Conjugated G0 metallo-dendrimers, functionalized with tridentate ‘pincer’-type ligands

Abstract

During the last decade there has been increasing interest in the development of new dendritic materials, 1 including organometallic dendrimers 2 and dendrimers containing conjugated π-systems. 3 These materials have a wide variety of applications, such as homogeneous catalysts, 2j-m organometallic sensors 2n or materials possessing electronic and optical properties. 2q,r In our research to construct nano-sized multimetallic materials based on tridentate 'pincer' type ligands, we are interested in rigid nano-size materials based on a hydrocarbon skeleton because they are potential homogeneous catalysts (the so-called cartwheel catalysts) which are expected to be suitable for separation from the reaction mixture by nanomembrane filtration. 4 The syntheses of new conjugated dendritic materials containing PCP-type ligands (Fig. 1) are reported here. These ligand systems are suitable for incorporation of transition-metals, giving rigid highly conjugated organometallic compounds.Compounds 1 and 2 were synthesized from 1,3,5-tribromobenzene and hexabromobenzene, respectively. The aryl bromides were converted into phosphine oxides 4 and 5 via 3-and 6-fold Sonogashira coupling reactions with 3,5-bis[(diphenylphosphinoxide)methyl]phenylacetylene (3) (Scheme 1). 5 The cross-coupling reactions were performed in THF at reflux for 100 (for 4) and 300 h (for 5) affording, after purification, 4 6 and 5 7 in 66 and 25% yield, respectively. Unfortunately, we also observed the formation * Corresponding authors.

Ring closing metathesis employing organometallic substrates and the templated synthesis of macrocycles

“…Dendritic supports offer many advantages in this area but, due to their flexible nature, are not retained by nanofiltration membranes to the same extent as rigid molecules of similar (or lesser) molecular weight. In part to address this, a number of rigid, shape persistent pincer containing "cartwheel" type complexes [57][58][59][60] were synthesized in which the pincer groups surround an arene core, Fig. 5.…”

Structure and in vitro antifungal activity of [2,6‐bis(dimethylaminomethyl)phenyl]diphenyltin(IV) compounds

“…The organometallic derivatives of the ligand C 6 H 3 -2,6-(CH 2 NMe 2 ) 2 Ð have interesting structures 1 and very good catalytic properties (Ni, 2 Pd, 3 and Pt 4 ). These types of compound are also well known for their coordination ability, due to one or two nitrogen donor centres.…”

Sensitive analysis of anti‐HIV drugs, efavirenz, lopinavir and ritonavir, in human hair by liquid chromatography coupled with tandem mass spectrometry

“…A single‐crystal structure determination of the hexapalladated complex revealed a diameter of 2.1 nm and a torsion angle of approximately 22° between the pincer aryl rings and the core benzene ring, which resulted in a cartwheel‐type structure. Modification of the dendritic dimension was demonstrated by the introduction of rigid acetylene spacers, which did not affect the macromolecular shape‐persistence 145. Thus far, however, the low solubility of these hexametallic systems have hampered their application as homogeneous catalysts considerably.…”