in many different fields, related to catalysis, nanomaterials, and biology/nanomedicine [8] They have been used successfully as soluble supports of catalytic entities, allowing for instance the use of less expensive metals such as copper [9]. We report the synthesis and characterization (often by X-ray crystal structure diffraction) of ligands incorporating one, two, or three nitrogen atoms in their. Otohthere2rp2-p2-phpy-hepyrneiryndoirdolii-nildan-eaimecnmcaieanricrnbebaeorodxbdxeaoaerllxriddviaevealhahdtityyveidvdheeeesys,aad,snnseududcachdndhiadi((a2s2s-d4-pp4-iy(a-y2ramri-mdipdiyniyynlor)lokp)ipdkehheyteotelnon)nkoneoelelhttoahovnaaevaefffebfohoebraerdedvneecancolobsmamoelpsepconooounucanodnlsndedond44sec,e,noadasnnewdddie4t4wnh--hsietyhd- wit dhrooytxdhyreobrxepynhbzehennyzodhlr-yaadzmirdaizenietdoedaetforfiovarafdftoicvrodemsc,posomuucpnhoduasns5d4sa-na5mda6inn.doTph6h.eseeTnhroeelastecotiraoefnafcsotraiodrnecssohamorewposnhuionwdSnc4h,ineamnde 4-hy 2.Sdcrhoexmyeb2e.nzhydrazide to afford compounds 5 and 6 DgEo:xo7pd3e%rriemwsueinltthtssocwobmtearipenoaeuldsnowdcia3thrr(etihendetr3oyuf6at)mwaiinltyhd, experiments were carried out using a lower quantity of catalysts (0.1 instead of 1 mol%) In these conditions, the conversion was still good: 73% with compound 3 (entry 6) and. Both 3 and 3-G1 afforded diphenylacetylene in 37% conversion (entries 8 and 9)

Discussion

Materials and Methods

Findings

Conclusions